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Amplifier Circuits:  Operational
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Last Updated: November 21, 2017 05:44 AM

 
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±120V Output Precision Op Amp -  Simple shunt regulators provide normal supply levels to the op amp and the external open-loop gain and buffer structure extends the output swing to nearly the high-voltage rails.  Output transistors are protected by current-limiting. __ Linear Technology/Analog Devices App Note, Jun 21, 2011

0A to 2A Current Source -  The LT1995 amplifies the sense resistor drop by 5V/V and subtracts that from VIN, providing an error signal to an LT1880 integrator.  The integrated error drives the PMOSFET as required to deliver the commanded current. __ Linear Technology/Analog Devices App Note, Mar 31, 2010

1 Op Amp achieves double-hysteresis-transfer characteristic -  09/27/07  EDN-Design Ideas An op amp combines with strategically placed zener diodes to yield a process-control circuit that has positive- and negative-going hysteresis bands __ Circuit Design by Herminio Martínez, Encarna García, and Juan Gámiz, Technical University of Catalonia, Barcelona, Spain

1.5A Rail-to-Rail Output Synchronous Step-Down Regulator Adjusts with a Single Resistor -  02/03/14EDN-Design Notes   One wire brings power & data to LCD moduleA new regulator architecture, the LTC3600   (first introduced with the LT3080 linear regulator), has wider output range and better regulation than traditional regulators.  Using a precision 50μA current source and a voltage follower, the output is adjustable from 0V to close to VIN.  Normally, the lowest output voltage is limited to the reference voltage __ Circuit Design by Jeff Zhang, also see Linear Technology Design Note 506

1µA Op Amp Permits Precision Portablery -  DN163 Design Notes __ Linear Technology/Analog Devices

100dB Range Logarithmic Photodiode Amplifier -  The photodiode current is processed by a form of trans-impedance amplifier   (TIA) that has a logarithmic I to V characteristic.  The Vbe of the logging transistor is scaled and offset to properly represent the desired dynamic range.  To prevent temperature variation from affecting the accuracy, another loop is used as a stabilized chip heater for the transistor array. __ Linear Technology/Analog Devices App Note, Jun 21, 2011

100MHz Op Amp Features Low Noise Rail-To-Rail Performance While Consuming Only 2.5ma -  DN308 Design Notes __ Linear Technology/Analog Devices

1Hz to 100MHz Voltage to Frequency Converter Has 160dB Dynamic Range, Runs from 5V Supply -  This circuit achieves a wider dynamic range and higher output frequency than any commercially available voltage to frequency   (V→F) converter.  Its 100MHz full scale output   (10% over range to 110MHz is provided) is at least ten times faster than available units.  The circuit’s 160dB dynamic range   (8 decades) allows continuous __ Linear Technology/Analog Devices App Note, Mar 25th 2010

1-NiCd Cells Drives Op Amp -  12/05/96 EDN-Design Ideas Low-supply-voltage op amps, such as the LMC6582 and LMC6681 families, feature rail-to-rail I/O with a gain-bandwidth product greater than 1 MHz operating from just 1.8V.  Although impressive, this voltage is not low enough to power these amps using a single alkaline or NiCd/NiMH
cell, which have typical voltages of 1.25 to 1.5V.  It is rather tempting to bridge this gap by designing a DC/DC converter __ Circuit Design by Alexander Belousov, Rego Park, NY

2 Op Amps Provide Averaged Absolute Value -  30-Oct-03 EDN-Design Ideas The circuit in Figure 1 is useful when you need amplitude demodulation or an averaged absolute-value conversion.  The circuit comprises two stages, the first of which, IC1A, is a differential-output absolute-value converter.  The second stage, IC1B, is a traditional differential amplifier.  The combination of the two stages performs single-ended absolute-value conversion but only if R3>>R2 __ Circuit Design by Dobromir Dobrev, Jet Electronics, Sofia, Bulgaria

2 OpAmps Make Fast Full Wave Rectifier -  03/14/96 EDN-Design Ideas The circuit in Figure 1 is a precision full-wave rectifier with the following characteristics. __ Circuit Design by Fernando Werlang, CPqD-Telebras, Campinas, Brazil

2-Op Amps Provide Averaged Absolute Value -  10/30/03  EDN-Design Ideas The circuit in Figure 1 is useful when you need amplitude demodulation or an averaged absolute-value conversion.  The circuit comprises two stages, the first of which, IC1A, is a differential-output absolute-value converter.  The sec __ Circuit Design by Dobromir Dobrev, Jet Electronics, Sofia, Bulgaria

30-Khz Bandwidth High Linearity Opto-Isolated Amplifier -  This App Note presents isolation amplifier circuit designs useful in industrial, instrumentation, medical, and communication systems.  It covers the IL300’s coupling specifications, and circuit topologies for photovoltaic and photoconductive amplifier design. __ Designed by Vishay Semiconductors, Application Note 50

3-op-amp state-variable filter perfects the notch -  EDN-Design Ideas 12/15/2014     There are many variants of the state-variable filter, but this one might just have the best notch output  (s).   The usual schematic of a state-variable filter with two inverting integrators is well known.
Curiously, the input signal is almost always connected to the minus input of U1.  Figure 1 is an example with ω0 = 1kHz and Q = 5.   Figure 1  Typical state-variable filter The circuit is known for its versatility, and ability to simultaneously provide low-pass, band-pass, and high-pass outputs.   Gain, center frequency, and Q may be adjusted separately. __ Circuit Design by Alain Temps

3V & 5V 12-Bit Rail-To-Rail Micropower DACs Combine Flexibility & Performance -  DN127 Design Notes __ Linear Technology/Analog Devices

3V Operation of Linear Technology Op Amps -  DN56 Design Notes __ Linear Technology/Analog Devices

40nVpp Noise, 0.05uV/C Drift, Chopped FET Amplifier -  For very high precision low frequency applications, chopping the dc input signal to create an ac signal and then synchronously demodulating the signal to restore the dc value eliminates all static dc errors of the components used.  This is a high gain   (Av=1001) example with excellent low offset voltage and drift with temperature __ Linear Technology/Analog Devices App Note, Mar 16th 2010

–48V Low Side Precision Current Sense -  This amplifier configuration is essentially the complementary implementation to the classic high-side configuration.  The op amp used must support common-mode operation at its lower rail.  A floating shunt-regulated local supply is provided by the Zener diode, and the transistor provides metered current to an output load __ Linear Technology/Analog Devices App Note, Mar 31st 2010

50MHz Thermistor RMS to DC Converter using 5V Supply -  The LT1014 is the first precision quad operational amplifier which directly upgrades designs in the industry standard 14-pin DIP LM324/LM348/OP-11/4156 pin configuration.  It is no longer necessary to compromise specifications, while saving board space and cost, as compared to single operational amplifiers. __ Linear Technology/Analog Devices App Note, Mar 30th 2010

5-Band Graphic Equaliser -  This equaliser uses low-cost op-amps.  Good-quality op-amps powered by a single voltage supply are readily available in the market.  The op-amp should have a noise density of less than 24nV/ VHz, __ Electronics Projects for You

5-Band Graphic Equalizer -  This complete high quality, low noise 5-BAND GRAPHIC EQUALIZER circuit is based around Monolithic Linear integrated circuit LA3600 manufactured by SANYO.  This circuit is very easy to build and has good Quality.  You can use it with Portable component stereos, tape-recorders, radio-cassette recorders, car stereos etc.  It is On-chip one operational amplifier. __ Designed by YMYA electronics-IZHAR FAREED

5V Powered, Linearized Platinum RTD 0°C to 400°C ±0.05°C Signal Conditioner -  The LT1014 is the first precision quad operational amplifier which directly upgrades designs in the industry standard 14-pin DIP LM324/LM348/OP-11/4156 pin configuration.  It is no longer necessary to compromise specifications, while saving board space and cost, as compared to single operational amplifiers. __ Linear Technology/Analog Devices App Note, Mar 29th 2010

5V Powered, Quartz-Stabilized 10kHz Voltage to Frequency Converter has 0.0015% Linearity & 8ppm/°C Temperature Coefficient -  Almost all precision voltage-to-frequency converters utilize charge pump based feedback for stability.  These schemes rely on a capacitor for stability.  A great deal of effort towards this approach has resulted in high performance V to F converters.  Obtaining temperature coefficients below 100ppm/°C requires careful attention __ Linear Technology/Analog Devices App Note, Mar 25th 2010

741 Op-Amp Tutorial -  What exactly is an OPerational AMPlifier? Let's define what that component is and look at the parameters of this amazing device.  An operational amplifier IC is a solid-state integrated circuit that uses external feedback to control its functions.  It is one of the most versatile devices in all of electronics.  The term 'op-amp' was originally used to describe a chain of high performance dc amplifiers that was used as a basis for the analog type computers of long ago.  The very high gain op-amp IC's our days uses external feedback networks to control responses.  The op-amp without any external devices is called 'open-loop' mode, referring actually to the so-called 'ideal' operational amplifier. __ Designed by Tony van Roon  VA3AVR

76V Over-the-Top® Input Op Amp Combines Precision, Versatility & Protection  -  With the increased-use of electronics in automotive and industrial applications, the need for robust and highly reliable components is essential to ensure a proper functioning system with low maintenance costs.  Automotive applications, for example have hostile environments where electronic components may be exposed to a variety __ Linear Technology/Analog Devices App Note, Arnold Nordeng Design Engineer-Signal Conditioning Products Mar 20th 2013

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A 133MHz Differential Amplifier with External Gain Set, Impedance Matching to a 75Ω Source & Level Shifting -  Complete single ended 75Ω input impedance to differential out, level shifting 2.5V input to 1.25V differential common mode, single ended to differential gain of 2 using external resistors circuit example. __ Linear Technology/Analog Devices App Note, Oct 3, 2012

A Fourth-Order Speech Filter (Based On Texas Instruments Application Note) -  Human speech generally occupies an audio spectrum of 300 to 3400 Hz.  There is a requirement, especially in telephone circuits, to limit the frequency response to this range.  The ‘Digital Speech __ Electronics Projects for You

A Self-Powered Op Amp Creates a Low-Leakage Rectifier -  10/20/11  EDN-Design Ideas An amplifier that works at 0.8V is key.  You can combine a carefully chosen op amp, a low-threshold P-channel MOSFET, and two feedback resistors to make a rectifier circuit with less forward drop than a diode   (Figure 1).  The rectified output voltage powers the active circuitry, so no additional power supply is necessary. __ Circuit Design by Martin Tomasz, Sageloop Designs, San Francisco, CA

A true op-amp made from inverters -  11/18/13  EDN-Design Ideas Designs that stretch parts beyond their intended use, like this true op-amp constructed from eight CMOS inverters, have a certain special appeal __ Circuit Design by Colin Weltin-Wu

Accelerometer Amplifier with DC Servo -  The feedback integrator amplifies the 100 Megohm feedback resistance to behave like about 1Gigohm, extending the low-frequency response downward by about an order of magnitude. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Accelerometer Signal Conditioner -  A piezoelectric accelerometer responds to any physical movement by generating a charge proportional to the acceleration of the movement.  This sensor has a capacitance of 750pF which produces a charge of 60pC per g of gravitational force.  This charge is transferred to the 1000pF feedback capacitor for an output of 60mV/g. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Active 2nd Order Filters -  The figures below illustrate using opamps as active 2nd order filters.  Three 2nd order filters are shown, low pass, high pass, and bandpass.  Each of these filters will attenuate frequencies outside their paSSBand at a rate of 12dB per octave or 1/4 the voltage amplitude for each octave of frequency increase or decrease outside the paSSBand __ Designed by Bill Bowden

Amplifier requires no DC bias -  03/16/00 EDN-Design Ideas Intrinsically capacitive transducers and or high-impedance signal sources usually require ac coupling and a buffer amplifier to condition  signal for furr processing.  Buffers take many forms, but most of m compromise signal quality through __ Circuit Design by John Guy, Maxim Integrated Products, Sunnyvale, CA

Amplifiers Deliver Accurate Complementary Voltages -  09/23/10 EDN-Design Ideas Two amplifiers produce voltages that you can use in a variety of applications. __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Amplify & Shift EPAD MOSFET Output with an Operational Amplifier -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

An LT1013 & LT1014 Op Amp SPICE Macromodel -  DN12 Design Notes __ Linear Technology/Analog Devices

An Op-Amp based battery voltage Monitor -  An ECU must have a way to monitor battery voltage.  Here is a simple op-amp based circuit which will illuminate the LED when the battery voltage drops to a certain level.  The turn-on point is set with R2.  You must be able to vary Vcc   (usually with a good power supply) to set the circuit.  Decide at what voltage you'd like the LED to illuminate, and apply this at Vcc.  Adjust R2 until the light just illuminates.  Use an LED which will light at the desired voltage level, and determine R3, using ohm's law   (E=IR), to keep the current flowing through the LED and op-amp to around 10mA. 

AN10Methods for Measuring Op Amp Settling Time -  Linear Technology AN10 __ Designed by Jim WilliamsJul 1st, 1985

AN6Applications of New Precision Op Amps -  Linear Technology AN6 __ Designed by Jim WilliamsJan 1st, 1985

AN9Application Considerations and Circuits for a New Chopper-Stabilized Op Amp -  Linear Technology AN9 __ Designed by Jim WilliamsAug 5th, 1986

Analog divider uses few components -  01/04/07 EDN-Design Ideas Low-cost op amp, CMOS timer perform analog math __ Circuit Design by David Cripe, Chatham, IL

Analogue Components for IoT Applications -  Numerous analogue components and chips are introduced to the market every year, but what is influencing their evolution? Read on to find out the

Analogue difference Detector -  This is an example using a Norton op-amp: these work by using differential input current rather than the differential input voltage used by conventional op-amps. __ Designed by Richard Torrens

APD DC Coupled Current Monitor from 20V to 90V APD Bias -  APD current monitor that operates at High Common Mode Voltage and simplifies signal conditioning using instrumentation amplifier and a Delta Sigma ADC. __ Linear Technology/Analog Devices App Note, Apr 7th 2010

Application Considerations and Circuits for a New Chopper-Stabilized Op Amp -  Linear Technology AN9 __ Designed by Jim WilliamsAug 5th, 1986

Applications of New Precision Op Amps -  Linear Technology AN6 __ Designed by Jim WilliamsJan 1st, 1985

Applicatons of the LT1366 Rail-To-Rail Amplifier -  DN89 Design Notes __ Linear Technology/Analog Devices

Audio equalizer features transimpedance Q enhancement topology -  6-Mar-08 EDN-Design Ideas A novel op-amp configuration enables a graphic equalizer with a minimal number of amplifiers __ Circuit Design by Herminio Martínez, Encarna García, and Eva Vidal, Technical University of Catalonia, Barcelona, Spain

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Balanced Frequency Converter (Suitable for Frequencies up to 50kHz) -  This circuit takes advantage of aliasing that occurs in any time sampled system.  The output signal frequency is the difference in frequency between the input signal and the switch sampling rate.  A 24KHz input signal sampled at 25KHz will be converted to a 1KHz output signal.  In addition by using the LTC1992 fully differential __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Bandpass Filter (Single Op-Amp) -  A bandpass filter passes a range of frequencies while rejecting frequencies outside the upper and lower limits of the paSSBand.  The range of frequencies to be passed is called the paSSBand and extends from a point below the center frequency to a point above the center frequency where the output voltage falls about 70% of the output voltage at the center frequency. __ Designed by Bill Bowden

Basic logarithmic Amplifier using op-amp & NPN transistor -  Schematic only

Basic Op Amp Model -  One of the challenges of simulating opamp circuits is modeling the op amp itself.  How is that accomplished? There's a couple of ways.  You can create a circuit of many transistors, resistors and caps that closely replicate the internals of an op amp   (spice design)

Basic opamps -  The op-amp is basically a differential amplifier having a large voltage gain, very high input impedance and low output impedance.  The op-amp has a "inverting" or   (-) input and "noninverting" or   (+) input and a single output.  The op-amp is usually powered by a dual polarity power supply in the range of +/- 5 volts to +/- 15 volts.  A simple dual polarity power supply is shown in the figure below which can be assembled with two 9 volt batteries. __ Designed by YO5OFH, Csaba Gajdos

Battery Powered (Li-Ion) Platinum RTD Signal Conditioner with Curvature Correction -  The LT2078 is a micropower dual op amp in 8-pin small outline, standard surface mount package, and LT2079 is a micropower quad op amp offered in the standard 14-pin surface mount package.  Both devices are optimized for single supply operation at 5V.  ±15V specifications are also provided. __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Bias Tee -  Schematic Only __ Designed by www.gbppr.org

Biasing Op-Amps into Class A -  "Class A" refers to configuring an amplifier so that its output devices remain turned on all the time.  This reduces thermal variation and eliminates crossover distortion, which makes the chip perform better.  To bias an op-amp into class A, you simply put a current source from the op-amp's output to one of the power rails.  Everything else is details.  This article is about those details __ Designed by contact me 2014 @ tangentsoft.com

Bidirectional Current Source -  The LT1990 is a differential amplifier with integrated precision resistors.  The circuit shown is the classic Howland current source, implemented by simply adding a sense resistor. __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Bipolar, Ground Referenced, Single-Ended Signal Interface to Unipolar, Differential Input ADC -  Differential amplifiers are useful for providing the input to a single supply differential ADC from a bipolar ground referenced input source.  All of the signal level shifting and gain requirements can be adjusted with external resistors. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Bootstrapping Allows Single-Rail Op Amp to Provide 0V Output -  02/06/03 EDN-Design Ideas __ Circuit offers improved active rectificationMany single-supply-powered applications require amplifier-output swings within 1 mV—or even submillivolts—of ground.  Amplifier-output-saturation limitations normally preclude such operation.  Figure 1's power-supply bootstrapping scheme achieves the desired characteristics with minimal parts count __ Circuit Design by Jim Williams, Linear Technology Corp, Milpitas, CA

Brake Failure Indicator -  Do you want to get an early warning of brake failure while driving? Here is a brake failure indicator circuit that constantly monitors the condition of the brake and gives an __ Electronics Projects for You

Build an Op Amp with Three Discrete Transistors -  12/01/11  EDN-Design Ideas This simple ac-coupled design inverts, runs off a single supply, and is self-biasingYou can use three discrete transistors to build an operational amplifier with an open-loop gain greater than 1 million   (Figure 1).  You bias the output at approximately one-half the supply voltage using the combined voltage drops across zener diode D1, the emitter-base voltage of input transistor Q1, and the 1V drop across 1-MΩ feedback resistor R2. __ Circuit Design by Lyle Russell Williams, St Charles, MO; Edited by Paul Rako and Fran Granville

Circuit Fault Protection with Latching Load Disconnect & Early Warning Indication -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Circuit Fault Protection with Very Fast Latching Load Disconnect -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator.  Two versions of the LT6108 are available.  The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator.  In addition, the current sense amplifier __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Circuit Forms Ideal Diode Function -  This circuit uses a low power op amp and a p-channel FET to form a diode function with a very low 0.05 volt voltage drop.  With the selected FET, the circuit can handle up to 2 amps of current.  Higher currents are possible with a FET with a lower channel. . . Circuit by David A. Johnson P.E.-January, 2008

Circuit forms industrial-grade digital potentiometer -  09/20/01 EDN-Design Ideas Both ac and dc motors in modern industrial systems often receive their control from PLCs(programmable-logic controllers] in a control room safely away from the process.  If an operator must manually set the motor speed while observing the process, the component of choice is usually an industrial-grade potentiometer __ Circuit Design by Phill Leyva, Maxim Integrated Products, Sunnyvale, CA

Circuit Provides Inverting/Noninverting Gain -  11/09/95 EDN-Design Ideas The amplifier in Figure 1a is a well-known circuit that provIdeas voltage gain of +1 or –1, depending on the logic voltage (0 or 5V) you apply to the MOSFET gate.  By adding one resistor (Figure 1b), the amplifier can provide gain of +AV or –AV with the same logic control.  The gain is ±R3/R2, and R1 is (R3R2)/(R3–R2.).  You need a driving source with low output impedance, and the input impedance of the circuit is different for the two states. __ Circuit Design by    Victor Koren, Orckit Communications Ltd  Tel Aviv, Israel

Circuit provides linear I-to-V conversion -  01/18/96 EDN-Design Ideas The circuit in Figure 1 provIdeas a 4to 20-mA voltage-to-current conversion for noise-immune data transmission in industrial data-acquisition systems.  The circuit supplies two voltages to the inverting input of the control amplifier IC1A.  The first voltage, from the follower IC1B, introduces an offset in the transfer function of the circuit __ Circuit Design by Jordan Dimitrov, N Pouskarov Institute, Sofia, Bulgaria

Circuit Yields Accurate Absolute Values -  07/05/01  EDN-Design Ideas The circuit in Figure 1 delivers the absolute value of the input signal with an accuracy better than 10 ppm of the full-scale range.  The circuit has low zero-crossing error.  You can use it as an asynchronous demodulator, as a source __ Circuit Design by Marco Pisani, Istituto di Metrologia G Colonnetti, Turin, Italy

Class a JFET Opamp Circuit -  First Generation design that means it is not our latest design __ Contact: info @ forsselltech . com

Classic High-Precision Low Side Current Sense -  This configuration is basically a standard non-inverting amplifier.  The op amp used must support common-mode operation at the lower rail and the use of a Zero-Drift type (as shown) provides excellent precision.  The output of this circuit is referenced to the lower Kelvin contact, which could be ground in a single-supply application. __ Linear Technology/Analog Devices App Note, Mar 31st 2010

C-Load Tm Op Amps Conquer Instabilities -  DN107)  Design Notes __ Linear Technology/Analog Devices

C-Load Tm Op Amps Tame Instabilities -  DN83 Design Notes __ Linear Technology/Analog Devices

Clock Timer -  With this simple clock-controlled timer, you will never again miss your favourite TV or radio programme.  The TV or radio will switch on automatically at the time preset by you and __ Electronics Projects for You

Collection of Crystal Radios -  Collection of Crystal Radio Circuits __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Common-Mode Rejection -  While real op amps do a fantastic job of rejecting voltages common to both inputs, it's not perfect.  A small output results from a change in input common-mode voltage.  What causes this output? Due to mismatching in the transistors and resistors of the input stage, the common-mode voltage produces a small differential error voltage at the input terminals.  Subsequently (spice design)

Controlled power supply increases OpAmps output voltage range -  03/15/07 EDN-Design Ideas External transistors and op amps increase the outputvoltage range of a precision op amp. __ Circuit Design by Yakov Velikson, Lexington, MA

Current Feedback Amplifier Do's & Don'ts -  DN46 Design Notes __ Linear Technology/Analog Devices

Current Source -  Getting optimum performance in certain applications requires that some components, sensors, DC motors, transistors, be driven or biased by a constant current.  We're mostly familiar with voltage regulators and their ability to maintain a constant voltage under varying current conditions.  In this application, your challenge is to provide a constant (spice design)

Current-source enables op Amp's output to go to ground -  5-Aug-04 EDN-Design Ideas The LM324 is a cost-effective choice for an op amp, especially when you need to apply ground-level inputs.  Although its output purportedly includes ground, its poor current-sinking capability limits the applications.  At output voltages lower than 0.5V, the op amp's sinking current ranges only from 2 to 100 µA __ Circuit Design by Frank Chan, Vancouver, BC, Canada

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DAC & Op Amp Generate Variable Negative Control Voltage -  App Note/ 107) 4 / Feb-05 __ Maxim Integrated

DAC & Op Amp Provide Variable Control Voltage -  12/06/01 EDN-Design Ideas Early DACs contained standard R-2R ladder networks, and produced a negative output voltage.  These early DACs, such as  MAX7837/7847 and  MAX523, require both positive and negative supply rails to accommodate ir negative output.  With  transition to single-supply ICs, however, many modern DACs operate with a single supply rail and an inverted R-2R ladder network __ Circuit Design by Chad Olson

DAC Reference Inverter & I-to-V Converter -  LT6011 dual op amp performs two functionsinverting a positive ref voltage to a negative ref voltage to allow bipolar output polarities and performing the current to voltage conversion on the DAC's current outputs as well buffering the outputs. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

DC Accurate Composite Amplifier -  Most individual op amp devices are optimized for either DC precision or for high speed operation.  A composite amplifier configuration uses a precision low offset and drift amplifier to control the dc biasing of a high speed amplifier.  This circuit has a gain bandwidth product of 1.25MHz yet an input offset voltage of only 25uV maximum. __ Linear Technology/Analog Devices App Note, Mar 26, 2010

Dead Zone Generator -  BIPOLAR SYMMETRY IS EXCELLENT BECAUSE ONE DEVICE, Q2, SETS BOTH LIMITS.  This circuit outputs 0V for a controlled range of input voltage.  When the input voltage exceeds the set voltage in either polarity the output signal moves with unity gain. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Design Notes 502: Matched Resistor Networks for Precision Amplifier Applications -  10/03/13  EDN-Design Notes   Two-quadrant multiplying DAC utilizes octal CMOS buffer.   Some ideal op amp configurations assume that the feedback resistors exhibit perfect matching.  In practice, resistor non-idealities can affect various circuit parameters such as common mode rejection ratio (CMRR), harmonic distortion and stability.  For instance, as shown in Figure 1, a single-ended amplifier configured to level-shift a ground-referenced signal to a common mode of 2.5V needs a good CMRR.  Assuming 34dB CMRR and no input signal, this 2.5V level shifter exhibits an output offset of 50mV, which can even overwhelm the LSB and offset errors of 12-bit ADCs and drivers. __ Circuit Design by Tyler Hutchison

Design Notes: 1.5A Rail-to-Rail Output Synchronous Step-Down Regulator Adjusts with a Single Resistor -  02/03/14EDN-Design Notes   One wire brings power & data to LCD moduleA new regulator architecture, the LTC3600   (first introduced with the LT3080 linear regulator), has wider output range and better regulation than traditional regulators.  Using a precision 50μA current source and a voltage follower, the output is adjustable from 0V to close to VIN.  Normally, the lowest output voltage is limited to the reference voltage __ Circuit Design by Jeff Zhang, also see Linear Technology Design Note 506

Differential Bridge Amplifier -  The LTC2050HV are zero-drift operational amplifi ers available in the 5- or 6-lead SOT-23 and SO-8 packages.  The LTC2050 operates from a single 2.7V to 6V supply.  The LTC2050HV operates on supplies from 2.7V to ±5.5V.  The current consumption is 800μA and the versions in the 6-lead SOT-23 and SO-8 packages offer power shutdown __ Linear Technology/Analog Devices App Note, Apr 29th 2010

Differential Bridge Amplifier with Gain Programmed through the Serial Interface & Analog to Digital Conversion (Standby Current Less than 100μA) -  The LTC6915 is a precision programmable gain instrumentation amplifier.  The gain can be programmed to 0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096 through a parallel or serial interface.  The CMRR is typically 125dB with a single 5V supply with any programmed gain.  The offset is below 10μV with a temperature __ Linear Technology/Analog Devices App Note, Apr 29th 2010

Differential Front-End for the LTC2400 Rail-To-Rail -  Design Solutions 2 Design Notes __ Linear Technology/Analog Devices

Differentiator -  (spice design) __ Designed by Rick 

Digital potentiometer autonulls op Amp -  10/22/98 EDN-Design Ideas Op-amp applications that need the highest possible dc accuracy are generally best served by CMOS chopper-stabilized amplifiers, such as the LTC1050.  But high-speed, low-noise applications may require high-performance rockets, such as the 700-MHz LT1226.  So what to do for applications __ Circuit Design by Stephen Woodward, University Of North Carolina, Chapel Hill, NC

Discrete Differential Amplifier  -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Discrete Op-Amp -  Class-A Output.  Intended as an experimental device, works extremely well __ Designed by Rod Elliott  ESP

Discrete Op-amps -  It is not at all difficult to make an op-amp using transistors.  This page shows you how and discusses how they work.  I am not giving all circuit values here, just enough to describe operation.  Actual circuit values will depend on exactly what you want to do with the circuit.  Anyway, it's not necessary to have circuit values when you're trying to gain an understanding of how the circuit works __ Designed by Richard Torrens

Dual 25µV Micropower Op Amp Fits in 3mm X 3mm Package -  DN331 Design Notes __ Linear Technology/Analog Devices

Dual Audio-Signal Tracer -  The circuit described here is of a dual audio-signal tracer.  An audio-signal tracer is a simple device used to troubleshoot for audio signals in radio and other electronic circuitry.  The device is __ Electronics Projects for You

Dual Buffered ±0.617V Reference Powered by Two AA Batteries -  Lower opamp is a precision inverter setting outputs to set the outputs at the same magnitude but opposite polarity.  The upper opamp drives the positive output so that the difference of the two outputs is the reference voltage, so the result is that half the reference voltage is the magnitude of the outputs __ Linear Technology/Analog Devices App Note, Jun 21, 2010

Dual Op Amp Doubles Output Current -  09/12/96 EDN-Design Ideas Standard linear output current for high-speed op amps is approximately 30 to 40 mA.  When more current is necessary, the next available op amps provide approximately 200 mA but with a significant increase in cost and quiescent current.  Depending on the amount of current you need, you may find it more cost-efficient to configure a dual op amp-- [Tamara Ahrens, Elantec Inc, Milpitas, CA] __ Circuit Design by Tamara Ahrens, Elantec Inc, Milpitas, CA

Dual Op Amp Takes Absolute Difference -  06/06/12  EDN-Design Ideas The circuit takes the absolute value of the differences of two voltages using two single-supply ground-referenced op amps.  A traditional implementation of an absolute-difference function comprises a difference circuit followed by an absolute-value circuit; the entire circuit requires at least three op amps.  The design problem is complicated in single-supply-only systems, which usually require an artificial ground, typically one-half of the supply.  The circuit in Figure 1 takes the absolute value of the difference of two voltages using only two single-supply, ground-referenced op amps.  The circuit is designed for dc or low-speed operation. __ Circuit Design by Jessica MacNeil

Dual Polarity Amplifier has Digital Control -  09/12/96 EDN-Design Ideas The circuit in Figure 1 can amplify a signal either in an inverting or a noninverting mode.  When switch S1 is on and S2 is off, the circuit behaves as a regular inverting amplifier.  When S2 is on and S1 is off, the circuit feeds the signal to the noninverting input of the op amp; thus, the circuit behaves as a noninverting amplifier.  If S1 and S2 are monolithic analog switches, you __ Circuit Design by Rick Downs, Dallas Semiconductor Corp, Dallas, TX

Electric Guitar Preamplifier -  This is a circuit for a guitar preamplifier that can capture mechanical vibrations (any standard guitar pickup) and then convert them into an electrical signal.  The signal is then amplified by an audio amplifier. __ Electronics Projects for You

Electronic Horn -  Here’s a simple circuit of an electronic horn that is built around quadruple op-amp IC LM3900 (IC1). IC LM3900 has four independent op-amps (A1 through A4) with a large output voltage __ Electronics Projects for You

Energy-Tripped Breaker Trips After a Time Interval that Varies as a Function of Sensed Load Current -  The circuit of this circuit has three distinct parts – circuit breaking, current sensing and timing.  The circuit breaking function can be any type of electronically controlled relay or solid state switch, properly sized for voltage and current ratings of the load being protected.  Load current sensing is achieved via __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Enkindle Your Appetite for the IoT -  RIOT RIOT is a free open source operating system (OS) based on micro-kernel architecture.  It is designed specifically for powering the Internet of Things (IoT).

Extended Dynamic Range 1MΩ Transimpedance Photodiode Amplifier -  The LTC6090 is a high voltage precision operational amplifier.  The low noise, low bias current input stage is ideal for high gain configurations.  The LTC6090 has low input offset voltage, a rail-to-rail output stage, and can be run from a single 140V or split ±70V supplies. __ Linear Technology/Analog Devices App Note, Dec 4th 2012

Extending Input Common Mode Range for LT1992 -  Tying the Vocm pin to the Vmid Pin and using two equal voltage dividers with external feedback resistors is used in this circuit to extend the input Common Mode Range of LTC1992. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

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Fast Op Amps Operate Rail-To-Rail on 2.7V -  DN241 Design Notes __ Linear Technology/Analog Devices

Fast, 16-Bit Current Comparator -  Precision op-amp used as pre-comparator.  Schottky diodes in feedback limit output swing of amplifier to minimize slew delay.  Resistive input structure can be tailored for different trip points; this one detects a current sink of >50uA at the input __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Feedback Network Silences Op-Amp Resistor Noise -  09/12/96 EDN-Design Ideas Once you've selected an op amp that offers low-voltage and -current noise terms, further noise reductions are hard to come by.  Broadband pulse amplifiers often require as low a noise as possible to accurately detect or convert the input signal.Figure 1a shows the full noise model and output noise (eo) equation for a noninverting op-amp configuration. __ Circuit Design by Michael Steffes, Burr-Brown Corp, Tucson, AZ

Fixed-gain op Amps simplify filter Design -  07/06/00 EDN-Design Ideas Simple second-order filters meet many filtering requirements.  A low-order lowpass filter, for example, is often adequate for antialiasing in ADC applications or for eliminating high-frequency noise in audio applications.  Similarly, a low-order highpass filter can easily remove power-supply noise.  When you design such filters with built-in gain, fixed-gain op amps can save space, cost, and time. __ Circuit Design by Dan Christman, Maxim Integrated Products, Sunnyvale, CA

FM Radio Transmitters with Opamp -  An low power FM Transmitter using an op-amp as the audio preamp and a single transistor as the RF amplifier. __ Designed by Kamran Ahmed

Fourth-Order Speech Filter (Based On Texas Instruments Application Note) -  Human speech generally occupies an audio spectrum of 300 to 3400 Hz.  There is a requirement, especially in telephone circuits, to limit the frequency response to this range.  The ‘Digital Speech __ Electronics Projects for You

Full-Bridge Load Current Monitor -  The LT1990 is a micropower precision difference amplifier with a very high common mode input voltage range.  It has pin selectable gains of 1 or 10.  The LT1990 operates over a ±250V common mode voltage range on a ±15V supply.  The inputs are fault protected from common mode voltage transients up to ±350V and differential voltages __ Linear Technology/Analog Devices App Note, Apr 5th 2010

Gain 1000 Amplifier with 0.01% Accuracy, DC to 5Hz -  With a typical open loop gain value of 20 million V/V, very high closed loop gain amplifiers can be implemented with remarkable accuracy.  Even with such a high gain, the trimmed precision produces a dc output offset of only 20mV. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

General Purpose Arithmetic Block -  This is the circuit for the general purpose arithmatic function, an Analog Computer block which solves the equation VO = (V1V2 + V3) ((RF + RG) /RG) in real time.  No A/D conversions or software needed! __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Ground Referred Precision Current Sources -  The zero drift LTC2054 instrumentation amplifier can be used in conjunction with one of Linear Technology's precision, low temperature drift shunt voltage references (in this example the LT1634) to create a precision, ground referred current source. __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Hall Sensor Amplifier Optimizes Sensitivity vs Supply Current -  Voltage across HALL-ELEMENT bridge is reduced to minimize bridge current from 2.5mA or 230µA then a dual LT6011 DC precision low current low drift and Vos OP AMP is used in an instrumentation AMP configuration at a gain of 101 to give a sensitivity of 40mV/mT. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Handbook of Operational Amplifier Applications -  While in the process of reviewing Texas Instruments applications notes, including those from Burr-Brown – I uncovered a couple of treasures, this handbook on op amp applications and one on active RC networks. __ Designed by Bruce Carter & Thomas R. Brown

HD Video Cable Driver using Economical LT6559 -  Single supply 5V HD Video Cable Driver with two resistors setting common voltage on capacitive coupled input.  Two 270pF takes care of 10MHz filtering.  This circuit depicts one of three channels. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

High Accuracy Oxygen Sensor -  High Accuracy Oxygen Sensor.  Accuracy is achieved using a transimpedance approach.  Reduction in noise gain gives a reduction in output offset error from 50mv to 500µa. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

High Linearity Components Simplify Direct Conversion Receiver Designs -  LT5575 Demodulator with 20MHz Low pass Filter, common mode output voltage can be set regardless of input voltage.  A filter at the output of the demodulator filters out of band signal and the filter at the inputs of the ADC performs the anti aliasing function. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

High Performance Op Amps Deliver Precision Waveform Synthesis -  DN306 Design Notes __ Linear Technology/Analog Devices

High Resolution Battery-Powered Robust Type K Thermocouple Signal Conditioning Amplifier with Cold Junction Compensation -  The circuit is used as a plug-in adapter for common digital multimeters and is completely portable.  This circuit employs the LT1025 thermocouple compensator to improve accuracy over a wide range of ambient conditions and is mounted close to the thermocouple connection points for optimal thermal tracking.  It precludes the need __ Linear Technology/Analog Devices App Note, Apr 8th 2010

High-Speed Op Amp Enables IR-Proximity Sensing -  06-Aug-09 EDN-Design Ideas IR (infrared]-proximity sensors can sense the presence of an object, its distance from a reference, or both.  Applications include speed detection, sensing of the hand in automatic faucets, automatic counting or detection of objects __ Circuit Design by Arpit Mehta, Maxim Integrated Products Inc, Sunnyvale, CA

Humidty Sensor to Data Aquisition System Interface -  The circuit shown in the schematic features zero drift operational amplifiers (LTC1250 and LTC1050) and a precision instrumentation switched capacitor block (LTC1043).  This design will maintain excellent DC accuracy down to microvolt levels.  This method was chosen over the use of a true RMS-to-DC or log converter because of __ Linear Technology/Analog Devices App Note, Mar 16th 2011

IF/RF Gain Block State-of-the-Art Performance the Easy Way -  Bandwidth has become more precious than gold.  As we push more and more data wirelessly through our smartphones, tablets, GPS, and video players, the spectrum has become more crowded.  Increasingly complex and efficient modulation schemes allow us to carry more MBits/mHz through the air.  However, the key to these demanding __ Linear Technology/Analog Devices App Note, Greg Fung-Senior Design Engineer Oct 4th 2012

i-Feedback Amplifier Puts Parasites to work -  11/09/95 EDN-Design Ideas Many an engineer designing with wideband op amps has battled parasitic capacitance at the inverting input.  What’s more, if you design a discrete gain-select circuit, you must deal with declining amplifier performance at higher gain levels.  The circuit in Figure 1, using a CLC404 wideband current-feedback amplifier, controls the parasitic capacitance to maintain performance in a discrete gain-select configuration. __ Circuit Design by Comlinear Corp Fort Collins, CO

Ignore Input Range Limits in Wideband OpAmp -  07/16/98 EDN-Design Ideas (This file has many circuits, plase scroll to this one)  Most of the recent wideband, single-supply op amps use a voltage-feedback design.  The error signal(differential input voltage] for a voltage-feedback op amp can operate over a range of common-mode input voltages, and its common-emitter output stage can provide output voltages near the supply rails.  Current-feedback op amps are becoming available with wide output swings,e __ Circuit Design by Michael Steffes, Burr-Brown Corp, Tuscon, AZ

Implementing a Low Cost, Battery Powered, TDS Meter using MCU & psoc -  One of the common method in determining the quality of water is the measurement of Total Dissolved Solids (TDS).  TDS meter is a widely

Improved 3 Transistor Audio Amp (80 milliwatt) -  This circuit is similar to the one above but uses positive feedback to get a little more amplitude to the speaker.  I copied it from a small 5 transistor radio that uses a 25 ohm speaker.  In the circuit above, the load resistor for the driver transistor is tied directly to the + supply.  This has a disadvantage __ Designed by Bill Bowden

Industrial-Grade Digital Potentiometer 09/20/01  EDN-Design Ideas Both ac and dc motors in modern industrial systems often receive their control from PLCs (programmable-logic controllers] in a control room safely away from the process.  If an operator must manually set the motor speed while observi __ Circuit Design by Phill Leyva, Maxim Integrated Products, Sunnyvale, CA

Infrared Remote Control Timer -  The circuit comprises two sections, namely, the transmitter section and the receiver section.  Fig.1 shows the IR transmitter section.  The astable multivibrator NE555 (IC1) is used to generate a 10kHz __ Electronics Projects for You

Instrumentation Amp makes noninverting integrator -  09/19/02 EDN-Design Ideas Figure 1a shows the classic implementation of an integrator.  The circuit has two properties that may be undesirable in same applications  It necessarily inverts, and it requires a split-supply or midsupply reference.  Figure 1b shows an implementation of an integrator that uses an LT1789 instrumentation amplifier __ Circuit Design by Glen Brisebois, Linear Technology Corp, Milpitas, CA

Instrumentation Amp Swings Rail-To-Rail -  03/03/94 EDN-Design Ideas You can combine an instrumentation amplifier and an inexpensive CMOS op amp to get the better of two worlds  the precision of a bipolar instrumentation amp and the5V single-supply operation of the CMOS op amp.  The characteristics of such a circuit __ Circuit Design by R Mark Stitt, Burr-Brown,  Tucson, AZ

Integrator forms picoammeter -  07/17/97 EDN-Design Ideas The analog circuitry necessary to precisely resolve picoamperes can challenge even the best designer.  At these minute current levels, noisy and nonreproducible circuit topologies are common.  A current-to-voltage (I/V) converter that uses an op amp and large feedback resistor is the obvious first design choice to acquire a small current.  However, the component errors that this method induces can swamp the measurable current (and can amount to throwing out the baby with the bath water). __ Circuit Design by Clayton B Grantham, Burr-Brown Corp, Tucson, AZ

Inverting Switched Capacitor Integrator -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Keep the heat down in power op Amps -  02/15/00 EDN-Design Ideas When you include a power op amp, such as PA05 from Apex Microtechnology, in your design, it is desirable to minimize the supply-to-output differential to a minimum to reduce power dissipation and to fully exploit the amplifier's output range.  Our goal was to design a power amplifier to yield 70V p-p output at __ Circuit Design by Vijay Damle

Kelvin-Sensed Temperature Sensor Amplifier for –50°C to 150°C Platinum RTD from 10V Reference -  The LT1012 is an internally compensated universal precision operational amplifier which can be used in practically all precision applications.  The LT1012 combines picoampere bias currents (which are maintained over the full –55°C to 125°C temperature range) , microvolt offset voltage (and low drift with time and temperature) , __ Linear Technology/Analog Devices App Note, Mar 29th 2010

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Lead-Acid Battery Charger with Voltage Analyser -  Nowadays maintenance-free lead-acid batteries are common in vehicles, inverters, and UPS systems.  If the battery is left in a poor state of charge, its useful life is shortened.  It also reduces __ Electronics Projects for You

LF071 Mic Amplifier -  A high quality microphone preamplifier using a single power supply, suitable for dynamic or electret microphones.  The op-amp used can be any low noise, high performance type, e.  g.  NE5534, TL071, OPA 371 etc __ Designed by Andy Collison

Light Monitor Circuit -  The circuit below takes advantage of a low power op amp with a “rail to rail” feature.  The single resistor R1 defines the light sensitivity of the circuit.  The output voltage is directly proportional to the intensity of light striking the small photodiode . . . Hobby Circuit designed by David A. Johnson P.E.-August, 2010

Linear power driver works from single supply -  07/25/02 EDN-Design Ideas In low-power, single-supply analog applications, it is often desirable to maintain precise control of voltages much greater than the positive-supply rail.  The circuit in Figure 1 allows you to amplify the input voltage, VIN, by a factor, A, which resistors R1 and R2 set.  The output voltage, VOUT, equals AVIN, where A=R2/(R1+R2] __ Circuit Design by Tom Gay, Darmstadt, Germany

Linear Thermometer -  T1 has a built in pair of thermistors with linearizing resistors custom scaled for a specific temperature range.  , 0C to 100C in this example.  The flying capacitor LTC1043 eliminates any dc loading on the precision network to maintain linearity over the entire temperature range.  Amplifier gain is scaled to provide an output __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Linear Timer for General Use -  This simple timer can be used to control any electrical appliance that needs to be switched off after certain time, like a small heater or a boiler, provided the relay-switch parameters __ Electronics Projects for You

Linearized Platinum Resistance Thermometer with ±0.025°C Accuracy Over 0 to 100°C -  Platinum RTD's are typically driven with a constant current so that their resistance value directly translates to a temperature dependant voltage.  Here the LT1001 and the LM129 create a constant current through the input 10K resistor which all flows through the sense resistor.  A second amplifier inverts the signal to provide __ Linear Technology/Analog Devices App Note, Jun 21st 2011

LM741 OpAmp Voltage Indicator -  Plans for a simple voltage high/low indicator built around an LM741 operational amplifier. __ Designed by REUK-Renewable Energy UK website

LME49710 Based Audio Amplifier -  Listening to music on a self-made system is great.  Good-quality audio amplifier circuits can be constructed with minimum components.  Described here is an LME49710 based audio amplifier.  Author’s prototype is shown __ Electronics Projects for You

Low Frequency Sine Wave Generator -  The two circuits below illustrate generating low frequency sine waves by shifting the phase of the signal through an RC network so that oscillation occurs where the total phase shift is360 degrees. __ Designed by Bill Bowden

Low Frequency Wien Bridge Sinewave Oscillators -  Three examples of Wien Bridge oscillators are shown below.  The first uses three bipolar transistors.  The second uses a bipolar and JFET, and the third is the more popular type using an op-amp for minimal parts.  The idea is to generate a 360 degree phase shift at some particular frequency using 2 resistors and caps of equal value.  One cap and resistor are in series, while another cap and resistor are in parallel.  The signal loss through the network is about 66 percent so the amplifier gain needs to be around 3 for a loop gain of 1 __ Designed by Bill Bowden

Low Noise AC Amplifier with Programmable Gain & Bandwidth -  Two LTC6910 programmable gain amplifiers can be combined to provide independent gain and bandwidth control using two 3 bit digital words.  The Gain Control PGA simply varies the circuit gain from 1 to 100.  The Bandwidth Control PGA puts signal gain inside the feedback loop of the amplifier.  As this gain is increased the effective value of feedback resistor R2 is decreased.  This pushes out the upper low pass corner frequency of the ac amplifier. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Low Noise Hydrophone Amplifier with DC Servo -  The LT1169 achieves a new standard of excellence in noise performance for a dual JFET op amp.  For the first time low voltage noise (6nV/rtHz) is simultaneously offered with extremely low current noise (1fA/rtHz) , providing the lowest total noise for high impedance transducer applications.  Unlike most JFET op amps, the __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Low Noise Single Supply Photodiode Amplifier -  Low Noise Single Supply Photodiode Amplifier Figure 1 shows the LTC6252 applied as a high performance transimpedance amplifier for a photodiode.  A low noise JFET acts as a current buffer, with R2 and R3 imposing a low frequency gain of approximately 1.  Transimpedance gain is set by feedback resistor R1 to 1MΩ.  R4 and __ Designed by Glen Brisebois-Applications Engineer-Linear Technology/Analog Devices App Notes, Feb 4th 2013

Low Noise, Low Power Photodiode Amplifier with DC Precision -  Instead of simply grounding the LT6202 noninverting input, an LTC2050 drives it (and therefore the source) exactly to where it needs to be for zero JFET gate voltage.  Output offset is 200mV and output noise is 2mVP-P measured in a 20MHz bandwidth. __ Linear Technology/Analog Devices App Note, Mar 22nd 2010

Low Part Count UXGA-Resolution Cable Driver on 5V Supply -  LT6557 UXGA-Resolution Cable Driver circuit operating from a single 5V Supply.  This circuit has a 400MHz large signal bandwidth.  Single input biasing system resistor programs eliminates then usual input divider resistors.  High resolution HD quality circuit, one of three shown. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Low Power Amp Monitors Light -  The circuit below takes advantage of a low power op amp with a “rail to rail” feature.  The single resistor R1 defines the light sensitivity of the circuit.  The output voltage is directly proportional to the intensity of light striking the small photodiode. . . Circuit by David Johnson P.E.-August, 2010

Low Power Comparator with <10uV Hysteresis -  The opamp is used as a precision comparator that drives an NPN transistor to form a logic-level output.  Controlled positive feedback into a trim pin makes precision microvolt hysteresis control practical. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Low Power Fast Op Amps Have Low Distortion -  DN148 Design Notes __ Linear Technology/Analog Devices

Low Power Op-Amp-Audio Amp Intercom -  The example below illustrates using an op-amp as an audio amplifier for a simple intercom.  A small 8 ohm speaker is used as a microphone which is coupled to the op-amp input through a 0.1uF capacitor.  The speaker is sensitive to low frequencies and the small value capacitor serves to attenuate the lower tones and produce a better overall response.  You can experiment with different value capacitors to improve the response for various speakers.  The op-amp voltage gain is determined by the ratio of the feedback resistor to the series input resistor which is around one thousand in this case __ Designed by Bill Bowden

Low Power, Bidirectional 60V Precision Hi Side Current Sense -  Using a very precise zero-drift amplifier as a pre-amp allows for the use of a very small sense resistor in a high voltage supply line.  A floating power supply regulates the voltage across the pre-amplifier on any voltage rail up to the 60V limit of the LT1787HV circuit.  Overall gain of this circuit is 1000.  A 1mA change in __ Linear Technology/Analog Devices App Note, Mar 31st 2010

Low Side Current Sense -  Sensing the amount of current through a load on the low side has the disadvantage of raising the return connection to the load from ground.  The advantage of such an approach is that it is very easy to implement using a basic non-inverting gain stage.  The LTC6081 operates linearly down to ground also in this single supply example. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Low-Cost Hearing Aid -  This hearing aid circuit offers the advantages of high sensitivity, low current consumption, low cost and light weight.Audio signals are sensed by the condenser microphone and amplified by two op-amps built __ Electronics Projects for You

LT1056 Improved JFET Op Amp Macromodel Slews Asymmetrically -  DN43 Design Notes __ Linear Technology/Analog Devices

LT1792/LT1097 Low Noise Hydrophone Amplifier with DC Servo -  The LT1792 achieves a new standard of excellence in noise performance for a JFET op amp.  The 4.2nV/ÖHz voltage noise combined with low current noise and picoampere bias currents make the LT1792 an ideal choice for amplifying low level signals from high impedance capacitive transducers. __ Linear Technology/Analog Devices App Note, Jun 21, 2011

LT1806: 325MHz Low Noise Rail-To-Rail SOT-23 Op Amp Saves Board Space -  DN254 Design Notes __ Linear Technology/Analog Devices

LT1880 SOT-23 Superbeta Op Amp Saves Board Space in Precision Applications -  DN266 Design Notes __ Linear Technology/Analog Devices

LT1970 Op Amp Provides On-The-Fly Adjustable Current Limit for Flexibility & Load Protection in High Current Applications -  DN298 Design Notes __ Linear Technology/Analog Devices

LT1991 Individual Battery Cell Monitor for a 4-Cell Battery -  High input impedance of LT1991 P3 and M3 inputs, (150K) , is used to eliminate errors introduced by the analog switch resistance which is very low compared to LT1991 input resistance.  The MSB signal is used to change the common mode voltage when reading the cells on the battery stack. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

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LTC Design Note: Precision op-amp enables fast multiplexing at low power -  EDN-Design Ideas 04/29/2016    A multiplexed DAQ design presents some subtle challenges, and parts selection plays a crucial role __ Circuit Design 

LTC Design Note: Robust high voltage Over-the-Top op-amps -  EDN-Design Ideas 01/29/2016    Learn how the innards of an “over-the-top” op-amp work (where inputs can be higher than V+), as well as related design considerations.  Maintains high input impedance with inputs driven apart or when powered down __ Circuit Design 

LTC1451/52/53: 12-Bit Rail-To-Rail Micropower DACs in an SO-8 -  DN96 Design Notes __ Linear Technology/Analog Devices

Matched Resistor Networks for Precision Amplifier Applications -  10/03/13  EDN-Design Notes   Two-quadrant multiplying DAC utilizes octal CMOS buffer.  Some ideal op amp configurations assume that the feedback resistors exhibit perfect matching.  In practice, resistor non-idealities can affect various circuit parameters such as common mode rejection ratio (CMRR), harmonic distortion and stability.  For instance, as shown in Figure 1, a single-ended amplifier configured to level-shift a ground-referenced signal to a common mode of 2.5V needs a good CMRR.  Assuming 34dB CMRR and no input signal, this 2.5V level shifter exhibits an output offset of 50mV, which can even overwhelm the LSB and offset errors of 12-bit ADCs and drivers. __ Circuit Design by Linear Technology Design Note 502

Maximize Dynamic Range with the LT1466l Micropower Rail-To-Rail Op Amp -  DN171 Design Notes __ Linear Technology/Analog Devices

Methods for Measuring Op Amp Settling Time -  Linear Technology AN10 __ Designed by Jim WilliamsJul 1st, 1985

Methods for Measuring Op Amp Settling Time -  AN10 The AN10 begins with a survey of methods for measuring op amp settling time.  This commentary develops into circuits for measuring settling time to 0.0005%.  Construction details and results are presented.  Appended.  (1/06) __ Linear Technology/Analog Devices

Micro Power Oxygen Sensor -  Micro Power Oxygen Sensor takes advantage of low and clean startup current characteristics and wide supply voltage range, 1.8V to 16V range. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Micropower Buffered Rail-to-Rail Adjustable Volatge Source -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Micropower Dead Zone Generator -  Opamp in lower left functions as a polarity detect comparator, controlling the FET switches in the circuit.  The upper left stage in conjunction with the FET, functions as an absolute value circuit so that only positive signal representation passes to the dead-zone function.  Q2 is held in cutoff by the control voltage on Q3, so when the signal exceeds the deadband, a signal passes to the central section that operates as an inverting stage. __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Micropower Thermocouple Signal Conditioner with Cold Junction Compensation -  A thermistor, shown as R3, is used to monitor the cold junction temperature.  Its resistance becomes smaller as the cold junction temperature increases.  An increase in cold junction temperature will reduce the output voltage of the Type J thermocouple by 52uV/C.  The voltage reference and scaling of resistor values creates an __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Mobile Bug Detector -  This handy, pocket-size mobile transmission detector (Mobile Bug) can sense the presence of an activated mobile phone from a distance of one and a-half metres.  So it can be used to __ Electronics Projects for You

Negative resistor cancels op-amp loA - D -  05/24/01 EDN-Design Ideas Accurate op amps have high openloop gain, low offset voltage and current, low voltage and current noise, and low distortion.  However, they often lack the ability to provide high output.   PDF have several circuits, scroll for this one. __ Circuit Design by Elliott Simons, Maxim Integrated Products, Sunnyvale, CA

Negatrons Enrich Filter, Oscillator Design -  EDN-Design Ideas 07/21/94    The latest wave of high-performance op amps allows you to incorporate "negatrons" (synthesized negative resistors) into your oscillators and filters.  Fig 1 shows the universal filter/oscillator circuit based on a simulated lossy inductor and a negative resistance, which compensates the lossy inductor.  Note that the circuit has no physical inductors.  The performance of this circuit is very predictable and repeatable __ Circuit Design by Aleksandr Belousov, Baltimore, MD

NiCd Cells Drives Op Amp -  12/05/96 EDN-Design Ideas Low-supply-voltage op amps, such as the LMC6582 and LMC6681 families, feature rail-to-rail I/O with a gain-bandwidth product greater than 1 MHz operating from just 1.8V.  Although impressive, this voltage is not low enough to power these amps using a single alkaline or NiCd/NiMH
cell, which have typical voltages of 1.25 to 1.5V.  It is rather tempting to bridge this gap by designing a DC/DC converter __ Circuit Design by Alexander Belousov, Rego Park, NY

Noise Calculations in Op Amps -  DN15 Design Notes __ Linear Technology/Analog Devices

Noninverting op-amp has Simple Circuit gain formula -  11/28/02 EDN-Design Ideas Basic textbooks describe inverting and noninverting amplifiers based on operational amplifiers.  These amplifiers have different gain equations.  Whereas in the inverting configuration, the gain is the ratio of the feedback and input resistances, in the noninverting amplifier, the gain ratio has an added term __ Circuit Design by José Carrasco and Ausias Garrigós, Universidad Miguel Hernández, Elche, Spain

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One Op Amp achieves double-hysteresis-transfer characteristic -  09/27/07  EDN-Design Ideas An op amp combines with strategically placed zener diodes to yield a process-control circuit that has positive- and negative-going hysteresis bands __ Circuit Design by Herminio Martínez, Encarna García, and Juan Gámiz, Technical University of Catalonia, Barcelona, Spain

Op Amp as a Set/Reset Flip-Flop -  05/24/12  EDN-Design Ideas Eliminate a flip-flop package by using a spare op amp for an SR latch function.  You can make a set/reset flip-flop from two NAND or NOR gates or use readily available set/reset flip-flop ICs, such as the 74HC279 quad-set/reset latch.  The drawback of these methods is that they require a large amount of space to form the flip-flop.  Even if you need only one flip-flop, you must use a large IC package with this approach.  However, you can use a spare rail-to-rail op amp to perform the needed latch function (Figure 1). __ Circuit Design by Aruna Rubasinghe

Op Amp Bandwidth -  (spice design) __ Designed by Rick 

Op Amp Based FM Transmitter -  An low power FM Transmitter using an op-amp as the audio preamp and a single transistor as the RF amplifier. __ Designed by Kamran Ahmed

Op Amp can source or sink current -  03/02/06 EDN-Design Ideas   Bipolar current source beats familiar Howland-current pump __ Circuit Design by Alfredo H Saab and Steve Logan, Maxim Integrated Products Inc,  Sunnyvale, CA; Edited by Brad Thompson and Fran GranvilleMarch 2, 2006

Op Amp Comparator & Reference IC Provides Micropower Monitoring Capability Design Note 190 -  DN190 Design Notes __ Linear Technology/Analog Devices

Op Amp Comparator & Reference IC Provides Miscropower Monitoring Capability -  Design Notes 190 __ Linear Technology/Analog Devices

Op Amp Comparator with Hysteresis with SPICE simulation -  The challenge sounds simple enough, take a 60 Hz (or 50 Hz) sinewave from the AC power line and convert it to a square wave.  This signal will serve as a clock to drive counters for a 24 hour time clock.  So you hook up an op amp as a comparator to do the job.  But your surprised to see the clock running too fast! With oscilloscope in hand you discover the AC line is noisy! And to your horror, you see glitches (spice design)

Op Amp Differentiator-Open Loop Analysis -  (spice design) __ Designed by Rick 

Op Amp Feedback Analysis -  (spice design) __ Designed by Rick 

Op Amp Improves Power Supply's Regulation -  6-Jun-96 EDN-Design Ideas A typical power supply has a voltage-regulation specification of 2 to 3% for all conditions, including initial setting, line, load, and temperature.  You can improve regulation if the power-supply has remote-sensing capability, however __ Circuit Design by Jimmie D Felps, Hewlett-Packard, Colorado Springs, CO

Op Amp increases potentiometer's resolution -  06/05/00 EDN-Design Ideas A key parameter of digitally controlled potentiometers(DCPs] is the number of taps(n] programmable positions of the wiper.  This parameter establishes the resolution in  programmable-voltage and -current applications.  A number of circuitPDF has many circuits, please scroll to find this one __ Circuit Design by Chuck Wojslaw, Xicor Inc, Milpitas, CA, and P Gareth Lloyd, Elab Ltd, Stoke-on-Trent, UK

Op Amp Input Voff & Ibias -  (spice design) __ Designed by Rick 

Op Amp Limiter -  (spice design) __ Designed by Rick 

Op Amp linearizes attenuator control response -  07/25/02 EDN-Design Ideas Professional-audio equipment commonly uses Analog Devices'(www.analog.com] high-performance, quad-voltage-controlled SSM2164 attenuator.  The control response is -30 dB/V, with 0V producing unity gain.  Attenuation increases as the applied control voltage increases in the positive direction.  The circuit in Figure 1 extends the range of applications for this versatile chip by providing a simple __ Circuit Design by Mike Irwin, Shawville, PQ, Canada

Op Amp linearizes response of FET VCA -  09/05/02 EDN-Design Ideas   FETs find common use in VCAs(voltage-controlled amplifiers]and attenuators, in which the FET serves as a variable resistance.  A control voltage applied to the gate sets the channel resistance and overall circuit gain __ Circuit Design by Mike Irwin, Shawville, PQ, Canada

Op Amp Macro-Models -  (spice design) __ Designed by Rick 

Op Amp makes precise 9V-battery splitter -  07/17/97 EDN-Design Ideas Alkaline 9V batteries are ideal for many portable, handheld applications, this circuit generates a bipolar supply of5V and ­2.3 to ­4V using a precision5V reference and one op amp as a supply splitter __ Circuit Design by Steve Hageman, Hewlett-Packard, Santa Rosa, CA

Op Amp PID Controller -  We've all heard about the wonders of the PID controller, bringing a system's output, temperature, velocity, light, to its desired set point quickly and accurately.  But now, your boss says okay, design one for us.  Although there's a number of ways to do it, the circuit above nicely separates the three terms (spice design)

Op Amp Provides On-The-Fly Adjustable Current Limit -  DN298 Design Notes __ Linear Technology/Analog Devices

Op Amp Radio -  Here is a simple radio that is easy to build and inexpensive.  In fact, you probobly have all the parts you need in your junk box.  You'll be suprised at the great reception with this little set. __ Designed by Aaron Cake

Op Amp Triangle-Wave Generator & SPICE simulation files -  This signal generator gives you two waveforms for the price of one: a triangle-wave and a square-wave. What is the central component of this circuit? The integrator capacitor CI

Op Amps Make Automatic-Oring Power Selector -  08/11/11  EDN-Design Ideas Replace diodes with FETs to reduce power loss.  Many systems must select among two or more low-voltage dc-input sources, such as an ac adapter, a USB (Universal Serial Bus) port, or an onboard battery, for example.  You can implement this selection using manual switches, but automatic switching is preferable.  You usually want to use the highest-available input voltage to power your system.  You can accomplish this task using a Schottky-diode ORing scheme (Figure 1).  Unfortunately, the forward-voltage drop of a Schottky diode ranges from 300 to 600 mV.  This voltage wastes power, creates heat, and decreases the voltage available to your system. __ Circuit Design by Bob Zwicker, Analog Devices, Fort Collins, CO

Op Amps make JFETs repeatable -  05/24/01 EDN-Design Ideas Because they use practically no bias current(a useful feature in itself), JFETs also have practically no current noise.  This feature means that you can use JFETs in very-high-resistance circuits and obtain good noisePDF has many circuits, scroll for this one __ Circuit Design by Glen Brisebois, Linear Technology Corp, Milpitas, CA

Op-amp Astable Timer -  An astable timing circuit made from the ubiquitous 741 op-amp. __ Designed by Andy Collison

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Op-Amp based battery voltage Monitor -  An ECU must have a way to monitor battery voltage.  Here is a simple op-amp based circuit which will illuminate the LED when the battery voltage drops to a certain level.  The turn-on point is set with R2.  You must be able to vary Vcc   (usually with a good power supply) to set the circuit.  Decide at what voltage you'd like the LED to illuminate, and apply this at Vcc.  Adjust R2 until the light just illuminates.  Use an LED which will light at the desired voltage level, and determine R3, using ohm's law   (E=IR), to keep the current flowing through the LED and op-amp to around 10mA. 

Op-amp based Nv nets -  A more complex, but more flexible way of implementing bicores and quadcores and such.  At first glance, just another bicore variation, but with a higher component count.  It seems to reverse the BEAM drive toward simplicity (i.  e.  , more parts, no apparent increase in functionality).  But wait __ Contact: Eric Seale

Opamp Based Power Amplifier -  This is a contributed project, and has some interest as a learning exercise __ Designed by Rohit Balkishan

Opamp Basics -  The op-amp is basically a differential amplifier having a large voltage gain, very high input impedance and low output impedance.  The op-amp has a "inverting" or (-) input and "noninverting" or (+) input and a single output.  The op-amp is usually powered by a dual polarity power supply in the range of +/- 5 volts to +/- 15 volts.  A simple dual polarity power __ Designed by Bill Bowden

OpAmp Doubles as Instrumentation Amp -  09/15/94 EDN-Design Ideas The circuit in Fig 1 shows an ordinary, off-the-shelf, general-purpose op amp configured as an instrumentation amplifier.  Such a configuration yields an instrumentation amplifier having higher bandwidth than currently available dedicated instrumentation/ __ Circuit Design by Moshe Gerstenhaber and Mike Gianino, Analog Devices, Wilmington, MA

Opamp Integrator -  The integrator basically works like this: whatever current I you get flowing in R1, gets integrated across capacitor C1.  The output voltage Vo is simply the voltage across C1.  One great application of the integrator is generating a ramp voltage.  You can do this by placing a fixed voltage

OpAmp Linearizes Response of FET VCA -  09/05/02 EDN-Design Ideas   FETs find common use in VCAs(voltage-controlled amplifiers]and attenuators, in which the FET serves as a variable resistance.  A control voltage applied to the gate sets the channel resistance and overall circuit gain __ Circuit Design by Mike Irwin, Shawville, PQ, CanadaSeptember 5, 2002

Op-Amp Microphone Preamplifier -  A high quality microphone preamplifier using a single power supply, suitable for dynamic or electret microphones.  The op-amp used can be any low noise, high performance type, e.  g.  NE5534, TL071, OPA 371 etc __ Designed by Andy Collison

Op-Amp Oscillators Simplify RF Design -  10/10/96 EDN-Design Ideas Figure 1 shows a novel circuit that uses a low-cost, high-speed op amp as a crystal-controlled RF sine-wave oscillator.  An op-amp oscillator offers several advantages.  Because an op amp is a complete amplifier with a high-impedance input __ Circuit Design by Charles Kitchin, Analog Devices, Wilmington, MA

Opamp Radio -  Here is a simple radio that is easy to build and inexpensive.  In fact, you probobly have all the parts you need in your junk box.  You'll be suprised at the great reception with this little set. __ Designed by Aaron Cake

Op-Amp Rectifier Signals Input State -  07/21/94 EDN-Design Ideas The op-amp rectifier in Fig 1 operates from a single supply and provIdeas a logic output and an LED that indicate the state of the input voltage.  The input-state indications are handy for calibration.  Because the circuit operates from a single supply, the 2.5V reference determines the level around which the circuit rectifies input waveforms __ Circuit Design by Lee E Scaggs, High Country TEK, Nevada City, CA

Op-Amps Basics for the beginner -  The 7 Basic Circuit Configurations for op-amps __ Designed by G.L. Chemelec

Op-Amps Basics for the beginner. -  The 7 Basic Circuit Configurations for op-amps __ Designed by G.L. Chemelec

Operational Amplifier gain & DC offset program -  Presented here is a program to find the gain and DC offset values of an operational amplifier (or op-amp).  While doing practical electronics experiments,

Operational Amplifier Selection Guide for Optimum Noise Performance #2 -  DN3 Design Notes __ Linear Technology/Analog Devices

Optical Smoke Detector -  This optical smoke detector uses a low-cost, readily-available, slotted, through-scan, infrared photo-switch.  When smoke is detected, the relay energises to activate the audio/visual warning alarm.  Fig.1 shows the circuit of the __ Electronics Projects for You

Overcurrent & Undervoltage Battery Fault Protection -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Overcurrent Battery Fault Protection -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator.  Two versions of the LT6108 are available.  The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator.  In addition, the current sense amplifier __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Over-Heat Detector -  NTC thermistors are often the preferred choice for temperature sensing and control in many applications, primarily because of their small package sizes and attractive price-performance ratios.  An NTC thermistor’s sensitivity to __ Electronics Projects for You

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Part 3 of 4: Defence Lasers & Optronic Systems: Semiconductor Diode Laser Electronic -  While semiconductor diode lasers, or simply laser diodes, are extensively used in a range of laser devices intended for tactical military applications, such as

P-channel power-MOSFET driver uses unity-gain op Amp -  21-Jan-10 EDN-Design Ideas Drive a power MOSFET to 100V dc with this signal-conditioning circuit __ Circuit Design by Suded Emmanuel, Emmanuel's Controls, Auckland, NZ

pH Probe Amplifier -  pH Probe amplifiers require buffer amplifiers with an input impedance greater than 10^13 ohms.  Without loading the probe, an output of approximately 60mV/pH unit is produce.  The thermistor is added to provide first order compensation for the inherent temperature coefficient of the pH probe output __ Linear Technology/Analog Devices App Note, Mar 16, 2010

Phase Compensation Counteracts Op-Amp Input Capacitance -  01/06/94  EDN-Design Ideas Although op amps are mature devices, many designers often ignore the effects of input capacitance on frequency stability.  A bode plot analysis lets you add compensation capacitors to counteract poles and zeros caused by an op amp's input capacitance.  A __ Circuit Design by Jerald Graeme, Burr-Brown Corp

Photodiode Amplifier -  Low input bias current amplifiers can be used to accurately detect the amount of current flowing in a photodiode.  An output voltage, 1V/uA, is created by forcing the reverse diode current to flow from the amplifier output through a large valued feedback resistor. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Photodiode Amplifier exhibits one-third the output noise of conventional transimpedance Amp -  04/26/07  EDN-Design Ideas Bumping the op amp's gain of a photodiode transimpedance amplifier by a factor of 10 and then dividing the output of a transistor gain stage by a factor of 10 achieves lower output noise __ Circuit Design by Glen Brisebois, Linear Technology Corp, Milpitas, CA

Piecewise Linear Amplifier Eschews Diode -  10/12/95 EDN-Design Ideas A common implementation of a piecewise linear amplifier uses diodes in the feedback loop of an op amp.  As the diodes become forward-biased, they effectively switch in resistors that alter the closed-loop gain of the amplifier.  This implementation has two disadvantages.  First, the diodes' shunt capacitance leads to poor high-frequency performance.  Second, __ Circuit Design by Brian Harrington, Analog Devices, Wilmington, MA

Piezoelectric Shock Sensor Amplifier -  A piezoelectric shock sensor generates a charge when physically accelerated.  This charge is transferred to the smaller feedback capacitor.  In this circuit a gain of 100 is given to the sensor’s open circuit voltage. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Platinum RTD Signal Conditioner with Curvature Correction -  The value of the resistance of the RTD sensor is converted to a voltage by running a constant current, 50uA, through it.  As the sensor heats the resistance increases and unbalances the bridges of 1K resistors.  The amplifier restores balance by sourcing more current into the lower fixed 1K resistor thus producing an increasing __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Positive Supply Rail Current Sense with Over-the-Top Op Amp -  This is a configuration similar to an LT6100 implemented with generic components.  A Rail-to-Rail or Over-the-Top input op amp type is required (for the first section).  The first section is a variation on the classic high-side where the P-MOSFET provides an accurate output current into R2 (compared to a BJT).  The second section __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Potentiometer Autonulls OpAmp -  10/22/98 EDN-Design Ideas Op-amp applications that need the highest possible dc accuracy are generally best served by CMOS chopper-stabilized amplifiers, such as the LTC1050.  But high-speed, low-noise applications may require high-performance rockets, such as the 700-MHz LT1226.  So what to do for applications __ Circuit Design by Stephen Woodward, University Of North Carolina, Chapel Hill, NC

Power Amplifier Has Transient Rail-To-Rail Swing -  09/29/94 EDN-Design Ideas Has transient rail-to-rail swing special common-drain MOSFET-based power op amp circuit __ Circuit Design by Yishay Netzer, Yuvalim, Israel

Precision Absolute Value -  An absolute value circuit as as a full wave rectifier.  Positive input voltqges cause the first amplifier to act as a unity gain inverter.  The second amplifier inverts thiis output again to produce a positive outut voltage.  Negative input voltages cause the + input of the second amplifier to move positive to a voltage of 2/3Vin. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Precision Amplifier Drives 500ohm Load to ±10V -  Two amplifiers can be combined to double the output current of just one amplifier.  In this circuit the gain is arranged in such a way that ensures that each amplifier contributes half of the load current.  One tenth of the output voltage is impressed across a resistor that is one fifth of the load resistor making its current __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Precision Amplifier with Digital Control -  This circuit is similar to the preceding circuit of the attenuator.  Gain of up to 100 can be achieved in this configuration, which is useful forb signal conditioning of low output __ Electronics Projects for You

Precision Charge Integrator -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Precision Current Sink -  A non-inverting amplifier configuration can force an input control voltage across a ground referred resistor.  This creates a precise amount of current flow.  This current must be sunk by the external transitors so the same amount of current flows to ground from a positive supply referred load circuit. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Precision Current Source -  A non-inverting amplifier configuration can force an input control voltage across a ground referred resistor.  This creates a precise amount of current flow.  This current must be sunk by the external transitors so the same amount of current flows from ground and sourced to a negative supply referred load circuit. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Precision High Voltage High Side Load Current Monitor (1754) -  The LT6016/LT6017 are dual and quad rail-to-rail input operational amplifiers with input offset voltage trimmed to less than 50μV.  These amplifiers operate on single and split supplies with a total voltage of 3V to 50V and draw only 315μA per amplifier.  The Over-The-Top input stage of the LT6016/LT6017 is designed to __ Linear Technology/Analog Devices App Note, Dec 4th 2012

Precision level shifter has excellent CMRR -  15-Apr-04 EDN-Design Ideas Most designers make level shifters with op amps and 1%-tolerance discrete resistors.  Discrete-resistor mismatching limits the op amp's CMMR(common-mode rejection ratio] to 40 dB, so you cannot use op amps in circuits that require high CMRR.  Differential amplifiers contain precision matched internal resistors, so ICs such as the INA133 can readily achieve CMRRs of approximately 90 dB __ Circuit Design by Ronald Mancini, Texas Instruments, Bushnell, FL

Precision op-amp enables fast multiplexing at low power -  EDN-Design Ideas 04/29/2016    LTC Design Notes: A multiplexed DAQ design presents some subtle challenges, and parts selection plays a crucial role __ Circuit Design by LTC Design Note

Precision Photodiode Amplifier -  The LT1880 provides a high degree of precision with very low bias current (IB = 150pA typical).  Total output offset is below 262mV, worst-case, over temperature (0°C to 70°C).  With a 5V output swing this implies a minimum 86dB dynamic range. __ Linear Technology/Analog Devices App Note, Mar 22nd 2010

Precision Voltage Controlled Current Source -  The ultra-precise LTC2053 instrumentation amplifier is configured to servo the voltage drop on sense resistor R to match the command VC.  The LTC2053 output capability limits this basic configuration to low current applications. __ Linear Technology/Analog Devices App Note, Mar 31st 2010

Program an Op-Amp Gain Block with a Limited-Adjustability, Monolithic, Solid-State Resistor -  08/21/08 EDN-Design Ideas An op-amp gain block allows a solid-state trimming potentiometer with limited adjustability to trim over the complete input range __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

Program Designs single-supply op-amp -  10/26/95 EDN-Design Ideas Mathematically, there is no difference between single- and dual-supply op-amp designs, except for the signal reference.  Dual-supply designs inherently reference signals to ground.  However, you must use biasing to reference signals to ground in a single-supply design, because the signals are inherently referenced to VCC/2.  This requirement for external bias schemes complicates the design procedure.  The Basic program, which you can download from. __ Circuit Design by Ronald Mancini and Dave Culver, Harris Semiconductor, Melbourne, FL

Provide Inverting/Noninverting Gain -  11/09/95 EDN-Design Ideas The amplifier in Figure 1a is a well-known circuit that provIdeas voltage gain of +1 or –1, depending on the logic voltage (0 or 5V) you apply to the MOSFET gate.  By adding one resistor (Figure 1b), the amplifier can provide gain of +AV or –AV with the same logic control.  The gain is ±R3/R2, and R1 is (R3R2)/(R3–R2.).  You need a driving source with low output impedance, and the input impedance of the circuit is different for the two states. __ Circuit Design by    Victor Koren, Orckit Communications Ltd  Tel Aviv, Israel

Provide linear I-to-V conversion -  01/18/96 EDN-Design Ideas The circuit in Figure 1 provIdeas a 4to 20-mA voltage-to-current conversion for noise-immune data transmission in industrial data-acquisition systems.  The circuit supplies two voltages to the inverting input of the control amplifier IC1A.  The first voltage, from the follower IC1B, introduces an offset in the transfer function of the circuit __ Circuit Design by Jordan Dimitrov, N Pouskarov Institute, Sofia, Bulgaria

PWM uses one Op Amp -  07/06/00 EDN-Design Ideas A previous Design Ideas is reminiscent of a similar but somewhat simpler circuit (see "Low-power PWM circuit is simple, inexpensive," EDN, Jan 6, 2000, pg 119).  This circuit delivers a rectangular signal with duty cycle varying between 0 and 100% in response to an input signal varying from 0 to 5V dc (Figure 1).  As with the above-mentioned circuit, the frequency is not constant (Figure 2), but the circuit is so simple that it can be useful in certain applications. __ Circuit Design by Ferran Bayes, Electronica Digital, Barcelona, SpainJuly 6, 2000

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Rail Gun, buiding project Research lab -  This page carries the images and videos of the Rail Gun construction effort; a 120-hour endeavor that cost approximately $800 of my own money, not counting sponsor-supplied materials.  All images are high resolution; the original can be seen by clicking on the thumbnail.

Rail to rail audio power amp -  In winter 2015, I built 5 HF regens plus 2 VHF super regenerative receivers.  I’ve run out of my better quality air variable capacitors, potentiometers and room — each version seems larger and uglier than the previous.  With all these experiments, I’ve advanced about 2 mm up the regen receiver design learning curve — and in standard form factor, more questions arose than answers. __ Contact: Vasily Ivanenko

Rail-to-Rail 1MHz Pulse Width Modulator -  In applications where a high frequency variable PWM generator is needed, the LT1715 provides a small and simple solution, as shown in the circuit of Figure 10.  The top comparator, U1A, acts as a ramp generator.  Biasing resistors R1 and R2 and a 7:1 positive feedback ratio through R3 set the positive input to approximately 2.5V±250mV. __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Rail-To-Rail Amplifiers Operate on 2.7V with 20µV Offset -  DN230 Design Notes __ Linear Technology/Analog Devices

Rail-To-Rail I/O & 2.4V Operation AlLow Ultrafast Comparators to Be Used on Low Voltage Supplies -  DN248 Design Notes __ Linear Technology/Analog Devices

Rail-to-rail Op Amp provides biasing in RF Amp -  01/20/00 EDN-Design Ideas It is often useful to monitor the dc level of an RF signal.  However, most RF systems use capacitive coupling; thus, the dc information is lost.  The circuit in Figure 1 is an RF amplifier comprising two monolithic microwave integrated circuits (MMICs), IC 1 and IC 2 , and a quad rail-to-rail op amp (IC 3 , an LT1633). IC 3A restores the dc level at the output. __ Circuit Design by Frank Cox

Rail-to-Rail Voltage Comparator -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Rail-to-Rail Voltage Comparator-23007.0 -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Rail-to-Rail Voltage follower/Buffer -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Rail-to-Rail Window Comparator-23008.0 -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

RC Notch Filter (Twin T) -  The twin T notch filter can be used block an unwanted frequency or if placed around an op-amp as a bandpass filter.  The notch frequency occurs where the capacitive reactance equals the resistance Xc=R and if the values are close, the attenuation can be very high and the notch frequency virtually eliminated __ Designed by Bill Bowden

Reduced Power Infra-Red Diode Driver -  Infra-Red LEDs can be used as continuously operating beams of light.  Sensing a break in the path of light between the source and a photodiode receiver is often used in safety and alarm systems.  To extend the run-time of the light source, the diode conducts the minimum current necessary, in this case 10mA.  Controlling the duty __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Regen receiver #4 -  This Winter, after a ~4 year hiatus from regenerative receivers, I built 4 while studying the plethora of published designs in print and on the web.  How do you describe the sounds that regens deliver? Perhaps the adjective "screechy", or adjective-verb phrase "alive with vibe" might do ---  and when tuning across a SWL band they emit those classic wee-woo sounds that signal we're close to receiving some yet unknown, far off, station __ Contact: Vasily Ivanenko

Regenerative receiver #5 -  In winter 2015, I built 5 HF regens plus 2 VHF super regenerative receivers.  I’ve run out of my better quality air variable capacitors, potentiometers and room — each version seems larger and uglier than the previous.  With all these experiments, I’ve advanced about 2 mm up the regen receiver design learning curve — and in standard form factor, more questions arose than answers. __ Contact: Vasily Ivanenko

Resistance Measurement using Sample & Hold Method -  A sample and hold circuit, as the name implies, samples an analogue input signal and holds its value until the input is again sampled.Fig.1 shows the basic principle of the __ Electronics Projects for You

Resistive DAC & Op Amp Form Hybrid Divider -  17-Sep-09 EDN-Design Ideas A programmable resistance is all you need in a feedback loop __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

RF oscillator uses current-feedback op Amp -  10/03/02 EDN-Design Ideas A current-feedback amplifier is a well-known component with many uses.  Its basic block diagram shows that its input stage is a voltage follower—in practice, a symmetrical emitter follower(Figure 1).  The configuration samples the output current, converts it to voltage across a large impedance, and amplifies it to the output using a high-power, low-output-impedance amplifier __ Circuit Design by Victor Koren, Tioga Technologies Ltd, Tel Aviv, Israel

Robust high voltage Over-the-Top op-amps -  EDN-Design Ideas 01/29/2016    LTC Design Notes: Learn how the innards of an “over-the-top” op-amp work (where inputs can be higher than V+), as well as related design considerations.  Maintains high input impedance with inputs driven apart or when powered down __ Circuit Design by LTC Design Note

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Saturated Standard Cell Amplifier -  The amplifier is a standard non-inverting gain stage that can be trimmed to any specific output level.  A low-leakage FET is used as a cell disconnect when power is removed. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Schmitt Trigger -  This circuit uses a single op-amp and the output is triggered by two different voltage levels. __ Designed by Andy Collison

Seismic Sensor -  This circuit simulates a seismic sensor to detect vibrations/sounds.  It is very sensitive and can detect vibrations caused by the movement of animals or human beings.  So it can be used __ Electronics Projects for You

Selecting Op Amps for Precision 16-Bit DACs -  DN214 Design Notes __ Linear Technology/Analog Devices

Self-Powered High Side Current Sense -  This circuit takes advantage of the microampere supply current and Rail-to-Rail input of the LT1494.  The circuit is simple because the supply draw is essentially equal to the load current developed through RA.  This supply current is simply passed through RB to form an output voltage that is appropriately amplified __ Linear Technology/Analog Devices App Note, Mar 30, 2010

Self-Trimming Op Amp Cuts Error -  12/05/00EDN-Design Ideas The TLC4502 dual op amp from Texas Instruments invokes an analog/digital self-calibration circuit and 300-msec procedure on power-up, yielding a maximum input offset voltage of less than 50 mV.  After the op amp completes a cycle, it automatically removes most of the calibration circuitry from the signal path, leaving a device that appears and operates as any conventional op amp.  It requires no external input, calibration, or control signals.  Applications include data-acquisition, sensor-interface, and automotive designs. __ Circuit Design by Bill Schwebe

Shadow Alarm -  This opto-sensitive circuit sounds an alarm whenever a shadow falls on it.  So it can be used at night by shopkeepers to protect the valuables in their showrooms.  A dim lighting __ Electronics Projects for You

Simple Adjustable Staircase Waveform Generator -  Staircase signals find many applications in the field of electronics, such as in television systems, telemetry, and analogue and digital communications.  Here is a circuit illustrating the basic principles of staircase __ Electronics Projects for You

Simple Circuit 3 Transistor Audio Amp (50 milliwatt) -  Here is a little audio Amplifier similar to what you might find in a small transistor radio __ Designed by Bill Bowden

Simple Circuit Bidirectional DC Motor Speed Controller Without a Tachometer -  For motor speed control without using a tachometer, the circuit in Figure 12 shows an approach.  Using the enable feature of the LT1970A, the drive to the motor can be removed periodically.  With no drive applied, the spinning motor presents a back EMF voltage proportional to its rotational speed.  The LT1782 is a tiny rail-to-rail __ Linear Technology/Analog Devices App Note, Dec 5th 2011

Simple Circuit Differential Front-End for the LTC2400 Simple Circuit Rail-To-Rail -  Design Solutions 2 Design Notes __ Linear Technology/Analog Devices

Simple Circuit Op-Amp Radio -  This is basically a crystal radio with an audio amplifier which is fairly sensitive and receives several strong stations in the Los Angeles area with a minimal 15 foot antenna.  Longer antennas will provide a stronger signal but the selectivity will be worse and strong stations may be heard in __ Designed by Bill Bowden

Simple Circuit Timer Exploits OpAmp Bias Current -  07/21/94 EDN-Design Ideas The simple, low-cost analog timer in Fig 1 exploits the parasitic input-bias current of op-amp IC1.  The timer achieves long time delays even though it uses only low-value, inexpensive ceramic chip capacitors.  After all, because the input-bias current is the minimum current flow into an op amp, __ Circuit Design by Aleksandr Belousov, Baltimore, MD

Simple Low-Noise Audio-Distribution Amplifier -  This article describes a low-cost audio-distribution low noise amplifier based on hybrid or mixed technology.  Input to the amplifier is from low-noise, high-gain npn transistor.  Output buffers are implemented with voltage followers __ Electronics Projects for You

Simple Low-Power Audio Amplifier -  The small-signal amplifier is generally referred to as a voltage amplifier because it usually converts a small input voltage into a much larger output voltage.  The audio power amplifier works on __ Electronics Projects for You

Simplified DC Motor Torque Control -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Simplified DC Motor Torque Control-LT6108 -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator.  Two versions of the LT6108 are available.  The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator.  In addition, the current sense amplifier __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Simplified DC Motor Torque Control-LT6109 -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same __ Linear Technology/Analog Devices App Note, Sep 7th 2011

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Single 2.7V to 20V Supply Current Source for –50°C to 600°C Platinum RTD -  The LT6010 op amp combines low noise and high precision input performance with low power consumption and rail-to-rail output swing.  Input offset voltage is trimmed to less than 35mV.  The low drift and excellent long-term stability guarantee a high accuracy over temperature and over time.  The 110pA maximum input bias current __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Single Ended Adder/Subtractor -  This circuit shows Using Vcom as third algebraic input in an addition/subtraction circuit.  This is useful for adding or translating signals. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Single NiCd Cells Drives Op Amp -  12/05/96 EDN-Design Ideas Low-supply-voltage op amps, such as the LMC6582 and LMC6681 families, feature rail-to-rail I/O with a gain-bandwidth product greater than 1 MHz operating from just 1.8V.  Although impressive, this voltage is not low enough to power these amps using a single alkaline or NiCd/NiMH
cell, which have typical voltages of 1.25 to 1.5V.  It is rather tempting to bridge this gap by designing a DC/DC converter __ Circuit Design by Alexander Belousov, Rego Park, NY

Single Op Amp achieves double-hysteresis-transfer characteristic -  09/27/07  EDN-Design Ideas An op amp combines with strategically placed zener diodes to yield a process-control circuit that has positive- and negative-going hysteresis bands __ Circuit Design by Herminio Martínez, Encarna García, and Juan Gámiz, Technical University of Catalonia, Barcelona, Spain

Single Op-Amp Bandpass Filter -  A bandpass filter passes a range of frequencies while rejecting frequencies outside the upper and lower limits of the paSSBand.  The range of frequencies to be passed is called the paSSBand and extends from a point below the center frequency to a point above the center frequency where the output voltage falls about 70%

Single Supply 10MHz Lowpass Filter Features the LT1819 Op Amp & Adjustable Bandwidth Up to 20MHz -  Low noise, low distortion LT1819 circuit trades parts count and components sensitivity for an adjustable bandwidthup to 20MHz Diff in diff out circuit.  Measured signal-to-noise plus distortion for LT1819 circuit is 71.5dB, just a little nosier than the fixed bandwidth LT6600-10 filter differential filter. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Single Supply 16-Bit ADC Driver -  This circuit shows the LT6203 driving an LTC1864 unipolar 16-bit, 250ksps A/D converter.  The bottom half of the LT6203 is in a gain of 1 and buffers the 0V negative fullscale signal VLOW into the negative input of the LTC1864.  The upper half of the LT6203 is in a gain of 10, referenced to the buffered voltage VLOW and drives __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Single Supply Current Source for Platinum RTD -  The LT1800's Precision and low bias input stage is used to good advantage in Fig.5 Single Supply Current Source for Platinum RTD circuit.  R4 and C1 stabilize the circuit making it insensitive to cable characteristics.  Output is 1.00V at 0şC and its gain factor is 3.85mV/şC. __ Linear Technology/Analog Devices App Note, Jul 2nd 2012

Single Supply Shock/Vibration Sensor Amplifier -  The LTC6087/LTC6088 are dual/quad, low noise, low offset, rail-to-rail input/output, unity-gain stable CMOS operational amplifiers that feature 1pA of input bias current.  A 14MHz gain bandwidth and 7.2V/μs slew rate, combined with low noise (10nV/√Hz) and a low 0.75mV offset, make the LTC6087/LTC6088 useful in a variety __ Linear Technology/Analog Devices App Note, Jul 25th 2012

Single Supply Strain Gauge Amplifier -  A dual CMOS amplifier with low supply voltage operation and rail to rail input and output performance makes single supply operation easy.  This circuit provides a gain of 1001 to the small differential input signal from a low voltage strain gauge bridge transducer.  High input impedance allows for high valued input resistors to minimize loading on the bridge network. __ Linear Technology/Analog Devices App Note, mar 16, 2010

Single Supply Type K Thermocouple Signal Conditioning Amplifier with Cold Junction Compensation -  The LTC2050 is a zero-drift precision chopper stabilized operational amplifier available in the 5- or 6-lead SOT-23 and SO-8 packages.  It minimizes board area while providing uncompromising DC performance, including 3mV (max) DC offset and 30nV/°C (max) DC offset drift.  It operates from a 2.7V supply while still supporting __ Linear Technology/Analog Devices App Note, Apr 9th 2010

Single Supply Video Line Driver (AC Coupled) -  When AC-coupling video, the waveform Dynamics change with respect to the bias point of the amplifi er according to the scene brightness of the video stream.  In the worst case, 1VP-P video (composite or Luminance + Sync in Y/C or YPBPR format) can exhibit a varying DC content of 0.56V, with the dynamic requirement being __ Linear Technology/Analog Devices App Note, Mar 25th 2010

Single Supply, Micropower Sample & Hold -  Two op amp buffers, CMOS switches and a low leakage capacitor create a simple sample/hold circuit.  The LT1006 has the ability to speed up response and reduce supply current through pin 8.  When sampling the amplifiers are sped up to acquire signals in just 20us.  When put into hold mode the supply current is throttled back to only 250uA __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Slow Op Amp makes fast multivibrator -  01/01/98 EDN-Design Ideas A classic one-shot multivibrator using an op amp(Figure 1a) needs a relatively long-duration triggering pulse, even though the circuit is in theory a slope-triggered configuration.  This limitation can be a problem when you want to use a "spare" op amp from a dual or quad package(LM324, LM358, LM6482, or LT1013, for example) triggered __ Circuit Design by Lukasz Sliwczynski, University of Mining and Metallurgy, Krakow, Poland

SOT-23 Micropower Rail-to-Rail Op Amps Operate with Inputs Above the Positive Supply -  DN221 Design Notes __ Linear Technology/Analog Devices

Source Resistance Induced Distortion in Op Amps -  DN84 Design Notes __ Linear Technology/Analog Devices

Square-Root Circuit -  This circuit generates the square root of the input at a reference voltage.  Such type of square-root output is normally used in R&D labs.  Fig.1 shows the proposed circuit.  A sawtooth __ Electronics Projects for You

Strain Gauge Signal Conditioner with Bridge Excitation -  A buffered 7V reference provides a 5V excitation voltage to a balanced strain gauge resistor bridge.  To provide a 0V output when the bridge is perfectly balanced, a second amplifier biases the bottom of the bridge to a negative compliment of the 5V excitation voltage.  Using a dual matched amplifier package such as the LT1002 __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Summing Amplifier -  The summing amplifier is a handy circuit enabling you to add several signals together.  What are some examples? If you're measuring temperature, you can add a negative offset to make the display read "0" at the freezing point.  On a precision amplifier, you may need to add (spice design)

Super Low Distortion Variable Sine Wave Oscillator -  The LT1028 (gain of –1 stable) /LT1128 (gain of +1 stable) achieve a new standard of excellence in noise performance with 0.85nV/rtHz 1kHz noise, 1.0nV/rtHz 10Hz noise.  This ultralow noise is combined with excellent high speed specifications (gain-bandwidth product is 75MHz for LT1028, 20MHz for LT1128) , distortion-free __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Switched-Gain Op Amp Serves as Phase Detector or Mixer -  05/01/08  EDN-Design Ideas By switching the disable input of an op amp at a reference frequency and lowpass-filtering its output, you can obtain a dc voltage proportional to the phase difference __ Circuit Design by W Bruce Warren, Marietta, GA

Switched-Capacitor Integrator -  We can strap this circuit onto the front end of an opamp to create the basic building block of many filter circuits the integrator.  However, the major obstacle to happy filtering is the mine field of stray capacitance.  These uncontrolled strays can add significant capacitance to the switched capacitor, destroying the accuracy of your desired filter __ Designed by Rick 

SwOpAmp Makes Square-wave Generator -  02/15/96 EDN-Design Ideas A simple technique provIdeas phase compensation for the oscillator in Figure 1a.  In this circuit, a tungsten lamp regulates the amplitude of a crystal bridge oscillator.  This type of oscillator produces a very low-distortion output at a very stable frequency.  The op amp must have a __ Circuit Design by Jim Todsen, Burr-Brown Corp Tucson, AZ

Synchronous Modulator -  File contains two versions.  This unique circuit uses a very small amount of battery current and has excellent carrier suppression.  Its only shortcoming is that you must limit the input signal to 0.7 Vp-p in order to prevent distortion.  To use higher input __ Designed by Andrew R. Morris

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TDA2822 Stereo Audio Amplifier -  TDA2822 is a low power stereo Op Amplifier used in Walkman players and Hearing aids.  It can give 250 mW output.  TDA2822 is an ideal Op amp for low output applications.  It is a good choice as a preamplifier in stereo high power amplifier circuits.  It has two inputs and two outputs which can deliver 250 milli watts output power. __ Designed by D Mohankumar

The LT1993-2 Driving an LTC2255 ADC Sampling at 96.12Msps with a 70MHz, 4-Channel WCDMA Signal -  70MHz IF signal driver into ADC.  Four to one transformer on input with capacitive coupling into input of LT1993-2, LC filter on output provides Out of Band Filtering. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

The LT6105 Can Monitor the Current of Either Positive or Negative Supplies, Without a Schematic Change. -  Positive or negative current flow is measured by just swapping inputs, -IN connected to most negative side of sense resistor.  +IN is connected to most positive side of sense resistor. __ Linear Technology/Analog Devices App Note, Jun 29th 2012

Thermally Controlled NiCad Charger -  A voltage controlled current (maximum of 1A) is used to charge a NiCd battery.  The control voltage is derived from the temperature difference between the battery and the ambient air.  The charge current is reduced as the battery heats up. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Thermistor Liquid Flowmeter -  The LT1014 is the first precision quad operational amplifier which directly upgrades designs in the industry standard 14-pin DIP LM324/LM348/OP-11/4156 pin configuration.  It is no longer necessary to compromise specifications, while saving board space and cost, as compared to single operational amplifiers. __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Three-op-amp state-variable filter perfects the notch -  EDN-Design Ideas 12/15/2014     There are many variants of the state-variable filter, but this one might just have the best notch output(s).   The usual schematic of a state-variable filter with two inverting integrators is well known.
Curiously, the input signal is almost always connected to the minus input of U1.  Figure 1 is an example with ω0 = 1kHz and Q = 5.   Figure 1  Typical state-variable filter The circuit is known for its versatility, and ability to simultaneously provide low-pass, band-pass, and high-pass outputs.   Gain, center frequency, and Q may be adjusted separately. __ Circuit Design by Alain Temps

Timer Exploits OpAmp Bias Current -  07/21/94 EDN-Design Ideas The simple, low-cost analog timer in Fig 1 exploits the parasitic input-bias current of op-amp IC1.  The timer achieves long time delays even though it uses only low-value, inexpensive ceramic chip capacitors.  After all, because the input-bias current is the minimum current flow into an op amp, __ Circuit Design by Aleksandr Belousov, Baltimore, MD

Tiny Dew Sensor -  Dew (condensed moisture) adversely affects the normal performance of sensitive electronic devices.  A low-cost circuit described here can be used to switch off any gadget automatically in case of excessive humidity.At __ Electronics Projects for You

Transimpedance Amplifier -  You may have noticed that most circuits work on a convenient principle: Voltage In, Voltage Out.  But, what about the large class of sensors, such as a photodiode, that produce a current? Photodiodes may be called into action for applications such as precision light meters or high-speed fiber-optic receivers.  If you need to amplify the signal from this type of sensor, you must first convert this current to a useful voltage (spice design)

Transimpedance synchronous Amplification nulls out background illumination -  12/03/07  EDN-Design Ideas In optical spectroscopy a correct intensity measurement of the probe beam is fundamental during material characterizationLight sensors find use in a host of important applications, spanning from consumer electronics, such as ambient-light measurements __ Circuit Design by Stefano Salvatori and Gennaro Conte, University Roma Tre, Rome, Italy; Editedby  Charles H Small and Fran Granville-December 3, 2007

True op-amp made from inverters -  11/18/13  EDN-Design Ideas Designs that stretch parts beyond their intended use, like this true op-amp constructed from eight CMOS inverters, have a certain special appeal __ Circuit Design by Colin Weltin-Wu

Two Op Amps Provide Averaged Absolute Value -  30-Oct-03 EDN-Design Ideas The circuit in Figure 1 is useful when you need amplitude demodulation or an averaged absolute-value conversion.  The circuit comprises two stages, the first of which, IC1A, is a differential-output absolute-value converter.  The second stage, IC1B, is a traditional differential amplifier.  The combination of the two stages performs single-ended absolute-value conversion but only if R3>>R2 __ Circuit Design by Dobromir Dobrev, Jet Electronics, Sofia, Bulgaria

Two OpAmps Make Fast Full Wave Rectifier -  03/14/96 EDN-Design Ideas The circuit in Figure 1 is a precision full-wave rectifier with the following characteristics. __ Circuit Design by Fernando Werlang, CPqD-Telebras, Campinas, Brazil

Two-Op Amps Provide Averaged Absolute Value -  10/30/03  EDN-Design Ideas The circuit in Figure 1 is useful when you need amplitude demodulation or an averaged absolute-value conversion.  The circuit comprises two stages, the first of which, IC1A, is a differential-output absolute-value converter.  The sec __ Circuit Design by Dobromir Dobrev, Jet Electronics, Sofia, Bulgaria

Typical Single-Ended to Differential Conversion -  Basic Single-Ended to Differential Conversion Circuit Example which shows a gain of 10 with no external resistors to set the gain.  The resistors are factory trimmed to give a very accurate gain and the gain setting resistors are closely matched to maximize CMRR.  A voltage applied to the Vocm pin sets the offset. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Ultra Long Time constant Integrator -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Ultra Low Noise Op Amp Combines Chopper & Bipolar Op Amps -  DN36 Design Notes __ Linear Technology/Analog Devices

Ultra Low Voltage Differential Amplifier -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Ultra-Low Noise Low Distortion Audio Op Amp -  LT1115 __ Linear Technology/Analog Devices

Ultraprecise Current Sensing with LTC6102 -  Very low input offset allows using low value resistors while maintaining high measurement resolution.  Using low value also reduces power losses and temperature rise. __ Linear Technology/Analog Devices App Note, Jul 2, 2012

Ultra-Precision, Wide Dynamic Range 10Hz Bandwidth Photodiode Amplifier -  The low input bias current and input noise current, combined with low voltage offset, provide a precision signal monitor.  A high degree of input sensitivity is provided to the circuit by the large dynamic range, characterized by low input offset and high DC gain of the LTC2054. __ Linear Technology/Analog Devices App Note, Mar 22nd 2010

Unique IC Buffer Enhances Op Amp Designs Tames Fast Amplifiers -  AN16 Linear Technology This note describes some of the unique IC design techniques incorporated into a fast, monolithic power buffer, the LT1010.  Also, some application ideas are described such as capacitive load driving, boosting fast op amp output current and power supply circuits. __ Linear Technology/Analog Devices

Use a Self-Powered Op Amp to Create a Low-Leakage Rectifier -  10/20/11  EDN-Design Ideas An amplifier that works at 0.8V is key.  You can combine a carefully chosen op amp, a low-threshold P-channel MOSFET, and two feedback resistors to make a rectifier circuit with less forward drop than a diode   (Figure 1).  The rectified output voltage powers the active circuitry, so no additional power supply is necessary. __ Circuit Design by Martin Tomasz, Sageloop Designs, San Francisco, CA

Use an Integrator Instead Of Coupling Capacitors -  02/16/12  EDN-Design Ideas Level-shift a signal with an unknown dc offset to a known offset without ac coupling.  An ultrasonic sensor circuit requiring self-adjustment to the level of an ac-input signal also must accommodate the signal’s unknown and variable dc-bias voltage.  The circuit cannot use an ac coupling capacitor, and the resulting output must be level-shifted to a known dc offset.  The design uses a dc-offset compensator (Figure 1). __ Circuit Design by Vladimir Rentyuk, Modul-98 Ltd, Zaporozhye, Ukraine

Use an Op Amp as a Set/Reset Flip-Flop -  05/24/12  EDN-Design Ideas Eliminate a flip-flop package by using a spare op amp for an SR latch function.  You can make a set/reset flip-flop from two NAND or NOR gates or use readily available set/reset flip-flop ICs, such as the 74HC279 quad-set/reset latch.  The drawback of these methods is that they require a large amount of space to form the flip-flop.  Even if you need only one flip-flop, you must use a large IC package with this approach.  However, you can use a spare rail-to-rail op amp to perform the needed latch function (Figure 1). __ Circuit Design by Aruna Rubasinghe

Use dual Op Amp in an instrumentation Amp -  01/18/07  EDN-Design Ideas Use op amps of your choice in an instrumentation amplifier __ Circuit Design by Jerald Graeme, Burr-Brown Corp, Tucson, AZ

Use Op Amps to Make Automatic-Oring Power Selector -  08/11/11  EDN-Design Ideas Replace diodes with FETs to reduce power loss.  Many systems must select among two or more low-voltage dc-input sources, such as an ac adapter, a USB (Universal Serial Bus) port, or an onboard battery, for example.  You can implement this selection using manual switches, but automatic switching is preferable.  You usually want to use the highest-available input voltage to power your system.  You can accomplish this task using a Schottky-diode ORing scheme (Figure 1).  Unfortunately, the forward-voltage drop of a Schottky diode ranges from 300 to 600 mV.  This voltage wastes power, creates heat, and decreases the voltage available to your system. __ Circuit Design by Bob Zwicker, Analog Devices, Fort Collins, CO

Use op-amp injection for Bode analysis -  16-Sep-04 EDN-Design Ideas Bode analysis is an excellent way to measure small-signal stability and loop response in power-supply designs.  Bode analysis monitors gain and phase of a control loop.  It performs this monitoring by breaking the feedback loop and injecting a signal into the feedback node and then comparing the injected signal with the output signal of the control loop __ Circuit Design by Martin Galinski, Micrel Semiconductor, San Jose, CA

Using All four Amplifiers of the LT1397 to Drive Large zCapacitive Loads -  Four paralleled amplifiers increase load capacitor current drive capability.  A small ballast resistor at each output increases isolates the effects of each amplifier's different output offset. __ Linear Technology/Analog Devices App Note, Jun 29th 2012

Using the LTC Op Amp Macromodels -  AN48 LTC's op amp macromodels are described in detail, along with the theory behind each model and complete schematics of each topology.  Extended modeling topics are discussed, such as phase/frequency response modifications and asymmetric slew rate for JFET op amp models __ Linear Technology/Analog Devices

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Vacuum Tube Opamp Circuit -  Published In Glass Audio #3/1995 __ Contact: info @ forsselltech . com

Video multiplexer uses high-speed op Amps -  08/21/03  EDN-Design Ideas Video multiplexers route video from several sources to a single channel.  Low-end consumer products use CMOS analog switches and multiplexers, such as the 4066 and 4051.  Unfortunately, these devices have a series on-resistance that __ Circuit Design by Bruce Carter, Texas Instruments, Dallas, TX

Voltage Controlled Current Source with Ground Referred Input & Output -  A flying capacitor device such as the LTC1043 can produce a precision voltage differential over a wide common mode range.  Here it converts a ground referred input voltage directly to a differential voltage across a fixed resistor which then forces a precise current sourced at the circuit output. __ Linear Technology/Analog Devices App Note, Jun 21st 2011

Voltage-Based Controller for Switches -  Here’s a simple circuit for controlling four switches from a distance through just a pair of wires.In the circuit, the inverting inputs (pin 2) of operational amplifiers IC1 through IC4 are __ Electronics Projects for You

Water Level Controller-Cum-Motor Protector -  Many a time we forget to switch off the motor pushing water into the overhead tank (OHT) in our households.  As a result, water keeps overflowing until we notice the overflow __ Electronics Projects for You

Wide Common Mode Range 10x Gain Instrumentation Amplifier -  The LTC6090 is a high voltage precision operational amplifier.  The low noise, low bias current input stage is ideal for high gain configurations.  The LTC6090 has low input offset voltage, a rail-to-rail output stage, and can be run from a single 140V or split ±70V supplies __ Linear Technology/Analog Devices App Note, Feb 15th 2013

Wideband Digitally Programmable Gain Amplifier -  The LTC6910 is a CMOS programmable gain (from 0 to 64) amplifier.  The amplifiers provide for a differential input signal and for dc biasing the output into a precise voltage reference based level in a single supply design. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Wien Bridge Oscillator -  The opamp Wien-bridge oscillator provides a nice view into classic oscillator design using feedback analysis.  Feedback analysis reveals if your circuit is stable (well behaved) or unstable (may oscillate).  When designing amplifiers (especially high-speed ones), the trick is to avoid the conditions that make the circuit oscillate.  When designing oscillators, you strive to achieve those conditions in a predictable way.

Wien Bridge Oscillator Rail-to-Rail Sine Wave Generator  -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

Wireless Switch -  Normally, home appliances are controlled by means of switches, sensors, etc.  However, physical contact with switches may be dangerous if there is any shorting.  The circuit described here requires no physical contact __ Electronics Projects for You

Yield Accurate Absolute Values -  07/05/01  EDN-Design Ideas The circuit in Figure 1 delivers the absolute value of the input signal with an accuracy better than 10 ppm of the full-scale range.  The circuit has low zero-crossing error.  You can use it as an asynchronous demodulator, as a source __ Circuit Design by Marco Pisani, Istituto di Metrologia G Colonnetti, Turin, Italy

 


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