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Amplifier Circuits:  Hi-Impedance
Amplifier -- Main Page     

 

Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E. :

Characteristics of CMOS Logic Inverter Amplifiers -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers . . . Hobby Circuit designed by David A. Johnson P.E.-February 11, 2002

High Impedance JFET Buffers   -  I have used these circuits many times.  They are great when you need a low gain AC signal amplifier with a very high input impedance.  It is good to beyond 50MHz . . . Hobby Circuit designed by David A. Johnson P.E.-July 11, 2006



Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:

AN-10-004  Diminutive Impedance-Matching Splitters -  AN-10-004 App Note __ MiniCircuits.com

AN-70-001  Fixed attenuators help minimize impedance mismatches -  AN-70-001 Application Note __ MiniCircuits.com

Audio-test accessory isolates & matches loads -  03/16/06  EDN-Design Ideas This low-cost, switchable, dual-impedance transformation circuit comprises a single conventional transformer and two minimum-loss pads Design by Richard M Kurzrok, RMK Consultants, Queens Village, NY

Bipolar current source maintains high output impedance at high frequencies -  12/05/05 EDN-Design Ideas Use line-receiver/amp ICs to build high-frequency constant-current sources Design by Alex Birkett, University College London, Hospital National Health Service, London, UK

characteristics of CMOS Logic Inverter Amplifiers -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

CMOS Logic Inverter Amplifier characteristics -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers. . . Circuit by David A. Johnson P.E.-February, 2002

Diminutive Impedance-Matching Splitters -  AN-10-004 App Note __ MiniCircuits.com

Fast Current Feedback Amplifiers Tame Low Impedance Loads -  DN132 Design Notes __ Linear Technology/Analog Devices

Fixed attenuators help minimize impedance mismatches -  AN-70-001 Application Note __ MiniCircuits.com

High Impedance JFET Buffers   -  I have used these circuits many times.  They are great when you need a low gain AC signal amplifier with a very high input impedance.  It is good to beyond 50MHz . . . Hobby Circuit designed by David A. Johnson P.E.-July 11, 2006

High Input Impedance DC Summing Amplifier -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

High Input Impedance Precision DC Summing Amplifier -  This circuit presents a simple precision DC summing amplifer that has high imput impedance of 10Mohm.  The obviouds advantage is that the 10Mohm high input resistance of the summing resistor(s) reduces the loading on the input signal sources and therefore affords better signal accuracy and integrity. __ Advanced Linear Devices, Inc

High-Impedance Audio Buffer with JFET -  The buffer circuit described here can be used to enhance the AC input impedance of audio amplifiers that are used with pickups in musical instruments.  Some signal sources for preamplifiers, passive pickups __ Electronics Projects for You

High-Impedance Buffer Amplifier's Input includes ESD Protection -  09/28/06 EDN-Design Ideas Diodes and guard traces suppress high-voltage static-discharge transients Design by Eugene Palatnik, Waukesha, WI; Edited by Brad Thompson and Fran GranvilleSeptember 28, 2006

High-Impedance FET probe extends RF-spectrum analyzer's usable range -  21-Jul-05 EDN-Design Ideas Op amp and careful design/construction build high-impedance RF probe Design by Steve Hageman, Windsor, CA

High-Impedance voltmeter -  An ideal voltmeter has infinite input impedance, meaning that it draws zero current from the circuit under test.  This way, there will be no "impact" on the circuit as the voltage is being measured.  The more current a voltmeter draws from the circuit under test, the more the measured voltage will "sag" under the loading effect of the meter, like a tire-pressure gauge __ Designed by © EETech Media, LLC.

High-voltage Amplifier drives piezo tubes -  7-Dec-04 EDN-Design Ideas Piezoelectric tubular positioners that drive manipulators in scanning tunneling microscopes require high-voltage, low-current drive circuits.  The circuit in Figure 1 can drive high-resistance, low-capacitance piezoelectric loads at a -3-dB bandwidth of 6 kHz.  It offers a low-cost alternative to commercial driversPDF has several circuits, please scroll to find this one Design by Bipin Duggal, Netaji Subhas Institute of Technology, New Delhi, India

High-voltage CMOS Amplifier enables high-Impedance sensing with a single IC -  06/30/14  EDN-Design Ideas Accurately measuring voltages requires minimizing the impact of the instrument connection to the tested circuit.  Typical digital voltmeters (DVMs) use 10MΩ resistor networks to keep loading effects to an inconspicuous level, but even this can introduce significant error, particularly in higher voltage circuits that involve high resistances. Design by LTC Design Note

Impedance transformer flags failed fuse -  17-Dec-04 EDN-Design Ideas Figure 1depicts a circuit that detects the opening of a miniature circuit breaker or high-rupture-capability fuse in a high-reliability telecommunications power supply.  The circuit generates an alarm when a failure changes the impedance of an electromagnetic sensor.  Traditional fault-detection circuits sense the voltage difference developed across an open fuse, leakage current flowing through Design by Kevin Ackerley, Future Electronics, Vancouver, BC, Canada

JFET High Impedance Buffers -  I have used these circuits many times.  They are great when you need a low gain AC signal amplifier with a very high input impedance.  It is good to beyond 50MHz. . . Circuit by David Johnson P.E.-July, 2006

Line Driver Economically Synthesizes Impedance -  01/06/94 EDN-Design Ideas The line-driver circuit in Fig 1 uses a second op amp to synthesize the output impedance.  The conventional line-driver circuit employs a single op amp having a resistor whose resistance is equal to the desired impedance in series with the op amp's Design by Victor Koren, Orckit Communication Ltd, Ramat-Gan, Israel

Low Cost High Impedance Buffers for Oscilloscopes & Voltmeters -  Introduction Most of the low cost digital oscilloscopes and voltmeters have input resistance around 1MOhm and input capacitance around 100pF.But in many case we are in need of input resistance above 10MOhm __ Electronics Projects for You

Low Voltage High Input Impedance Precision DC Summing Amplifier -  Circuit Ideas for Designers App Note __ Advanced Linear Devices, Inc

LTC Design Note: High-voltage CMOS Amplifier enables high-Impedance sensing with a single IC -  06/30/14  EDN-Design Ideas Accurately measuring voltages requires minimizing the impact of the instrument connection to the tested circuit.  Typical digital voltmeters (DVMs) use 10MΩ resistor networks to keep loading effects to an inconspicuous level, but even this can introduce significant error, particularly in higher voltage circuits that involve high resistances. Design by John Munson

Variable Amplifier Impedance -  Figure 1 shows two amplifiers (shown as opamps) , with (a) being conventional voltage drive, and (b) is current drive.  The output impedances are in the order of zero ohms and infinite ohms in each case (this IS a theoretical discussion at the moment!).  The gain will appear to be exactly the same for each into an 8 ohm resistive load, __ Designed by Rod Elliott  ESP

Variable Amplifier Impedance -  This is a circuit where a microphone and preamp circuit   (voice circuit) have priority over any other audio signal.  You can think of this as a one way intercom, if the main amplifier is used for listening to music, then when the push to talk switch is pressed, the amplifier is switched to the voice signal. __ Designed by Andy Collison


Amplifier Circuits:  Hi Impedance


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