0.02% V/F converter consumes only 26 µA:  07/04/96 EDN-Design Ideas / (added 11/05) 

10 kHz VFC uses Charge Pump Variation:  04/09/98 EDN-Design Ideas / (Electronic Circuit diagram added 03/03)  In telemetry or security applications in which a modem connection automatically establishes itself between two systems, a failure in one of the systems can interrupt the data exchange while the connection remains established until someone physically breaks the line or restarts the failed system. This situation can also happen if your PC crashes during a long-lasting Internet download. To prevent this problem, the circuit in Figure 1 continuously supervises the RS-232C data lines (TxD and RxD) and automatically hangs up the connection when the circuit detects a long period without transmitted or received data....

8 pin µC forms one-chip Programmable VCO :  09/24/98 EDN-Design Ideas  / (Circuit / schematic design added 6/06)   The circuit in Figure 1 uses a Microchip 8-pin µC (PIC12C671) as a voltage-controlled oscillator (VCO). Because the PIC12C671 has an internal 4-MHz oscillator, four-channel 8-bit A/D converters, and built-in power-reset circuitry, you need no external components to configure the VCO. The µC reads two analog inputs through AN0 and AN1. The reference voltage for the A/D conversion is the µC's power supply VDD. The converted 8-bit data determines the duration of output high and output low. Assume, for example, the digitized outputs from AN0 and AN1 are 43 and 87, respectively. Timer 0 loads the 43 after the µC sets output GP2 to logic one. Timer 0 receives its timing from the internal clock....

AC and Op Amp Provide Variable Control Voltage:  12/06/01 EDN - Design Ideas / (Circuit / schematic design added 4/08)  Early DACs contained standard R-2R ladder networks, and produced a negative output voltage. These early DACs, such as the MAX7837/7847 and the MAX523, require both positive and negative supply rails to accommodate their negative output. With the transition to single-supply ICs, however, many modern DACs operate with a single supply rail and an inverted R-2R ladder network. .

Acolpitts VCO for Wideband (0.95-2.15 GHz) Set-Top TV Tuner Applications:  Alpha Industries Application Note 1006 (Circuit / schematic design added 6/06)

AN-1174: Startup Time[comma] Profile Measurement of PLL VCOs and Crystal Oscillators:  National Semiconductor - Application Note   (Circuit / schematic design added 6/06)

AN-213: Low Cost, Two-Chip, Voltage-Controlled Amplifier and Video Switch:  AN-213 - Analog Devices Application Notes  (Circuit / schematic design added 6/06)

AN-45-001  Automated load measurement of VCO's:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

AN-45-002  Line Stretchers Ease VCO Load-Pull Testing:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

AN-95-003  Glossary of VCO terms:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

AN-95-004  Wide Modulation Bandwidth Measurements:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

AN-95-005  How VCO Parameters Affect Each Other:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

AN-95-006  Optimizing VCO/PLL Evaluations and PLL Synthesizer Designs:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

Automated load measurement of VCO's  AN-45-001:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

Characterizing and minimizing VCO phase noise:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

Circuit Tests VCOM Drivers:  11/11/04 EDN Design Ideas  / (Circuit / schematic design added 6/06)  Flat-panel LCD monitors offer excellent image quality and more compact form factor than CRTs—hence, their steadily increasing popularity. Unfortunately, the complexity of their manufacturing process makes LCD monitors considerably more expensive than CRTs. The amplifier that drives VCOM, the voltage on the backplane of the LCD panel, must be able to drive large capacitive loads, deliver h...

CMOS Inverter VCO tunes octave to UHF:  11/19/98 EDN-Design Ideas / (Electronic Circuit diagram added 03/03) 

Design features of a synthesizer using Mini-Circuits VCOs:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

Designing VCOs and Buffers Using the UPA family of Dual Transistors (3/99) :  Application Note - California Eastern Laboratories - Doc #927  (Circuit / schematic design added 6/06)

DPP adds versatility to VFC:  11/14/02 EDN Design Ideas (added 12/04)  The basic VFC (voltage-to-frequency converter) in Figure 1 comprises an integrator (IC1) and a Schmitt-trigger circuit (IC2). The integrator converts the dc input voltage, VIN , to a linear voltage ramp, and the Schmitt trigger sets the limits of the integrator's output voltage. Feedback around both circuits provides the condition for oscillation....

Enhancing CLC031 Jitter Performance with Easy-To-Use VCXOs:  National Semiconductor - Application Note   (added 2/06)

GBSE: Gate Boost Solar Engine:  Voltage-Controlled Solar Engine: The "Gate Boost Solar Engine" is a new (6/2002) Wilf Rigter 1381-based design. This uses an internal voltage doubler to turn on a FET more efficiently.   (added 11/05)

Glossary of VCO terms  AN-95-003:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

How VCO Parameters Affect Each Other  AN-95-005:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

Inverters form three phase VCO:  08/02/01 EDN Design Ideas (added 12/04)  You sometimes need an inexpensive VCO that can produce evenly spaced three-phase outputs over a wide frequency range. You could use tracking all-phase filters with only one oscillator, but this technique is difficult to implement and offers limited range. Other methods, such as using a DSP, are feasible, but they're complex and expensive....

Inverting Latches Make Simple VCO:  06/19/97 EDN-Design Ideas / (Electronic Circuit diagram added 03/03) The output frequency of the simple VCO in Figure 1, which is synthesized from inverting latch stages, is tunable to an integer multiple of the input frequency by selecting which output phases feed back to the input multiplexer. The circuit has worked successfully in on-chip clock multiplication in ASICs. The number of latch stages that you can cascade in a real-world design limits the multiplication factor. However, this circuit is practical for applications that require low size, cost, and power consumption but that don't require output frequencies in the hundreds of megahertz. You can also use this circuit to implement a fixed delay, such as a 90° delay of a master clock (Figure 3c)....

Line Stretchers Ease VCO Load-Pull Testing  AN-45-002:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

Low Cost Circuit Biases VCOs for Cable and TV:  11/20/97 EDN-Design Ideas / (Circuit / schematic design added 6/06)   -- PLLs are useful in a variety of applications, most notably cable and TV tuners

Multilayer capacitor doubles as varactor:  03/20/03 EDN Design Ideas (added 12/04)  The main purpose for building the circuit in Figure 1 is to study the idiosyncrasies of X5R, Z5U, and Y5V multilayer ceramic capacitors. The circuit is also an inexpensive VCO (voltage-controlled oscillator) with only five components. Many types of ceramic capacitors for surface-mount placement are on the market....

Optimizing VCO/PLL Evaluations and PLL Synthesizer Designs  AN-95-006:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

PIC controlled DDS VFO 0 to 6 MHz:  (circuit added 7/02)

Programmable Clock Oscillator:  voltage controller oscillator that was designed as a wide range oscillator to generate clock pulses for a stepper motor drive system, frequency could be varied over1,000,000:1 (Electronic circuit added 5/02)

Reducing power supply noise in VCO's:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

Simple VCOM adjustment uses any logIC Supply Voltage:  09/30/04 EDN Design Ideas  / (Circuit / schematic design added 6/06)   All TFT (thin-film-transistor) LCD panels require at least one appropriately tuned VCOM signal to provide a reference point for the panel's backplane. The exact value of VCOM varies from panel to panel, so the manufacturer must program the voltage at the factory to match the characteristics of each screen.

Startup Time[comma] Profile Measurement of PLL VCOs and Crystal Oscillators:  National Semiconductor - Application Note   (Circuit / schematic design added 6/06)

Testing Dual-Chip Transistor Arrays for VCO/Buffer Amp Combinations and Two-Stage Amplifier Applications (11/28/97) :  Application Note - California Eastern Laboratories - Doc #907  (Circuit / schematic design added 6/06)

Trimless IF VCO part 2:  Maxim Application Note 688, February 5, 2001 (added 02/06)

Trimless IF VCO: Part 1: Design Considerations:  This application note explores the design fundamentals needed to implement a trimless, fixed-frequency, IF voltage-controlled oscillator (VCO) and points out the challenges in guaranteeing proper circuit operation. VCOs are essential components in the architecture of most wireless systems. In dual-conversion approaches, a fixed-frequency IF VCO is required to control the frequency translation from IF to baseband and/or baseband to IF.   APP 711: Feb 05, 2001  (added 02/06)

Universal Watchdog Fully Controls µ Preset:  05/25/95 EDN-Design Ideas / (Electronic Circuit diagram added 03/03)

Use PSPICE for Behavioral modeling of VCOs:  12/12/02 EDN Design Ideas  /  (Circuit / schematic design added 6/06)  PSpice, a member of the Spice family for PC users, is becoming a standard tool for analog and mixed analog-digital simulation. Many analog designers are familiar with the software of Design Center, Design Lab, and OrCad (www.orcad.com) PSpice and use the software in their everyday lives. This Design Idea should be helpful to those who design and simulate PLL systems at a behavioral level....

Using the LTC6900 Low Power SOT-23 Oscillator as a VCO:  DN293 -  Design Notes (Linear Technology) (added 1/06)

VCO footprints and layout considerations to improve Performance:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

VCO fundamentals and concepts:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

VCO has Digitally Programmable Center Frequency:  04/25/96 EDN-Design Ideas / (Electronic Circuit diagram added 03/03) The circuits in Figure 1 illustrates a narrowband VCO, which has a digitally programmable center-frequency ratio of greater than 2-to-1. With a VCO having center-frequency ratio (F HIGH/FLOW) of greater than 2-to-1, you can derive any output frequency by simple binary division. The VCO has extremely high spectral purity, and typically operates at frequencies greater than 230 MHz by using high-performance ECL. Also, you can enable and disable the VCO almost instantaneously...

VCO produces positive and negative output frequencies:  12/25/03 EDN Design Ideas (added 12/04)  The circuit in Figure 1 is a quadrature-output VCO that provides both positive and negative output frequencies, depending on the polarity of the control-voltage input. The circuit provides a function that designers traditionally implement in analog music-effects units, such as Bode/Moog frequency shifters....

VCO test methods:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

VCO uses Programmable logic:  11/14/02 EDN Design Ideas (added 12/04)  A VCO (voltage-controlled oscillator) is an analog circuit, so you cannot find it in the libraries for the design of digital programmable chips. When you need such a circuit for synchronization or clock multiplication, you need to find a circuit that works with the standard digital functions, such as AND and NAND....

VCOM Adjustment uses Any Logic Supply Voltage:  09/30/04 EDN Design Ideas  / (Circuit / schematic design added 6/06)   All TFT (thin-film-transistor) LCD panels require at least one appropriately tuned VCOM signal to provide a reference point for the panel's backplane. The exact value of VCOM varies from panel to panel, so the manufacturer must program the voltage at the factory to match the characteristics of each screen.

Versatile Monolithic  Volt/Fs can Compute as Well as Convert with High Accuracy:  National Semiconductor Application Note 04-Nov-1995 (Electronic Schematic / circuit added 4/02)

Volt/F Converter Draws Flea Power:  04/24/97 EDN-Design Ideas / (Electronic Circuit diagram added 03/03) The V/F converter in Figure 1 is unique because it draws less than 30 µA from one unregulated supply while converting bipolar input voltages. It produces three CMOS-compatible, 0- to 10-kHz outputs: one (F+) that becomes active when the input voltage is positive, another (F­) that takes over for negative inputs, and a third (FABS) that produces a frequency proportional to the absolute value of the input. Linearity is better than 0.1%, and the full-scale span and offset drift are typically less than 100 ppm/ºC and 2 µV/ºC, respectively....

Voltage Controlled Amplifier:  (Circuit / schematic design added 6/06)

Voltage Controlled Oscillator ( VCO ):  The oscillation frequency of the voltage controlled oscillator is controlled by the output of the PLL synthesizer and does the stable oscillation of 119.3 MHz.  (added 02/06)

Voltage controlled Panner:  (Electronic circuit added 7/03)

Voltage Controlled Resistor:  Circuit Ideas for Designers - Application Notes - Advanced Linear Devices, Inc.  (Circuit / schematic design added 6/06)

Voltage Controls Sine Wave Frequency:  08/17/95 EDN-Design Ideas / (Electronic Circuit diagram added 03/03) The circuit in Fig 1 generates a 50-Hz to 1-kHz sinusoidal waveform that exhibits lower than 60-dB THD. The input voltage controls the output frequency with the relationship 1 kHz/V. The output amplitude is invariant with frequency over the entire operating range. IC1 is a V/F converter with an input control range of 0 to 1V. You adjust R5 so that the output frequency equals 1 kHz with a 1V input....

Wide Modulation Bandwidth Measurements  AN-95-004:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)