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Oscillators:  Voltage Controlled (VCO)
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Oscillator Circuits -- Main Page


Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E. :

200Mhz-400Mhz Voltage Controlled Oscillator (VCO) - If you need a clean emitter coupled logic   (ECL) type signal between 200MHz and 400MHz this circuit works fine.  It uses four voltage-controlled capacitors to change the frequency. . . Circuit by Dave Johnson P.E.-March, 1999

40Khz Voltage to Frequency Converter - This circuit was designed to frequency modulate a 40KHz carrier, using human voice frequencies.  A common flip/flop is used at the core of the circuit. . . Circuit by David Johnson P.E.-December, 2004

AIR Transparency Monitor, Xenon Flash Receiver - I designed this receiver circuit many years ago to monitor the quality of a mile long column of air for future optical communications experiments.  The transmitter system   (circuit 72 below) uses a powerful xenon flash in conjunction with a large 12 inch. . . Circuit by David A. Johnson P.E.-June, 2000

AIR Transparency Monitor-Pg2 - This is Page 2 of the receiver circuit AIR TRANSPARENCY MONITOR, XENON FLASH RECEIVER. . . Circuit by Dave Johnson P.E.-June, 2000

CMOS Schmitt Trigger IC Makes VCO - By changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a range of 50:1.  A 74HCU04 inverter is used at the output of the 4584 to maintain a constant TTL logic level signal. . . Circuit by Dave Johnson P.E.-December, 2002

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

T3SE - Type 3 (charge rate controlled) Solar Engines

Ten kHz VFC uses Charge Pump Variation -  04/09/98 EDN-Design Ideas - (Several circuits included, scroll to find this one) A diode-capacitor charge pump is the starting point for many voltage-to-frequency-converter (VFC] designs.  The circuit in Figure 1 uses a variation on that classic theme to achieve linearity less than 0.05%, micropower operation of approximately 10-�A total draw from a 5 to 36V rail, and bipolar-input capability Design by Stephen Woodward, University of North Carolina, Chapel Hill, NC

Testing Dual-Chip Transistor Arrays for VCO/Buffer Amp Combinations & Two-Stage Amplifier Applications 11/28/97  -  App Note  Doc #907) __ California Eastern Laboratories

The "Miller engine" - Type 1 (Voltage Controlled) Solar Engine -  This is a slightly more-sophisticated design based on a 1381* voltage discriminator. __ Designed by Wilf Rigter

Tritium - Type 3 (charge rate controlled) Solar Engines

Universal Watchdog Fully Controls Preset -  05/25/95 EDN-Design Ideas - Many Ps contain internal watchdog timers, and you may wonder why you need another stand-alone circuit.  Unfortunately, more highly integrated functions have preset parameters that you may want to change.  Design by Terje Kvinge, Nera AS, Kokstad, Norway

Use PSpice for behavioral Modeling of VCOs -  12-Dec-02 EDN-Design Ideas - 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 Design by Dobromir Dobrev, Jet Electronics, Sofia, Bulgaria

Using the LTC6900 Low Power SOT-23 Oscillator as a VCO -  DN293 Design Notes__ Linear Technology/Analog Devices

V/F Converter Draws Flea Power -  04/24/97 EDN-Design Ideas - The V/F converter in Figure 1 is unique because it draws less than 30 A from one unregulated supply while converting bipolar input voltages.  It produces three CMOS -compatible, 0to 10-kHz outputs one (F+]that becomes active when the input voltage is positive, another (F]that takes Design by W Stephen Woodward, University of North Carolina, Chapel Hill, NC

VCO covers 300MHz to 500MHz based on Maxim MAX2608 VCO -  The datasheet says this VCO covers 300 to 500 Mhz,  in this test setup with one coil it covers 350 to 475 Mhz with the controlling voltage.  The output should be about -10dBm, but it's -20dBm.  The stability and sideband noise was not good enough for my HAM radio project, sorry.   But I'm sure it will be perfect to be used with a PLL. __ Designed by Thomas Scherrer OZ2CPU

VCO footprints & layout considerations to improve performance -  Application Note__ MiniCircuits.com

VCO fundamentals & concepts -  Application Note__ MiniCircuits.com

VCO Has Digitally Programmable Center Frequency -  04/25/96 EDN-Design Ideas - 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 Design by Paul Sofianos, Motorola LICD, Chandler, AZ

VCO produces positive & negative output frequencies -  12/25/03  EDN-Design Ideas - The circuit in Figure 1 is a quadrature-output VCO that provide as both positive and negative output frequencies, depending on the polarity of the control-voltage input.  The circuit provide as a function that designers traditionally  __ Circuit Design by Henry Walmsley, Farnborough, UK

VCO test methods -  Application Note__ MiniCircuits.com

VCO uses programmable logic -  14-Nov-02 EDN-Design Ideas - 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 Design by Susanne Nell, Breitenfurt, Austria

VCO using the TL431 reference -  10/10/13  EDN-Design Ideas - The ubiquitous TL431 voltage reference has found something else its good at Design by R O Ocaya

VCOM adjustment uses any logic-supply voltage -  09/30/04 EDN-Design Ideas - All TFT [thin-film-transistor] LCD panels require at least one appropriately tuned VCOM signal to provide a reference point for the panels backplane.  The exact value of VCOM  varies Page includes several designs.  Scroll to find this one Design by Peter Khairolomour and Alan Li, Analog Devices, San Jose, CA

Volt/F Converter Draws Flea Power -  04/24/97 EDN-Design Ideas - The V/F converter in Figure 1 is unique because it draws less than 30 A from one unregulated supply while converting bipolar input voltages.  It produces three CMOS -compatible, 0to 10-kHz outputs one (F+]that becomes active when the input voltage is positive, another (F]that takes Design by W Stephen Woodward, University of North Carolina, Chapel Hill, NC

Voltage Controlled Amplifier -  In truth this, like many (most) VCAs is really a current controlled amplifier but there is really not too much difference since if you want to turn a CCA into a VCA you simply feed the current input from a voltage via a voltage to current converter (a.  k.  a.  'resistor')  __ Designed by Richard Torrens

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 21, 2011

Voltage Controlled Low Frequency Oscillator with Sync  -  Voltage Controlled Low Frequency Oscillator with Sync__ 

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 __ Designed by Seiichi Inoue

Voltage Controlled Resistor -  Circuit Ideas for Designers App Note__ Advanced Linear Devices, Inc

Voltage Controls Sine-Wave Frequency -  08/17/95 EDN-Design Ideas - 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 Design by Yongping Xia, EBT Inc, Torrance, CA

VTSE - Type 1 (Voltage Controlled) Solar Engine -  The "Variable Threshold Solar Engine" is Wilf Rigter's 1381-based design -- with a variable "trip" threshold. __ Designed by Wilf Rigter

Vx2SE - Type 1 (Voltage Controlled) Solar Engine -  The VTSE uses the popular 1381 chip and that is its main advantage.  The potentiometer (or two fixed resistors) connects one leg between the output and input of the 1381 and the other leg to the supply voltage.  These resistors acts like a voltage divider when the SE is off and the 1381 output is low.  In that case, the voltage that appears at the 1381 input is determined by the ratio of the pot or the two resistors and is usually set for 2 times rated 1381 voltage.   __ Designed by Wilf Rigter

Wide Frequency Range 555 VCO -  The 555 frequency can be varied via adjusting the voltage at pin 5.  However, the range and linearity of frequency adjustment is very limited.  This is a way to greatly improve performance using the inverted 555 timer circuit that was previously posted.555 VCO Schematic Current source Q2 is connected in the common base __ Designed by Jim Keith

Wide Modulation Bandwidth Measurements -  AN-95-004 Application Note__ MiniCircuits.com

Zener-based - Type 1 (Voltage Controlled) Solar Engine -  This design uses a Zener diode to determine the voltage trip level.  Simple variants of this design use LEDs or plain old diodes in series to accomplish the same thing. __ Designed by Wilf Rigter

Voltage Controlled Oscillators:   #'s - D      E - S       T - Z

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