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What is VCO | Voltage Controlled Oscillator basics

This page what is VCO describes basics and function of VCO.The full form of VCO is Voltage Controlled Oscillator. The page covers VCO application note for low frequency and high frequency case.

Oscillators whose frequencies are controlled using external input DC voltage are referred as VCO. The full form of VCO as mentioned is Voltage Control Oscillator. A voltage control crystal oscillator is known as VXO.

They are used in applications where in voltage to frequency conversion is needed. They are also used in FM modulator as well as RF synthesizer design. Refer rf synthesizer design which uses VCO in its applications.

VCO used as FM modulator

There are many ways VCOs can be constructed.
• Implemented using discrete transistor and varactor diode circuits in high frequency applications.
• Implemented using IC with RC multi-vibrator. Here frequency is controlled using wide range of AC/DC input voltages. These low frequency VCOs have frequency range of operation from 1 Hz to about 1 MHz. Normally IC NE566 is used for such application. Figure above shows IC NE-566 used as FM modulator application.

The Center frequency of the circuit is set using R1 and C1. RF Carrier frequency up to 1MHz can be used with this VCO circuit.

VCO is also referred as SCO. The full form of SCO is SubCarrier Oscillator.

Basics of VCO types and VCO tuning methods

VCO in PLL

Refer VCO types and VCO tuning methods➤.

VCO related resources

DDS basics
RF synthesizer manufacturers
RF synthesizer basics

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