Voltage Controlled Oscillator Circuit

A voltage controlled oscillator is an oscillator with an output signal whose output can be varied over a range which is controlled by the input dc voltage.

Voltage controlled oscillator circuit. The voltage controlled oscillator performance governs many aspects of the performance of the whole phase locked loop or frequency synthesizer. For now you can imagine a voltage controlled oscillator vco to be a black box which takes in voltage of variable magnitude and produces an output signal of variable frequency and the frequency of the output signal is directly proportional to the magnitude of the input voltage. A wide variety of circuit designs can be made to implement a voltage controlled oscillator using different voltage control electronic components like transistors varactor diodes op amps etc. The frequency of this waveform is varied by varying the magnitude of the input voltage.

This is phase locked loop ic. A voltage controlled oscillator vco is an electronic oscillator whose oscillation frequency is controlled by a voltage input. The figure below shows a simple voltage control oscillator using astable multivibrator. Basically the voltage input into the vco chip controls how many times a digital signal will oscillate in a given time period.

The applied input voltage determines the instantaneous oscillation frequency. The performance of the voltage controlled oscillator in any phase locked loop is a key circuit block determining many aspects of the overall performance. Consequently a vco can be used for frequency modulation fm or phase modulation pm by applying a modulating signal to the control input. The chip we will use is a 4046 chip.

A voltage controlled oscillator is an oscillator whose oscillation frequency is controlled by an input voltage. A vco is also an integral part of a phase locked loop. The oscillation frequency varies from few hertz to hundreds of ghz.