Voltage Controlled Oscillator Circuit

The chip we will use is a 4046 chip.

Voltage controlled oscillator circuit. 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. Consequently a vco can be used for frequency modulation fm or phase modulation pm by applying a modulating signal to the control input. A voltage controlled oscillator is an oscillator whose oscillation frequency is controlled by an input voltage. A voltage controlled oscillator vco is an electronic oscillator whose oscillation frequency is controlled by a voltage input.

A vco is also an integral part of a phase locked loop. 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. The voltage controlled oscillator performance governs many aspects of the performance of the whole phase locked loop or frequency synthesizer. A voltage controlled oscillator is an oscillator which produces oscillating signals waveforms with variable frequency.

The applied input voltage determines the instantaneous oscillation frequency. Basically the voltage input into the vco chip controls how many times a digital signal will oscillate in a given time period. Within a phase locked loop pll or frequency synthesizer the performance of the voltage controlled oscillator vco is key. The frequency of this waveform is varied by varying the magnitude of the input voltage.

The figure below shows a simple voltage control oscillator using astable multivibrator. 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. This is phase locked loop ic.