VCO Oscillators

VCO (Voltage Controlled Oscillators) can also be known as silicon oscillators or VCOs. They are electronic devices designed to control oscillation frequency by varying the DC voltage input. Oscillation frequencies can be adjusted from a few Hz to hundreds of GHz. The VCO's can also work as modulators of both frequency and phase by delivering a modulating signal to the control input. Voltage Controlled Oscillators are also commonly used as an integral part of the phase-locked loop.

What are the types of VCO Oscillators?

Voltage Controlled Oscillators can be categorized into 2 types according to the type of waveform generated:

Linear / Harmonic Oscillator - this type of oscillator generates a sinusoidal type of waveform.

Relaxation Oscillator - This type of VCO is able to generate a triangular waveform or a sawtooth waveform.

What are the voltage-controlled oscillators used for?

There are several typical applications of VCOs and they are:

• Function Generators
• Phase-Locked Loops
• Tone Generators
• Clock Generators
• Electronic Jamming Equipment
• Frequency Synthesizers

How to choose the right VCO?

Some key parameters that need to be considered before selecting the VCO are:

• The Frequency Range - the minimum and maximum tunable oscillation frequency (MHz)
• Output Power - The output power produced by the VCO (dbm)
• Tuning Voltage - the voltage level applied to the device to tune and set the desired oscillation frequency (V)
• Tunning Sensitivity - the level of variation of the oscillation frequency with different voltages applied to the VCO (MHz/V)
• Supply Voltage - a DC Voltage required to correct operation (V)
• Pulling - drift in the output frequency due to load variation (MHz/V)
• Pushing - drift in the output frequency due to variation in the supply voltage (MHz/V)
• Phase Noise - a clarity of the output signal from the VCO (dBc/Hz)