Voltage-controlled Oscillator - Applications

Applications

VCOs are used in:

• Function generators,
• The production of electronic music, to generate variable tones,
• Phase-locked loops,
• Frequency synthesizers used in communication equipment.

Voltage-to-Frequency converters are voltage-controlled oscillators, with a highly linear relation between applied voltage and frequency. They are used to convert a slow analog signal (such as from a temperature transducer) to a digital signal for transmission over a long distance, since the frequency will not drift or be affected by noise. VCOs may have sine and/or square wave outputs. Function generators are low-frequency oscillators which feature multiple waveforms, typically sine, square, and triangle waves. Monolithic function generators are voltage-controlled. Analog phase-locked loops typically contain VCOs. High-frequency VCOs are usually used in phase-locked loops for radio receivers. Phase noise is the most important specification for them. Low-frequency VCOs are used in analog music synthesizers. For these, sweep range, linearity, and distortion are often most important specs. Audio-frequency VCOs for use in musical contexts have largely been superseded by their digital counterparts, DCOs, due to their output stability in the face of temperature changes during operation.