A voltage controlled oscillator (VCO) is an electronic circuit that produces an oscillating electric signal (typically a sine wave) whose frequency can be varied by changing the input voltage.
The main purpose of a VCO is to generate a stable and variable frequency signal that can be used in a variety of electronic applications such as frequency modulation, phase-locked loops, and frequency synthesizers.
A VCO typically consists of a voltage-controlled amplifier (VCA) and a frequency-determining circuit, such as a capacitor or inductor. The VCA adjusts the amplitude of the input voltage, which in turn changes the frequency of the output signal.
The key parameters of a VCO include frequency range, frequency stability, tuning range, linearity, and phase noise. These parameters determine the performance and accuracy of the VCO in producing a stable and adjustable frequency signal.
VCOs are commonly used in communication systems, audio equipment, synthesizers, and test and measurement instruments. They are also used in various industrial and scientific applications that require precise and adjustable frequency signals.