Contents
What is VCO frequency?
A voltage-controlled oscillator (VCO) is an electronic oscillator whose oscillation frequency is controlled by a voltage input. The applied input voltage determines the instantaneous oscillation frequency. A VCO is also an integral part of a phase-locked loop.
What is VCO function?
A voltage-controlled oscillator (VCO) is an oscillator circuit whose frequency can be controlled or varied by a DC input voltage. This type of circuit is also called a voltage-to-frequency converter (VFC). The output waveform from the VCO may be sine, square, or other waveshape depending on the circuit design.
How does the frequency of a VCO change with voltage?
The frequency increases with increase in control voltage above the nominal value and the frequency decrease with decrease in Vc below the nominal voltage. For achieving this variable voltage, variable capacitance diodes, varactors are used which are available at different range of capacitance.
How are voltage controlled oscillators used in ICS?
These VCOs are used to generate a triangle or sawtooth waveform. These can be easily implemented on monolithic ICs which can be tunable over a wide range of frequencies. These oscillators again classified into emitter coupled VCO, grounded capacitor VCO and delay based ring VCO.
Why are VCOs better than fixed frequency oscillators?
VCOs generally have lower Q factor compared to similar fixed-frequency oscillators, and so suffer more jitter. The jitter can be made low enough for many applications (such as driving an ASIC), in which case VCOs enjoy the advantages of having no off-chip components (expensive) or on-chip inductors (low yields on generic CMOS processes).
Which is the output of a voltage controlled oscillator?
Square wave is the output of this type of oscillator. This scheme is simple in operation, less costly and works with low power supply currents. Another common form of VCO is essentially built with comparator, integrator, switch and a Schmitt trigger. A timing capacitor charges over a definite voltage range by a buffer inside the VCO IC.