Design of Voltage Controlled Oscillators

A VCO is an oscillator, where the control voltage controls the oscillator output frequency. VCOs are perhaps the most ubiquitous element in all communication systems, wired or wireless. In today¿s wireless communication systems greater frequency range is required by the VCOs. In recent years, ring oscillators have become an essential building block in VCO¿s. They can provide a wide operating range, a small layout area and ease of integration.