Design of Voltage Controlled Oscillators: ring VCO

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.