A Design of Voltage Controlled Oscillator in ADC or DAC

Abstract

A low power and high performance voltage controlled oscillator (VCO) is designed by 0.18µm CMOS process. The output is stable, output frequency of the VCO has high linearity, and can be changed by regulation the voltage of input control pin VT. The output frequency is from 200 to 500MHz, and the operation voltage is from 1.2V to 3.3V. The operation current is only 2.5mA and Anti-interference ability has improved by using current hunger type ring oscillator. Between 40 to 125C, the Linear Rate of central frequency is only 0.2%. The final chip size is only 200µm X100µm.