Design of Ring Oscillator with Transmission Gate Tuning Method

This paper presents modern design of ring oscillator circuit with the help of three transistor XOR gate employed as inverter delay stage. The load variations at the output of delay cell has been achieved by means of gate voltage variations of the CMOS transmission gate connected at the output node of inverter delay stage. The different three, five and seven stages VCO circuits have been formed in 180nm CMOS technology with power supply of 1.8V. In the 3 stages VCO the output frequency varies from 0.859 to 1.525 GHz with power variations of 0.277 mW to 4.03 mW. In the 5 stages VCO, the output frequency is varied from 0.447 GHz to 0.904 GHz. Power consumed by VCO varies from 0.39 mW to 6.19 mW. Seven stages VCO shows frequency in the range of 0.423 GHz to 0.645 GHz. Power consumed by seven stages VCO varies from 1.08 mW to 7.51mW. Proposed VCO design approach is very effective method to control the output frequency with low power consumption.