0.5 V 1.3 GHz voltage controlled ring oscillator

A three stage ultra low power, low voltage ring oscillator is presented in this paper. The bulk of the PMOS transistor is used as the control voltage, the substrate of the NMOS transistor is also forward biased to reduce the threshold of the NMOS transistor for low voltage operation. The proposed VCO is designed and simulated in 0.18 ¿m RF CMOS process. Simulation results show that the proposed VCO can work at 0.5 V power supply, the oscillation frequency of VCO is from 124 MHz to 1.3 GHz. The power consumption is 85 ¿W when the VCO works at 1.3 GHz.