A Wide Range 4.5 GHz VCO Using 45nm CMOS Technology

This paper presents design of ring oscillator based voltage controlled oscillator for wide frequency range applications requiring on-chip oscillators to generate clocks at low power. The structure and operating principle of ring oscillator have been described and the expression for the frequency of oscillation of a CMOS delay cell based conventional ring oscillator is presented. The VCO is designed and simulated in 45nm CMOS technology with BSIM 4.3.0 MOSFET model, level 54 parameters using SPICE simulator. At constant supply voltage (VDD) of 1V, as input control voltage varies from 0.3V to 1V in a step of 0.2V the output frequency changes from 0.54GHz to 4.5GHz, thus providing a maximum tuning range of 88%. The total power dissipation is of the order of 60 μW, with center drain current of 60.0 μA for current mirror formed with MOSFETs M3 & M4. The Phase Noise obtained for the proposed design is 0.116mV/Hz1/2 at 1MHz.