Closed-loop, nonlinearity analysis and design of dual tuning, different control, high FOM two stage ring oscillator

A two-stage voltage-controlled ring oscillator is designed. Based on closed-loop system and nonlinearity analysis, oscillation start-up and oscillation frequency is predicted by poles and zeros position in s-plane. With the help of this theory analysis, a high FOM, dual tuning, differential controlled VCO is designed. Jazz 0.18 ¿m CMOS technology is implemented and the layout area is 47 ¿m×80 ¿m including buffers. Current consumption is 5.1 mA under a supply voltage of 1.8 V. Post simulation results show that the coarse tuning range covers 1.894 GHz with center frequency 4.5 GHz while the gain is only 66 MHz/V. The phase noise is -96.31 dBc/Hz at 1 MHz offset. The FOM value is 166.28 at 1 MHz offset.