27.1GHz CMOS distributed voltage controlled oscillators with body bias for frequency tuning of 1.28GHz

The feasibility of using standard 0.18mum CMOS technology for low cost wideband monolithic microwave integrated circuits (MMICs) at ~27GHz is demonstrated. Three monolithically integrated distributed voltage controlled oscillators (DVCOs) with a novel gain cell comprising of n-FET common source with p-FET current-source load are designed. Two of the DVCO´s have 3 stages of the gain cell while the third has 4 stages. Top Layer metal is used a coplanar waveguide for producing on-chip inductive elements. An important feature of these DVCOs is the use of body bias variation for very large frequency tuning. Simulation results indicate that the 4-stage DVCO achieves a tuning range of 22.43-23.42 GHz i.e 990 MHz whereas the 3-stage DVCO has a tuning range of 25.82-27.10 GHz i.e 1.28 GHz, with respectively ~0.5 dBm and ~1 dBm change in output power over tuning range for DVCOs. The best value of phase noise for 3-stage DVCO is obtained by applying reverse body bias on n-FETs. For a reverse body bias voltage of -1V, the phase noise is -97.39 dBc/Hz at 1 MHz offset from 26.87 GHz.