Design of Parasitic and Process-Variation Aware Nano-CMOS RF Circuits: A VCO Case Study

This paper proposes a novel flow for parasitic and process-variation aware design of radio-frequency integrated circuits (RFICs). A nano-CMOS current-starved voltage controlled oscillator (VCO) circuit has been designed using this flow as a case study. The oscillation frequency is considered as the objective optimization function with the area overhead as constraint. Extensive Monte Carlo simulations have been carried out on the parasitic extracted netlist of the VCO to study the effect of process variation on the oscillation frequency. In the design cycle, a performance degradation of 43.5% is observed when the parasitic extracted netlist is subjected to worst-case process variation. The proposed design flow could bring the oscillation frequency within 4.5% of the target, leading to convergence of the complete design in only one design iteration. To the best of the authors´ knowledge, this paper presents the first work focussed on a current starved VCO in which the combined effect of parasitics and process variations has been considered.