Design of subthreshold wide band down conversion mixer

In this paper, a subthreshold driven low power wide band Gilbert cell mixer in two different architectures is presented. The first is Common Source (CS) architecture with RC degeneration for bandwidth extension and capacitive cross coupling for gain boosting. Next is a conventional Common Gate architecture driven in weak inversion region for low power consumption. Both architectures are designed to work for Ultra Wide Band (UWB) applications (2GHz to 8GHz). From the simulation results, the CS topology provides 10dB (including 6dB loss in buffer) conversion gain over same bandwidth while consuming 1.38mWDC power from 1.8V supply. On the other hand, the CG topology provides 13.5dB (accounting 6dB loss in buffer)conversion gain over the same bandwidth while consuming 2.51mW DC power from 1.8V supply. The achieved input referred 1dB compression points are -11dBm for CS and -7dBm for CG topologies. Simulated performance on PVT variation and layout extraction are closely follow with the original design performances.