A low-voltage 5.1-5.8-GHz image-reject downconverter RF IC

This paper describes a single-chip implementation of a low-voltage image-reject downconverter for a 5.1-5.8-GHz radio receiver. It consists of a low-noise preamplifier (LNA) that is simultaneously noise and power matched to the RF source, and dual doubly balanced mixers coupled to the LNA by a monolithic trifilar transformer. The image-reject architecture eliminates an RF filter, thereby simplifying packaging requirements. The downconverter realizes over 36 dB of image rejection while dissipating 24 mW from a 0.9 V supply, or 18.5 mW at 1.8 V. Conversion gain is 14 dB, IIP3=-5.5 dBm, and noise figure is 6.8 dB (single sideband 50 /spl Omega/) when operating from a 0.9 V supply.