Implementation of a CMOS LNA plus mixer for GPS applications with no external components

A fully differential 0.35-mum CMOS LNA plus mixer, for GPS applications, us ing no external component apart from an input balun, has been realized. The LNA makes use of an inductively degenerated input stage and a resonant LC load, featuring 12% frequency tuning, accomplished by a MOS varactor. The m ixer is a Gilbert cell type in which an NMOS and a PMOS differential pair, shunt together realize the input stage. This topology allows one to save po wer for given mixer gain and linearity. The front-end measured performances are: 40-dB gain, 3.8-dB NF, -25.5-dBm IIP3, 1.3-GHz input frequency, 140-M Hz output frequency, with 8 mA from a 2.8-V supply.