Low-Power Programmable Gain CMOS Distributed LNA

A design methodology for low power MOS distributed amplifiers (DAs) is presented. The bias point of the MOS devices is optimized so that the DA can be used as a low-noise amplifier (LNA) in broadband applications. A prototype 9-mW LNA with programmable gain was implemented in a 0.18-/spl mu/m CMOS process. The LNA provides a flat gain, S/sub 21/, of 8 /spl plusmn/ 0.6dB from DC to 6.2 GHz, with an input impedance match, S/sub 11/, of -16 dB and an output impedance match, S/sub 22/, of -10 dB over the entire band. The 3-dB bandwidth of the distributed amplifier is 7GHz, the IIP3 is +3 dBm, and the noise figure ranges from 4.2 to 6.2 dB. The gain is programmable from -10 dB to +8 dB while gain flatness and matching are maintained.