Low-Power, Low-Cost CMOS Direct-Conversion Receiver Front-End for

Abstract

A broadband CMOS direct-conversion receiver with on-chip frequency divider has been integrated in a 0.13- m CMOS process. The key feature of the proposed receiver front-end is a single low-noise transconductance ampli fier (LNTA) driving a current-mode passive mixer termi nated by a low-input-impedance transimpedance amplifier (TIA). The receiver chain has improved robustness to out-of-band interference and ou tstanding linearity. We employ a broadband common-gate (CG) LNTA with dual feed- back to improve both gain and noise figure (NF) without breaking the fixed relationship between input impedan ce, transconductance gain, and load impedance. A LNTA load impedance boosting technique suppresses noise-ampli fication due to TIA, commonly found in passive mixers. The core circ uit (RF and baseband signal p a t h )c o n s u m e so n l y1 3m W ,a n dt h eprototype receiver achieves 22.4-dB conversion gain, 8.3 dB NF, and 1.5 dBm from 1.4 to 5.2 GHz. Maximum convers ion gain of 24.3 dB and minimum NF of 6.5 dB are achieved at 1.4 and 2 GHz, respectively. T h ec h i pa c t i v ea r e ai s1 . 1m m with the entire RF signal path operated from a 1.2-V supply. The LO portion is biased from a 1.5-V supply.