4.2–4.8 GHz CMOS variable gain LNA for Chinese UWB application

Abstract

The CMOS variable gain low noise amplifier (LNA) presented in this paper is designed for frequency band 4.2-4.8 GHz ultra-wideband (UWB) application specified in China. Wideband input matching with low noise performance co-design method is shown. A three-bit digital programmable gain control circuit is exploited to achieve variable gain. Fabricated with 0.13-μm RF CMOS process, the die size with ESD-pads is 0.9 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Drawn 18 mA from 1.2 V DC supply, the LNA exhibits 2.3 dB minimum noise figure, S(1,1) less than -9 dB and S(2,2) less than -10 dB. Maximum and minimum power gain are 28 dB and 16 dB respectively, about 4 dB/step with four gain modes in all. Input 1 dB compression point is -10 dBm and input third order intercept point (IIP3) is -2 dBm.