A 40~900MHz Broadband CMOS Differential LNA with Gain-Control for DTV RF Tuner

This paper presents a 40-900 MHz broadband CMOS differential LNA with gain control for DTV RF tuner application. The LNA is fabricated in a TSMC 0.18-mum CMOS process. The broadband differential LNA uses dual-feedback and shunt-shunt feedback topologies to achieve high and flat broadband response. The LNA is designed with 75 Omega/75 Omega differential input/output impedance for 75-Omega TV system application. The circuit measurement is performed using an FR-4 PCB test fixture. In the frequency range of 40~900MHz, the LNA exhibits a gain of 20.26 plusmn 0.41 dB, noise figure less than 5dB, and input P_1dB between -19.5 ~ plusmn;20.3 dBm. The gain tuning range is from 20 to -42.8 ~ 5 dB over 40-900 MHz range. The power consumption is 43 mW at VDD = 1 8 V