A CMOS Variable Gain Front-end for a WCDMA Receiver

This paper describes a variable gain WCDMA front-end receiver based on a direct conversion architecture in 0.18-μm CMOS. The front-end comprises a low noise variable gain amplifier (LNA) and a mixer. The LNA provides a 50-Ω input impedance and utilizes a tuned load to provide high selectivity. The front-end achieves a voltage conversion gain of 29.3 dB in the high gain mode of the LNA within 1-dB compression point dBm (
iCP_1dB
) of -21 dBm. The front-end acquires an NF of 4.4 dB with an input return loss, S
₁₁
, of -12.4 dB. The front-end achieves an in-band IIP3 of -6.16 dBm. The integrated LNA and mixer consumes approximately 9.2 mA of current from a 1.8-V power supply.