A tunable differential duplexer in 90nm CMOS

An integrated duplexer for frequency division duplex wireless standards around 2GHz is presented. The duplexer utilizes a differential version of a planar hybrid transformer to enable wideband differential to differential and differential to common-mode isolation between the transmitter and receiver. It covers WCDMA bands I, II, III, and IX, with worst-case isolation of 60dB and 40dB at the TX and RX frequencies respectively. The duplexer with a cascaded LNA achieves a noise figure of 5.6dB, and 14dB of gain. The insertion loss in the TX path is 3.7dB. The duplexer and LNA, implemented in a 90nm CMOS process, consume 20mA and occupy an active area of 0.6mm
²
.