A tunable differential duplexer in 90nm CMOS

Abstract

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 .

A +70-dBm IIP3 Electrical-Balance Duplexer for Highly Integrated Tunable Front-Ends

“…The common-mode isolation can be improved by shorting the common-mode tap of that winding to ground, but in most cases this technique will still not provide satisfactory common-mode isolation [7], [14]. Therefore, a fully differential hybrid transformer structure has been proposed [8], [9], [11] to achieve both common-and differential-mode isolation, which comes at the price of increased size and loss.…”