A Dual-Band SP6T T/R Switch in SOI CMOS With 37-dBm P-0.1 dB for GSM/W-CDMA Handsets

This paper presents the circuit techniques to achieve superior linearity and isolation for a single-pole six-throw transmit/receive (T/R) switch designed for GSM/W-CDMA dual-band operation at 0.85-0.9 and 1.8-1.9 GHz. Implemented in a 0.18-mu m thick-film silicon-on-insulator (SOI) CMOS process, the switch employs an LC-tuned asymmetric topology for the transmit (Tx) and receive (Rx) branch to handle the high-power GSM transmitter requirement. The proposed design also features a switchable double LC-tank acting as a variable impedance block to relax the tradeoff among linearity, insertion loss (IL), and isolation. Feed-forward capacitors, ac-floating bias techniques, and floating-body SOI devices are utilized to further improve the linearity. The measured, P-0.1 (dB,) IL and Tx-Rx isolation in the lower and upper band are 37.2-35.6 dBm, 0.43-0.75 dB, and 45-37 dB, respectively. The proposed T/R switch design in SOI CMOS is an important building block toward more compact and lower cost RF frond-end modules, which integrate the switch, antenna tuning module, and control logic on the same chip.