A high-linearity, LC-Tuned, 24-GHz T/R switch in 90-nm CMOS

This paper presents an LC-tuned, 24-GHz single-pole double-throw (SPDT) transmit/receive (T/R) switch implemented in 90-nm CMOS. The design focuses on the techniques to increase the power handling capability in the transmit (Tx) mode under 1.2-V operation. The switch achieves a measured P-1dB of 28.7 dBm, which represents the highest linearity, reported to date, for CMOS millimeter-wave T/R switches. The transmit and receive (Rx) branches employ different switch topologies to minimize the power leakage into the Rx path during Tx mode, and hence improve the linearity. To accommodate large signal swing, AC floating bias is applied using large bias resistors to all terminals of the switch devices. Triple-well devices are utilized to effectively float the substrate terminals. The switch uses a single 1.2-V digital control signal for T/R mode selection and for source/drain bias. The measured insertion loss is 3.5 dB and return loss is better than -10 dB at 24 GHz.