An S/X-band CMOS power amplifier using a transformer-based reconfigurable output matching network

A dual-band power amplifier (PA) with an integrated reconfigurable transformer is presented. The PA operating in the S/X-band is fully integrated using a 0.18-μm RF CMOS process. The switchable transformer is designed by tuning its primary winding and a shunt capacitor at 50Ω load with passive efficiency more than 62%/67% for S/X-band. The measurement results show saturated output power (P
_SAT
) of 24.3/21.2 dBm with peak drain efficiency (DE) of 34.8%/12.2% at 3.1/8.0 GHz, respectively. The 1-dB bandwidth is 0.7/1.25 GHz (2.8-3.5/7.5-8.75 GHz) for the S/X-band. This amplifier with the proposed transformer is suitable for use in an integrated dual-band high-resolution radar transceiver.