An X-band half-watt CMOS power amplifier using interweaved parallel combining transformer

An X-band half-watt fully integrated power amplifier (PA) using standard 0.18-μm 1P6M CMOS technology is presented in this letter. Utilizing an interweaved three-primary parallel combining transformer, the CMOS PA delivers 27.1 dBm of measured saturation output power (P_sat) with 22.7% of power-added efficiency at 9 GHz from a 3.3-V power supply. The measured output 1-dB gain compression point (OP_{1 dB}) is 24.2 dBm and the gain performance is 11.2 dB at 9 GHz. The chip size is 1.045 × 0.84 mm². To the best of our knowledge, the PA is the first half-watt CMOS PA with excellent power density at the X-band.