A methodology for obtaining semi-custom high-power amplifiers (HPAs) is described. The semi-custom concept pertains to the notion that a selectable output power is attainable by replacing only transistors. To compensate for the mismatch loss, a new output matching network that can be easily tuned by wiring is proposed. Design equations were derived to determine the circuit parameters and specify the bandwidth limitations. To verify this methodology, a semi-custom HPA with GaN HEMTs was fabricated in the S-band. A selectable output power from 240 to 150 W was successfully achieved while maintaining a PAE of over 50% in a 19% relative bandwidth.

A four-stage power amplifier (PA) with 10 GHz 1-dB bandwidth (56–66 GHz) is presented. The broadband performance is achieved owing to π-section interstage matching network. Three-stage-current-reuse topology is proposed to enhance efficiency. The amplifier has been fabricated in 65 nm digital CMOS. 18 dB power gain and 9.6 dBm saturated power (Psat) are achieved at 60 GHz. The PA consumes current of 50 mA at 1.2 V supply voltage, and has a peak power-added efficiency (PAE) of 13.6%. To the best of the authors' knowledge, this work shows the highest PAE among the reported CMOS PAs that covers the worldwide 9 GHz ISM millimeter-wave band with less-than-1.2 V supply voltage.