71–95 GHz (23–40% PAE) and 96–120 GHz (19–22% PAE) high efficiency 100–130 mW power amplifiers in InP HBT

Two solid-state power amplifiers with record high power added efficiency (PAE) and 100-130 mW output power in 250 nm InP HBT are reported. The 71-95 GHz PA demonstrates 20.7 dB S21 and 25 GHz 3-dB bandwidth at 432.5 mW PDC. Pout is 105-138 mW (21-36% PAE) and RF power density is 1.64-2.15 W/mm. At 81 GHz, 135.6 mW Pout is achieved with 36.0% PAE and 14.1 dB gain. At 81 GHz with reduced input-stage bias, 129.6 mW Pout is achieved with 40.0% PAE and 13.0 dB gain. The 96- 120 GHz PA demonstrates 17.8 dB S21 and 26 GHz 3-dB bandwidth at 442.4 mW PDC. Pout is 84.9-107 mW and RF power density is 1.33-1.64 W/mm. At 102.5 GHz, 98.1 mW Pout is achieved with 21.2% PAE and 12.1 dB gain. The results were obtained class-A DC biasing the PA's. The amplifiers utilizes a novel, compact, and stackable power cell topology for multi-finger HBTs operating at mm-wave and THz frequencies, where 8-way PA cell combining can be realized for future 0.6-0.8 W Pout designs - these designs are currently under development. This work represents record PAE for 100 mW PA's at these frequencies. 40% PAE at E-band (81 GHz) is demonstrated for the first time under class-A bias, as well as PAE greater than 23% across the 71-76, 81-86, and 92-95 GHz bands. The 18.9-22.5% PAE at 100 mW power for the 96-120 GHz PA is a 1.5-3× improvement to state-of-the-art PAE at these frequencies.