A 220-294 GHz Power Amplifier with 10-dBm Psat and 2.2% PAE in 250-nm InP DHBT

Abstract

We designed and fabricated a 300-GHz-band power amplifier (PA) with a wide bandwidth, high output power, and high power-added efficiency (PAE) in in-house 250-nm indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology having an fmax of 480 GHz. To obtain high PAE, we investigated an optimization method for designing the PA at an optimum point in the trade-off between the output power and DC power consumption (PDC). We proposed a low-loss T-junction power combiner with impedance convertors to maximize the output power and the PAE. Furthermore, we used dense through substrate vias (TSVs) to stabilize the ground and to suppress the oscillation to ensure a high gain and high PAE. The fabricated PA achieved a -3 dB bandwidth of 74 GHz from 220 GHz to 294 GHz, saturation power (Psat) of 10.6 dBm, and PAE of 2.24%.