A High-Efficiency D-Band Linear Amplifier With 25.2% Peak PAE and 40-GHz Large-Signal Bandwidth in 250-nm InP DHBT

This letter presents a broadband D-band amplifier in 250-nm indium phosphide double heterojunction bipolar transistors (InP DHBT) technology. To enhance the output power and improve efficiency, the amplifier operates at class-AB and contains two transistors in parallel. The integrated active biasing is designed to mitigate the inherent self-heating effect of bipolar transistors while also improving linearity. The use of a small resistor and an inductor between the base and bias circuity boosts the gain and overall circuit stability. According to the measured results, the proposed single-stage amplifier achieves a maximum gain of 6.2 dB with a flattened bandwidth across the D band and delivers a 40-GHz large-signal bandwidth at output power levels exceeding 6 dBm. The measured maximum P_sat and PAE achieve 9.2 dBm and 25.2% at 130 GHz under the power dissipation of 25.1 mW within a power supply of 1.2V, respectively. The compact chip occupies 0.55 x 0.47 mm, with an active area of 0.09 mm². The proposed monolithic microwave integrated circuit (MMIC) achieves excellent PAE and bandwidth performance, making it possible for wireless systems exceeding 100 GHz.