A Compact 59-154 GHz Hybrid Cascaded Amplifier with 22.7 dB Gain in 250 nm InP DHBT

This paper presents a high-gain and high-flatness wideband hybrid cascaded power amplifier (PA) based on 250 nm indium phosphide (InP) double-heterojunction bipolar transistor (DHBT). The compact amplifier utilizes two common emitter (CE) structures in conjunction with a parallel configuration of double cascode structures, with an interdigital capacitor introduced at the base to form a resistancecapacitance (RC) circuit. The electromagnetic (EM) simulation results show that the S-parameter has a good input / output return loss $(\gt10 \mathrm{~dB})$ in the range of 70 - 190 GHz, and provides a maximum gain of 22.7 dB at 131 GHz, with a 3-dB bandwidth of 59 - 154 GHz. The designed PA is capable of providing 9 dBm saturated output power ($P_{\text {sat }}$) at<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup>|40 GHz and the maximum power added efficiency (PAE) achieves 14% at the cost power of 70 mW. Index Terms-Power amplifier, hybrid cascaded, highflatness wideband, InP DHBT, interdigitated capacitor.