High Power InP/Ga(In)AsSb DHBTs for Millimeter-Wave PAs: 14.5 dBm Output Power and 10.4 mw/μm² Power Density at 94 GHz

Abstract

We report the 94 GHz large-signal load-pull performance of (0.3 × 9) μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> InP/Ga(In)AsSb double heterojunction bipolar transistors (DHBTs) in the common-emitter (CE) and common-base (CB) configurations. Both configurations were implemented side-by-side on either 20-nm-thick graded GaAsSb- or GaInAsSb-base layers. A measured record saturated output power <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OUT,SAT</sub> = 14.5 dBm with a corresponding power density 10.4 mW/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> were achieved in the GaInAsSb-base CB configuration. The performance follows from <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</i> ) the higher power gain in the CB topology and, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ii</i> ) the superior <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BV</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CEO</sub> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BV</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CBO</sub> breakdown voltages obtained with the quaternary base which allow degradation-free operation at higher voltages. Load-pull contours show a combination of high output power and power gain in the proximity of 50 Ω for a wide range of load impedances. In contrast, CB InP/GaAsSb DHBTs deliver <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OUT,SAT</sub> = 10.6 dBm and 4.3 mW/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . For all devices considered here, CB operation improves transistor robustness against high-power device degradation. The present work provides the first report on the power performance of quaternary InP/GaInAsSb DHBTs in CE/CB topologies, with comparison to ternary InP/GaAsSb DHBTs.