An optimized 0.1 um T-gate AlGaAs/InGaAs/GaAs PHEMT power amplifier MMIC for Ka-band applications

Abstract

In this paper, a AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuit (MMIC) power amplifier for Ka band applications is presented. PHEMT AlGaAs/InGaAs/GaAs epi-layers are grown by metal organic chemical vapor deposition (MOCVD) and 100 nm gate lengths is realized by double exposure e-beam lithography method. The device fabricated by the double exposure processes is presented maximum saturation current densities (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS max</sub> ) of 680 mA/mm and the peak extrinsic transconductance (g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m max</sub> ) of 485 mS/mm, respectively. In case of RF performance, current gain cutoff frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) of 56 GHz, maximum stable gain (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ) of 84 GHz and yielding a power density of 10 W/mm at 30GHz are indicated. The three-stage MMIC power amplifier is designed to fully match the 50 Ω input and output impedances. With 6 V and -0.75 V DC bias, a 1 dB compression power (P1dB) of 29.5 dBm, a power added efficiency (PAE) of 31% are achieved from 28.5 to 31.5 GHz. The proposed Ka-band power amplifier is designed within a die size of about 3.3 × 1.9 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> on GaAs substrate.