Broadband 300-GHz power amplifier MMICs in InGaAs mHEMT technology

In this paper we report on compact solid-state power amplifier (SSPA) millimeter-wave monolithic integrated circuits (MMICs) covering the 280-330-GHz frequency range. The technology used is a 35-nm gate-length InGaAs metamorphic high-electron-mobility transistor (mHEMT) technology. Two power amplifier MMICs are reported, based on a compact unit amplifier cell which is parallelized two times using two different Wilkinson power combiners. The Wilkinson combiners are designed using elevated coplanar waveguide (CPW) and air-bridge thin-film transmission lines in order to implement low-loss 70- Olines in the back-end-of-line (BEOL) of this InGaAs mHEMT technology. The five-stage SSPA MMICs achieve a measured small-signal gain around 20dB over the 280-335-GHz frequency band. State of-the-art output power performance is reported, achieving at least 13dBm over the 286-310-GHz frequency band, with a peak output power of 13.7dBm (23.4mW) at 300GHz. The PA MMICs are designed for a reduced chip width while maximizing the total gate width of 512µm in the output stage, using a compact topology based on cascode and common-source devices, improving the output power per required chip width significantly.