Investigation of compact power amplifier cells at THz frequencies using InGaAs mHEMT technology

In this paper a design approach for compact power amplifier cells at frequencies around and above 300 GHz is presented, using a 35nm InGaAs mHEMT technology. Up to 8-finger common-source (CS) and cascode devices are developed based on 2-finger multiport models without feeding structures. Two power amplifier MMICs are presented with more than 15 dB measured small-signal gain between 290 - 335 GHz. 6.8 - 8.6-dBm output power is reported for the frequency range of 280 - 320 GHz, which is state-of-the-art for InGaAs based mHEMT technologies at these frequencies. Due to the compact CS and cascode cells, the required width of the PA core is significantly reduced, achieving high output power levels per required chip width and enabling further parallelization.