Reactively Matched WR-3.4 Power Amplifier with a Large-Signal Bandwidth of 40% enabled by an Impedance-Optimized Transforming Wilkinson

This article presents a reactively matched sub-millimeter-wave power amplifier with a measured record large-signal bandwidth of 40 %. Coverage of the entire WR-3.4 waveguide band from 220 to 330 GHz is enabled by applying an impedance-transforming four-way in-phase power combiner structure. For the first time, the usage of an impedance-transforming Wilkinson power combiner that doesn’t require additional lossy matching elements in conjunction with two direct parallelizations for facilitating the novel broadband low-loss four-way power combining is proposed for sub-millimeter wave applications. A crucial step for obtaining a broadband large-signal bandwidth is the optimization of the value of the intermediate impedance between the impedance transforming Wilkinson and the two direct parallelizations, which can be performed by the derived equation for the proposed combiner structure. Applying the presented technique solves the bandwidth limitation for the power matching of the final stage for reactively matched power amplifiers and hence, enables a maximum power bandwidth. This broadband large-signal bandwidth is mandatory for high-capacity communication and high-resolution sensing applications. Besides the state-of-the-art large-signal bandwidth, a state-of-the-art power-added efficiency of 4.6 % for indium gallium arsenide-based designs is achieved when the power amplifier is driven at its 1-dB compressed output power level of 8.1 dBm at 300 GHz.