High Power mm-Wave Spatial Power Combiner Employing On-Chip Isolation Resistors

A spatial power combiner interfacing four power amplifiers (PAs) with isolation load resistors to a single substrate integrated waveguide (SIW) is presented. The isolation load resistors are envisioned on-chip and have been optimized to provide both the optimal active load impedance for the interconnected PAs as well as to mitigate undesired power combiner coupling effects due to non-equal excitations between PA channels. The proposed solution is compared to an ideal Wilkinson combiner in the presence of non-ideal PAs. The main performance targets are the combined output power, gain, and power efficiency at the 1-dB compression point. Simulation results demonstrate that introducing isolation load resistors allows to significantly reduce the impact of a non-uniform excitation on the combiner performance metrics.