Broadband 100-W Ka-Band SSPA Based on GaN Power Amplifiers

We report on the realization of a two-stage 16-way solid-state power amplifier (SSPA) in the Ka band. To that end, we describe the design of a high-power amplifier in a 100-nm gallium nitride (GaN) process and its integration into a split-block waveguide module. The PA module achieves an output power of more than 7.6W between 28 and 39GHz. In conjunction with 16 of these PA modules, we then employed a custom low-loss radial splitter and combiner to create a compact SSPA system. The two-stage SSPA configuration exhibits a small-signal gain of up to 44dB and a peak output power of 127W at 31GHz in 5dB of gain compression. Furthermore, we measured an output power of close to 100W and state-of-the-art efficiency values of more than 19% between 28 and 38GHz. To our knowledge, this is the most broadband high-power SSPA demonstrated so far in this frequency range.