Potential of Coplanar X-band GaN-MMIC Power Amplifiers

While the vast majority of GaN X-band PAs is realized as microstrip circuits, this paper reports design, fabrication and measurement of a coplanar version. The amplifier is processed using the FBH 4-inch GaN-on-SiC technology with 0.25 µm-gate GaN HEMTs. The two-stage power amplifier circuit delivers more than 12 W cw output power at 10 GHz, with a large-signal gain of 20 dB and a final stage drain efficiency of 45%. Benchmarking shows that these are best-in-class values for a coplanar X-band MMIC, which come very close to the state-of-the-art microstrip counterparts.