A Compact 70 Watt Power Amplifier MMIC Utilizing S-Band GaN on SiC HEMT Process

The design and measured performance of a compact power amplifier MMIC utilizing a 0.25 μm S-band GaN HEMT process technology is presented. Measured in-fixture results for the two-stage amplifier at 35V drain bias showed a nominal small-signal gain of 30 dB, a minimum output power of 50 W and a minimum PAE of 45% in the 3.1-4.3 GHz band. A peak output power of 60W, PAE of 48.3% were measured at 3.3 GHz with 35V operation. At 40V operation, this MMIC is capable of greater than 70W output power. With a compact 4.1×3.1 mm² die area, an output power density of 5.6W/mm² Psat per die area for a single fully monolithic S-band HPA is demonstrated. In addition, the MMIC PA provides near constant efficiency over a wide range of bias voltages enabling desirable Psat control with modulation of drain voltage.