2.6- and 4-W E-Band GaN Power Amplifiers With a Peak Efficiency of 22% and 15.3%

In this letter, we report two high-power gallium nitride (GaN) power amplifiers (PAs) in the Satcom $E$ -band (71–86 GHz) with an output power of 2.6 and 4 W, designed by incorporating an ultralow-loss ON-chip integrated power combiner. The first one is a three-stage four-way combining (unit) PA, and the second one is an eight-way combining balanced PA. The unit PA produces a saturated output power ( $P_{\mathrm{SAT}}$ ) of 34.2 dBm (2.6 W), a peak power-added-efficiency (PAE) of 22%, and an associated power gain of 16.2 dB at 74 GHz. This performance was partly made possible by the design and optimization of the low-loss integrated power combiner, which minimized the losses in the matching networks. In addition, the balanced PA produces a $P_{\mathrm{SAT}}$ of 36 dBm (4 W), $P_{\text {1 dB}}$ of 35.6 dBm (3.63 W), with an associated PAE of 15.3% at 80 GHz. To the best of the authors’ knowledge, this is the highest output power (4 W) and the highest PAE (22%) for a PA > 2.5 W reported in any of the III–V technologies at $E$ -band.