This paper presents a 3-stage E-band (71 -83 GHz) power amplifier (PA) that employs a compact low-loss distributed matching network (DMN), which performs both the output matching and power combining. As a result of this, the measured PA achieves an output power of 30.4 dBm ± 0.9 dB (1.12 W ± 0.23 W) across the band. The PA achieves a peak output power of 1.35 W with a power-added efficiency (PAE) of 20.8 % and a power gain of 16.3 dB at 78 GHz. The associated power density is 1.87 W/mm. When biased with 10 V supply voltage, a peak PAE of 25 % is reached. To the best of the authors' knowledge, the peak PAE with the power gain and associated power density are the highest values reported in GaN technologies at E-band.

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 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 SAT of 36 dBm (4 W), P 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. Index Terms-E-band, gallium nitride (GaN), high efficiency, high frequency, high output power, low-loss, mm-wave, monolithic microwave integrated circuit (MMIC), ON-chip, power amplifier (PA), power combining, W -band.