A $W$ -Band SSPA With 100–140-mW $P_{\text{out}}$ , >20% PAE, and 26–30-dB $S_{21}$ Gain Across 88–104 GHz

We report a three-gain-stage 88–104-GHz $W$ -band solid-state power amplifier (SSPA) monolithic microwave integrated circuit (MMIC) having modest 100–140-mW output power ( $P_{\mathrm {out}}$ ), high gain, and high power-added efficiency (PAE). The MMIC technology is 250-nm InP HBT. PA $S_{21}$ gain is 29.5 dB with ±0.5-dB variation. PA 3-dB $S_{21}$ gain roll-off is between 88 and 104.5 GHz with high $\vert S_{11}\vert $ and $\vert S_{22}\vert $ return losses. DC power ( $P_{\mathrm {dc}}$ ) is 0.41 W. Across 88 –104 GHz, the PA-saturated output power $P_{\mathrm {sat}}$ is 100–120 mW with greater than 20-dB power gain and 20% PAE. At 92 GHz, peak 120-mW $P_{\mathrm {out}}$ with 20-dB gain and 24.7% PAE is demonstrated. $P_{\mathrm {out}}$ at 1-dB gain compression OP $_{\mathrm {1-dB}}$ is estimated to be 15–17 dBm. At 94 GHz and an elevated output stage bias (0.50-W $P_{\mathrm {dc}}$ ), 140-mW $P_{\mathrm {out}}$ with 20-dB gain and 24.4% PAE is demonstrated. This work contributes to and improves the state of the art for $W$ -band PAs in the simultaneous performance areas of power, gain, and PAE.