First Full W-Band GaN Power Amplifier MMICs with Novel Broadband Radial Stubs and 50 GHz of Bandwidth

We report on the first-ever GaN power amplifier MMICs covering the full W-band (75-110 GHz). They can provide more than 8 dB (3-stage version) and 11 dB (4-stage) of gain over 50 GHz of bandwidth. The average output power and power-added efficiency of the 3-stage PA over 70-110 GHz are 26.2 dBm and 6.5 %, respectively, while for the 4-stage PA they are 26.6 dBm and 5.2 %, respectively. Additionally, in this work we introduce for the first time a novel layout of a radial stub, able to deliver -15 dB rejection bandwidth of 28.7 %, which is nearly a factor of two improvement over the conventional radial stub without any substantial area penalty. Applying this type of stub in the design allowed for a significant boost of the overall bandwidth. Due to their unique combination of bandwidth and output power, these amplifiers could be a suitable building block for wideband communication, measurement, or phased-array systems.