A W-Band GaN MMIC Single-Chip T/R Front End

A single-chip transmit–receive (T/R) front end covering (75–110) GHz is implemented in a 40-nm GaN on SiC HEMT process. The transmit path consists of a balanced power amplifier (PA) with three-stage unit PAs and an additional single-HEMT driver to achieve above 17-dB small-signal gain over the range and over 15 dB of large-signal gain across 75–108 GHz. The receive path consists of a three-stage low-noise amplifier (LNA) with a small-signal gain of 16–22 dB and de-embedded calculated noise figure (NF) of 4–6.5 dB across the range. A single pole double throw (SPDT) shunt switch with an insertion loss of 1–1.5 dB and an isolation between 15 and 20 dB across the band selects the transmit or receive paths in this half-duplex front end and does not show compression in transmit mode. In transmit mode, the front end measures >25 dBm over 75–110 GHz with a measured maximum of 29 dBm of output power at 92 GHz. In receive mode, the front end shows an NF of 5.2–7.8 dB with a gain of 16–22 dB. The demonstrated output power in transmit and NF in receive modes, with sufficient isolation, makes this single-die T/R component suitable for communications, imaging, and sensing.