300-GHz-Band 120-Gb/s Wireless Front-End Based on InP-HEMT PAs and Mixers

We developed a 300-GHz-band 120-Gb/s wireless transceiver front-ends (TRX) using our in-house InP-based high-electron-mobility-transistor (InP-HEMT) technology for beyond-5G. The TRX is composed of the RF power amplifiers (PAs), mixers, and local oscillation (LO) PAs which are all packaged in individual waveguide (WG) modules by using a ridge coupler for low-loss WG-to-IC transition. RF PAs are designed using the low-impedance inter-stage-matching technique to reduce the inter-stage matching loss of the amplifier stages, and the back-side DC line (BDCL) technique is used to simplify the layout and to improve the gain of the PAs. The fabricated RF PAs show a high output 1-dB compression point of more than 6 dBm from 278 to 302 GHz. The mixers are used for both up- and down-conversion in the transmitter and receiver. These mixers are designed to have high conversion gain (CG) over the wideband even after packaging by enhancing the isolation between the RF and IF ports. The measured CG of mixer module is -15 dB, and the 3-dB IF-bandwidth is 32 GHz. The LO PAs are also designed using the BDCL technique so that they can supply the required LO power to the mixers. The TRX with these InP building blocks enables the data transmission of a 120 Gb/s 16QAM signal over a link distance of 9.8 m.