This paper presents a 300-GHz transceiver based on 80-nm InP-HEMT technology. To improve the signal-to-noise-and-distortion-ratio (SNDR) characteristics, a high-isolation fundamental mixer is used in which the matching networks are designed for good RF/IF isolation to simultaneously achieve high conversion gain and feasible module packaging. The measured conversion gain of the fabricated mixer module is -15±2 dB, where the LO frequency, IF, and RF are 270, 2-32, and 272-302 GHz. The 300-GHz transceiver consists of the high-isolation mixer, 300-GHz amplifiers, and commercially available frequency multipliers as the LO source. It achieves 100-Gb/s wireless data transmission using 16QAM over a distance of 2.22 m with a 50-dBi antenna. To the best of the authors' knowledge, this is the highest wireless data rate ever achieved using only electronic devices.