A 300-GHz CMOS receiver module with a WR-3.4 waveguide interface is presented. The CMOS receiver is flip-chip mounted on a low-cost multilayered glass epoxy printed circuit board (PCB). A transmission-line-to-waveguide transition with a back-short structure is built into the PCB. The measured conversion gain, noise figure, and 3-dB bandwidth of the receiver module are approximately -23.7 dB, 33 dB and 18.4 GHz, respectively. Packaging loss is estimated to be approximately 4 dB from the conversion gain of the CMOS chip of -19.5 dB. A wireless data rate of 20 Gbit/s with 16-QAM was achieved using the designed modules.