A D-band radar/communication fusion-mode transceiver featuring dual-function multiplexers, a two-point modulation (TPM) FMCW digital PLL with a dual-core DCO, wideband I/Q LO generators, current choking high-gain mixers, and a power-combining PA with high output power is implemented in 28nm CMOS. In the radar mode, the RF front-end demonstrates 46GHz bandwidth, and the on-chip PLL/LO generated FMCW chirp achieves a wide bandwidth of 30GHz and a fast slope of 30GHz/50μs. In the communication mode, the transceiver including analog baseband realizes 20GHz BW and the IRR is better than 40dB. The measured TX saturated P out is 13 dBm and output P1dB is 8.3 dBm. The measured PLL phase noise is -112dBc/Hz at 1MHz offset from the 11.69GHz carrier. The TX-to-RX over-the-air (OTA) modulation-demodulation measurement with QPSK and 16QAM signals shows the EVM of -20.7dB and -19.7dB, respectively.