This work presents a fully integrated D -band transceiver (TRX) in 28-nm CMOS. The system architecture introduces a radio-frequency digital-to-analog converter (RF-DAC) and the complete mixed-signal baseband (BB) circuitry, including the equalizer, realizing fully digital BB interfaces at 24-Gb/s quadrature phase shift keying (QPSK) and 48-Gb/s 16-quadrature amplitude modulation (16-QAM). Innovations at the circuit level encompass: 1) the D -band RF front end (FE) using the proposed hybrid matching technique; 2) the two-stage conversion paths highlighting the Cartesian RF-DAC with an embedded four-tap finite impulse response (FIR) filter; 3) the local oscillator (LO) including an all-digital phase-locked loop (ADPLL) and the LO distribution network; and 4) the mixed-signal BB circuitry. The TRX achieves a transmitter (TX) bandwidth of 21 GHz, a receiver (RX) bandwidth of 18 GHz, a TX saturated output power ( Psat ) of 13.1 dBm, a TX output 1-dB compression point ( OP1 dB ) of 7.5 dBm, and an RX noise figure (NF) of 9.3 dB.