150-GHz CMOS TX/RX with Digitally Pre-distorted PAM-4 Modulation for Terahertz Contactless/Plastic-Waveguide Communications

150—GHz CMOS transmitter (TX) and receiver (RX) are presented for contactless and plastic waveguide communications. The implemented system employs a four-level pulse amplitude modulation and non-coherent detection. The direct up-conversion TX and self-mixing RX suffer amplitude non-linearity and distort the carrier-modulated multi-level signals. A current-mode digital pre-distortion (DPD) is integrated in the PAM-4 modulator to correct the non-linearity for the carrier-modulated multi-level signaling. Coupling antennas are designed on FR4—HR substrates. The same antenna launches electromagnetic energy into plastic waveguides to extend the communication distance. A plastic-printed-circuit-board (PCB) is introduced by inserting plastic waveguides into copper-coated slots on PCBs to realize terahertz PCB communications. The TX and RX are fabricated in the 28—nm standard bulk CMOS process. The system consumes 60.2—mW under 1.2/1.5—V supply while transferring 30—Gb/s PAM—4 data, achieving 2.01—pJ/bit energy efficiency.