A 300-GHz Dual-Polarized CMOS Waveguide Receiver for High-Density Terahertz Integrated Multichannel Wireless Systems-on-Chip

This article presents a class of high-density waveguide dual-polarized receivers operating at terahertz (THz) frequencies, fully integrated on a single complimentary metal-oxide–semiconductor (CMOS) die. Unlike conventional TEM-mode dual-polarized receivers, which require doubled chip size for polarization diversity, our proposed nonTEM-mode substrate integrated waveguide (SIW) receiver features both vertical (V) and horizontal (H) polarization channels. This design is achieved through a 3-D on-chip integration that leverages the multilayer stack-up nature of advanced CMOS fabrication processes. The receiver, employing an interferometric receiving architecture, enables direct conversion of dual-polarized signals to baseband or intermediate frequency (IF) without increasing chip size, effectively halving the overall chip dimensions. This approach, particularly advantageous for large-scale integrated receiver arrays, also reduces topological complexity, structural loss, and power consumption. Consequently, the proposed receiver supports high data transmission throughput based on polarization diversity while maintaining the same chip footprint, marking a significant advancement for future high-density THz-integrated multichannel wireless systems. We designed, fabricated, and tested a proof-of-concept experimental prototype using a standard 65-nm CMOS process. Successful transmission and demodulation of a digitally modulated signal using M-quadrature amplitude modulation (M-QAM) at 300 GHz were achieved, supported by both simulated and measured results.