A D-Band 120-GHz 2-D Scalable 4 × 4 Relay Array With Orthogonally Polarized On-Chip Antennas and In-Front-End Fast 2-D Angle-of-Arrival

Abstract

This work presents a 120-GHz 4 × 4 active reconfigurable reflective relay array that can enable D-band non- line-of-sight (NLOS) wireless communication links in scenarios with heavily blocked line-of-sight (LOS) paths. The relay array employs orthogonally linear-polarized on-chip 4 × 4 transmit- ting/receiving antenna arrays, and is 2-D scalable on a λ/×λ/2 grid. In addition, mixed-signal and low-latency loops are inte- grated within the front ends of the relay’s channels to detect the angle-of-arrival (AoA) of the external incident beam in both 2-D azimuth /elevation planes. These detection loops operate on the fly, at the carrier frequency, without the need of down- conversion, which avoids lossy mixers, complex local-oscillator (LO) distributions, and additional signal delays, ensuring a low- complexity and a high-scalability relay array design. The relay array operation is analyzed in the presence of non-idealities, including the finite isolation between the transmitting /receiving antennas and the channels’ mismatches. The 4 × 4 reflective relay array is implemented in GlobalFoundaries 22-nm CMOS fully-depleted silicon-on-insulator (FD-SOI) technology with a total area of 5 × 5 mm. Each channel achieves a measured average gain of 23.6 dB with a 3-dB bandwidth from 110 to 125 GHz, while o ffering a 360 ◦ reconfigurable phase range with a step of 11.25 ◦. Without any prior knowledge of the AoA of the external incident beam, over-the-air (OTA) measurement results demonstrate succe