A D-Band Scalable 128-Channel Dual-Polarized Receive Phased-Array with On-Chip Down Converters for 2×2 MIMO Achieving 2×42Gbps

This paper demonstrates a scalable dual-polarized receive (RX) phased array at D-band (132–142 GHz) with on-chip down converters. The wafer-scale beamformer chip is composed of 128 RX channels for an 8×8 dual-polarized array. RF beamforming is employed with 4-bit phase and gain controls on every element, and on-chip dual down-converters are used for an intermediate-frequency (IF) interface at 9–14 GHz. Also, a ×6 local-oscillator (LO) multiplier chain is used with an input at 20–23 GHz for both channels. Two 64:1 Wilkinson combiners are employed for the RF distribution network with signal amplification within the combining network. The 8×8 dual-polarization chip is fabricated in the GlobalFoundries CMOS 45RFSOI process and occupies an overall area of 9.7×9.6mm². To construct the phased array, the chip is flipped on a low loss organic interposer (RF PCB) containing the RF transitions, LO, and IF distribution networks, and which feeds an 8×8 dual-polarized microstrip antenna array with a spacing of 0.57λ×0.57λ (at 140 GHz) in azimuth and elevation planes. The array scans to ±45° in all planes for both polarizations, and the measured response supports 64 QAM operation with 2×42 Gb/s links. Application areas are in D-band dual-polarized 2×2 MIMO communication links and phased arrays.