A Ka-Band 64-Element Four-Beam Phased Array Receiver With Inter-Beam Interference Cancellation

This article presents a Ka-band 64-element phased-array receiver with four simultaneously reconfigurable beams for millimeter-wave (mmW) satellite communications, where each beam utilizes the maximum available antenna aperture to enhance the combining gain. To address the design challenge of the large area induced by the multiple beamforming networks (BFNs), the beamformer utilizes a digital-assisted variable-gain phase-shifting technique and an active combining scheme to enable compact implementation and facilitate array design. This article also proposes a cancellation-based inter-beam interference reduction technique using multiple beams to support steerable nulling to boost beam-to-beam isolation, which offers an alternative solution to reduce array sidelobes. The proposed $8\times 4$ beamformer integrates 32-path independent plural weighting channels and is fabricated in 65-nm CMOS with a compact chip area of $5.3\times 4$ mm2. Each element achieves a gain of 26.7 dB, a noise figure (NF) of 3.7–4.5 dB, and an input-referred 1-dB gain compression point (IP1dB) of −32.5 dBm at 29.5 GHz. The proposed 64-element receive phased array is capable of scanning ±50° at 29.5 GHz without grating lobes at both the azimuth and elevation directions. To the authors’ best knowledge, the proposed phased-array receiver presents the largest number of co-aperture reconfigurable beams among mmW-integrated RF-beamforming phased arrays.

I. Introduction

The emerging low-earth-orbit satellite communication (LEO SATCOM) employs low-cost large-scale K- and Ka-band transmit and receive phased-array antennas and enables global high-speed internet access, especially in low-connectivity-density areas [1], [2]. The spaceborne multibeam phased-array antenna (MBPAA) is one of the primary payloads of the LEO satellite system. Beamforming techniques are utilized to simultaneously achieve multiple independent high-gain beams, thus widening the field-of-view (FoV) coverage and enabling random access and multi-point communication, as shown in Fig. 1. Fig. 1.

Spaceborne phased-array antennas from subarray-based to fully connected multibeam.