A Millimeter-wave CMOS Cross-Polarization Leakage Canceller for Dual-Polarized MIMO Systems

Abstract

This article introduces a power-efficient millimeter-wave CMOS cross-polarization canceller for dual-polarized multiple-in-multiple-out (MIMO) systems. The dual-polarized MIMO systems can transmit two independent data streams at the same time using a horizontally polarized and vertically polarized waves. A dual-polarized antenna provides a cross-polarization isolation, which offers spatial diversity. However, the module placement, propagation, and antenna/package non-idealities cause polarization coupling resulting in degradation of the error vector magnitude. To reduce cross-polarization leakage from these non-idealities, a power-efficient passive cross-polarization leakage cancellation path is introduced. The cross-polarization leakage canceller consists of horizontal path (H-path), vertical to horizontal cancellation (V-H C) path, vertical path (V-path), and horizontal to vertical cancellation (H-V C) path. The H-path and V-path consist of the variable gain amplifier (VGA), and the V-H C path and H-V C path consist of reflection type attenuator, 0/90° 1-bit phase shifter, 0/180° 1-bit phase shifter, and 0 to 90° continuous phase shifter. Implemented in 65 nm CMOS, the proposed cross-polarization canceller improved the cross-polarization isolation better than 21.7 dB.