Analysis and Design of a Full-Duplex Two-Element MIMO Circulator-Receiver With High TX Power Handling Exploiting MIMO RF and Shared-Delay Baseband Self-Interference Cancellation

摘要

In this article, we present how full-duplex (FD) operation can be integrated with multi-input multi-output (MIMO) operation using RF and baseband (BB) self-interference cancellation (SIC). MIMO operation increases the SIC requirements by a factor of N-2 , resulting in severe area, power consumption, and noise penalty. We present the detailed analysis, design, and implementation of RF/BB cancellers that address this challenge, as well as a bootstrapping technique to enhance the power handling of integrated circulator-receivers (circ.-RX). A 65-nm CMOS scalable two-element MIMO FD circ.-RX array with integrated N-path-filter-based nonmagnetic circulators is described that: 1) exploits bootstrapping in the circulator N-path filters to enhance Transmitter (TX) power handling by 8 dB and 2) features area- and power-efficient passive RF and active BB wideband MIMO cancellation with shared-delay elements to address the O(N-2) cancellation challenge. The prototype exhibits: 1) up to 35-/45-dB average SIC across 40-/20-MHz BW; 2) more than 42-/53-dB average crosstalk (CT)SIC across 40-/20-MHz BW with <2.1-dB degradation in RX NF; and 3) overall TX power handling of +14 dBm enabled by clock bootstrapping.