Joint Digital Online Compensation of TX and RX Time-Varying I/Q Mismatch and DC-Offset in mmWave Transceiver System

Millimeter-wave (mmWave) RF and analog front-end circuits are very susceptible to chip process and temperature variation, which cause I/Q mismatch and DC offset. As a consequence, the system performance can be seriously degraded, especially in wideband multi-Gb/s systems. This paper proposes an online estimation and compensation in the baseband receiver end of a single carrier (SC) system for TX and RX frequency independent (FI) initial and time-varying (TV) I/Q mismatch and DC-offset. Based on specification of IEEE 802.11ay, the compensated image rejection ratio (IRR) performance of the TX and RX FI I/Q mismatch effects can be improved from 16.43 dB to 54.70 dB at SNR of 25.52 dB. Moreover, we propose a novel algorithm based on the Golay sequence for estimation and compensation to cancel TX and RX initial/TV DC-offset. The DC-offset in the I/Q channel is improved from -56.46 dB/-58.56 dB to -97.30 dB/-98.70 dB at SNR of 25.52 dB. In the hardware implementation, a four-time parallelism architecture are proposed to work at a 625 MHz clock rate with a 28-nm HPC_PLUS CMOS process under 64-QAM mode for 15 Gbps transmission. Using a clock gating control scheme for FI I/Q mismatch and DC-offset estimator, the total power of the proposed the module can be reduced from 59.5 mW to 32.7 mW. The gate count and power of the proposed estimation/compensation design are only 2.94% and 1.69% of the overall digital RX baseband gate count and power consumption.