1.4-GHz Bandwidth Frequency-Dependent I/Q Imbalance Calibration for 5G mmWave Communications

This paper presents a frequency-dependent in-phase and quadrature-phase (IQ) imbalance calibration technique for ultra-wide bandwidth 5G millimeter-wave communication chipsets. Using a multi-tone training signal and a phase shifter inserted in the transceiver local loopback path, the transmitter and receiver IQ imbalances can be estimated separately. The complex finite-impulse response filter introduced in this work compensates the spectrum flatness and the IQ imbalance concurrently and achieved an average image-rejection ratio of 51.6 dB over 1.4 GHz of bandwidth.