On I/Q imbalance compensation based on adaptive filtering in Low-IF and Zero-IF radio

This paper deals with adaptive filters, based on symmetric adaptive decorrelation, used for I/Q imbalance compensation in wireless receivers. Analytical analysis of two such filters reported in the literature shows that the output signal suffers a distortion due to the adaptive process. A formula for the distortion factor is deduced, which is then validated experimentally: a filter was implemented on a FPGA platform and tests have been carried out for imbalanced QAM-16 input signals. Moreover, this work shows that the effects of I/Q imbalance can be described analytically in a similar manner for both Low- and Zero-IF.