Towards an analytical model of I/Q imbalance in OFDM based direct conversion receivers

Abstract

Architectural simplicity, the possibility of monolithic integration as well as the lack of image filter problems make homodyne receivers very popular. However, their I/Q architecture is sensitive to impairments. OFDM based systems are particularly likely to suffer from imbalances due to distortions introduced by the time-to-frequency transformation of the filtered signal in the case of a mismatch between the I and Q branches. The paper focuses on clarifying how phase and amplitude imbalances influence the baseband signal processing of an OFDM based homodyne receiver. A novel analytical impairments model is presented, discussed and compared with simulations of an IEEE 802.11a system.