Complex intermediate frequency mixer stage and calibration thereof

摘要

The invention relates to a complex intermediate frequency (CIF) mixer stage, methods of operation thereof, and methods of calibration thereof. The CIF mixer stage comprises numerous individual mixers driven by IF clock signals to down-convert received IF signals into a set of signals at baseband frequency which are further combined to form a lower side band signal and an upper side band signal. The IF clock signals used have a predefined phase relationship among them, which involves tuneable phase skews. By calibration of the conversion gains and the phases of the IF clock signals the gain and phase imbalance introduced in a preceding radio frequency mixer stage and/or the CIF mixer stage can be cancelled. Further, in-channel IQ leakage control can be applied to the lower side band signal and/or the upper side band signal. The CIF mixer stage can thus effectively suppress image interference and IQ leakage.