Non-data-aided approach to I/Q mismatch compensation in Low-IF receivers

A digital signal processing (DSP) technique is presented that can compensate for the in-phase/quadrature-phase (I/Q) mismatch in low-intermediate frequency (IF) receivers. In particular, a non-data-aided (NDA) I/Q mismatch estimator is derived by exploiting the statistical independence between desired and image signals. The proposed technique obtains two baseband signals (uncompensated desired and image signals) from a digital IF signal and processes them to estimate and compensate for the I/Q mismatch. The mean-square error (MSE) of the estimate is analyzed. Computer simulation results indicate that the proposed technique can outperform existing adaptive DSP techniques that are based on the use of blind signal separation algorithms. It is observed that, the image rejection ratio (IRR) of the proposed technique decreases monotonically with the number of observed samples for estimation, while that of conventional methods exhibits some floor.