Mirror signal IQ-imbalance correction

摘要

A system and method are provided for calibrating the IQ-imbalance in a low-IF receiver. A Test Signal can be generated in a mirror frequency and conveyed to the receiver. The power of the signal produced in the receiver from the conveyed Test Signal can be measured. In the absence of an IQ-imbalance, the Test Signal can be completely eliminated in the receiver and the corresponding measured power of the produced signal can be minimized. Accordingly, a two dimensional algorithm is described for calibrating a receiver and correcting the IQ-imbalance by adjusting the phase and gain difference between the I and Q channels in the receiver based on the measured power of the signal produced in the receiver.

主权项

1. A system comprising:
a low-IF receiver configured to be tunable for selected channels; a synthesizer configured to produce a Test Signal in mirror frequencies for a selected channel and for conveying the Test Signal to the receiver; an IQ Imbalance Estimator configured for estimating a phase imbalance and a gain imbalance in the receiver based on a signal produced in the receiver from the Test Signal; and a power detector configured to produce a Power Estimate of the signal produced in the receiver from the conveyed Test Signal, wherein the system is further configured for: setting a first searching region for gain imbalance and phase imbalance in the receiver; selecting a first plurality of grid-points within the first searching region; and measuring a Power Estimate for each grid-point in the first plurality of grid-points by setting a gain-correction and a phase-correction in the receiver corresponding to the coordinates of each grid-point in the first plurality of grid-points.