Considerations in the autocalibration of quadrature receivers

This paper develops a calibration procedure for gain and phase imbalances in quadrature receivers. Quadrature demodulation has many applications in communications and array processing. Frequently, the output of the in-phase (I) and quadrature (Q) channels are considered the real and imaginary parts, respectively, of a complex random process which belongs to the Goodman (1963) class. Mismatch in the gain and phase of the I and Q channels results in a departure from this statistical model and a degradation in the performance of subsequent signal processing algorithms. The calibration algorithm presented in this paper estimates the relative imbalance between the I and Q channels, based on data from a sinusoid of known frequency but unknown amplitude and phase