Patent ID: 8976914
Filing Date: 2015-03-10
Classification: H03D,H04L

Abstract:
1. A system for correcting gain imbalance and phase imbalance between first and second signals which are 90° out of phase, the system comprising: (a) circuitry for estimating a phase mismatch and gain mismatch between the first signal and the second signal at a plurality of frequency bands; (b) circuitry for performing an inverse fast Fourier transform (IFFT) on each of a number of arrays of the phase mismatch estimates and the gain mismatch estimates to generate correction filter coefficients for a N tap correction filter, N is a positive non-zero integer; and (c) wherein the N tap correction filter filters an uncorrected value of the second signal to generate a corrected value of the second signal, (d) circuitry for splitting each of the first and second signals into a predetermined number of frequency bands to provide a plurality of in-phase and quadrature-phase signals in the frequency bands, respectively, and (e) the circuitry for estimating comprising circuitry for successively producing a phase mismatch estimate and a gain mismatch estimate corresponding to successive frequency bands, respectively, on the basis of samples of the in-phase and quadrature-phase signals in the frequency bands, wherein the splitting circuitry includes a bank of filters for splitting each of the first and second signals into the predetermined number of frequency bands, and wherein the estimating circuitry operates to successively produce a plurality of pairs of mismatch estimates corresponding to the plurality of successive frequency bands, respectively, on the basis of samples of in-phase and quadrature-phase signal values generated by the bank of filters, each pair including a phase mismatch estimate and a gain mismatch estimate, and circuit for DC offset correction including a DC phase correction circuit including a mixer for mixing the first signal with a DC mismatch adjustment value and an adder for adding an output of the mixer to the second signal to generate the uncorrected value of the second signal such that the N tap filter essentially eliminates the gain imbalance and the phase imbalance between the first and second signals across all of the frequency bands.