Patent ID: 8014444
Filing Date: 2011-09-06
Classification: H03C,H03D,H04L

Abstract:
1. A method for detecting and correcting for DC offsets, amplitude imbalance and phase imbalance in the in-phase (I) and quadrature-phase (Q) baseband signal processing paths of a communication device, comprising: a. injecting an I test signal into the I signal processing path to produce an I signal and a Q test signal into the Q signal processing path to produce a Q signal; b. analyzing the I signal and the Q signal to determine their DC offsets and computing I and Q DC offset correction values to correct for the DC offsets of the I signal and Q signal, respectively; c. applying the I and Q DC offset correction values in the I and Q signal processing paths, respectively, to produce DC offset corrected I and Q signals; d. analyzing the DC offset corrected I and Q signals to determine an amplitude imbalance and computing at least one amplitude compensation factor to compensate for the amplitude imbalance, wherein computing the at least one amplitude imbalance compensation factor comprises determining a maximum value of the DC offset corrected I signal and a maximum value of the DC offset corrected Q signal, determining a ratio between the maximum values of the DC offset corrected I and Q signals, respectively, and computing the at least one amplitude imbalance compensation factor from the ratio; e. applying the amplitude imbalance correction factor to at least one of the DC offset corrected I and Q signals to produce DC offset corrected and amplitude compensated I and Q signals, wherein applying comprises applying the at least one amplitude imbalance compensation factor to at least one of the I and Q signal processing paths so that the I and Q signal processing paths produce DC offset corrected and amplitude compensated I and Q signals, respectively, that have substantially the same amplitude; f. analyzing the DC offset corrected and amplitude compensated I and Q signals to determine phase imbalance with respect to a desired orthogonal relationship and computing a phase imbalance compensation value to compensate for the phase imbalance; and g. applying the phase imbalance compensation value to at least one of the DC offset corrected and amplitude compensated I and Q signals to produce orthogonal DC offset corrected and amplitude compensated I and Q signals.