Patent ID: 8135094

Claim:
A quadrature receiver, comprising: an analog portion for receiving a radio frequency signal, the analog portion including an in-phase channel including an analog-to-digital converter for outputting an in-phase digital signal including discrete samples of the in-phase digital signal, and a quadrature-phase channel including an analog-to-digital converter for outputting a quadrature-phase digital signal including discrete samples of the quadrature-phase digital signal; and a digital portion, coupled to the analog portion, the digital portion including a group delay equalizer for receiving the in-phase digital signal and the quadrature-phase digital signal from the analog portion, wherein the group delay equalizer delays one of the in-phase and quadrature-phase digital signals by one or more samples based upon an amount of a group delay mismatch, the group delay equalizer producing a linear group delay mismatch versus frequency response to approximately counteract a non-linear group delay mismatch versus frequency response at an output of the analog portion, the group delay equalizer having an in-phase output and a quadrature-phase output, and circuitry for determining a phase imbalance between the in-phase channel and the quadrature-phase channel of the received radio frequency signal at a calibration frequency, the circuitry for determining including a processor for producing a complex number whose value is based on the amount of the phase imbalance, an I-channel downsampling filter, a Q-channel downsampling filter, a single-tap complex multiplier, coupled to an output of the Q-channel downsampling filter, for multiplying the output of the Q-channel downsampling filter with the complex number, the single-tap complex multiplier having a real output, and an adder for adding the real output of the single-tap complex multiplier to an output of the I-channel oversampling filter to reduce the phase imbalance between the in-phase channel and the quadrature-phase channel of the received radio frequency signal.