Patent ID: 7856050

Claim:
A method of calibrating a receiver (Rx) to compensate for a frequency-dependent imbalance in the amplitude and/or the quadrature phase of analog in-phase (I) and quadrature (Q) received-signal components that have passed through receiver circuit paths that cause said imbalance, wherein the receiver is adapted for demodulating signal carriers at variable frequencies to provide received signals at one or more of a plurality of different received frequencies, the method comprising the steps of: (a) processing samples of digital I and Q components of Rx-test signals generated at a plurality of different calibration frequencies within an Rx-calibration bandwidth to thereby estimate I-channel and Q-channel Rx-correction coefficients for each of the different calibration frequencies, wherein the digital I and Q components are provided by analog-to-digital conversion of analog I and Q components of the Rx-test signals that have been passed through said receiver circuit paths; (b) in a look-up table, storing the estimated Rx-correction coefficients for the different calibration frequencies within the Rx-calibration bandwidth; (c) from the look-up table, accessing estimated Rx-correction coefficients for calibrating the receiver for one or more of a plurality of signals at different received frequencies within the Rx-calibration bandwidth, by selecting the estimated Rx-correction coefficients for the calibration frequency or frequencies within the Rx-calibration bandwidth that are the same as or closest to the respective received frequency or frequencies; and (d) using the accessed Rx-correction coefficients to calibrate the receiver so that for the respective received frequency or frequencies the accessed estimated I-channel and Q-channel Rx-correction coefficients are combined with digital I and Q components of received signals that have been provided by analog-to-digital conversion of analog I and Q components of received signals that have passed through said receiver circuit paths upon demodulation at the received frequency.