Channel calibrator for use with a quadrature mixing receiver and a method of operation thereof
View Patent ↗The present invention is directed to a channel calibrator and a method of calibrating in-phase and quadrature phase channels for use with a quadrature mixing receiver. In one embodiment, the channel calibrator includes a balancer and an equalizer. The balancer reduces frequency dependent imbalance between an in-phase channel and a quadrature phase channel associated with the receiver. The equalizer decreases frequency independent mismatch between the in-phase channel and the quadrature phase channel.
1. A channel calibrator for use with a quadrature mixing receiver, comprising:
a balancer configured to reduce a frequency dependent imbalance between an in-phase channel and a quadrature phase channel associated with said receiver;
an equalizer configured to decrease a frequency independent mismatch between said in-phase channel and said quadrature phase channel; and
an isolation circuit, coupled to said balancer and said equalizer, configured to separate said balancer and said equalizer during at least a portion of calibration of said in-phase channel and said quadrature phase channel.
2. The channel calibrator as recited in claim 1 wherein said isolation circuit is configured to separate said balancer and said equalizer when said in-phase channel and said quadrature phase channel are calibrated due to frequency dependent imbalance sources.
3. The channel calibrator as recited in claim 1 wherein said balancer employs a pair of linear phase finite-impulse-response pre-equalizers.
4. The channel calibrator as recited in claim 3 wherein said balancer includes a coefficient adapter employing a sign algorithm.
5. The channel calibrator as recited in claim 1 wherein said equalizer employs a single adaptive filter.
6. The channel calibrator as recited in claim 1 wherein said equalizer includes a coefficient adjuster employing an adaptive algorithm.
7. The channel calibrator as recited in claim 1 wherein said balancer employs a pair of adaptive filters.
8. A method of calibrating in-phase and quadrature phase channels for use with a quadrature mixing receiver, comprising:
separating a balancer from an equalizer during at least a portion of calibration of said in-phase channel and said quadrature phase channel, said balancer for reducing a frequency dependent imbalance between said in-phase channel and said quadrature phase channel and said equalizer for decreasing a frequency independent mismatch between said in-phase channel and said quadrature phase channel;
reducing said frequency dependent imbalance; and
decreasing said frequency independent mismatch.
9. The method as recited in claim 8 further comprising separating sources of said frequency dependent imbalance and said frequency independent mismatch during calibration of said in-phase channel and said quadrature phase channel due to frequency dependent imbalance sources.
10. The method as recited in claim 9 wherein said calibration due to frequency dependent imbalance sources occurs for a specific time.
11. The method as recited in claim 10 wherein calibration due to frequency independent mismatch occurs after said specific time.
12. The method as recited in claim 11 wherein sources are connected before said calibration due to frequency independent mismatch.
13. The method as recited in claim 12 wherein said balancer and said equalizer are connected for said calibration due to frequency independent mismatch.
14. The method as recited in claim 10 wherein said specific time is derived from a magnitude of an error signal.
15. A quadrature mixing receiver for use with a wireless communications system, comprising:
a radio frequency front end;
a baseband signal processor; and
a channel calibrator, including:
a balancer that reduces frequency dependent imbalance between an in-phase channel and a quadrature phase channel associated with said receiver,
an equalizer that decreases frequency independent mismatch between said in-phase channel and said quadrature phase channel, and
an isolation circuit, coupled to said balancer and said equalizer, configured to separate said balancer and said equalizer during at least a portion of calibration of said in-phase channel and said quadrature phase channel.
16. The quadrature mixing receiver as recited in claim 15 wherein said isolation circuit is configured to separate said balancer and said equalizer when said in-phase channel and said quadrature phase channel are calibrated due to frequency dependent imbalance sources.
17. The quadrature mixing receiver as recited in claim 15 wherein said balancer employs a pair of linear phase finite-impulse-response pre-equalizers.
18. The quadrature mixing receiver as recited in claim 15 wherein said balancer includes a coefficient adapter employing a sign algorithm.
19. The quadrature mixing receiver as recited in claim 15 wherein said equalizer employs a single adaptive filter.
20. The quadrature mixing receiver as recited in claim 15 wherein said equalizer includes a coefficient adjuster employing an adaptive algorithm.
21. The quadrature mixing receiver as recited in claim 15 wherein said balancer employs a pair of adaptive filters.