Receiver having decisional feedback equalizer with remodulation and related methods

1. A receiver for processing a received signal comprising:

a filter stage that receives, filters, and equalizes the received signal; and

a decisional feedback loop coupled to the filter stage that receives and processes a filtered equalized signal from the filter stage using remodulation to compensate for inter-symbol interference introduced by the filter stage, the decisional feedback loop having

a carrier loop that generates a frequency correction signal from the processed filtered equalized signal and provides a frequency-offset estimate;

a converter that receives the filtered equalized signal and generates a baseband signal;

a detector that receives the baseband signal and generates a decision signal; and

a restorative signal generator that receives the decision signal and generates a restorative signal,

wherein the restorative signal and the frequency correction signal are provided to the converter to compensate for inter-symbol interference introduced by the filter stage, and

wherein the converter includes

a combiner that combines the filtered equalized signal and the restorative signal and outputs a combined signal; and

a converter multiplier that receives the combined signal and the frequency correction signal and outputs the baseband signal.

2. The receiver of claim 1 , wherein the filter stage comprises;

a filter that receives the received signal and outputs a filtered input signal; and

an equalizer coupled to the filter that receives and equalizes the filtered input signal and outputs the filtered equalized signal.

3. The receiver of claim 2 , wherein the equalizer comprises:

a feed-forward equalizer.

4. The receiver of claim 1 , wherein the carrier loop includes:

the converter multiplier;

the detector; and

carrier circuitry,

wherein the carrier circuitry receives the decision signal from the detector and provides the frequency correction signal to the converter multiplier and to the restorative signal generator.

5. A receiver for processing a received signal comprising:

a filter stage that receives, filters, and equalizes the received signal; and

a decisional feedback loop coupled to the filter stage that receives and processes a filtered equalized signal from the filter stage using remodulation to compensate for inter-symbol interference introduced by the filter stage, the decisional feedback loop having

a carrier loop that generates a frequency correction signal from the processed filtered equalized signal and provides a frequency-offset estimate;

a converter that receives the filtered equalized signal and generates a baseband signal;

a detector that receives the baseband signal and generates a decision signal; and

a restorative signal generator that receives the decision signal and generates a restorative signal, the restorative signal generator having

a remodulator that receives the decision signal and the frequency correction signal and remodulates the decision signal using the frequency correction signal, producing a frequency-shifted decision signal; and

a decisional feedback equalizer that receives the frequency-shifted decision signal and generates the restorative signals

wherein the restorative signal and the frequency correction signal are provided to the converter to compensate for inter-symbol interference introduced by the filter stage.

6. The receiver of claim 5 , wherein the remodulator comprises:

a transformer that transforms the frequency correction signal into a conjugated frequency correction signal; and

a multiplier that receives the conjugated frequency correction signal and the decision signal and outputs the frequency-shifted decision signal.

7. The receiver of claim 5 , wherein the restorative signal generator further comprises:

a restorative multiplier that receives the frequency correction signal and the restorative signal and outputs a frequency-shifted restorative signal to the converter.

8. The receiver of claim 7 , wherein the converter includes:

a converter multiplier that receives the filtered equalized signal and the frequency correction signal and outputs an intermediate signal; and

a combiner that combines the intermediate signal and the frequency-shifted restorative signal and outputs the baseband signal.

9. The receiver of claim 8 , wherein the carrier loop includes:

the restorative multiplier;

the converter multiplier;

the combiner;

the detector; and

carrier circuitry,

wherein the carrier circuitry receives the decision signal from the detector and provides the frequency correction signal to the converter multiplier and to the restorative multiplier.

10. The receiver of claim 5 , wherein the decisional feedback equalizer comprises:

a delay stage that receives the frequency-shifted decision signal and outputs delayed signals;

a weighting stage that receives the delayed signals and outputs weighted delayed signals; and

an equalizer combiner that receives the weighted delayed signals and outputs the restorative signal.

11. A receiver for processing a received signal comprising:

a filter stage that receives, filters, and equalizes the received signal; and

a decisional feedback loop coupled to the filter stage that receives and processes a filtered equalized signal from the filter stage using remodulation to compensate for inter-symbol interference introduced by the filter stage, the decisional feedback loop having

a carrier loop that generates a frequency correction signal from the processed filtered equalized signal and provides a frequency-offset estimate;

a converter that receives the filtered equalized signal and generates a baseband signal;

a detector that receives the baseband signal and generates a decision signal; and

a restorative signal generator that receives the decision signal and generates a restorative signal.

wherein the restorative signal and the frequency correction signal are provided to the converter to compensate for inter-symbol interference introduced by the filter stage. and

wherein the converter includes

a converter multiplier that receives the filtered equalized signal and the frequency correction signal and outputs an intermediate signal; and

a combiner that combines the intermediate signal and the restorative signal and outputs the baseband signal.

12. The receiver of claim 11 , wherein the carrier loop includes:

the converter multiplier;

the combiner;

the detector; and

carrier circuitry,

wherein the carrier circuitry receives the decision signal from the detector and provides the frequency correction signal to the converter multiplier and the frequency-offset estimate to the restorative signal generator.

13. The receiver of claim 12 , wherein the carrier circuitry comprises:

a reference oscillator that produces a reference signal;

a carrier detector that receives the reference signal and the decision signal and outputs an error signal;

a loop filter that receives the error signal and outputs the frequency-offset estimate; and

a frequency tunable oscillator that receives the frequency-offset estimate and outputs the frequency correction signal.

14. A receiver for processing a received signal comprising:

a filter stage that receives, filters, and equalizes the received signal; and

a decisional feedback loop coupled to the filter stage that receives and processes a filtered equalized signal from the filter stage using remodulation to compensate for inter-symbol interference introduced by the filter stage, the decisional feedback loop having

a carrier loop that generates a frequency correction signal from the processed filtered equalized signal and provides a frequency-offset estimate;

a converter that receives the filtered equalized signal and generates a baseband signal;

a detector that receives the baseband signal and generates a decision signal; and

a restorative signal generator that receives the decision signal and generates a restorative signal, the restorative signal generator having

a delay stage that receives the decision signal and outputs delayed signals;

a remodulation stage that receives the frequency-offset estimate and delayed signals and outputs remodulated delayed signals;

a weighting stage that receives the remodulated delayed signals and outputs weighted remodulated delayed signals; and

a restorative combiner that receives the weighted remodulated delayed signals and outputs the restorative signal,

wherein the restorative signal and the frequency correction signal are provided to the converter to compensate for inter-symbol interference introduced by the filter stage.

15. A method of processing a received signal that compensates for inter-symbol interference, the method comprising:

receiving an input signal;

filtering the input signal to produce a filtered input signal;

equalizing the filtered input signal to produce an equalized filtered input signal; and

processing the equalized filtered input signal using remodulation to compensate for inter-symbol interference, wherein the processing includes

generating a baseband signal from the equalized filtered input signal, a frequency correction signal, and a restorative signal;

generating a decision signal from the baseband signal;

generating the frequency correction signal from the decision signal; and

generating the restorative signal from the decision signal and the frequency correction signal, wherein the generating the restorative signal includes

remodulating the decision signal based on the frequency correction signal to produce a remodulated signal; and

equalizing the remodulated signal to produce the restorative signal.

16. The method of claim 15 wherein remodulating includes:

transforming the frequency correction signal into a conjugated frequency correction signal; and

frequency-shifting the decision signal based on the conjugated frequency correction signal.

17. The method of claim 15 wherein equalizing includes:

generating delayed signals from the remodulated signal;

weighting the delayed signals to produce weighted delayed signals; and

combining the weighted delayed signals to produce the restorative signal.

18. The method of claim 15 , wherein generating the restorative signal further includes:

frequency-shifting the restorative signal.

19. A method of processing a received signal that compensates for inter-symbol interference, the method comprising:

receiving an input signal;

filtering the input signal to produce a filtered input signal;

equalizing the filtered input signal to produce an equalized filtered input signal; and

processing the equalized filtered input signal using remodulation to compensate for inter-symbol interference, wherein the processing includes

generating a baseband signal from the equalized filtered input signal, a frequency correction signal, and a restorative signal;

generating a decision signal from the baseband signal;

generating the frequency correction signal and a frequency offset estimate from the decision signal; and generating the restorative signal from the decision signal and the frequency offset estimate, wherein the generating the restorative signal includes

generating delayed signals from the decision signal;

remodulating the delayed signals based on the frequency offset estimate to produce remodulated delayed signals;

weighting the remodulated delayed signals to produce weighted remodulated delayed signals; and

combining the weighted remodulated delayed signals to produce the restorative signal.