Method and system for slicing a communication signal

• US 20050180520A1
• Filed: 12/22/2004
• Published: 08/18/2005
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Quellan, Inc. (Renesas Electronics Corporation)
• Inventors: Kim, Andrew Joo, Gebara, Edward, Pelard, Cattalen
• Granted Patent: US 7,616,700 B2
• Time in Patent Office: Days
• US Class Current: 375/287
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03312 Arrangements specific to the provision of output signals

Abstract

A slicer can receive a communication signal having a level or amplitude that is between two discrete levels of a multilevel digital communication scheme. The slicer can compare the communication signal to a plurality of references such that multiple comparisons proceed essentially in parallel. A summation node can add the results of the comparisons to provide an output signal set to one of the discrete levels. The slicer can process the communication signal and provide the output signal on a symbol-by-symbol basis. A decision feedback equalizer (“DFE”) can comprise the slicer. A feedback circuit of the DFE can delay and scale the output signal and apply the delayed and scaled signal to the communication signal to reduce intersymbol interference (“ISI”).

Claims

1. A method for processing a multilevel communication signal comprising the steps of:

generating a first signal in response to comparing the multilevel communication signal to a first threshold;

generating a second signal in response to comparing the multilevel communication signal to a second threshold; and

setting an output signal to a selected level of a multilevel communication scheme in response to adding the first signal and the second signal.

2. The method of claim 1, further comprising the step of scaling the first signal and the second signal, wherein adding the first signal to the second signal comprises adding the scaled first signal to the scaled second signal.

3. The method of claim 1, further comprising the step of generating a third signal in response to comparing the multilevel communication signal to a third threshold,

wherein the setting step comprises setting the output signal to the selected level of the multilevel communication scheme in response to adding the first signal, the second signal, and the third signal.

4. The method of claim 1, further comprising the steps of:

delaying and attenuating the output signal; and

suppressing intersymbol interference on the multilevel communication signal in response to applying the delayed and attenuated output signal to the multilevel communication signal.

5. The method of claim 1, wherein comparing the multilevel communication signal to the first threshold comprises processing the multilevel communication signal with a first comparator, and wherein comparing the multilevel communication signal to the second threshold comprises processing the multilevel communication signal with a second comparator.

6. The method of claim 1, wherein the step of generating the first signal proceeds in parallel with the step of generating the second signal.

7. The method of claim 1, wherein the multilevel communication scheme has at least a first level, a second level, and the selected level.

8. The method of claim 1, wherein:

the multilevel communication signal is between a first level and a second level of the multilevel communication scheme; and

the selected level comprises one of the first level and the second level.

9. The method of claim 1, wherein the multilevel communication signal has a symbol period and the steps of generating the first signal, generating the second signal, and setting the output signal delay the multilevel communication signal less than the symbol period.

10. The method of claim 1, wherein:

the multilevel communication signal is operative to communicate a series of symbols in accordance with the multilevel communication scheme;

the step of generating the first signal comprises generating the first signal for each symbol in the series in response to comparing the multilevel communication signal to the first threshold;

the step of generating the second signal comprises generating the second signal for each symbol in the series in response to comparing the multilevel communication signal to the second threshold; and

the setting step comprises setting the output signal to the selected level of the multilevel communication scheme for each symbol in the series in response to summing the first signal and the second signal.

11. A system, for reducing intersymbol interference on a communication signal, comprising:

a plurality of comparators, each comparing the communication signal to a respective reference and outputting a result;

a summation node, coupled to the plurality of the comparators, that provides an output signal comprising each of the results; and

a circuit that applies the output signal to the communication signal to reduce the intersymbol interference.

12. The system of claim 11, wherein the circuit comprises a feedback circuit.

13. The system of claim 11, wherein the communication signal conveys an element of data during a time period, and

wherein a feedback loop comprises the plurality of comparators, the summation node, and the circuit, and

wherein the feedback loop has a propagation delay shorter than the time period.

14. The system of claim 11, further comprising a plurality of amplifiers, each amplifier disposed between a respective one of the comparators and the summation node.

15. The system of claim 11, wherein a multilevel slicer comprises the plurality of comparators and the summation node.

16. The system of claim 11, wherein the communication signal has a symbol period, and wherein the plurality of comparators, the summation node, and the circuit provide an aggregate propagation delay that is less than the symbol period.

17. The system of claim 11, wherein the communication signal is between a first level and a second level of a communication scheme having at least the first level, the second level, and a third level, and

wherein the output signal is set to the first level or the second level.

18. A method for processing a communication signal, having an amplitude between a first level and a second level, comprising the steps of:

comparing the amplitude to a plurality of references;

for each of the references, providing a respective comparison signal in response to the comparing step;

generating an output signal, having an amplitude set to the first level or the second level, in response to summing the respective comparison signals.

19. The method of claim 18, wherein the communication signal comprises a series of symbols, and wherein the method further comprises performing each of the comparing step, the providing step, and the generating step for each symbol of the series.

20. The method of claim 18, further comprising the step of scaling each of the respective comparison signals, wherein summing the respective comparison signals comprises summing the scaled respective comparison signals.