Methods and circuits for decision-feedback equalization using compensated decision regions
AssigneeCadence Design Systems, Inc.
InventorNanyan Wang
Life of this patent
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Abstract
A decision-feedback equalizer (DFE) samples an input signal with respect to a gamut of p reference-voltage levels to place the symbol represented by the input signal within a voltage region. The DFE derives a set of tentative decisions for the voltage region, the set excluding at least one of the possible values for the symbol under consideration. A feedback stage then selects a final decision from among the tentative decisions.
Claims20
A decision-feedback equalizer (DFE) comprising:
- an input node to receive an input signal expressing a series of symbols, each of the symbols representing one of a set of possible symbol values;
- a first open-loop stage coupled to the input node to receive the series of symbols and a gamut of reference-voltage levels, the first open-loop stage to compare each symbol in the series of symbols with only a subset of the reference-voltage levels to identify a voltage region;
- a second open-loop stage coupled to the first open-loop stage to derive from the voltage region a set of tentative decisions representing a subset of the set of possible symbol values;
- and
- a feedback stage coupled to the second open-loop stage to select one of the set of tentative decisions as a final decision responsive to a prior final decision.
A method of interpreting an input signal expressing a series of symbols, each of the symbols representing one of a set of possible symbol values, the method comprising:
- providing p reference-voltage levels;
- and
- for each of the series of symbols:
- comparing the symbol with a first of the reference-voltage levels to produce a first partial decision;
- selecting a second of the reference-voltage levels responsive to the first partial decision;
- comparing the symbol with the second of the reference-voltage levels to produce a second partial decision;
- providing a set of tentative decision as to the value of the symbol based on the first and second partial decisions, wherein the set of tentative decisions includes more than one tentative decision for some of the symbols in the series of symbols;
- and
- selecting one of the at least one tentative decisions as a final decision.
A decision-feedback equalizer (DFE) comprising:
- an input node to receive an input signal expressing a series of symbols, each of the symbols representing one of a set of possible symbol values;
- a reference-level generator to provide a gamut of reference-voltage levels;
- and
- an open-loop stage coupled to the input node to receive the series of symbols, the open-loop stage to compare each symbol in the series of symbols to a first of the gamut of reference-voltage levels to make a first partial decision as to the value of the symbol, select a second of the gamut of reference-voltage levels responsive to the first partial decision, and compare the symbol to the second of the gamut of reference-voltage levels to make a second partial decision as to the value of the symbol.
Dependencies are inferred from the claim text.