High-speed parallel decision feedback equalizer
First Claim
1. A high speed equalization method that comprises:
- deriving at each of multiple consecutive time intervals a set of tentative decisions, each tentative decision accounting for a respective degree of trailing intersymbol interference;
forming a parallel group from a series of said sets of tentative decisions;
applying the parallel group to a set of pipelined DFE multiplexer units, each said unit selecting a contingent symbol decision from each set of tentative decisions in the group to form a group of contingent symbol decisions based on a different presumed sequence of preceding symbol decisions; and
choosing, based on an actual sequence of preceding symbol decisions, one of said groups of contingent symbol decisions as a group of actual symbol decisions.
2 Assignments
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Accused Products
Abstract
A decision-feedback equalizer (DFE) can be operated at higher frequencies when parallelization and pre-computation techniques are employed. Disclosed herein is a DFE design suitable for equalizing receive signals with bit rates above 10 GHz, making it feasible to employ decision feedback equalization in silicon-based optical transceiver modules. One illustrative embodiment includes a front end filter to reduce leading intersymbol interference in a receive signal; a serial-to-parallel converter and at least one pre-compensation unit that together convert the filtered signal into grouped sets of tentative decisions, the sets in each group being made available in parallel; a set of pipelined DFE multiplexer units to select a contingent symbol decision from each set of tentative decisions to form groups of contingent symbol decisions based on a presumed sequence of preceding symbol decisions; and an output multiplexer that chooses, based on preceding symbol decisions, one of said groups of contingent symbol decisions.
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Citations
23 Claims
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1. A high speed equalization method that comprises:
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deriving at each of multiple consecutive time intervals a set of tentative decisions, each tentative decision accounting for a respective degree of trailing intersymbol interference; forming a parallel group from a series of said sets of tentative decisions; applying the parallel group to a set of pipelined DFE multiplexer units, each said unit selecting a contingent symbol decision from each set of tentative decisions in the group to form a group of contingent symbol decisions based on a different presumed sequence of preceding symbol decisions; and choosing, based on an actual sequence of preceding symbol decisions, one of said groups of contingent symbol decisions as a group of actual symbol decisions. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A high speed equalizer that comprises:
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a front end filter that reduces leading intersymbol interference in a receive signal to provide a filtered signal; a serial-to-parallel converter and at least one precompensation unit that together convert the filtered signal into grouped sets of tentative decisions, the sets in each group being made available in parallel; a set of pipelined DFE multiplexer units, each multiplexer unit selecting a contingent symbol decision from each set of tentative decisions in each group to form groups of contingent symbol decisions based on a different presumed sequence of preceding symbol decisions; and an output multiplexer that chooses, based on an actual sequence of preceding symbol decisions, one of said groups of contingent symbol decisions as a group of actual symbol decisions. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A channel interface module that comprises a receiver having:
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a sensor that converts receive channel signals into electrical signals; a front end filter that enhances the signal-to-noise ratio of the electrical signals; at least one precompensation unit and a serial-to-parallel converter that together produce groups of tentative decision sets, the sets in each group being made available in parallel; a set of multiplexer units that each operate on each group to obtain a group of contingent decisions based on a different presumed sequence of preceding symbol decisions; an output multiplexer that, based on actual preceding symbol decisions, chooses a group of actual symbol decisions from the groups of contingent decisions; and a device interface that provides a host node with a received data stream derived from the group of actual symbol decisions. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification