DECISION FEEDBACK EQUALIZATION
First Claim
1. A signal sampling system comprising N latching samplers, whereinN is an integer equal to or greater than four;
- each sampler of the N latching samplers includes a sample clock input to couple to a sample clock, and the sample clocks of the N latching samplers are spaced in phase through 360 degrees;
each sampler of the N latching samplers further includes a data input having a decision logic level threshold, a plurality of offset control inputs, a plurality of offset magnitude inputs, an un-buffered output, and a buffered output; and
each sampler of the N latching samplers further includes circuitry coupled between the inputs and outputs that causes a time delay from an input signal transition to an output signal transition wherein,after an offset control input changes from a first voltage to a second voltage, the decision logic level threshold changes in a time less than one gate delay, andafter the sample clock transitions from a first logic state to a second logic state, the un-buffered output transitions within a time substantially equal to one gate delay and the buffered output transitions within a time substantially equal to two gate delays.
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Abstract
A signal sampling system that includes N samplers is disclosed. Each sampler includes a data input having a decision logic level threshold, a plurality of offset control inputs, a plurality of offset magnitude inputs, an un-buffered output, and a buffered output. Each sampler further includes circuitry coupled between the inputs and outputs that is configured to cause a time delay from an input signal transition to an output signal transition such that, after an offset control input transitions from a first voltage to a second voltage, the decision logic level threshold changes in a time substantially less than one gate delay, and after the sample clock transitions from a first logic state to a second logic state, the un-buffered output transitions within a time substantially equal to one gate delay and the buffered output transitions within a time substantially equal to two gate delays.
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Citations
20 Claims
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1. A signal sampling system comprising N latching samplers, wherein
N is an integer equal to or greater than four; -
each sampler of the N latching samplers includes a sample clock input to couple to a sample clock, and the sample clocks of the N latching samplers are spaced in phase through 360 degrees; each sampler of the N latching samplers further includes a data input having a decision logic level threshold, a plurality of offset control inputs, a plurality of offset magnitude inputs, an un-buffered output, and a buffered output; and each sampler of the N latching samplers further includes circuitry coupled between the inputs and outputs that causes a time delay from an input signal transition to an output signal transition wherein, after an offset control input changes from a first voltage to a second voltage, the decision logic level threshold changes in a time less than one gate delay, and after the sample clock transitions from a first logic state to a second logic state, the un-buffered output transitions within a time substantially equal to one gate delay and the buffered output transitions within a time substantially equal to two gate delays. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A signal sampling system, comprising
N latching samplers, wherein N is an integer equal to or greater than four; - and
a decision feedback equalizer providing communication between the N latching samplers, the decision feedback equalizer comprising, for each sampler of the N latching samplers, integer N/2 offset control inputs and integer N/2 offset magnitude inputs that are configured to provide feedback to adjust a decision logic level threshold for the latching sampler of the N latching samplers, wherein a first offset control input of the integer N/2 offset control inputs is coupled to an un-buffered sampler output of one or more other samplers of the N latching samplers, and a second offset control input of the integer N/2 offset control inputs is coupled to a buffered sampler output of one or more other samplers of the N latching samplers. - View Dependent Claims (10, 11, 12, 13)
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14. A method of operating a signal sampling system including N latching samplers, the method comprising:
for each sampler of the N latching samplers, receiving, at each of a plurality of offset control inputs, a buffered output signal or an un-buffered output signal from another sampler of the N latching samplers; receiving, at each of a plurality of offset magnitude inputs, an offset magnitude signal, the offset magnitude signal indicating an amount of contribution from a respective offset control input to an adjustment of a decision logic level threshold of the sampler; adjusting the decision logic level threshold of the sampler based at least one of the signals received at the plurality of offset control inputs and the plurality of offset magnitude signals received at the plurality of offset magnitude inputs, where the decision logic level threshold changes within a time less than one gate delay after an offset control input of the sampler transitions from a first voltage to a second voltage; receiving, at a data input of the sampler, a data signal; and sampling the data signal as a logic level based on a comparison of the data signal to the decision logic level threshold. - View Dependent Claims (15, 16, 17, 18, 19, 20)
Specification