Signal interleaving for serial clock and data recovery
First Claim
1. A system for recovering timing information from a serial data stream, comprising:
- a sampling circuit that produces a recovered data signal by using one or more feedback signals of a plurality of feedback signals to sample a serial data stream; and
an interleaving feedback network that produces the plurality of feedback signals, comprising;
a control circuit that produces control signals based on the recovered data signal;
a first multiplexer that is coupled to receive a plurality of periodic signals and select an individual periodic signal based on a first control signal from the control circuit;
a first delay-locked loop having a first series of delay cells that produce a plurality of delayed signals based on the selected periodic signal;
a second multiplexer that is coupled to receive the plurality of delayed signals and selects an individual delayed signal as based on a second control signal from the control circuit; and
a second delay-locked loop coupled with the second multiplexer and having a second series of delay cells that produces the plurality of feedback signals based on the selected delayed signal, wherein the second delay-locked loop further includes a third multiplexer that is coupled to receive a third control signal from the control circuit, the third multiplexer causing the second delay-locked loop to enter either an open mode of operation or a closed mode of operation in response to the third control signal.
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Accused Products
Abstract
A clock and data recovery (CDR) system and method for recovering timing information and data from a serial data stream. The CDR system includes a sampling circuit that produces a recovered clock/data signal and an interleaving feedback network that provides feedback to the sampling circuit. The feedback network includes a logic circuit that produces control signals based on the recovered clock/data signal, a first multiplexer that selects from four phases of a global clock signal based on a control signal, a first delay-locked loop having a first set of delay cells coupled to a second multiplexer that produces a delayed signal based on the selected global clock signal, and a second delay-locked loop having a second set of delay cells that produces a set of phase-shifted feedback signals that are applied to the sampling circuit to phase-align the sampling circuit with the transitions in the received serial data stream.
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Citations
21 Claims
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1. A system for recovering timing information from a serial data stream, comprising:
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a sampling circuit that produces a recovered data signal by using one or more feedback signals of a plurality of feedback signals to sample a serial data stream; and an interleaving feedback network that produces the plurality of feedback signals, comprising; a control circuit that produces control signals based on the recovered data signal; a first multiplexer that is coupled to receive a plurality of periodic signals and select an individual periodic signal based on a first control signal from the control circuit; a first delay-locked loop having a first series of delay cells that produce a plurality of delayed signals based on the selected periodic signal; a second multiplexer that is coupled to receive the plurality of delayed signals and selects an individual delayed signal as based on a second control signal from the control circuit; and a second delay-locked loop coupled with the second multiplexer and having a second series of delay cells that produces the plurality of feedback signals based on the selected delayed signal, wherein the second delay-locked loop further includes a third multiplexer that is coupled to receive a third control signal from the control circuit, the third multiplexer causing the second delay-locked loop to enter either an open mode of operation or a closed mode of operation in response to the third control signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for recovering timing information from a serial data stream, the method comprising:
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selecting one of a plurality of periodic signals based on a data signal associated with a serial data stream that is recovered by a sampling circuit; delaying the selected periodic signal to produce a plurality of delayed signals, wherein the plurality of delayed signals are produced by a first delay-locked loop; selecting one of the first plurality of delayed signals based on the recovered data signal; delaying the selected delay signal to produce a plurality of feedback signals, wherein the plurality of feedback signals are produced by a second delay-locked loop, wherein the second delay-locked loop includes a first multiplexer receiving a control signal from a control circuit; using one or more of the plurality of feedback signals as feedback for the sampling circuit that produces the recovered data signal in order to phase-align to transitions in the data stream; and placing the second delay-locked loop in either an open mode of operation or a closed mode of operation in response to the control signal received by the first multiplexer from the control circuit. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A serial clock data recovery circuit, comprising:
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a reference clock providing a plurality of clock signals having different phases; a first delay-locked loop coupled to the reference clock and generating a plurality of delayed signals from a selected one of the plurality of clock signals; a second delay-locked loop coupled to the first delay-locked loop and generating a plurality of feedback signal signals from a selected one of the plurality of delayed signals; a sampler array receiving the feedback signal from the second delay-locked loop, wherein the sampler array uses one or more of the plurality of feedback signals to sample an incoming serial bit stream and recover serial data, the sampler array further outputting signals that are used to select the one of the plurality of clock signals and the one of the plurality of delayed signals; a control circuit for receiving the signals output from the sampler array and generating a plurality of control signals; and a first switch coupled to the second delay-locked loop and the control circuit, the first switch causing the second delay-locked loop to enter either an open mode of operation or a closed mode of operation in response to a first control signal from the control circuit. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification