Method for clock and data recovery
First Claim
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1. A method for recovering clock and data from an input bit stream, comprising:
- receiving the input bit stream;
oversampling the received input bit stream using a plurality of phases of a reference clock signal to obtain one or more sets of data samples;
identifying one or more sets of non-transitioning phases of the one or more sets of data samples;
identifying one or more center phases corresponding to the one or more sets of non-transitioning phases, wherein a center phase corresponds to a set of non-transitioning phases;
calculating one or more bit-wise transition vectors corresponding to the identified one or more center phases;
comparing the one or more bit-wise transition vectors with one or more predefined bitmasks;
selecting a first final center phase from the identified one or more center phases based on the comparison of the bit-wise transition vectors with the one or more predefined bitmasks; and
recovering data by extracting data samples from the input bit stream corresponding to the selected first final center phase.
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Abstract
An input bit stream including a clock signal and data bits is oversampled to obtain one or more sets of data samples. One or more sets of non-transitioning phases corresponding to data samples that do not switch between zero and one are then identified. Center phases corresponding to the one or more sets of non-transitioning phases are identified and then a final center phase that accurately represents the bits belonging to the input bit stream is selected. The data samples corresponding to the final center phase are extracted, thereby recovering the clock signal and data bits from the input bit stream.
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Citations
20 Claims
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1. A method for recovering clock and data from an input bit stream, comprising:
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receiving the input bit stream; oversampling the received input bit stream using a plurality of phases of a reference clock signal to obtain one or more sets of data samples; identifying one or more sets of non-transitioning phases of the one or more sets of data samples; identifying one or more center phases corresponding to the one or more sets of non-transitioning phases, wherein a center phase corresponds to a set of non-transitioning phases; calculating one or more bit-wise transition vectors corresponding to the identified one or more center phases; comparing the one or more bit-wise transition vectors with one or more predefined bitmasks; selecting a first final center phase from the identified one or more center phases based on the comparison of the bit-wise transition vectors with the one or more predefined bitmasks; and recovering data by extracting data samples from the input bit stream corresponding to the selected first final center phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for recovering clock and data from an input bit stream, comprising:
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receiving the input bit stream; oversampling the received input bit stream using a plurality of phases of a reference clock signal to obtain one or more sets of data samples, wherein each set of data samples corresponds to one bit width of received data of the received input bit stream, and wherein each set of data samples includes one of a received data bit and contiguous portions of more than one received data bit corresponding to one bit duration of the received data; identifying one or more sets of non-transitioning phases corresponding to data samples that do not switch between zero and one; identifying one or more center phases corresponding to the one or more sets of non-transitioning phases, wherein a center phase corresponds to a set of non-transitioning phases, and wherein each center phase is determined based on a count of non-transitioning phases associated with the one or more sets of non-transitioning phases; identifying one or more final center phases selected in one or more previous clock and data recovery cycles; calculating an average center phase based on the identified one or more final center phases in previous clock and data recovery cycles; selecting a set of non-transitioning phases from the identified one or more sets of non-transitioning phases in the current clock and data recovery cycle based on the calculated average center phase; selecting a first final center phase from the identified one or more center phases corresponding to the selected set of non-transitioning phases; and recovering data by extracting data samples corresponding to the selected first final center phase. - View Dependent Claims (15, 16)
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17. A receiver system for recovering clock and data from an input bit stream, comprising:
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a sampling unit for receiving the input bit stream and oversampling the received input bit stream using a plurality of phases of a reference clock signal to obtain one or more sets of data samples, wherein each set of data samples corresponds to one bit width of received data of the received input bit stream, and wherein each set of data samples comprises a received data bit or contiguous portions of more than one received data bit corresponding to one bit duration of the received data; a serial to parallel data converter, connected to the sampling unit, for converting a serial stream of the one or more sets of data samples into one or more parallel streams of sets of data samples; a clock and data recovery unit, connected to the serial to parallel data converter, for recovering clock and data from the one or more parallel streams of sets of data samples, wherein the clock and data recovery unit comprises; a memory for storing the parallel streams of sets of data samples; a non-transitioning phases identification unit, connected to the memory, for identifying one or more sets of non-transitioning phases corresponding to data samples that do not switch between zero and one; a center phase identification unit, connected to the non-transitioning phases identification unit, for identifying one or more center phases corresponding to the one or more sets of non-transitioning phases, wherein a center phase corresponds to a set of non-transitioning phases, and wherein each of the identified one or more center phases is determined based on a count of non-transitioning phases associated with the identified one or more sets of non-transitioning phases; a bit-wise transition vector calculation unit, connected to the center phase identification unit and the memory, for identifying one or more bit-wise transition vectors corresponding to the identified one or more center phases, based on switching of the data samples associated with the identified one or more center phases between zero and one; a final center phase selection unit, connected to the bit-wise transition vector calculation unit, for selecting a final center phase from the identified one or more center phases for recovering data; and a data recovery unit, connected to the final center phase selection unit and the memory, for recovering data by extracting data samples corresponding to the selected final center phase. - View Dependent Claims (18, 19, 20)
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Specification