System and method for selecting optimal data transition types for clock and data recovery
First Claim
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1. A clock recovery circuit comprising:
- a. transition detector that receives a plurality of data transitions of various data-transition types, the transition detector including a plurality of data-transition output terminals, each data-transition output terminal producing a data-transition signal in response to a respective one of the data-transition types;
b. transition select logic having a plurality of select-logic input nodes, a select-logic output node, and select-logic control terminals, each select-logic input node coupled to a respective one of the data-transition output terminals, wherein the transition select logic conveys at least one of the data-transition signals from a respective one of the select-logic input nodes to the select-logic output node in response to select-logic control signals to the select-logic control terminals; and
c. a select-logic control circuit having control-circuit output terminals coupled to the select logic control terminals;
wherein the select-logic control circuit issues transition select signals to the transition select logic via the select logic control terminals.
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Abstract
A clock recovery circuit samples an incoming data stream that includes sequences of signal transitions. A transition detector categorizes the received signal transitions into various types, such as those associated with 2PAM and 4PAM signaling schemes. Select logic control circuitry analyzes the signal-transition types to determine which of the transition types is best suited for clock recovery. This determination relies upon a number of factors, including for example whether the received signal is a 4PAM signal or a 2PAM signal, the existence of a pattern within the received data, or the relative abundance or scarcity of certain types of transitions.
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41 Claims
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1. A clock recovery circuit comprising:
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a. transition detector that receives a plurality of data transitions of various data-transition types, the transition detector including a plurality of data-transition output terminals, each data-transition output terminal producing a data-transition signal in response to a respective one of the data-transition types; b. transition select logic having a plurality of select-logic input nodes, a select-logic output node, and select-logic control terminals, each select-logic input node coupled to a respective one of the data-transition output terminals, wherein the transition select logic conveys at least one of the data-transition signals from a respective one of the select-logic input nodes to the select-logic output node in response to select-logic control signals to the select-logic control terminals; and c. a select-logic control circuit having control-circuit output terminals coupled to the select logic control terminals; wherein the select-logic control circuit issues transition select signals to the transition select logic via the select logic control terminals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A clock recovery method comprising:
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a. sampling a data stream using a receive clock to generate sampled data; b. monitoring the sampled data for data transitions of a plurality of possible data-transition types; c. automatically selecting a subset of the data transitions based upon the monitoring; d. adjusting the receive clock relative to the sampled data using the subset of the data transitions; and e. wherein automatically selecting the subset of the data transitions includes determining whether the data stream is a multi-level signal. - View Dependent Claims (15, 16, 17)
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18. A clock recovery method comprising:
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a. sampling a data stream using a receive clock to generate sampled data; b. monitoring the sampled data for data, transitions of a plurality of possible data-transition types; c. automatically selecting a subset, of the data transitions based upon the monitoring; and d. adjusting the receive clock relative to the sampled data using the subset of the data transitions; e. wherein automatically selecting a subset of the data transitions comprises separating the data transitions into at least two of the data-transition types. - View Dependent Claims (19, 20, 21)
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22. A clock recovery dircuit comprising:
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a. a transition detector that receives a plurality of data transitions of various data-transition types, the transition detector including a plurality of data-transition output terminals, each data-transition output terminal producing a data-transition signal in response to a respective one of the data-transition types; b. transition select logic having a plurality of select-logic input nodes, a select-logic output node, and select-logic control terminals, each select-logic input node coupled to a respective one of the data-transition output terminals, wherein the transition select logic conveys at least one of the data-transition signals from a respective one of the select-logic input nodes to the select-logic output node in response to select-logic control signals to the select-logic control terminals; and c. control means connected to the select-logic control terminals, wherein the control means issues transition select signals to the transition select logic in response to the data transitions. - View Dependent Claims (23)
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24. A clock recovery circuit comprising:
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a. a transition detector that receives a plurality of data transitions of various data-trahsition types; b. transition select logic that receives the data transitions and that conveys a feedback signal in response to at least one of the data-transition types; and c. a select-logic control circuit that controls the transition select logic to select the at least one of the data-transition types based on the received data transitions. - View Dependent Claims (25, 26)
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27. A clock recovery circuit comprising:
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a. a transition detector that receives a plurality of data transitions of various data-transition types and produces unique data-transition signals in response to respective ones of the data-transition types; and b. select logic that selects ones of the data-transition signals based upon the received data-transition types. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification