Method and apparatus for data recovery

• US 7,489,739 B2
• Filed: 09/17/2004
• Issued: 02/10/2009
• Est. Priority Date: 09/17/2004
• Status: Active Grant

• Current Assignee: Rambus Inc.
• Original Assignee: Rambus Inc.
• Inventors: Dally, William J
• Primary Examiner(s): Ghayour; Mohammad H
• Assistant Examiner(s): Panwalkar; Vineeta S
• Application Number:
  US10/944,616
• Publication Number:
  US 20060062327A1
• Time in Patent Office: 1,607 Days
• Field of Search: 375354-376, 375/316, 375/322, 375/324, 375/327, 375/326, 375/229, 375/340, 327/141, 327/144, 713/375, 713/400, 713500-503, 713/600, 713/601, 714/699, 714/798, 360/51, 360/39, 365/230.01, 365/230.03, 365/230.06, 365/230.08, 365/231, 365/233.1, 365/233.17
• US Class Current: 375/316
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop

Abstract

A method for recovering data includes oversampling an input data signal to provide sample sets, and storing a plurality of sample sets in addressable memory. The sample sets are processed, using sequential logic to make determinations of respective samples suitable for use in data recovery from corresponding sample sets. One function applied for the determination, includes taking a first mean transition position in a first group of sample sets, taking a second mean transition position in a second group of sample sets, computing a slope value for change in transition position, and making the determination based on the order of the plurality of samples, the first and second means, and the slope. The determined samples are obtained and data recovery is achieved. Sample sets can be modified according to equalization functions. Other modifications include encoding the sample sets for data compression.

Claims

1. A method for recovering data from a data signal, comprising:

oversampling the data signal with reference to a sample parameter to provide a plurality of sample sets, the sample sets including samples of respective data symbols;

modifying sample sets in the plurality of sample sets by adjusting transition positions within a sample set, to provide modified sample sets;

storing the plurality of sample sets including the modified sample sets in memory;

sequentially processing in response to a sequential logic clock, sample sets in the plurality of sample sets including the modified sample sets to make, in more than one cycle of the sequential logic clock, determinations of respective subsets for particular sample sets in the plurality of sample sets including the modified sample sets, the respective subsets including one or more samples suitable for use in data recovery, said determination being a function of the samples in more than two sample sets; and

obtaining the respective subsets for the plurality of sample sets including the modified sample sets from the memory for recovering data.

2. The method of claim 1, wherein the sample parameter is phase of a receiver clock.

3. The method of claim 1, wherein the data signal is plesiochronous relative to the receiver clock.

4. The method of claim 1, wherein said processing includes computing a pattern of change in the plurality of sample sets, and applying the pattern to make said determination.

6. The method of claim 1, including encoding the plurality of sample sets in the memory, and wherein said obtaining includes decoding the encoded sample sets.

7. The method of claim 1, including modifying at least one sample set in the plurality of sample sets based on an equalization function.

8. The method of claim 1, wherein the plurality of sample sets consists of 6 or more samples per data symbol.

9. The method of claim 1, wherein the plurality of sample sets consists of more than 100 samples.

5. A method for recovering data from a data signal, comprising:

oversampling the data signal with reference to a sample parameter to provide a plurality of sample sets, the sample sets including samples of respective data symbols;

storing the plurality of sample sets in memory;

sequentially processing in response to a sequential logic clock, sample sets in the plurality of sample sets to make, in more than one cycle of the sequential logic clock, determinations of respective subsets for particular sample sets in the plurality of sample, the respective subsets including one or more samples suitable for use in data recovery, said determination being a function of the samples in more than two sample sets; and

obtaining the respective subsets for the plurality of sample sets from the memory for recovering data,

wherein said plurality of sample sets include transition positions, and said processing includes;

computing a first mean transition position over a first group of sample sets in the plurality of sample sets, and a second mean transition position over a second group of sample sets in the plurality of sample sets, and computing a change in transition positions over the plurality of sample sets in response to the first and second means.

10. An integrated circuit comprising:

an input adapted for connection to a data signal;

oversampling circuitry coupled to the input, which oversamples the data signal with reference to a sample parameter to provide a plurality of sample sets, the sample sets including samples of the respective data symbols;

a modifier that modifies sample sets in the plurality of sample sets by adjusting transition positions within a sample set, to provide modified sample sets;

memory coupled to the oversampling circuitry to store the plurality of sample sets including the modified sample sets;

a sequential processor responsive to a sequential logic clock arranged to make, after a plurality of cycles of the sequential logic clock, determinations of respective subsets for particular sample sets in the plurality of sample sets including the modified sample sets, the respective subsets including one or more samples suitable for use in data recovery, said determination being a function of the samples in more than two sample sets; and

logic to obtain the respective subsets for the plurality of sample sets including the modified sample sets from the memory for recovering data.

11. The integrated circuit of claim 10, wherein the sample parameter is phase of a receiver clock.

12. The integrated circuit of claim 10, wherein the data signal is plesiochronous relative to the receiver clock.

13. The integrated circuit of claim 10, wherein said sequential processor includes logic to compute a pattern of change in the plurality of sample sets, and to apply the pattern to make said determination.

15. The integrated circuit of claim 10, including an encoder to encode the plurality of sample sets in the memory, and a decoder to decode the sample sets obtained from the memory.

16. The integrated circuit of claim 10, including a sample set modifier that modifies at least one sample set in the plurality of sample sets based on an equalization function.

17. The integrated circuit of claim 10, wherein the plurality of sample sets consist of 6 or more samples per data symbol.

18. The integrated circuit of claim 10, wherein the plurality of sample sets consist of more than 100 samples.

14. An integrated circuit comprising:

an input adapted for connection to a data signal;

oversampling circuitry coupled to the input, which oversamples the data signal with reference to a sample parameter to provide a plurality of sample sets, the sample sets including samples of the respective data symbols;

memory coupled to the oversampling circuitry to store the plurality of sample sets;

a sequential processor responsive to a sequential logic clock arranged to make after a plurality of cycles of the sequential logic clock, determinations of respective subsets for particular sample sets in the plurality of sample sets, the respective subsets including one or more samples suitable for use in data recovery, said determination being a function of the samples in more than two sample sets; and

logic to obtain the respective subsets for the plurality of sample sets from the memory for recovering data,

wherein said plurality of sample sets include transition positions, and said processing includes;

computing a first mean transition position over a first group of sample sets in the plurality of sample sets, and a second mean transition position over a second group of sample sets in the plurality of sample sets, and computing a change in transition positions over the plurality of sample sets in response to the first and second means.