Signal edge detection circuitry and methods
First Claim
1. A method comprising:
- sampling a data signal with a clock signal, wherein first and second consecutive samples in each consecutive pair of samples of the sampled data signal have a same logic value;
adjusting the clock signal used to sample the data signal by each one of a predetermined plurality of phase offsets;
determining whether the first and second consecutive samples in at least one of each said consecutive pair of samples of the data signal sampled with the adjusted clock signal have different logic values,wherein the data signal is grouped into consecutive pair of samples that remain unaltered during the adjusting of the clock signal; and
selecting one of the predetermined plurality of phase offsets based on the determining performed for each one of the predetermined plurality of phase offsets.
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Abstract
Double data rate (“DDR”) circuitry or the like is modified or enhanced to include edge detection capability. During edge detection mode the circuitry is supplied with serial training data that includes successive pairs of equal-valued bits. Several, differently-phased, candidate clock signals are used one after another in order of increasing phase to clock the DDR circuitry. Adjacent bits in the training data that should be equal-valued are captured by the DDR circuitry and compared. Any candidate clock signal that causes the bits thus compared to be unequal is flagged as having phase close to edges in the data. The approximate phase of data edges is thereby indicated by the phase (or phases) of the candidate clock signal (or signals) causing the bits compared as described above to be unequal.
43 Citations
20 Claims
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1. A method comprising:
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sampling a data signal with a clock signal, wherein first and second consecutive samples in each consecutive pair of samples of the sampled data signal have a same logic value; adjusting the clock signal used to sample the data signal by each one of a predetermined plurality of phase offsets; determining whether the first and second consecutive samples in at least one of each said consecutive pair of samples of the data signal sampled with the adjusted clock signal have different logic values, wherein the data signal is grouped into consecutive pair of samples that remain unaltered during the adjusting of the clock signal; and selecting one of the predetermined plurality of phase offsets based on the determining performed for each one of the predetermined plurality of phase offsets. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A circuit comprising:
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a circuitry configured to; sample a data signal with a clock signal, wherein first and second consecutive samples in each consecutive pair of samples of the sampled data signal have a same logic value; adjust the clock signal used to sample the data signal by each one of a predetermined plurality of phase offsets; and determine whether the first and second consecutive samples in at least one of each said consecutive pair of samples of the data signal sampled with the adjusted clock signal have different logic values, wherein the data signal is grouped into said each consecutive pair of samples that remains unaltered during the adjusting of the clock signal; and the circuitry further configured to select one of the predetermined plurality of phase offsets based on the determining performed for each one of the predetermined plurality of phase offsets. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A circuit comprising:
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a circuitry configured to; sample a data signal with a clock signal, wherein first and second consecutive samples in each consecutive pair of samples of the sampled data signal have a same logic value; adjust the clock signal used to sample the data signal by each one of a predetermined plurality of phase offsets, wherein; the sampling of the data signal is continuous during the adjusting of the clock signal, and grouping of the data signal into each of the consecutive pair of samples remains unaltered during the adjusting of the clock signal; and determine whether the first and second consecutive samples in at least one of each said consecutive pair of samples of the data signal sampled with the adjusted clock signal have different logic values; and the circuitry further configured to select one of the predetermined plurality of the phase offsets for which it is determined that the first and second consecutive samples of each said consecutive pair of samples of the data signal sampled with the adjusted clock signal have the same logic value. - View Dependent Claims (20)
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Specification