Claims
- 1. A method for mismatch shaping comprising the steps of:
(a) receiving a digital input code; (b) splitting the digital input code into a set of K sub-codes corresponding to the digital input code, wherein the set of K sub-codes can have one of at least N different sub-code orders that specify an order of each of the K sub-codes with respect to one another, wherein N>2, and wherein a sum of the K sub-codes equals the digital input code; (c) selecting one of the at least N different sub-code orders using a shuffling algorithm; and (d) outputting each sub-code in the set of K sub-codes in accordance with the selected sub-code order.
- 2. The method of claim 1, where each of the K sub-codes is not different than any of the other K−1 sub-codes within the set of K sub-codes by more than one level.
- 3. The method of claim 1, wherein the shuffling algorithm comprises a dynamic element mismatch shaping algorithm, and wherein step (c) comprises selecting the one of the at least N different sub-code orders using the dynamic element mismatch shaping algorithm.
- 4. The method of claim 1, wherein step (c) comprises selecting the one of the at least N different sub-code orders based on at least one of:
(c.1) one or more sub-code orders that were previously selected, and (c.2) a pseudo random code.
- 5. The method of claim 1, wherein step (d) further comprises providing each sub-code in the set of K sub-codes to a respective one of K shufflers in accordance with the selected sub-code order.
- 6. The method of claim 5, further comprising the step of:
(f) separately shuffling each of the K sub-codes using the respective shuffler to thereby produce K separate multi-bit shuffled density codes.
- 7. The method of claim 6, further comprising the step of:
(g) providing each of the K shuffled density codes to a respective one of K multi-element sub-digital-to-analog converters (sub-DACs), in accordance with the selected sub-code order; and (h) driving each of the K multi-element sub-DACs using the respective one of the K shuffled density codes.
- 8. The method of claim 7, further comprising repeating steps (a) through (h) a plurality of times.
- 9. The method of claim 1, further comprising repeating steps (a) through (d) a plurality of times.
- 10. The method of claim 1, wherein steps (b) and (c) occur simultaneously.
- 11. The method of claim 1, wherein step (c) comprises selecting the one of the at least N different sub-code orders based on the one or more sub-code orders that were previously selected.
- 12. The method of claim 1, wherein step (c) comprises selecting the one of the at least N different sub-code orders based on the pseudo random code.
- 13. The method of claim 1, wherein step (c) comprises selecting the one of the at least N different sub-code orders based on the one or more sub-code orders that were previously selected and on the pseudo random code.
- 14. A method for mismatch shaping comprising the steps of:
(a) receiving a sequence of multi-level digital input codes; (b) splitting each of the multi-level digital input codes into a set of K sub-codes corresponding to the multi-level digital input code, wherein the set of K sub-codes can have one of at least N different sub-code orders that specify an order of each of the K sub-codes with respect to one another, wherein N>2, and wherein a sum of the K sub-codes equals the multi-level digital input code; (c) for each of the multi-level digital input codes, selecting one of the at least N different sub-code orders using a shuffling algorithm; and (d) for each of the multi-level digital input codes, outputting each sub-code in the set of K sub-codes in accordance with the selected sub-code order.
- 15. The method of claim 14, where each of the K sub-codes is not different than any of the other K−1 sub-codes within the set of K sub-codes by more than one level.
- 16. The method of claim 14, wherein the shuffling algorithm comprises a dynamic element mismatch shaping algorithm, and wherein step (c) comprises, for each of the multi-level digital input codes, selecting the one of the at least N different sub-code orders using the dynamic element mismatch shaping algorithm.
- 17. The method of claim 14, wherein step (c) comprises, for each of the multi-level digital input codes, selecting the one of the at least N different sub-code orders based on at least one of:
(c.1) one or more sub-code orders that were previously selected, and (c.2) a pseudo random code.
- 18. The method of claim 14, wherein step (d) further comprises providing each sub-code in the set of K sub-codes to a respective one of K shufflers in accordance with the selected sub-code order.
- 19. The method of claim 18, further comprising the step of:
(f) separately shuffling each of the K sub-codes using the respective shuffler to thereby produce K separate multi-bit shuffled density codes.
- 20. The method of claim 19, further comprising the step of:
(g) providing each of the K shuffled density codes to a respective one of K multi-element sub-digital-to-analog converters (sub-DACs), in accordance with the selected sub-code order; and (h) driving each of the K multi-element sub-DACs using the respective one of the K shuffled density codes.
- 21. The method of claim 19, further comprising repeating steps (a) through (h) a plurality of times.
- 22. The method of claim 14, further comprising repeating steps (a) through (d) a plurality of times.
- 23. The method of claim 14, wherein steps (b) and (c) occur simultaneously.
- 24. A method for mismatch shaping comprising the steps of:
(a) receiving a sequence of digital input codes,
wherein each of the plurality of digital input codes represents one of L distinct levels, wherein each of the plurality of digital input codes representing a same one of the L distinct levels is associated with a set of K sub-codes including K sub-code members that can have one of a plurality of different sub-code orders that specify an order of each of the K sub-codes with respect to one another, wherein L is an integer greater than K, and K is an integer greater than 2, wherein a sum of each set of K sub-codes equals one of the L different digital input codes with which the set of K sub-codes is associated, and wherein each of the sub-codes within each set of K sub-codes is not different than any of the other K−1 sub-codes within the set of K sub-codes by more than one level; and (b) for each digital input code,
(b.1) selecting a set of K sub-codes based on a level of the digital input code, and (b.2) selecting one of the plurality of different sub-code orders using a shuffling algorithm.
- 25. A method for mismatch shaping, comprising the steps of:
(a) receiving a digital input code that can represent one of L distinct levels; (b) splitting the digital input code into K separate sub-codes that can represent one of N distinct levels, where L>N>2, and L>K>2, a sum of the K separate sub-codes equaling the digital input code; (c) specifying an order of the K separate sub-codes using a shuffling algorithm; (d) shuffling each of the K separate sub-codes to produce K shuffled sub-codes; and (e) outputting the K shuffled sub-codes in accordance with the specified order,
wherein each of the K shuffled sub-codes is representative of one of the K sub-codes.
- 26. The method of claim 25, wherein the shuffling algorithm comprises a dynamic element mismatch shaping algorithm, and wherein step (c) comprises specifying the order of the K separate sub-code using the dynamic element mismatch shaping algorithm.
- 27. The method of claim 25, wherein step (c) comprises specifying the order of the K separate sub-code based on at least one of:
(c.1) one or more sub-code orders that were previously selected, and (c.2) a pseudo random code; and
- 28. The method of claim 25, further comprising the step of:
providing the K shuffled sub-codes to K multi-element sub-digital-to-analog converters (sub-DACs) in accordance with the specified order.
- 29. The method of claim 28, wherein each of the K multi-element sub-DACs includes N−1 substantially equal weighted unit elements.
- 30. The method of claim 29, wherein each shuffled sub-code comprises an N−1 bit density code, and wherein each of the unit elements converts a bit of a density code into an analog signal.
- 31. The method of claim 29, further comprising the step of combining the resultant analog signals into a combined analog signal representative of the digital input signal.
- 32. The method of claim 28, wherein each of the multi-element sub-DACs comprises binary weighted elements.
- 33. The method of claim 28, wherein each multi-element sub-DAC comprises N−1 elements, where N−1>2.
- 34. The method of claim 25, wherein K=4.
- 35. The method of claim 25, further comprising the step of providing the K shuffled sub-codes directly to L−1 elements.
- 36. An apparatus for mismatch shaping, comprising:
means for receiving a sequence of digital input codes,
wherein each of the digital input codes represents one of L distinct levels, wherein each of the of digital input codes representing a same one of the L distinct levels is associated with a set of K sub-codes including K sub-code members that can have one of a plurality of different sub-code orders that specify an order of each of the K sub-codes with respect to one another, wherein L is an integer greater than K, and K is an integer greater than 2, wherein a sum of each set of K sub-codes equals one of the L different digital input codes with which the set of K sub-codes is associated, and wherein each of the sub-codes within each set of K sub-codes is not different than any of the other K−1 sub-codes within the set of K sub-codes by more than one level; and a code splitter and code shuffler to select a set of K sub-codes based on a level of the digital input code, and to select one of the plurality of different sub-code orders using a shuffling algorithm.
- 37. An apparatus for mismatch shaping, comprising:
a code splitter and code shuffler (CSCS) to spit a received digital input code into K separate sub-codes that can represent one of N distinct levels and to specify an order of the K separate sub-codes using a shuffling algorithm, wherein L>N>2, L>K>2, and a sum of the K separate sub-codes equaling the digital input code; and K shufflers, each to receive one of the K separate sub-codes in accordance with the specified order, and each to shuffle the received one of the K separate sub-codes to thereby produce K shuffled sub-codes that are output in accordance with the specified order, wherein each of the K shuffled sub-codes is representative of one of the K sub-codes.
- 38. The apparatus of claim 37, wherein the CSCS comprises a dynamic element mismatch shaping circuit that is used to specify the order of the K separate sub-codes.
- 39. The apparatus of claim 37, wherein the CSCS specifies the order of the K separate sub-codes based on at least one of:
(a) one or more sub-code orders that were previously selected, and (b) a pseudo random code.
- 40. The apparatus of claim 37, wherein each of the K shufflers each comprise a dynamic element mismatch shaping circuit.
- 41. The apparatus of claim 37, further comprising:
K multi-element sub-digital-to-analog converters (sub-DACs) to receive the K shuffled density codes in accordance with the specified order and to produce analog signals therefrom.
- 42. The apparatus of claim 41, wherein each of the K multi-element sub-DACs includes N−1 substantially equal weighted unit elements.
- 43. The apparatus of claim 42, wherein each shuffled sub-code comprises an N−1 bit density code, and wherein each of the unit elements converts a bit of a density code into an analog signal.
- 44. The apparatus of claim 41, further comprising a means for combining the analog signals into a combined analog signal representative of the digital input signal.
- 45. The apparatus of claim 41, wherein each of the multi-element sub-DACs comprises binary weighted elements.
- 46. The apparatus of claim 41, wherein each multi-element sub-DAC comprises N−1 elements, where N−1>2.
- 47. The apparatus of claim 37, wherein K=4.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The application claims priority to U.S. Provisional Patent Application No. 60/231,991, entitled “A Mismatch Shaping Method for Oversampled Data Converters,” filed Sep. 11, 2000, and U.S. Provisional Patent Application No. 60/232,155, entitled “A Mismatched Shaping Method for Oversampled Data Converters for Use in an Analog Front End in a DOCSIS Compatible Cable Modem,” filed Sep. 11, 2000, both of which are assigned to the assignee of the present invention, and both of which are incorporated herein by reference in their entirety.
[0002] This application is related to commonly assigned U.S. patent application Ser. No. ______, (Attorney Docket No. 1875.0870001), also entitled “Method and Apparatus for Mismatch Shaping of an Oversampled Converter,” filed the same day as the present application, and incorporated herein by reference.
Provisional Applications (2)
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Number |
Date |
Country |
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60231991 |
Sep 2000 |
US |
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60232155 |
Sep 2000 |
US |