Granted Patent B2

US 8,314,727 · App. 12/977,820 · Granted Nov 20, 2012

Assignee: NXP B.V.

Abstract

Claims (40)

1. A method of providing a value for each element of a sequence of elements in a multi-bit data converter, the values being for a present conversion cycle in operation of the converter, wherein a pointer position identifies an element in the sequence of elements for a conversion cycle, the method comprising:

calculating a pointer position for the present conversion cycle (P i+1 ) in accordance with an N th order noise shaped function based on pointer positions for N previous conversion cycles (P i to P i−(N−1) );

determining if the pointer position for the present conversion cycle (P i+1 ) is in excess of the number of elements in the sequence;

attributing a first component-value to all of the elements, comprising:

attributing a first component-value of +1 if the pointer position for the present conversion cycle (P i+1 ) is in excess of the number of elements in the sequence; and

attributing a first component-value of −1 if the pointer position for the present conversion cycle (P i+1 ) is not in excess of the number of elements in the sequence;

updating the new pointer position (P i+1 ) by performing a modulo operation and replacing the new pointer position (P i+1 ) with the remainder value;

attributing a second component-value to the elements in accordance with a (N−1) th order algorithm;

attributing a third component-value to the elements in accordance with the inverse of the second component-value for the previous conversion cycle; and

adding the first, second and third component-values for each element in order to provide a value for each of the elements for the present conversion cycle.

2. The method of claim 1 , wherein the N th order noise shaped function is a first order function, and:

calculating the new pointer position (P i+1 ) comprises adding an index to the previous pointer position (P i ); and

attributing the second component-value to the elements comprises:

attributing a value of −1 for all elements at a position less than, or equal to, the new pointer position (P i+1 ); and

attributing a value of +1 for all elements at a position greater than the new pointer position (P i+1 ).

3. The method of claim 1 , wherein the N th order noise shaped function is a second order function, and:

calculating the new pointer position (Pi+1) comprises multiplying the present pointer position (Pi) by two, adding an index and subtracting the previous pointer position (P i−1 ); and

attributing the second component-value to the elements comprises:

attributing a value of +1 for all elements at a position between the present pointer position (P i ) and the new pointer position (P i+1 ), and attributing a value of −1 for all other elements; and

attributing the third component-value to the elements comprises:

attributing a value of −1 for all elements at a position between the previous pointer position (P i−1 ) and the present pointer position (P i ), and attributing a value of +1 for all other elements.

4. The method of claim 1 , further comprising, prior to calculating the pointer position for the present conversion cycle:

updating the N previous pointer positions to remove any overflow between successive pointer positions; and

after attributing the first component-values:

performing a modulo operation and replacing the N previous pointer positions with the remainder value.

5. The method of claim 1 , wherein determining if the pointer position for the present conversion cycle (P i+1 ) is in excess of the number of elements in the sequence comprises identifying whether or not the pointer position will rollover the sequence of elements.

6. The method of claim 1 , wherein the step of adding the first, second and third component-values for each element can result in a plurality of different values, the method further comprising:

providing the value for each of the elements for the present conversion cycle by providing a temporal sequence of sub-values to an element for the conversion cycle, wherein the sequence of sub-values is symmetrical.

7. The method of claim 1 , wherein determining if the pointer position for the present conversion cycle (P i+1 ) is in excess of the number of elements in the sequence comprises determining if the difference between the pointer position for the present conversion cycle (P i+1 ) and the pointer position for the previous conversion cycle (P i ) is in excess of the number of elements in the sequence.

8. The method of claim 1 , comprising a method of dynamic element matching/digital weight averaging.

9. The method of claim 1 , wherein the elements are digital-to-analogue units.

10. The method of claim 9 , wherein the elements are configured to provide one of a plurality of discrete values therefrom.

11. A converter configured to implement the method of claim 1 .

12. The converter of claim 11 , wherein the converter is a switched-capacitor digital to analogue converter.

13. A sigma-delta converter comprising:

both a digital implementation and an analogue implementation of a digital to analogue converter according to claim 11 in the feedback loop of the sigma-delta converter.

14. An integrated circuit comprising the converter of claim 11 .

15. A computer program, which when run on a computer, causes the computer to configure the integrated circuit of claim 14 .

16. A computer program, which when run on a computer, causes the computer to configure the converter of claim 11 .

17. A computer program, which when run on a computer, causes the computer to perform the method of claim 1 .

Assignments (10)

Priority Claims (1)

Continuity (1)