Dynamic element matching method and system thereof

1. A dynamic element matching (DEM) method, comprising:

grouping a plurality of switches into a plurality of groups;

allocating a plurality of to-be-turned-on switches among the switches for an input signal to the groups; and

maintaining a switch activity for each group including:

recording a switch history for each switch by a plurality of weightings;

sorting the weightings; and

determining a plurality of statuses for the switches according to the sorted weightings.

2. The method as claimed in claim 1 , wherein the maintaining step substantially maintains the switch activity at a predetermined value.

3. The method as claimed in claim 1 , wherein the groups form a tree structure.

4. The method as claimed in claim 1 , wherein the to-be-turned-on switches are averagely allocated to all of the groups, and a plurality of remaining switches of the switches is averagely allocated to a plurality of partial groups of the groups.

5. The method as claimed in claim 1 , wherein the maintaining step substantially maintains the switch activity at half of the number of switches of each group.

6. The method as claimed in claim 1 , wherein the maintaining step maintains the switch activity for each group utilizing an overlapping approach.

7. The method as claimed in claim 1 , wherein the sorting step sorts the weightings utilizing a complete sorting approach.

8. The method as claimed in claim 1 , wherein a switch with a smallest weighting among the switches is assigned with a highest priority.

9. The method as claimed in claim 1 , wherein the allocating step averagely allocates the to-be-turned-on switches for the input signal to the groups.

10. A dynamic element matching (DEM) system, comprising:

a plurality of switches associated with a plurality of groups;

an allocating apparatus, for allocating a plurality of to-be-turned-on switches among the switches for an input signal to the groups; and

a plurality of switch activity control devices, coupled to the allocating apparatus, for maintaining a switch activity for each group, wherein each activity control device comprises:

a counter, for counting a plurality of count values for a plurality of weightings for the switches, respectively;

an on-to-off quantity generator, for generating a switch number for to-be-turned-off switches according to outputs of the allocating apparatus and the switch activity;

an off-to-on quantity generator, for generating a switch number for to-be-turned-on switches according to outputs of the allocating apparatus and the switch activity;

an on-to-off decider, for determining which switches need to be turned off according to the switch number of the to-be-turned-off switches and a previous output signal of the activity control device;

an off-to-on decider, for determining which switches need to be turned on according to the switch number of the to-be-turned-on switches and the previous output signal of the activity control device; and

a logical circuit, coupled to the on-to-off decider and the off-to-on decider, for generating an output signal of the activity control device to turn on or turn off the switches.

11. The DEM system as claimed in claim 10 , wherein the switch activity is substantially maintained at a predetermined value.

12. The DEM system as claimed in claim 10 , wherein the switch activity equals to half of the number of switches of each group.

13. The DEM system as claimed in claim 10 , wherein the allocating apparatus comprises:

a divider, for dividing a first number of to-be-turned-on switches by a number of groups to obtain a quotient and a remainder, wherein the quotient represents a second number of to-be-turned-on switches that are allocated to each group;

a remainder-rotating allocator, for generating a plurality of outputs for a plurality of partial groups among the groups according to the remainder;

a plurality of adders, for respectively adding the outputs of the remainder-rotating allocator with the quotient.

14. The DEM system as claimed in claim 10 , wherein the on-to-off decider or the off-to-on decider further comprises a sorting device for sorting weightings of switches.

15. The DEM system as claimed in claim 14 , wherein the sorting is realized via a complete sorting approach.

16. The DEM system as claimed in claim 14 , wherein the sorting device comprises a plurality of comparators for respectively comparing two weightings.

17. The DEM system as claimed in claim 10 , wherein each of the groups comprises a same number of switches.

18. The DEM system as claimed in claim 10 , wherein the allocating apparatus averagely allocates the to-be-turned-on switches for the input signal to the groups.