Zero Skew Clock tree Implementation

1. Zero Skew Clock tree Implementation

2. Skew & Wirelength • What is skew • Definition : the max difference in arrival times of receivers. • About zero skew

3. Skew & Wirelength • About wirelength Problem: zero skew & minimize the wirelength

4. Clock tree • A binary tree • Root = source • Leaves = sinks clock entry A B C D E F G H

5. Problem: zero skew & minimize the wirelength Topology generation DME algorithm point set topology Clock tree output

6. DME algorithm • DME ( deferred-merge embedding ) • Given any topology (tree)  exact zero skew • Two Phase • Bottom-Up (build tree of merging segments) • Top-Down (embedding of nodes)

7. DME algorithm Bottom-Up phase Top-Down phase • Example : D E 4.5 C 5 F A B C D E F G H 8.5 8 12 G 3 A H 3.5 B

8. Manhattan & X architecture

9. Topology generation • How to match? • Good topology  smaller wirelength. • Some method of topology generation • BB (Balanced Bipartition) • MMM (Method of Means and Medians) • NS (Nearest-neighbor Selection)

10. Topology generation • For k sinks, it have different trees. • Complexity: • Good method  save time

11. Topology generation • About MMM

12. Topology generation • About my method : complexity:

13. Topology generation • Still have bugs • Under Elmore Delay Model

14. Result: Manhattan, My method Sample: r1.pin 267 sinks

15. Result: Manhattan, MMM Sample: r1.pin 267 sinks

16. Result: X ,my method Sample: r1.pin 267 sinks

17. Result: X, MMM Sample: r1.pin 267 sinks

18. R1.pin Result

19. Future Work • wirelength

20. Future Work • Matching on X

21. Thank You