Zero Skew Clock tree Implementation Skew Wirelength What

Zero Skew Clock tree Implementation

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

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

Clock tree • A binary tree • Root = source • Leaves = sinks A BC DE F G H clock entry

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

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)

DME algorithm • Example : Bottom-Upphase Top-Down phase D E 4. 5 C 5 F 8. 5 12 A 3. 5 B A B C DE F G 8 G 3 H H

Manhattan & X architecture

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)

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

Topology generation • About MMM

Topology generation • About my method : complexity:

Topology generation • Still have bugs – Under Elmore Delay Model

Result: Manhattan, My method Sample: r 1. pin 267 sinks

Result: Manhattan, MMM Sample: r 1. pin 267 sinks

Result: X , my method Sample: r 1. pin 267 sinks

Result: X, MMM Sample: r 1. pin 267 sinks

R 1. pin Result wirelength My method, Manhattan 1. 59299 e+006 My method, X 1. 38574 e+006 MMM, Manhattan 1. 51683 e+006 MMM, X 1. 35145 e+006 % My method v. s. MMM, Manhattan -5. 02% My method v. s. MMM, X -2. 53% MMM, Manhattan 13. 01% MMM, X 10. 9%

Future Work • wirelength

Future Work • Matching on X

Thank You