1. ECE734 Course Project: A Survey on Retiming — Algorithm and Applications
James D. Z. Ma
Department of Electrical and Computer Engineering
University of Wisconsin — Madison

2. Outline Introduction to retiming Fundamental algorithms of retiming
Non-trivial extensions of retiming algorithms
Application of retiming techniques to VLSI/DSP
Project progress

3. Definitions and Applications
Retiming
Change locations of delay elements in a circuit without affecting the functionality of the circuit
Clock period minimization
Register count minimization
Switching activity and power reduction
Logic synthesis

4. First Retiming Algorithm
For clock period and register count minimization
Charles E. Leiserson and James B. Saxe, “Optimizing synchronous circuitry by retiming”, in The Third Caltech Conference on VLSI, pp , 1983
Two quantities
W(u,v): minimum number of registers on any path from node u to node v
D(u,v): maximum computation time among all paths from node u to node v with weight W(u,v)

5. More efficient algorithm to be presented in the report
Algorithm Outline
Compute W and D based on all-pair-shortest-path algorithm
Sort the values of D(u,v)
Binary search these values to find a retiming solution with the minimum clock period by solving a system of inequalities, based on linear programming framework
More efficient algorithm
to be presented in the report

6. Non-Trivial Extensions of the Fundamental Retiming Algorithm
Consider different constraints on delay elements, initial states, setup and hold
Consider manufacturing effect — probabilistic retiming
Incorporate interconnect delay and clock skew into retiming
Multi-dimensional retiming
Scheduling, (un)folding, and retiming

7. Applications of Retiming
Resynthesis for sequential network optimization using combinational techniques
Retiming for power and switching activity reduction
Scheduling, (un)folding, and parallelism
Embedded system and communications
Software pipelining, partial scan, TPG, BIST, equivalence checking, FPGA technology mapping, physical design automation

8. Project progress Thank you!
Literature search — done
Fundamental algorithms and non-trivial extensions — done
Applications — in progress
Thank you!