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Timing Optimization Methodology Based on Replacing Flip-Flops by Latches
Ko YOSHIKAWA Keisuke KANAMARU Yasuhiko HAGIHARA Shigeto INUI Yuichi NAKAMURA Takeshi YOSHIMURA
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/12/01
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
Category: Logic Synthesis
logic synthesis, sequential circuit, timing optimization, level-sensitive latch, formal verification,
Full Text: PDF(402.1KB)>>
Latch-based circuits have advantages for timing and are widely used for high-speed custom circuits. ASIC design flows, however, are based on circuits with flip-flops. This paper describes a new timing optimization algorithm by replacing the flip-flops in high-end ASICs by latches without changing the functionality of the circuits. Timing is optimized by using a fixed-phase retiming minimizing the impact of clock skew and jitter. A formal equivalence verification method that assures the logical correctness of the latch-replaced circuits is also proposed. Experimental results show that the optimization algorithm decreases the delay of benchmark circuits by as much as 17%.