International Business Machines Corporation

Hong Wei Dai

Jun Tan

Hong Hua Song

Suo Ming Pu

Jia Niu

Gong Qiong Li

The present invention relates to a method and an apparatus for estimating a clock skew. The method comprises: obtaining a basic clock skew of each clock tree in the circuit; judging whether two units are in a same clock domain; if they are in different clock domains, estimating the clock skew between units to be a larger one of basic clock skews of the clock trees corresponding to these two unit; if these two units are in the same clock domain, further judging whether they are in a same hierarchical logic block; if they are in different hierarchical logic blocks, estimating the clock skew between units to be the basic clock skew of the clock tree of these two units plus additional clock skew caused by different hierarchical logic blocks. The apparatus is corresponding to the method. With the method and apparatus, the clock skew in the circuit can be estimated more accurately, which improves the efficiency of circuit design.

Estimating clock skew

The present invention discloses a method and apparatus for detecting timing constraint conflicts, the method comprising: receiving a timing constraint file; taking all test points in the timing constraint file as nodes, determining directed edges between the nodes and weights of the directed edges according to timing constraints relevant to the test points in the timing constraint file to establish a directed graph; searching for all directed cycles of the directed graph; and for each directed cycle, if the sum of the weights of the directed edges constituting the directed cycle satisfies a required condition, determining that a timing constraint conflict exists among the test points and the timing constraints constituting the directed cycle. The method and apparatus can automatically detect timing constraint conflicts with one hundred percent to reduce design turnaround time and engineer resources in ASIC projects.

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Shanghai, China

Hong Wei Dai