standard cell characterization
Thanks for all your help.
I knew the bisection algorithm in hspice. But I think the setup time value calculated by bisection is not a well-exact value. Nowadays, the setup time is defined as follow, there is a typical D-Q delay with an infinite setup time, the expected setup time will make the D-Q delay larger than the typical delay for 10 or 30 percent. Well in bisection algorithm, the setup time judgement is pass or fail. So its precision is poor.
So I think the bisection algorithm is not suitable in standard cell characterizing definition.