US 2012/0084066 A1 · SYSTEM AND METHOD FOR EFFICIENT MODELING OF NPSKEW EFFECTS ON STATIC TIMING TESTS

Abstract

A computer-implemented method that simulates NPskew effects on a combination NFET (Negative Field Effect Transistor)/PFET (Positive Field Effect Transistor) semiconductor device using slew perturbations includes performing a timing test by a computing device, by: (1) evaluating perturb slews in Strong N/Weak P directions on the combination semiconductor device for a timing test result; (2) evaluation perturb slews in Weak N/Strong P directions on the combination semiconductor device for a timing test result; and (3) evaluating unperturbed slews in a balanced condition on the combination semiconductor device for a timing test result. After each test is performed, a determination is made as to which evaluation of the perturbed and unperturbed slews produces a most conservative timing test result for the combination semiconductor device. An NPskew effect adjusted timing test result is finally output based on determining the most conservative timing test result.

Claims21

Dependent claims

performing a timing test by a computing device, by:
evaluating, by said computing device, perturb slews in Strong N/Weak P directions on said combination semiconductor device for a first timing test result;
evaluating, by said computing device, perturb slews in Weak N/Strong P directions on said combination semiconductor device for a second timing test result;
and
evaluating, by said computing device, unperturbed slews in a balanced condition on said combination semiconductor device for a third timing test result;
determining, by said computing device, which evaluation of said perturbed and unperturbed slews produces a most conservative timing test result from said first timing test result, said second timing test result and said third timing test result, for said combination semiconductor device;
and
outputting a NPskew effect adjusted timing test result based on said determining said most conservative timing test result.

5 more elements

performing a timing test by a computing device by:
evaluating, by said computing device, perturb slews in Strong N/Weak P directions on said combination semiconductor device for a first timing test result;
evaluating, by said computing device, perturb slews in Weak N/Strong P directions on said combination semiconductor device for a second timing test result;
considering a balanced condition on said combination semiconductor device having a null (0) timing test result;
selecting, by said computing device, a smallest solution of said evaluated a timing test result and said null (0) a timing test result as a selected timing test result for said combination semiconductor device;
and
outputting a NPskew effect based on said selecting.

4 more elements

performing a timing test by a computer by evaluating, a slack adjust amount directly in a single perturbation difference equation on said combination semiconductor device for a slack adjust value,
where P1 is equal in value to P2, and
the ratio of SL1 to X1 is equal in value to the ratio of SL2 to X2,
where P1 is a percentage of a total time of a first signal transition time to where a first arrival time on a first signal occurs along the first signal transition, defined relative to an end of the first signal transition,
where P2 is a percentage of a total time of a second signal transition time to where a second arrival time on a second signal occurs along the second signal transition, defined relative to a start of the second signal transition,
where SL1 is a first slew time on the first signal, defined as a first total transition time for the first signal,
where SL2 is a second slew time on the second signal, defined as a second total transition time for the second signal,
where X1 is one of a negatively signed perturbation value applied on the first slew time if the first signal transition is falling, and a positively signed perturbation value applied on the first slew time if the first signal transition is rising, where X1 is equal to the product of the first slew time and one of a constant value, a derived variable adder value and a scalar value, and
where X2 is one of a negatively signed perturbation value applied on the second slew time if the second signal transition is falling, and a positively signed perturbation value applied on the second slew time if the second signal transition is rising, where X2 is equal to the product of the second slew time and one of a constant value, a derived variable adder value and a scalar value.

6 more elements

Dependencies are inferred from the claim text.

System and method for efficient modeling of npskew effects on static timing tests

Life of this patent

System and method for efficient modeling of npskew effects on static timing tests

Life of this patent

Abstract

Claims21