US 2009/0276743 A1Published application

System and method for computing proxy slack during statistic analysis of digital integrated circuits

AssigneeInternational Business Machines Corporation

InventorsJoseph M. Frank, David J. Hathaway, Kerim Kalafala

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Abstract

A method of optimizing timing of signals within an integrated circuit design using proxy slack values propagates signals through the integrated circuit design to output timing signals. For early mode timing analysis, the method sets an early proxy slack value to zero if the late slack value is less than zero. Otherwise, if the late slack value is not less than zero, the method restricts the early proxy slack value to a maximum of the early slack value and the negative of the late slack value. To the contrary, for late mode timing analysis, the method sets a late proxy slack value to zero if the early slack value is less than zero. Otherwise, if the early proxy slack value is not less than zero, the method restricts the late proxy slack value to a maximum of the late slack value and the negative of the early slack value.

Claims6

Dependent claims

A method of optimizing timing of signals within an integrated circuit design using proxy slack values, said method comprising:

propagating signals through said integrated circuit design to output timing signals, wherein said timing signals comprise at least one late slack value associated with a longest path through said integrated circuit design and at least one early slack value associated with a shortest path through said integrated circuit design;
for early mode timing analysis,
setting an early proxy slack value to zero if said late slack value is less than zero, and
if said late slack value is not less than zero, restricting said early proxy slack value to a maximum of the early slack value and the negative of the late slack value;
for late mode timing analysis,
setting a late proxy slack value to zero, if said early slack value is less than zero, and
if said early proxy slack value is not less than zero, restricting said late proxy slack value to a maximum of the late slack value and the negative of the early slack value;
performing timing optimization with said early proxy slack value and said late proxy slack value to produce optimized timing values;
and
outputting said optimized timing values for said integrated circuit design.

7 more elements

A method of optimizing timing of signals within an integrated circuit design using proxy slack values, said method comprising:

establishing an early slack threshold value and a late slack threshold value;
propagating signals through said integrated circuit design to output timing signals, wherein said timing signals comprise at least one late slack value associated with a longest path through said integrated circuit design and at least one early slack value associated with a shortest path through said integrated circuit design;
for early mode analysis,
setting an early proxy slack value to said early slack threshold value if said late slack value is less than late slack threshold value, and
if said late slack value is not less than late slack threshold value, restricting said early proxy slack value to a maximum of the early slack value and the early threshold minus the difference between the late slack value and the late slack threshold value;
for late mode timing analysis,
setting a late proxy slack value to said late slack threshold value if said early slack value is less than early slack threshold value, and
if said early slack value is not less than early slack threshold value, restricting said late proxy slack value to a maximum of absolute values of said late slack value, and the late threshold minus the difference between the early slack value and the early slack threshold values,
performing timing optimization with said late proxy slack value and said early proxy slack value to produce optimized timing values;
and
outputting said optimized timing values for said integrated circuit design.

8 more elements

Dependencies are inferred from the claim text.