US 2006/0085776 A1Published application

Method for circuit sensitivity driven parasitic extraction

AssigneeTexas Instruments Incorporated

InventorsUsha Narasimha, Anthony Hill, Nagaraj Savithri

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Abstract

The method of this invention determines the timing of an integrated circuit design. At each node, the method determines if the timing of signal propagation at that node is critical. If this timing is critical, method calculates the capacitance at said current node using a highly accurate but computationally intensive model. If this timing is not critical, the method uses a less accurate but less computationally intensive model. The method calculates a signal delay for each mode from the drive strength, calculated capacitance and fan-out. This signal delay is compared to a design goal. This method achieves a better trade-off between timing determination run-time and accuracy. Timing criticality can be determined from one or more of conductor length/area, fan-out, logic depth and timing slack.

Claims9

Dependent claims

A method for determining timing of an integrated circuit design comprising the steps of:

for each node of the netlist of the integrated circuit design:
determining if the timing of signal propagation at a current node is critical,
if said timing at said current node is critical, calculating the capacitance at said current node using a first model, said first having a first accuracy and a first computation requirement,
if said timing at said current node in not critical, calculating the capacitance at said current node using a second model, said second model having a second accuracy less than said first accuracy and a second computational requirement less than said first computation requirement,
calculating a signal delay for said current mode from a drive strength of a circuit supplying said current node, said calculated capacitance and a fan-out of said current node, and
determining if said calculated signal delay for said current node meets a design goal for said current node.

3 more elements

Dependencies are inferred from the claim text.