Timing shell generation through netlist reduction
First Claim
1. An apparatus for reducing a netlist which defines circuit paths and cells in a first circuit to provide a timing shell having the same timing constraints as said netlist, the timing shell netlist representing a second circuit, said apparatus comprising:
- a memory for storing the netlist; and
a processor connected to the memory for executing a program, to reduce the netlist to the timing shell netlist by removing entries in the netlist that correspond to cells that are internal to the first circuit, the removed entries being chosen such that the second circuit has the same inputs and outputs as the first circuit and the same timing constraints with respect to signals entering and leaving the inputs and outputs, respectively, and the second circuit having a different circuit functionality than said first circuit.
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Accused Products
Abstract
Gate level netlists used for timing analysis in integrated circuit design are reduced using a timing shell generator while preserving critical information for timing analysis. After verification of timings, the gate level netlist is convened into a shell containing block boundary information. The function of the shell generator is to delete internal cells meeting a set of criteria. The result is a shell netlist containing a subset of the original netlist. Thus, the design cycle time involved and computing time and resources needed in ASIC development for chips using circuits represented by timing shell netlists are decreased by substituting design verification at the top level of large hierarchical netlists or large flat netlists by bottom up verification procedures using timing shells.
50 Citations
12 Claims
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1. An apparatus for reducing a netlist which defines circuit paths and cells in a first circuit to provide a timing shell having the same timing constraints as said netlist, the timing shell netlist representing a second circuit, said apparatus comprising:
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a memory for storing the netlist; and a processor connected to the memory for executing a program, to reduce the netlist to the timing shell netlist by removing entries in the netlist that correspond to cells that are internal to the first circuit, the removed entries being chosen such that the second circuit has the same inputs and outputs as the first circuit and the same timing constraints with respect to signals entering and leaving the inputs and outputs, respectively, and the second circuit having a different circuit functionality than said first circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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- 10. A method for operating a computing system to generate a timing shell netlist for a first circuit from a netlist which defines circuit paths and cell in the circuit, said timing shell netlist representing a second circuit, the method comprising the steps of recursively examining cells connected to nets at inputs and outputs of the circuit and removing internal cells meeting a set of criteria while preserving in the timing shell netlist information for timing analysis of a system incorporating the circuit, the second circuit having a different circuit functionality than the first circuit.
Specification