Method and system for crosstalk analysis

• US 7,761,826 B1
• Filed: 07/24/2007
• Issued: 07/20/2010
• Est. Priority Date: 07/24/2006
• Status: Expired due to Fees

• Current Assignee: Cadence Design Systems Incorporated (Cadence Group)
• Original Assignee: Cadence Design Systems Incorporated (Cadence Group)
• Inventors: Thanvantri, Venkat, Raja, Shiva, Keller, Igor, Zhang, Lizheng
• Primary Examiner(s): Lin; Sun J
• Application Number:
  US11/782,619
• Time in Patent Office: 1,092 Days
• Field of Search: 716/4, 716/5, 716/6
• US Class Current: 716/108
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods

Abstract

Method and system for crosstalk analysis relating to a statistical crosstalk path delay model that fits into existing static timing framework with little overhead in performance and capacity. More realistic models or assumptions are utilized rather than the more aggressive and less likely deterministic model.

Claims

1. A computer implemented method of crosstalk analysis, comprising:

using a computer system which comprises at least one processor and is configured for performing a process comprising;

identifying a set of nets in a design;

determining, for each net of the set in a path in the design, a probability distribution function (pdf) of a crosstalk delay for the each net of the set, wherein the probability distribution function corresponds to one or more aggressors that contribute to the crosstalk delay;

generating a combined or composite probability distribution file for the path that combines probability distribution functions from nets along the path;

receiving a desired probability level from a user, and

determining a statistical crosstalk path delay for the path using the desired probability level according to the combined or composite probability distribution file.

2. The computer implemented method of claim 1, wherein the probability distribution functions include contributions from the all nets along the path, and the probability distribution functions are combined or composited into the combined or composite probability distribution file via a convolution procedure.

3. The computer implemented method of claim 1, further comprising computing a worse-case crosstalk delay for the path.

4. The computer implemented method of claim 3, further comprising linearly computing a pessimism reduction for the each net in the set.

5. The computer implemented method of claim 4, further comprising determining an overall pessimism reduction for the path that is approximated by a summation of the crosstalk delay from the all nets along the path.

6. The computer implemented method of claim 1, further comprising using a non-linear optimization algorithm in the act of determining a statistical crosstalk path delay for the path.

7. The computer implemented method of claim 1, wherein the process is not based on a deterministic model of the design.

8. The computer implemented method of claim 1, further comprising:

separating one or more statistical checks from one or more deterministic checks within the design.

9. A system for crosstalk analysis, comprising:

a computer system which comprises at least one processor and is configured for performing a process comprising;

identifying a set of nets in a design;

determining, for each net of the set in a path in the design, a probability distribution function (pdf) of a crosstalk delay for the each net of the set, wherein the probability distribution function corresponds to one or more aggressors that contribute to the crosstalk delay;

generating a combined or composite probability distribution file for the path that combines probability distribution functions from nets along the path;

receiving a desired probability level from a user, and

determining a statistical crosstalk path delay for the path using the desired probability level according to the combined or composite probability distribution file.

10. The system of claim 9, wherein the probability distribution functions include contributions from the all nets along the path, and the probability distribution functions are combined or composited into the combined or composite probability distribution file via a convolution procedure.

11. The system of claim 9, the computer system is further configured for computing a worse-case crosstalk delay for the path.

12. The system of claim 11, the computer system is further configured for linearly computing a pessimism reduction for the each net in the set.

13. The system of claim 12, the computer system is further configured for determining an overall pessimism reduction for the path that is approximated by a summation of the crosstalk delay from the all nets along the path.

14. The system of claim 9, the computer system is further configured for using a non-linear optimization algorithm in the act of determining a statistical crosstalk path delay for the path.

15. A computer-readable storage medium comprising an executable program which, when executed by a computer system, causes the computer system to execute a process for crosstalk analysis, the process comprising:

using the computer system which comprises at least one processor and is configured for performing a process comprising;

identifying a set of nets in a design;

determining, for each net of the set in a path in the design, a probability distribution function (pdf) of a crosstalk delay for the each net of the set, wherein the probability distribution function corresponds to one or more aggressors that contribute to the crosstalk delay;

generating a combined or composite probability distribution file for the path that combines probability distribution functions from nets along the path;

receiving a desired probability level from a user, and

determining a statistical crosstalk path delay for the path using the desired probability level according to the combined or composite probability distribution file.

16. The computer-readable storage medium of claim 15, wherein the probability distribution functions include contributions from the all nets along the path, and the probability distribution functions are combined or composited into the combined or composite probability distribution file via a convolution procedure.

17. The computer-readable storage medium of claim 15, the process further comprising computing a worse-case crosstalk delay for the path.

18. The computer-readable storage medium of claim 17, the process further comprising linearly computing a pessimism reduction for the each net in the set.

19. The computer-readable storage medium of claim 18, the process further comprising an overall pessimism reduction for the path that is approximated by a summation of the crosstalk delay from the all nets along the path.

20. The computer-readable storage medium of claim 15, the process further comprising using a non-linear optimization algorithm in the act of determining a statistical crosstalk path delay for the path.