Patents by Inventor Peihua Qi

Peihua Qi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8689158
    Abstract: A method of applying common path credit in a static timing analysis in the presence of correlations between asserted arrival times, comprising the steps of using a computer, identifying one or more pairs of asserted arrival times for which one or more correlations exist; propagating to each of the one or more pairs of asserted arrival times a timing value dependent on the one or more correlations; and performing a subsequent common path pessimism removal analysis for at least one test during which a timing value dependent on the one or more correlations between asserted arrival times is used to compute an adjusted test slack.
    Type: Grant
    Filed: November 11, 2010
    Date of Patent: April 1, 2014
    Assignee: International Business Machines Corporation
    Inventors: Kerim Kalafala, Jennifer E. Basile, David J. Hathaway, Jeffrey G. Hemmett, Peihua Qi, Natesan Venkateswaran, Chandramouli Visweswariah, Vladimir Zolotov
  • Patent number: 8381150
    Abstract: A method for efficient multithreaded analysis of a timing graph is described. The method is applicable to multithreaded common path pessimism removal, critical path traversing for timing report generation, and other types of analysis requiring traversal of sub-graphs of timing graph. In order to achieve high efficiency and scalability for parallel multithreaded execution, the number of access locks is minimized. One parent computation thread and multiple child threads are employed. The parent computational thread identifies the tasks for analysis and distributes them among child threads. Each child thread identifies a sub-graph to be analyzed, creates a thread-specific replica of the identified sub-graph, and performs the analysis required. After completing the analysis, the child thread transfers the results back to the main timing graph and waits for next task.
    Type: Grant
    Filed: June 2, 2011
    Date of Patent: February 19, 2013
    Assignee: International Business Machines Corporation
    Inventors: Vladimir Zolotov, David J. Hathaway, Kerim Kalafala, Mark A. Lavin, Peihua Qi
  • Publication number: 20120311515
    Abstract: A method for efficient multithreaded analysis of a timing graph is described. The method is applicable to multithreaded common path pessimism removal, critical path traversing for timing report generation, and other types of analysis requiring traversal of sub-graphs of timing graph. In order to achieve high efficiency and scalability for parallel multithreaded execution, the number of access locks is minimized. One parent computation thread and multiple child threads are employed. The parent computational thread identifies the tasks for analysis and distributes them among child threads. Each child thread identifies a sub-graph to be analyzed, creates a thread-specific replica of the identified sub-graph, and performs the analysis required. After completing the analysis, the child thread transfers the results back to the main timing graph and waits for next task.
    Type: Application
    Filed: June 2, 2011
    Publication date: December 6, 2012
    Applicant: International Business Machines Corporation
    Inventors: Vladimir Zolotov, David J. Hathaway, Kerim Kalafala, Mark A. Lavin, Peihua Qi
  • Publication number: 20120124534
    Abstract: A method of applying common path credit in a static timing analysis in the presence of correlations between asserted arrival times, comprising the steps of using a computer, identifying one or more pairs of asserted arrival times for which one or more correlations exist; propagating to each of the one or more pairs of asserted arrival times a timing value dependent on the one or more correlations; and performing a subsequent common path pessimism removal analysis for at least one test during which a timing value dependent on the one or more correlations between asserted arrival times is used to compute an adjusted test slack.
    Type: Application
    Filed: November 11, 2010
    Publication date: May 17, 2012
    Applicant: International Business Machines Corporation
    Inventors: Kerim Kalafala, Jennifer E. Basile, David J. Hathaway, Jeffrey G. Hemmett, Peihua Qi, Natesan Venkateswaran, Chandramouli Visweswariah, Vladimir Zolotov
  • Patent number: 7797657
    Abstract: A method and system for decreasing processing time in multi-corner static timing analysis. In one embodiment, parameters are ordered in a parameter order by decreasing magnitude of impact on variability of timing. In one example, a decreasing parameter order is utilized to order slack cutoff values that are assigned across a parameter process space. In another example, a decreasing parameter order is utilized to perform a multi-corner timing analysis on one or more dependent parameters in an independent fashion.
    Type: Grant
    Filed: February 27, 2007
    Date of Patent: September 14, 2010
    Assignee: International Business Machines Corporation
    Inventors: Nathan C. Buck, John P. Dubuque, Eric A. Foreman, Peter A. Habitz, Kerim Kalafala, Peihua Qi, Chandramouli Visweswariah, Xiaoyue Wang
  • Patent number: 7681157
    Abstract: A method and system for decreasing processing time in multi-corner static timing analysis. In one embodiment, slack cutoff values are assigned across a parameter process space. For example, a slack cutoff value is assigned to each parameter in a process space by determining an estimated maximum slack change between a starting corner and any other corner in a corresponding process sub-space. In another embodiment, parameters are ordered in a parameter order by decreasing magnitude of impact on variability of timing.
    Type: Grant
    Filed: February 27, 2007
    Date of Patent: March 16, 2010
    Assignee: International Business Machines Corporation
    Inventors: Nathan C. Buck, John P. Dubuque, Eric A. Foreman, Peter A. Habitz, Kerim Kalafala, Peihua Qi, Chandramouli Visweswariah, Xiaoyue Wang
  • Patent number: 7555740
    Abstract: Methods, systems and computer program products for analyzing a timing design of an integrated circuit are disclosed. According to an embodiment, a method for analyzing a timing design of an integrated circuit comprises: providing an initial static timing analysis of the integrated circuit; selecting a static timing test with respect to a static timing test point based on the initial static timing analysis; selecting a timing path leading to the static timing test point for the static timing test; determining an integrated slack path variability for the timing path based on a joint probability distribution of at least one statistically independent parameter; and analyzing the timing design based on the integrated slack path variability.
    Type: Grant
    Filed: February 27, 2007
    Date of Patent: June 30, 2009
    Assignee: International Business Machines Corporation
    Inventors: Nathan C. Buck, John P. Dubuque, Eric A. Foreman, Peter A. Habitz, Kerim Kalafala, Peihua Qi, Chandramouli Visweswariah, Xiaoyue Wang
  • Publication number: 20080209374
    Abstract: A method and system for decreasing processing time in multi-corner static timing analysis. In one embodiment, parameters are ordered in a parameter order by decreasing magnitude of impact on variability of timing. In one example, a decreasing parameter order is utilized to order slack cutoff values that are assigned across a parameter process space. In another example, a decreasing parameter order is utilized to perform a multi-corner timing analysis on one or more dependent parameters in an independent fashion.
    Type: Application
    Filed: February 27, 2007
    Publication date: August 28, 2008
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Nathan C. Buck, John P. Dubuque, Eric A. Foreman, Peter A. Habitz, Kerim Kalafala, Peihua Qi, Chandramouli Visweswariah, Xiaoyue Wang
  • Publication number: 20080209375
    Abstract: A method and system for decreasing processing time in multi-corner static timing analysis. In one embodiment, slack cutoff values are assigned across a parameter process space. For example, a slack cutoff value is assigned to each parameter in a process space by determining an estimated maximum slack change between a starting corner and any other corner in a corresponding process sub-space. In another embodiment, parameters are ordered in a parameter order by decreasing magnitude of impact on variability of timing.
    Type: Application
    Filed: February 27, 2007
    Publication date: August 28, 2008
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Nathan C. Buck, John P. Dubuque, Eric A. Foreman, Peter A. Habitz, Kerim Kalafala, Peihua Qi, Chandramouli Visweswariah, Xiaoyue Wang
  • Publication number: 20080209373
    Abstract: Methods, systems and computer program products for analyzing a timing design of an integrated circuit are disclosed. According to an embodiment, a method for analyzing a timing design of an integrated circuit comprises: providing an initial static timing analysis of the integrated circuit; selecting a static timing test with respect to a static timing test point based on the initial static timing analysis; selecting a timing path leading to the static timing test point for the static timing test; determining an integrated slack path variability for the timing path based on a joint probability distribution of at least one statistically independent parameter; and analyzing the timing design based on the integrated slack path variability.
    Type: Application
    Filed: February 27, 2007
    Publication date: August 28, 2008
    Inventors: Nathan C. Buck, John P. Dubuque, Eric A. Foreman, Peter A. Habitz, Kerim Kalafala, Peihua Qi, Chandramouli Visweswariah, Xiaoyue Wang
  • Patent number: 7117466
    Abstract: A method of removing pessimism in static timing analysis is described. Delays are expressed as a function of discrete parameter settings allowing for both local and global variation to be taken in to account. Based on a specified target slack, each failing timing test is examined to determine a consistent set of parameter settings which produces the worst possible slack. The analysis is performed on a path basis. By considering only parameters which are in common to a particular data/clock path-pair, the number of process combinations that need to be explored is reduced when compared to analyzing all combinations of the global parameter settings. Further, if parameters are separable and linear, worst-case variable assignments for a particular clock/data path pair can be computed in linear time by independently assigning each parameter value.
    Type: Grant
    Filed: September 18, 2003
    Date of Patent: October 3, 2006
    Assignee: International Business Machines Corporation
    Inventors: Kerim Kalafala, Peihua Qi, David J. Hathaway, Alexander J. Suess, Chandramouli Visweswariah
  • Publication number: 20050066297
    Abstract: A method of removing pessimism in static timing analysis is described. Delays are expressed as a function of discrete parameter settings allowing for both local and global variation to be taken in to account. Based on a specified target slack, each failing timing test is examined to determine a consistent set of parameter settings which produces the worst possible slack. The analysis is performed on a path basis. By considering only parameters which are in common to a particular data/clock path-pair, the number of process combinations that need to be explored is reduced when compared to analyzing all combinations of the global parameter settings. Further, if parameters are separable and linear, worst-case variable assignments for a particular clock/data path pair can be computed in linear time by independently assigning each parameter value.
    Type: Application
    Filed: September 18, 2003
    Publication date: March 24, 2005
    Inventors: Kerim Kalafala, Peihua Qi, David Hathaway, Alexander Suess, Chandramouli Visweswariah