Patents by Inventor Chong-Nuen Chu

Chong-Nuen Chu 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: 7266796
    Abstract: A method for efficient analytical placement of standard cell designs includes obtaining a placement of cells using a wirelength objective function, modifying the placement of cells by cell shifting to redistribute cells to thereby reduce cell overlap, and refining the placement of cells to thereby reduce wirelength using a half-perimeter bounding rectangle-measure. Preferably the wirelength the wirelength objective function is a quadratic objective function which is solved using a hybrid net model. The hybrid net model preferably uses a clique model for two-pin and three-pin nets and a star model for nets having at least four pins. The use of the hybrid net model reduces a number of non-zero entries in a connectivity matrix.
    Type: Grant
    Filed: April 8, 2005
    Date of Patent: September 4, 2007
    Assignee: Iowa State University Research Foundation, Inc.
    Inventors: Chris Chong-Nuen Chu, Natarajan Viswanathan
  • Patent number: 6915496
    Abstract: An apparatus and method for incorporating driver sizing into buffer insertion such that the two optimization techniques are performed simultaneously are provided. The apparatus and method extends van Ginneken's algorithm to handle driver sizing by treating a source node as a “driver library.” With the apparatus and method, the circuit design is converted to a Steiner tree representation of the circuit design. Buffer insertion is performed on the Steiner tree using the van Ginneken algorithm to generate a first set of possible optimal solutions. For each solution in the first set, a driver of the same type as the original driver in the Steiner tree is selected from a driver library and virtually inserted into the solution. A delay penalty is retrieved for the selected driver, which is then used long with the new driver's characteristics to generate a second set of solutions based o the first set of solutions.
    Type: Grant
    Filed: September 26, 2002
    Date of Patent: July 5, 2005
    Assignee: International Business Machines Corporation
    Inventors: Charles Jay Alpert, Chong-Nuen Chu, Rama Gopal Gandham, Milos Hrkic, Jiang Hu, Chandramouli V. Kashyap, Stephen Thomas Quay
  • Publication number: 20040064793
    Abstract: An apparatus and method for incorporating driver sizing into buffer insertion such that the two optimization techniques are performed simultaneously are provided. In particular, the apparatus and method extends van Ginneken's algorithm to handle driver sizing by treating a source node as a “driver library”. With the apparatus and method, the circuit design is converted to a Steiner tree representation of the circuit design. Buffer insertion is performed on the Steiner tree using the van Ginneken algorithm to generate a first set of possible optimal solutions. For each solution in the first set, a driver of the same type as the original driver in the Steiner tree is selected from a driver library and virtually inserted into the solution. A delay penalty is retrieved for the selected driver. This delay penalty is then used along with the new driver's characteristics to generate a second set of solutions based on the first set of solutions.
    Type: Application
    Filed: September 26, 2002
    Publication date: April 1, 2004
    Applicant: International Business Machines Corporation
    Inventors: Charles Jay Alpert, Chong-Nuen Chu, Rama Gopal Gandham, Milos Hrkic, Jiang Hu, Chandramouli V. Kashyap, Stephen Thomas Quay