Patents Represented by Attorney Stephen C. Durant
  • Patent number: 7747971
    Abstract: Verification model of static state retention behavior of a state saving element design during power shut off of the state saving element in an integrated circuit design including: creating in a computer readable medium a model of a single edge triggered state saving element; and creating in the computer readable medium clock gate logic that suspends saving of new states by the single state saving element upon the occurrence of a first state retention signal in preparation for power shut off.
    Type: Grant
    Filed: June 30, 2007
    Date of Patent: June 29, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventors: Manu Chopra, Alok Jain, Erich Marschner
  • Patent number: 7739629
    Abstract: A method of adding power control circuitry to a circuit design at each of an RTL and a netlist level comprising: demarcating multiple power domains within the circuit design; specifying multiple power modes each power mode corresponding to a different combination of on/off states of the multiple demarcated power domains; and defining isolation behavior relative to respective power domains.
    Type: Grant
    Filed: October 30, 2006
    Date of Patent: June 15, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventors: Qi Wang, Ankur Gupta, Pinhong Chen, Christina Chu, Manish Pandey, Huan-Chih Tsai, Sandeep Bhatia, Yonghao Chen, Steven Sharp, Vivek Chickermane, Patrick Gallagher
  • Patent number: 7739642
    Abstract: A method is provided that includes: determining a minimum clock cycle that can be used to propagate a signal about the critical cycle in a circuit design; wherein the critical cycle is a cycle in the design that has a highest proportionality of delay to number of registers; determining for a circuit element in the circuit design, sequential slack associated with the circuit element; wherein the sequential slack represents a minimum delay from among respective maximum delays that can be added to respective structural cycles of which the circuit element is a constituent, based upon the determined limit upon clock cycle duration; using the sequential slack to ascertain sequential optimization based design flexibility throughout multiple stages of a design flow.
    Type: Grant
    Filed: May 2, 2007
    Date of Patent: June 15, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventor: Christoph Albrecht
  • Patent number: 7735048
    Abstract: Methods achieve fast parasitic closure in IC (integrated circuit) synthesis flow with particular application to RFIC (radio frequency integrated circuit) synthesis flow. Parasitic corners generated based on earlier layout statistics are incorporated into circuit resizing to enable parasitic robust designs. The worst-case parasitic corners are generated efficiently without expensive statistical computations. A performance-driven placement with simultaneous fast rough routing and device tuning generates high quality placements and compensates for layout induced performance degradations. A regression-tree based macromodeling methodology is introduced for modeling of electrical performances to enable true performance-driven layout synthesis. To improve sampling quality, an annealing-based placer can be used to perform sampling. The modeling methodology can be adapted to include automatically adjusting the device tuning ranges to meet certain model accuracy requirements.
    Type: Grant
    Filed: November 24, 2004
    Date of Patent: June 8, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventors: Gang Zhang, Enis Aykut Dengi, Ronald A. Rohrer
  • Patent number: 7735030
    Abstract: A method of simulating a restorable register in a power domain of an RTL (register transfer level) design includes: specifying the power domain in the RTL design, wherein the power domain includes one or more registers and is configured to change power levels separately from other portions of the RTL design; identifying the restorable register in the power domain, wherein the restorable register is updated during power-on operations in the power domain; simulating the restorable register in a power cycle; and saving one or more values from the simulated restorable register. Simulating the restorable register includes: maintaining one or more backup values during a power-off operation for updating the restorable register after the power-off operation; and updating the restorable register during a power-on operation after the power-off operation by using the one or more backup values.
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: June 8, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventors: Nadeem Kalil, Philip Giangarra, Ritesh Goel, Tarun Batra
  • Patent number: 7735036
    Abstract: A computer-implemented method of identifying sub-circuits in circuit designs includes: receiving a selection of a sub-circuit; specifying a match expression for the sub-circuit, where the match expression characterizes matching properties of components of the sub-circuit; modifying the match expression to change the matching properties of components of the sub-circuit; and producing an information structure in a computer readable medium, where the information structure associates a graph representing a topology of the selected sub-circuit with the modified match expression. Subsequently, the information structure corresponding to the selected sub-circuit can be identified in a given circuit design.
    Type: Grant
    Filed: May 8, 2007
    Date of Patent: June 8, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventors: Ian Campbell Dennison, Mark Baker, Bogdan Arsintescu, Donald John O'Riordan
  • Patent number: 7711536
    Abstract: A method of synthesis of a model representing a design of an integrated circuit is provided including associating a test environment with a first model representing a design of an integrated circuit; translating the first model of the design to a second model of the design; and automatically generating an adaptor that adapts the second model to the test environment.
    Type: Grant
    Filed: December 30, 2005
    Date of Patent: May 4, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventor: Michael McNamara
  • Patent number: 7694251
    Abstract: Method and system for verifying power specifications of a low power design are disclosed. The method includes receiving a register-transfer level (RTL) netlist representation of the low power design, receiving a power specification file for describing power requirements of the low power design and verifying the power specification file in accordance with the RTL netlist representation of the low power design. The method further includes verifying completeness, compatibility, and consistency of power requirements for the low power design.
    Type: Grant
    Filed: October 30, 2006
    Date of Patent: April 6, 2010
    Assignee: Cadence Design Systems, Inc.
    Inventors: Bharat Chandramouli, Huan-Chih Tsai, Manish Pandey, Chih-Chang Lin, Madan M. Das
  • Patent number: 4967346
    Abstract: Interface circuitry (24) is provided which automatically detects which of two types of microprocessor is connected to the interface and configures the interface accordingly. A "type" flip-flop (36, 38) is initially set to expect a first type of microprocessor (10) and the interface is configured to expect a read and a write strobe. When a write cycle is performed by a second type (14) of microprocessor, the "type" flip-flop changes state and reconfigures the interface to expect a data strobe and a read/write indicator signal.
    Type: Grant
    Filed: March 14, 1988
    Date of Patent: October 30, 1990
    Assignee: Advanced Micro Devices, Inc.
    Inventor: Philip Freidin
  • Patent number: 4742493
    Abstract: An integrated circuit device which includes a memory array comprising a plurality of respective memory locations for storing binary data, each respective memory location corresponding to a respective combination of binary address signals, the device further comprising: at least two respective ports for receiving respective combinations of binary address signals corresponding to respective locations of said memory array; transition detection and signal providing circuitry for detecting a change in a respective binary address signal combination received by either a first or second of the at least two ports and for providing a first transition signal in response to a change in a respective first combination of binary address signals received by the first port and for providing a second respective transition signal in response to a change in a respective second combination of binary address signals received by the second port; and contention detection and signal providing means for receiving the first and the sec
    Type: Grant
    Filed: May 19, 1986
    Date of Patent: May 3, 1988
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Kent D. Lewallen, Moon-Seng Kok, Steve Schumann, Woei-Jian Liu
  • Patent number: 4740971
    Abstract: A tag buffer having built-in testing capabilities is disclosed. In a single-chip, integrated-circuit design which includes a SRAM, a parity generator and checker, and a comparator, a method and capability of testing the functionality of the SRAM and parity components is defined. For an embodiment in which the SRAM component includes a redundancy scheme for replacing a defective memory array row, a test for determining whether a redundant row has been used is also provided.
    Type: Grant
    Filed: February 28, 1986
    Date of Patent: April 26, 1988
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Aloysius T. Tam, Thomas S. Wong, Jim L. Michelsen, David F. Naren, David Wang
  • Patent number: 4731758
    Abstract: A high access speed memory for the internal storage of data and the addressable input/output transfer of data thereto, the memory comprising means for the dynamic storage of data, means for the static storage of data, and means for transferring data between the dynamic storage means and the static storage means. The intimate interfacing of the static and dynamic memories provides a high access speed pathway to the dynamically stored data while impacting minimally on sense amplification timing and the use of a redundant dynamic memory scheme.
    Type: Grant
    Filed: June 21, 1985
    Date of Patent: March 15, 1988
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Heng-Mun Lam, Paul D. Keswick
  • Patent number: 4722822
    Abstract: Current switches are used to control current into the columns during READ operations of a PROM. The circuit provides one such switch for each of the columns of the PROM and makes possible the use of a single current source which is connected to each of the switches but supplies current only to the column of the PROM that is currently selected for reading. A high voltage pre-bias is applied to the collectors of the NPN transistors used as current switches such that turn-on speed is improved because the collector parasitic capacitances are pre-charged to near the supply potential.
    Type: Grant
    Filed: November 27, 1985
    Date of Patent: February 2, 1988
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Phi Thai, Barry S. Cornell
  • Patent number: 4672670
    Abstract: In an ADPCM (Adaptive Differential PCM) system, in which the signal is commonly coded in C.sub.i, Q.sub.n, and .sigma. parameters, a lower sampling rate which normally causes distortion is made possible by deriving additional parameters A.sub.k, B.sub.k as a function of the error (distortion) between the original signal S.sub.n and the sampled signal Y.sub.n. The A.sub.k, B.sub.k coefficients control a distortion filter at the receiver.
    Type: Grant
    Filed: July 26, 1983
    Date of Patent: June 9, 1987
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Bu-Chin Wang, Shankar S. Narayan