# Eric A. Foreman, Fairfax US

## Eric A. Foreman, Fairfax, VT US

Patent application number | Description | Published |
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20080209372 | Estimation Of Process Variation Impact Of Slack In Multi-Corner Path-Based Static Timing Analysis - A method and system for reducing a number of paths to be analyzed in a multi-corner static timing analysis. An estimated upper slack variation based on a non-common path delay for a racing path is utilized in determining if a multi-corner static timing analysis may be bypassed for a racing path. In another example, an estimated maximum RSS credit based on a total delay for a racing path is utilized in determining if a multi-corner static timing analysis may be bypassed for a racing path. | 08-28-2008 |

20080209373 | METHOD AND SYSTEM FOR EVALUATING STATISTICAL SENSITIVITY CREDIT IN PATH-BASED HYBRID MULTI-CORNER STATIC TIMING ANALYSIS - 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. | 08-28-2008 |

20080209374 | Parameter Ordering For Multi-Corner Static Timing Analysis - 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. | 08-28-2008 |

20080209375 | Variable Threshold System and Method For Multi-Corner Static Timing Analysis - 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. | 08-28-2008 |

20080216036 | SLACK SENSITIVITY TO PARAMETER VARIATION BASED TIMING ANALYSIS - A method, system and program product are disclosed for improving an IC design that prioritize failure coefficients of slacks that lead to correction according to their probability of failure. With an identified set of independent parameters, a sensitivity analysis is performed on each parameter by noting the difference in timing, typically on endpoint slacks, when the parameter is varied. This step is repeated for every independent parameter. A failure coefficient is then calculated from the reference slack and the sensitivity of slack for each of the timing endpoints and a determination is made as to whether at least one timing endpoint fails a threshold test. Failing timing endpoints are then prioritized for modification according to their failure coefficients. The total number of runs required is one run that is used as a reference run, plus one additional run for each parameter. | 09-04-2008 |

20080270953 | IC CHIP AT-FUNCTIONAL-SPEED TESTING WITH PROCESS COVERAGE EVALUATION - Methods, systems and program products for evaluating an IC chip are disclosed. In one embodiment, the method includes running a statistical static timing analysis (SSTA) of a full IC chip design; creating at-functional-speed test (AFST) robust paths for an IC chip, the created robust paths representing a non-comprehensive list of AFST robust paths for the IC chip; and re-running the SSTA with the SSTA delay model setup based on the created robust paths. A process coverage is calculated for evaluation from the SSTA runnings; and a particular IC chip is evaluated based on the process coverage. | 10-30-2008 |

20080313590 | METHOD AND SYSTEM FOR EVALUATING TIMING IN AN INTEGRATED CIRCUIT - Methods for analyzing the timing in integrated circuits and for reducing the pessimism in timing slack calculations in static timing analysis (STA). The methods involve grouping and canceling the delay contributions of elements having similar delays in early and late circuit paths. An adjusted timing slack is calculated using the delay contributions of elements having dissimilar delays. In some embodiments, the delay contributions of elements having dissimilar delays are root sum squared. Embodiments of the invention provide methods for reducing the pessimism due to both cell-based and wire-dependent delays. The delays considered in embodiments of the invention may include delays due to the location of elements in a path. | 12-18-2008 |

20090210839 | TIMING CLOSURE USING MULTIPLE TIMING RUNS WHICH DISTRIBUTE THE FREQUENCY OF IDENTIFIED FAILS PER TIMING CORNER - A method of timing closure for integrated circuit designs uses multiple timing runs which distribute the frequency of identified fails per timing corner (between starting timing corners and remaining timing corners) to maximize efficiency in timing analysis. More specifically, the method closes timing for a chosen set of starting timing corners, verifies the remaining timing corners are orthogonal to the starting timing corners, closes timing for the remaining timing corners using multi-corner analysis, and verifies that all timing corners have positive slack margin. | 08-20-2009 |

20090235217 | METHOD TO IDENTIFY TIMING VIOLATIONS OUTSIDE OF MANUFACTURING SPECIFICATION LIMITS - A method of evaluating an integrated circuit design selects manufacturing parameters of interest which are outside of manufacturing specification limits. Then, the method runs timing tests on the integrated circuit design and successively evaluates the timing test results in an iterative process that considers the timing performance sensitivity to the selected manufacturing parameters of interest. The design is made more robust to each parameter out of manufacturing range. | 09-17-2009 |

20090243630 | METHOD TO QUICKLY ESTIMATE INDUCTANCE FOR TIMING MODELS - A method of estimating an inductance delay includes determining a resistance-capacitance (RC) delay with resistances and capacitances of a network and estimating an inductance delay of the network by determining a propagation delay of an electromagnetic (EM) field across wires of the network. Additionally, the method includes determining if the RC delay is below a specified threshold and adding the estimated inductance delay to the RC delay to determine a total time to propagate voltage swings through the network if the RC delay is below the specified threshold. | 10-01-2009 |

20090249270 | METHODS FOR PRACTICAL WORST TEST DEFINITION AND DEBUG DURING BLOCK BASED STATISTICAL STATIC TIMING ANALYSIS - Methods for analyzing timing of an integrated circuit using block-based static statistical timing analysis and for practical worst test definition and debug. The method includes building a timing graph, determining a slack for each of the nodes in the timing graph, and identifying a statistically worst slack for at least one of the nodes. The method further includes replacing this statistically worst slack with a proxy worst slack. | 10-01-2009 |

20090265674 | METHODS FOR IDENTIFYING FAILING TIMING REQUIREMENTS IN A DIGITAL DESIGN - Methods for identifying failing timing requirements in a digital design. The method includes identifying at least one timing test in the digital design that has a passing slack in a base process corner and a failing slack in a different process corner. The method further includes computing a sensitivity of the failing slack to each of a plurality of variables and comparing each sensitivity to a respective sensitivity threshold. If the sensitivity of at least one of the variables is greater than the respective sensitivity threshold, then the at least one timing test is considered to fail. | 10-22-2009 |

20090307645 | METHOD AND SYSTEM FOR ANALYZING CROSS-TALK COUPLING NOISE EVENTS IN BLOCK-BASED STATISTICAL STATIC TIMING - A method of performing statistical timing analysis of a logic design, including effects of signal coupling, includes performing a deterministic analysis to determine deterministic coupling information for at least one aggressor/victim net pair of the logic design. Additionally, the method includes performing a statistical timing analysis in which the deterministic coupling information for the at least one aggressor/victim net pair is combined with statistical values of the statistical timing analysis to determine a statistical effective capacitance of a victim of the aggressor/victim net pair. Furthermore, the method includes using the statistical effective capacitance to determine timing data used in the statistical timing analysis. | 12-10-2009 |

20100180243 | Method of Performing Timing Analysis on Integrated Circuit Chips with Consideration of Process Variations - A method for verifying whether a circuit meets timing constraints by performing an incremental static timing analysis in which slack is represented by a distribution that includes sensitivities to various process variables. The slack at an endpoint is computed by propagating the arrival times and required arrival times of paths leading up to the endpoint. The computation of arrival and required arrival times needs the computation of delays of individual gate and wire segments in each path that leads to the endpoint. The mixed mode adds a deterministic timing to the statistical timing (DSTA+SSTA). | 07-15-2010 |

20100293512 | CHIP DESIGN AND FABRICATION METHOD OPTIMIZED FOR PROFIT - Disclosed is a computer-implemented method for designing a chip to optimize yielding parts in different bins as a function of multiple diverse metrics and further to maximize the profit potential of the resulting chip bins. The method separately calculates joint probability distributions (JPD), each JPD being a function of a different metric (e.g., performance, power consumption, etc.). Based on the JPDs, corresponding yield curves are generated. A profit function then reduces the values of all of these metrics (e.g., performance values, power consumption values, etc.) to a common profit denominator (e.g., to monetary values indicating profit that may be associated with a given metric value). The profit function and, more particularly, the monetary values can be used to combine the various yield curves into a combined profit-based yield curve from which a profit model can be generated. Based on this profit model, changes to the chip design can be made in order to optimize yield as a function of all of the diverse metrics (e.g., performance, power consumption, etc.) and further to maximize the profit potential of the resulting chips. | 11-18-2010 |

20110126163 | METHOD TO REDUCE DELAY VARIATION BY SENSITIVITY CANCELLATION - A method receives an initial circuit design. The circuit design includes at least one path having at least one beginning point comprising a source, at least one ending point comprising a sink, and one or more circuit elements between the source and the sink. The method evaluates timing performance parameter sensitivities to manufacturing variations of each of the elements to identify how much each element will increase or decrease the timing performance parameter of the path for each change in each manufacturing variable associated with manufacturing the elements. Further, the method alters the elements within the path until elements that produce positive changes to the timing performance parameter for a given manufacturing variable change approximately equals (in magnitude) elements that produce negative changes to the timing performance parameter for the given manufacturing variable change, to produce an altered circuit design. | 05-26-2011 |

20110140745 | Method for Modeling Variation in a Feedback Loop of a Phase-Locked Loop - A method performs statistical static timing analysis of a network that includes a phase-locked loop and a feedback path. The feedback path comprises a set of delays operatively connected from the output of the phase-locked loop back to the input of the phase-locked loop. One embodiment herein computes a statistical feedback path delay for the feedback path. The method can use a separate statistical parameter to represent random uncorrelated delay variation for each delay in the feedback path. The method also computes an output arrival time for the phase-locked loop based on the negative of the statistical feedback path delay. | 06-16-2011 |

20120084066 | SYSTEM AND METHOD FOR EFFICIENT MODELING OF NPSKEW EFFECTS ON STATIC TIMING TESTS - A computer-implemented method that simulates NPskew effects on a combination NFET (Negative Field Effect Transistor)/PFET (Positive Field Effect Transistor) semiconductor device using slew perturbations includes performing a timing test by a computing device, by: (1) evaluating perturb slews in Strong N/Weak P directions on the combination semiconductor device for a timing test result; (2) evaluation perturb slews in Weak N/Strong P directions on the combination semiconductor device for a timing test result; and (3) evaluating unperturbed slews in a balanced condition on the combination semiconductor device for a timing test result. After each test is performed, a determination is made as to which evaluation of the perturbed and unperturbed slews produces a most conservative timing test result for the combination semiconductor device. An NPskew effect adjusted timing test result is finally output based on determining the most conservative timing test result. | 04-05-2012 |

20130018617 | INTEGRATING MANUFACTURING FEEDBACK INTO INTEGRATED CIRCUIT STRUCTURE DESIGNAANM Buck; Nathan C.AACI UnderhillAAST VTAACO USAAGP Buck; Nathan C. Underhill VT USAANM Dreibelbis; Brian M.AACI UnderhillAAST VTAACO USAAGP Dreibelbis; Brian M. Underhill VT USAANM Dubuque; John P.AACI JerichoAAST VTAACO USAAGP Dubuque; John P. Jericho VT USAANM Foreman; Eric A.AACI FairfaxAAST VTAACO USAAGP Foreman; Eric A. Fairfax VT USAANM Habitz; Peter A.AACI HinesburgAAST VTAACO USAAGP Habitz; Peter A. Hinesburg VT USAANM Hemmett; Jeffrey G.AACI St. GeorgeAAST VTAACO USAAGP Hemmett; Jeffrey G. St. George VT USAANM Venkateswaran; NatesanAACI Hopewell JunctionAAST NYAACO USAAGP Venkateswaran; Natesan Hopewell Junction NY USAANM Visweswariah; ChandramouliAACI Croton-on-HudsonAAST NYAACO USAAGP Visweswariah; Chandramouli Croton-on-Hudson NY USAANM Wang; XiaoyueAACI KanataAACO CAAAGP Wang; Xiaoyue Kanata CAAANM Zolotov; VladmimirAACI Putnam ValleyAAST NYAACO USAAGP Zolotov; Vladmimir Putnam Valley NY US - Solutions for integrating manufacturing feedback into an integrated circuit design are disclosed. In one embodiment, a computer-implemented method is disclosed including: defining an acceptable yield requirement for a first integrated circuit product; obtaining manufacturing data about the first integrated circuit product; performing a regression analysis on data representing paths in the first integrated circuit product to define a plurality of parameter settings based upon the acceptable yield requirement and the manufacturing data; determining a projection corner associated with the parameter settings for satisfying the acceptable yield requirement; and modifying a design of a second integrated circuit product based upon the projection corner and the plurality of parameter settings. | 01-17-2013 |

20130031523 | SYSTEMS AND METHODS FOR CORRELATED PARAMETERS IN STATISTICAL STATIC TIMING ANALYSIS - Systems and methods for accommodating correlated parameters in SSTA are provided. The method includes determining a correlation between at least two parameters. The method further includes calculating a new parameter or a new parameter set based on the correlation between the at least two parameters. The method further includes performing the SSTA such that the new parameter or the new parameter set is propagated into the SSTA. The method further includes projecting slack using the correlation between the at least two parameters and using a processor. | 01-31-2013 |

20130036395 | EFFICIENT SLACK PROJECTION FOR TRUNCATED DISTRIBUTIONS - Aspects of the present invention provide solutions for projecting slack in an integrated circuit. A statistical static timing analysis (SSTA) is computed to get a set of Gaussian distributions over a plurality of variation sources in the integrated circuit. Based on the Gaussian distributions, a truncated subset and a remainder subset of the Gaussian distributions are identified. Then data factors that represent a ratio between the remainder subset and the truncated subset are obtained. These data factors are applied to the SSTA to root sum square (RSS) project the slack for the integrated circuit that takes into account the absence of the truncated subset. | 02-07-2013 |

20130104092 | METHOD, SYSTEM AND PROGRAM STORAGE DEVICE FOR PERFORMING A PARAMETERIZED STATISTICAL STATIC TIMING ANALYSIS (SSTA) OF AN INTEGRATED CIRCUIT TAKING INTO ACCOUNT SETUP AND HOLD MARGIN INTERDEPENDENCE - In embodiments of a statistical static timing analysis (SSTA) method, system and program storage device, the interdependence between the setup time and hold time margins of a circuit block (e.g., a latch, flip-flop, etc., which requires the checking of setup and hold timing constraints) is determined, taking into account possible variations in multiple parameters (e.g., using a variation-aware characterizing technique). A parameterized statistical static timing analysis (SSTA) of a circuit incorporating the circuit block is performed in order to determine, in statistical parameterized form, setup and hold times for the circuit block. Based on the interdependence between the setup and hold time margins, setup and hold time constraints can be determined in statistical parameterized form. Finally, the setup and hold times determined during the SSTA can be checked against the setup and hold time constraints to determine, if the time constraints are violated or not and to what degree. | 04-25-2013 |

20130145333 | STATISTICAL CLOCK CYCLE COMPUTATION - Systems and methods for statistical clock cycle computation and closing timing of an integrated circuit design to a maximum clock cycle or period. The method includes loading a design and timing model for at least one circuit path of an integrated circuit or a region of the integrated circuit into a computing device. The method further includes performing a statistical static timing analysis (SSTA) of the at least one circuit path using the loaded design and timing model to obtain slack canonical data. The method further includes calculating a maximum circuit clock cycle for the integrated circuit or the specified region of the integrated circuit in linear canonical form based upon the slack canonical data obtained from the SSTA. | 06-06-2013 |

20130326459 | POWER/PERFORMANCE OPTIMIZATION THROUGH TEMPERATURE/VOLTAGE CONTROL - A method of optimizing power and timing for an integrated circuit (IC) chip, identifies a plurality of valid temperature and voltage combinations that allow integrated circuit chips produced according to the integrated circuit chip design to operate within average power consumption goals and timing delay goals. Such a method selects temperature cut points from the valid temperature and voltage combinations for each of the integrated circuit chips, calculates a power consumption amount of each of the temperature cut points, and adjusts the temperature cut points based on the power consumption amount until the temperature cut points achieve the average power consumption goals. Next, this method tests each of the integrated circuit chips, and records the temperature cut points in the memory of the integrated circuit chips. | 12-05-2013 |