# Vladimir Zolotov, Putnam Valley US

## Vladimir Zolotov, Putnam Valley, NY US

Patent application number | Description | Published |
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20080201676 | SYSTEM AND METHOD FOR ACCOMMODATING NON-GAUSSIAN AND NON-LINEAR SOURCES OF VARIATION IN STATISTICAL STATIC TIMING ANALYSIS - There is provided a system and method for statistical timing analysis and optimization of an electrical circuit having two or more digital elements. The system includes at least one parameter input and a statistical static timing analyzer and electrical circuit optimizer. The at least one parameter input is for receiving parameters of the electrical circuit. At least one of the parameters has at least one of a non-Gaussian probability distribution and a non-linear delay effect. The statistical static timing analyzer and electrical circuit optimizer is for calculating at least one of a signal arrival time and a signal required time for the electrical circuit using the at least one parameter and for modifying a component size of the electrical circuit to alter gate timing characteristics of the electrical circuit based upon the at least one of the signal arrival time and the signal required time. | 08-21-2008 |

20080250370 | REPRESENTING AND PROPAGATING A VARIATIONAL VOLTAGE WAVEFORM IN STATISTICAL STATIC TIMING ANALYSIS OF DIGITAL CIRCUITS - An approach that represents and propagates a variational voltage waveform in statistical static timing analysis of digital circuits is described. In one embodiment, there is a statistical static timing analysis tool for analyzing digital circuit designs. The statistical static timing analysis tool includes a variational waveform modeling component that is configured to generate a variational waveform model that approximate arbitrary waveform transformations of waveforms at nodes of a digital circuit. The variational waveform model transforms a nominal waveform into a perturbed waveform in accordance with a plurality of waveform transformation operators that account for variations that occur between the nominal waveform and the perturbed waveform. A variational waveform propagating component is configured to propagate variational waveforms through a timing arc from at least one input to at least one output of the digital circuit in accordance with the variational waveform model. | 10-09-2008 |

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 |

20090100393 | METHOD AND APPARATUS FOR INCREMENTALLY COMPUTING CRITICALITY AND YIELD GRADIENT - In one embodiment, the invention is a method and apparatus for incrementally computing criticality and yield gradient. One embodiment of a method for computing a diagnostic metric for a circuit includes modeling the circuit as a timing graph, determining a chip slack for the circuit, determining a slack of at least one diagnostic entity, and computing a diagnostic metric relating to the diagnostic entity(ies) from the chip slack and the slack of the diagnostic entity(ies). | 04-16-2009 |

20090119629 | SYSTEM AND METHOD FOR GENERATING AT-SPEED STRUCTURAL TESTS TO IMPROVE PROCESS AND ENVIRONMENTAL PARAMETER SPACE COVERAGE - A system for enhancing the practicability of at-speed structural testing (ASST). In one embodiment, the system includes first means for performing statistical timing analysis on a design of logic circuitry. A second means performs a criticality analysis on the logic circuitry as a function of the statistical timing analysis so as to determine a criticality probability for each node of the logic circuitry. A third means selects nodes of the logic circuitry as a function of the criticality analysis. A fourth means selects timing paths as a function of the criticality probabilities of the selected nodes. A fifth means generates an ASST pattern for each of the selected timing paths. A sixth mean is provided to perform ASST on a fabricated instantiation of the design at functional speed using the generated ASST pattern. | 05-07-2009 |

20090241078 | METHODS FOR CONSERVING MEMORY IN STATISTICAL STATIC TIMING ANALYSIS - A method is provided for memory conservation in statistical static timing analysis. A timing graph is created with a timing run in a statistical static timing analysis program. A plurality of nodes in the timing graph that are candidates for a partial store and constraint points are identified. Timing data is persistently stored at constraint points. The persistent timing data is retrieved from the constraint points and used to calculate intermediate timing data at the plurality of nodes during timing analysis. | 09-24-2009 |

20090271751 | METHOD AND APPARATUS FOR STATISTICAL PATH SELECTION FOR AT-SPEED TESTING - In one embodiment, the invention is a method and apparatus for statistical path selection for at-speed testing. One embodiment of a method for selecting a path of an integrated circuit chip for at-speed testing includes computing a process coverage metric for a plurality of paths in the integrated circuit chip and selecting at least one path that maximizes the process coverage metric. | 10-29-2009 |

20090288051 | METHODS FOR STATISTICAL SLEW PROPAGATION DURING BLOCK-BASED STATISTICAL STATIC TIMING ANALYSIS - Methods for statistical slew propagation in static statistical timing analysis. The method includes projecting a canonical approximation of an input slew over a timing path to a first corner and using the projected input slew to calculate a delay and an output slew at the first corner. The method further includes perturbing the canonical approximation of the input slew to a different corner, calculating a delay and an output slew at the different corner using the perturbed input slew canonical, and determining a sensitivity of the delay and the output slew to a plurality of parameters, simultaneous with implicit sensitivity calculations to the input slew, with finite difference calculations between the first corner and perturbed data. | 11-19-2009 |

20100088658 | METHOD AND APPARATUS FOR EFFICIENT INCREMENTAL STATISTICAL TIMING ANALYSIS AND OPTIMIZATION - In one embodiment, the invention is a method and apparatus for efficient incremental statistical timing analysis and optimization. One embodiment of a method for determining an incremental extrema of n random variables, given a change to at least one of the n random variables, includes obtaining the n random variables, obtaining a first extrema for the n random variables, where the first extrema is an extrema computed prior to the change to the at least one of the n random variables, removing the at least one of the n random variables to form an (n−1) subset, computing a second extrema for the (n−1) subset in accordance with the first extrema and the at least one of the n random variables, and outputting a new extrema of the n random variables incrementally based on the extrema of the (n−1) subset and the at least one of the n random variables that changed. | 04-08-2010 |

20100162064 | METHOD AND APPARATUS FOR COVERING A MULTILAYER PROCESS SPACE DURING AT-SPEED TESTING - In one embodiment, the invention is a method and apparatus covering a multilayer process space during at-speed testing. One embodiment of a method for selecting a set of paths with which to test a process space includes determining a number N of paths to be included in the set of paths such that at least number M of paths in N for which testing of the process space will fail, computing a metric that substantially ensures that the set of paths satisfies the requirements of N and M, and outputting the metric for use in selecting the set of paths. | 06-24-2010 |

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 |

20100287432 | METHOD AND APPARATUS FOR GENERATING TEST PATTERNS FOR USE IN AT-SPEED TESTING - In one embodiment, the invention is a method and apparatus generating test patterns for use in at-speed testing. One embodiment of a method for use by a general purpose computing device that is configured to generate a set of test patterns with which to test an integrated circuit chip includes receiving, by an input device of the general purpose computing device, statistical timing information relating to the integrated circuit chip and a logic circuit of the integrated circuit chip and generating, by a processor of the general purpose computing device, the set of test patterns in accordance with the statistical timing information while simultaneously selecting a set of paths on which to test the set of test patterns. | 11-11-2010 |

20110106483 | METHOD AND APPARATUS FOR SELECTING PATHS FOR USE IN AT-SPEED TESTING - In one embodiment, the invention is a method and apparatus for selecting paths for use in at-speed testing. One embodiment of a method for selecting a set of n paths with which to test an integrated circuit chip includes: organizing the set of n paths into a plurality of sub-sets, receiving a new candidate path, and adding the new candidate path to one of the sub-sets when the new candidate path improves the process coverage metric of the sub-sets. | 05-05-2011 |

20120010837 | Design-Dependent Integrated Circuit Disposition - A method of integrated circuit (IC) disposition includes the steps of determining one or more disposition criteria based at least in part on statistical timing of a given IC design; and determining whether a given IC according to the given IC design satisfies the one or more disposition criteria based at least in part on one or more measurements of at least one test structure. | 01-12-2012 |

20120047477 | Method of Measuring the Impact of Clock Skew on Slack During a Statistical Static Timing Analysis - Computing accurately and effectively the impact of clock skew on statistical slack in the presence of statistically variable timing quantities that accounts for both common path credit in the common portion of the clock tree, and RSS credit in the non-common of the clock tree. The clock skew is measured on a per launch and capture path-pair basis as a function of on the post-CPPR path-specific slack (including RSS credit), total mean value of latch-to-latch delay, RSS value of random latch-to-latch delay, test guard time and test adjust. The method includes: performing an initial block-based SSTA including CPPR analysis; selecting at least one launch and capture path-pair for skew analysis; for the at least one path pair, recording post CPPR slack, total mean value of latch-to-latch delay, RSS value of latch to latch delay, test guard time and test adjust; and quantifying the impact of clock skew on statistical slack thereof. | 02-23-2012 |

20120117527 | PERFORMING STATISTICAL TIMING ANALYSIS WITH NON-SEPARABLE STATISTICAL AND DETERMINISTIC VARIATIONS - In one embodiment, the invention is a method and apparatus for performing statistical timing analysis with non-separable statistical and deterministic variations. One embodiment of a method for performing timing analysis of an integrated circuit chip includes computing delays and slews of chip gates and wires, wherein the delays and slews depend on at least a first process parameter that is deterministic and corner-based and a second process parameter that is statistical and non-separable with the first process parameter, and performing a single timing run using the timing quantity, wherein the single timing run produces arrival times, required arrival times, and timing slacks at outputs, latches, and circuit nodes of the integrated circuit chip. The computed arrival times, required arrival times, and timing slacks can be projected to a corner value of deterministic variations in order to obtain a statistical model of the delays and stews at the corresponding corner. | 05-10-2012 |

20120124534 | System and Method for Performing Static Timing Analysis in the Presence of Correlations Between Asserted Arrival Times - 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. | 05-17-2012 |

20120124535 | Optimal Chip Acceptance Criterion and its Applications - At least one target metric is identified for an integrated circuit chip design for which manufacturing chip testing is to be optimized. At least one surrogate metric is also identified for the integrated circuit chip design for which manufacturing chip testing is to be optimized. A relationship between the at least one target metric and the at least one surrogate metric is modeled using a general joint probability density function. A chip disposition criterion is determined based on the general joint probability density function. The chip disposition criterion determines, for a given physical chip putatively manufactured in accordance with the design, based on the at least one surrogate metric for the given physical chip, whether the given physical chip is to be accepted or discarded during the manufacturing chip testing. | 05-17-2012 |

20120130669 | VARIATION AWARE TESTING OF SMALL RANDOM DELAY DEFECTS - In one embodiment, the invention is a method and apparatus for variation aware testing of small random delay defects. One embodiment of a method for selecting a set of paths with which to test an integrated circuit chip includes computing a metric that considers the joint impact of parametric process variation delay defects and single random delay defects and selecting the set of paths such that the value of the metric is at least as great as a target value. | 05-24-2012 |

20120191401 | METHOD AND APPARATUS FOR GENERATING TEST PATTERNS FOR USE IN AT-SPEED TESTING - In one embodiment, the invention is a method and apparatus generating test patterns for use in at-speed testing. One embodiment of a method for use by a general purpose computing device that is configured to generate a set of test patterns with which to test an integrated circuit chip includes receiving, by an input device of the general purpose computing device, statistical timing information relating to the integrated circuit chip and a logic circuit of the integrated circuit chip and generating, by a processor of the general purpose computing device, the set of test patterns in accordance with the statistical timing information while simultaneously selecting a set of paths on which to test the set of test patterns. | 07-26-2012 |

20120311515 | Method For Performing A Parallel Static Timing Analysis Using Thread-Specific Sub-Graphs - 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. As all data structures of each child thread are accessed only by the child thread owing them, no access locks are required for construction and processing of thread specific graph replica of the timing sub-graph. The construction of each thread specific graph replica is performed by the child thread without locking the main timing graph data structures. Access locks are used only for transferring results of the analysis back to the main timing graph where the results computed by all child threads are combined together. | 12-06-2012 |

20130014075 | DESIGN-DEPENDENT INTEGRATED CIRCUIT DISPOSITION - A method of integrated circuit (IC) disposition includes the steps of determining one or more disposition criteria based at least in part on statistical timing of a given IC design; and determining whether a given IC according to the given IC design satisfies the one or more disposition criteria based at least in part on one or more measurements of at least one test structure. | 01-10-2013 |

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 |

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 |

20130283223 | ENABLING STATISTICAL TESTING USING DETERMINISTIC MULTI-CORNER TIMING ANALYSIS - In one embodiment, the invention is a method and apparatus for variation enabling statistical testing using deterministic multi-corner timing analysis. One embodiment of a method for obtaining statistical timing data for an integrated circuit chip includes obtaining deterministic multi-corner timing data for the integrated circuit chip and constructing the statistical timing data from the deterministic multi-corner timing data. | 10-24-2013 |