Abstract: A system performs timing analysis of three-dimensional integrated circuits (3DICs). The circuit design is targeted for implementation on a stacked die that has a plurality of dies. The circuit design includes portions of the circuit design, each portion of the targeted for a different die. The system selects a net that crosses die boundaries and determines a plurality of sets of timing values of the net. The system determines a worst case slack value for the net based on the sets of timing values. The system determines a timing adjustment value for the net based on aggregate timing values determined from the sets of timing values. The system adjusts the worst case slack value for a net based on the timing adjustment value for each load pin of the net. The adjustment of the worst case slack reduces pessimism of the worst case slack value.

Abstract: Some embodiments determine a merged timing graph for a multi-instance module (MIM), wherein each node in the merged timing graph corresponds to a pin in the MIM, and wherein each node in the merged timing graph stores timing information associated with the corresponding pins in multiple instances of the MIM in a circuit design. The embodiments can then determine an ECO for the MIM based on the merged timing graph.

Abstract: Some embodiments determine a merged timing graph for a multi-instance module (MIM), wherein each node in the merged timing graph corresponds to a pin in the MIM, and wherein each node in the merged timing graph stores timing information associated with the corresponding pins in multiple instances of the MIM in a circuit design. The embodiments can then determine an ECO for the MIM based on the merged timing graph.

Abstract: A mode of a circuit design is simplified by eliminating clocks and corresponding timing exceptions and timing constraints from the mode. A system receives a description of a mode of a circuit. The system identifies sets of clock pairs and corresponding timing exceptions associated with timing nodes of the mode, each clock pair comprising a launch clock and a capture clock. The system compares time intervals between an edge of the launch clock and a corresponding edge of the capture clock for the clock pairs subject to timing exceptions associated with the timing path. The system identifies certain clock pairs as critical based on a comparison of the time interval associated with each clock pair. The system simplifies the mode by eliminating non-critical clocks and corresponding timing exceptions. The modified mode is used for performing timing analysis.

Abstract: A mode of a circuit design is simplified by eliminating clocks and corresponding exceptions and timing constraints from the mode. A system receives a description of a mode of a circuit. The system identifies sets of clock pairs and corresponding exceptions associated with timing nodes of the mode, each clock pair comprising a launch clock and a capture clock and corresponding exceptions for a timing path. The system compares time intervals between an edge of the launch clock and a corresponding edge of the capture clock for the clock pairs subject to timing exceptions associated with the timing path. The system identifies certain clock pairs as critical based on the comparison of the time interval associated with each clock pair. The system simplifies the mode by eliminating non-critical clocks and corresponding exceptions and timing constraints. The modified mode is used for performing timing analysis.

Abstract: A computer-implemented method of determining an attribute of a circuit includes using a computationally expensive technique to simulate the attribute (such as timing delay or slew) of a portion of the circuit, at predetermined values of various parameters (e.g. nominal values of channel length or metal width), to obtain at least a first value of the attribute. The method also uses a computationally inexpensive technique to estimate the same attribute, thereby to obtain at least a second value which is less accurate than the first value. Then the computationally inexpensive technique is repeatedly used on other values of the parameter(s), to obtain a number of additional second values of the attribute. Applying to the additional second values, a function obtained by calibrating the at least one second value to the at least one first value, can yield calibrated estimates very quickly, which represent the attribute's variation relatively accurately.

Abstract: Modes of a circuit are merged together to reduce the number of modes. Subsets of modes are identified such that modes belonging to each subset are mergeable. A set of modes is mergeable if every pair of modes in the set is mergeable. Constraints of modes belonging to each pair of modes are compared to determine whether two modes are mergeable. To allow two modes to be merged, a constraint is transformed such that it affects the same paths in the merged mode and the first mode but excludes paths from the second mode. Determining whether two modes are mergeable may include verifying whether a clock in one mode blocks propagation of a clock in another mode and whether a value specified in a constraint in a mode is within specified tolerance of the value of a corresponding constraint in another mode.

Abstract: A computer-implemented method of determining an attribute of a circuit includes using a computationally expensive technique to simulate the attribute (such as timing delay or slew) of a portion of the circuit, at predetermined values of various parameters (e.g. nominal values of channel length or metal width), to obtain at least a first value of the attribute. The method also uses a computationally inexpensive technique to estimate the same attribute, thereby to obtain at least a second value which is less accurate than the first value. Then the computationally inexpensive technique is repeatedly used on other values of the parameter(s), to obtain a number of additional second values of the attribute. Applying to the additional second values, a function obtained by calibrating the at least one second value to the at least one first value, can yield calibrated estimates very quickly, which represent the attribute's variation relatively accurately.

Abstract: Individual mode timing constraints associated with a set of netlists are combined into merged mode timing constraints. An initial merged mode constraint is generated by combining timing constraints from individual modes. The initial merged mode includes the union of all timing constraints from individual modes that add timing relationships and the intersection of all timing constraints from the individual modes that remove timing relationships. Extraneous timing relationships are identified in the merged mode and eliminated by introducing timing constraints in the merged mode. Equivalence between the merged mode and the individual modes is verified by comparing timing relationships in the merged mode with timing relationships in the individual modes. The merged mode is considered equivalent to the individual modes if every timing relationship present in an individual mode is present in the merged mode and every timing relationship present in the merged mode is present in any of individual modes.

Abstract: Individual mode timing constraints associated with a set of netlists are combined into merged mode timing constraints. An initial merged mode constraint is generated by combining timing constraints from individual modes. The initial merged mode includes the union of all timing constraints from individual modes that add timing relationships and the intersection of all timing constraints from the individual modes that remove timing relationships. Extraneous timing relationships are identified in the merged mode and eliminated by introducing timing constraints in the merged mode. Equivalence between the merged mode and the individual modes is verified by comparing timing relationships in the merged mode with timing relationships in the individual modes. The merged mode is considered equivalent to the individual modes if every timing relationship present in an individual mode is present in the merged mode and every timing relationship present in the merged mode is present in any of individual modes.

Abstract: A computer-implemented method of determining an attribute of a circuit includes using a computationally expensive technique to simulate the attribute (such as timing delay or slew) of a portion of the circuit, at predetermined values of various parameters (e.g. nominal values of channel length or metal width), to obtain at least a first value of the attribute. The method also uses a computationally inexpensive technique to estimate the same attribute, thereby to obtain at least a second value which is less accurate than the first value. Then the computationally inexpensive technique is repeatedly used on other values of the parameter(s), to obtain a number of additional second values of the attribute. Applying to the additional second values, a function obtained by calibrating the at least one second value to the at least one first value, can yield calibrated estimates very quickly, which represent the attribute's variation relatively accurately.

Abstract: A static timing analysis (STA) technique including a main process and a parallel process is described. In the main process, an IC design can be loaded and then linked to a cell library. Timing constraints to be applied to the IC design can be loaded. A timing update for the IC design can be performed. A report based on the timing update can be output. In the parallel process, the interconnect parasitics can be back-annotated onto the IC design. In one embodiment, the interconnect parasitics can be processed and stored on disk. Information on attaching to the stored parasitic data can be generated and provided to the main process during the step of performing the timing update. The parallel process can run concurrently and asynchronously with the main process.

Abstract: Modes of a circuit are merged together to reduce the number of modes. Subsets of modes are identified such that modes belonging to each subset are mergeable. A set of modes is mergeable if every pair of modes in the set is mergeable. Constraints of modes belonging to each pair of modes are compared to determine whether two modes are mergeable. To allow two modes to be merged, a constraint is transformed such that it affects the same paths in the merged mode and the first mode but excludes paths from the second mode. Determining whether two modes are mergeable may include verifying whether a clock in one mode blocks propagation of a clock in another mode and whether a value specified in a constraint in a mode is within specified tolerance of the value of a corresponding constraint in another mode.

Abstract: A static timing analysis (STA) technique including a main process and a parallel process is described. In the main process, an IC design can be loaded and then linked to a cell library. Timing constraints to be applied to the IC design can be loaded. A timing update for the IC design can be performed. A report based on the timing update can be output. In the parallel process, the interconnect parasitics can be back-annotated onto the IC design. In one embodiment, the interconnect parasitics can be processed and stored on disk. Information on attaching to the stored parasitic data can be generated and provided to the main process during the step of performing the timing update. The parallel process can run concurrently and asynchronously with the main process.

Abstract: Individual mode timing constraints associated with a set of netlists are combined into merged mode timing constraints. An initial merged mode constraint is generated by combining timing constraints from individual modes. The initial merged mode includes the union of all timing constraints from individual modes that add timing relationships and the intersection of all timing constraints from the individual modes that remove timing relationships. Extraneous timing relationships are identified in the merged mode and eliminated by introducing timing constraints in the merged mode. Equivalence between the merged mode and the individual modes is verified by comparing timing relationships in the merged mode with timing relationships in the individual modes. The merged mode is considered equivalent to the individual modes if every timing relationship present in an individual mode is present in the merged mode and every timing relationship present in the merged mode is present in any of individual modes.

Abstract: Individual mode timing constraints associated with a set of netlists are combined into merged mode timing constraints. An initial merged mode constraint is generated by combining timing constraints from individual modes. The initial merged mode includes the union of all timing constraints from individual modes that add timing relationships and the intersection of all timing constraints from the individual modes that remove timing relationships. Extraneous timing relationships are identified in the merged mode and eliminated by introducing timing constraints in the merged mode. Equivalence between the merged mode and the individual modes is verified by comparing timing relationships in the merged mode with timing relationships in the individual modes. The merged mode is considered equivalent to the individual modes if every timing relationship present in an individual mode is present in the merged mode and every timing relationship present in the merged mode is present in any of individual modes.

Abstract: A computer-implemented method of determining an attribute of a circuit includes using a computationally expensive technique to simulate the attribute (such as timing delay or slew) of a portion of the circuit, at predetermined values of various parameters (e.g. nominal values of channel length or metal width), to obtain at least a first value of the attribute. The method also uses a computationally inexpensive technique to estimate the same attribute, thereby to obtain at least a second value which is less accurate than the first value. Then the computationally inexpensive technique is repeatedly used on other values of the parameter(s), to obtain a number of additional second values of the attribute. Applying to the additional second values, a function obtained by calibrating the at least one second value to the at least one first value, can yield calibrated estimates very quickly, which represent the attribute's variation relatively accurately.

Abstract: A computer-implemented method of determining an attribute of a circuit includes using a computationally expensive technique to simulate the attribute (such as timing delay or slew) of a portion of the circuit, at predetermined values of various parameters (e.g. nominal values of channel length or metal width), to obtain at least a first value of the attribute. The method also uses a computationally inexpensive technique to estimate the same attribute, thereby to obtain at least a second value which is less accurate than the first value. Then the computationally inexpensive technique is repeatedly used on other values of the parameter(s), to obtain a number of additional second values of the attribute. Applying to the additional second values, a function obtained by calibrating the at least one second value to the at least one first value, can yield calibrated estimates very quickly, which represent the attribute's variation relatively accurately.

Abstract: Static timing analysis attempts to exhaustively analyze all critical paths of a design. With ever decreasing geometries and ever increasing design complexity, manually identifying timing violations with standard static timing analysis can be very complex and time consuming. A static timing analysis tool can advantageously manage multiple runs having different modes and corners and automatically merge the results generated by the runs. The STA tool can perform the runs either in parallel or in series. Advantageously, the STA tool can save the full timing analysis generated by each run and then extract information from these saved results to form merged results for the design. These merged results can provide different levels of analysis coverage, supply path information at various levels of detail, allow selectable accessibility to information, and highlight propagation of timing changes/violations in the design.

Abstract: Performing signal integrity (SI) analysis on integrated circuit designs is becoming increasingly important as these designs increase in size and complexity. Dividing a design into blocks can simplify the resulting analysis. Additionally, such blocks can be replaced with timing models, which provide a compact means of exchanging interface timing information for the blocks. To further increase the speed and accuracy of SI analysis, enhanced interface logic models (SI-ILMs) can be used. An SI-ILM can include cells in timing paths that serve as the interface between the block and other parts of the design. The SI-ILM can also include internal nets that have cross-coupling effects on interface nets and nets outside the block. By including these internal nets, SI analysis at the top-level can be both fast and accurate.