Abstract: Parameterized cells are cached and provided by the plug-in to increase the speed and efficiency of an application for circuit design. This allows source design to be read-interoperable and also enables some basic write-interoperability in the source design.

Abstract: A method for timing verification of very large scale integrated circuits reduces required CPU speed and memory usage. The method involves steps including partitioning the circuit into a plurality of blocks and then partitioning the verification between shell path components and core path components. Timing verification is then conducted for only shell path components while core path components are abstracted or ignored. Finally, timing verification for core path components in each block completes the process for the entire design.

Abstract: A feasible floorplan of a circuit is determined and budgeted in the early phases of circuit design. The process of determining the floorplan and budget includes estimating RTL complexity, physical partitioning, block placement, block i/o placement and top level global routing, and verifying feasibility of the floorplan. Allocation of global timing constraints to each block is performed by producing logic cones representing timing of circuit paths in each block. The circuit paths are optimized to determine a feasible timing for each block. The global constraints are allocated proportionally to each block based on the feasible timing for each block.

Abstract: A method and system are disclosed for finding the best match from a target library of simple logic cells for a complex logic circuit conception. The inventive method is flexible and can be adapted to several cost functions or criteria. The inventive method finds the best children nodes for a match of simple gates (AND, OR, NAND, NOR). The method allows one to improve the overall area of the final design while respecting the time constrains. It also allows one to smartly speed up the tiler process as this process does not have to investigate exhaustive lists of possible children. Two preferred embodiments are disclosed. One such embodiment is designed to improve slack time and the other is designed to minimize required area.

Abstract: A method for estimating the position of a matched cell takes into account the interconnectivities of that cell, without relying on the location of cells connected to the matched cell. The new method is referred to as the Weighted Center of Mass of Covered method. In this method, weights are given to the various nodes which are part of the match. These weights are based on the number of connections between the nodes and child nodes of the match. The placment of the matched cell is based on the initial positions given to the nodes makeing up the match, and the weights calculated for those nodes.

Abstract: A method for selecting which covers to retain for each node reduces the computational burden for large logic cones and large cell libraries. At each node only K covers are retained. These covers have timing performances which are centered around the ideal timing performance for that node, and do not include inferior covers. The computational burden in selecting the covers for each node is based on the number K, and the number of inputs to that node.

Abstract: A method and a system implement a circuit design in an integrated chip. A floorplan of the circuit design is arranged at a high level of abstraction. The design is synthesized based on the floorplan, and the synthesized design is laid out physically on the integrated circuit.

Abstract: A set of flat net descriptors are added to a hierarchical representation of a specified circuit design so as to provide a hierarchical view and a flat net view of the circuit design. The hierarchical representation includes a set of cell descriptors representing hierarchical cells in the specified circuit design, and a set of net descriptors representing portions of interconnections located within each hierarchical cell. Each net descriptor has associated therewith a list of endpoint descriptors representing endpoints of a corresponding one of the interconnections located within a respective hierarchical cell. The procedure for generating flat nets generates a flat net descriptor for each interconnection in the specified circuit. Each flat net descriptor has associated therewith a list of endpoint descriptors representing all endpoints of the interconnection.

Abstract: A method and a system allocate a budget to a circuit design. A timing analysis is prepared for a circuit and a budget is automatically allocated to each of the blocks of the circuit.

Abstract: A method of automatically optimizing a hierarchical netlist of integrated circuit cells comprising at least one upper-level cell containing a multiplicity of subsidiary cells of lower hierachical level includes receiving data defining said netlist and timing constraints for it, and establishing abstract timing models for all the subsidiary cells. Timing constraints are propagated to at least one selected subsidiary cell and this cell is optimized by means of a flat optimizer to produced an optimized version of the selected subsidiary cell. The optimized version of the selected cell is inserted into the netlist. The timing constraints denote arrival times for signals at inputs of a cell and required times for signals at outputs of a cell and each abstract timing model of a cell comprises timing parameters which enable a delay time between a specified input of a cell to a specified output of a cell to be computed.

Abstract: The invention relates to a computer implemented process for fixing hold time violations in hierarchical designs of electronic circuits. The process comprises the steps of:1) synthesizing a RTL-HDL type description of the circuit to form a synthesized design,2) synthesizing a clock tree and adding it to the synthesized design produced in step 1,3) optimizing the synthesized design resulting from step 2, and fixing upper-bounded timing constraints by using a real clock timing (latency and skew) and worst case conditions,4) fixing lower-bounded timing violations in the optimized synthesized design resulting from step 3, using a real clock timing, using best case conditions,5) re-fixing possible upper-bounded timing constraints newly created and possible upper-bounded timing constraints increased in step 4,6) fixing post-layout upper-bounded timing violations.

Abstract: A method and apparatus for designing circuits uses parameterized Hardware Description Language (HDL) modules stored in a library. A datapath synthesizer accesses the library and assigns values to parameters to form specific implementations of the parameterized HDL modules. The specific implementations of the parameterized HDL modules are used by the datapath synthesizer to implement an HDL circuit description.

Abstract: In a computer aided design system for assisting in the design and analysis of integrated circuits, users can specify an integrated circuit using either a conventional circuit component netlist, or an HDL circuit description. Timing constraints are specified using conventional system level timing constraints, at least one clock timing constraint and a plurality multi-cycle timing constraints specifying clock based timing constraints for the transmission of data between sequential data elements in which at least a subset of the clock based timing constraints concern timing constraints for duration longer than a single clock period. In addition, the user may provide the system with a plurality of constraint based timing path specifications, each indicating signal paths through the integrated circuit to which specified ones of the multi-cycle timing constraints are applicable and signal paths to which the specified ones of the multi-cycle timing constraints are not applicable.

Abstract: A method of designing a circuit is described. A netlist for a circuit is generated. An analysis of the netlist is then executed to generate a set of cell instance performance values that characterize the performance of multiple gate instance-level components of the circuit in view of a selected parameter, such as circuit timing, circuit power consumption, or circuit area. Relying upon the set of cell instance performance values, a problematic component within the circuit is identified for replacement. A set of functionally equivalent candidate components are then identified. Each candidate component is analyzed with respect to the selected parameter. The analysis identifies an optimally performing candidate component. An instance of the optimally performing candidate component is then substituted into the netlist for the problematic component to improve the performance of the circuit.

Abstract: A computer aided design system converts system level timing constraints to the minimum number of path-based timing constraints necessary to represent the same timing constraints as the system level timing constraints. Using a data structure for each node of the circuit, signal arrival times and required arrival times for each node are generated for each high level timing constraint, and the worst slack time is identified for each node. Then, a node with a worst slack time is selected, the constraint associated with that worst slack time is identified, and then a worst case path from a start node of the identified constraint through the selected node to an end node of the identified constraint is determined. The start and required signal arrival times associated with the identified constraint's start and end nodes in the determined path are also identified.

Abstract: A method and apparatus for characterizing the timing behavior of datapath in integrated circuit design and fabrication. A set of circuit specifications for an integrated circuit are developed and described in a hardware description language (HDL) description. A datapath library including datapath cells and a gate library including primitive gate cells are provided, and a netlist is synthesized from the HDL description. The netlist is composed of datapath cells from the datapath library and primitive gate cells from the gate library. If a datapath cell instance in the netlist does not meet the timing constraints imposed by a user for the circuit, an alternative datapath cell instance can be substituted for that cell instance in a resynthesis and optimization step. An integrated circuit is preferably fabricated as specified by the resynthesized netlist. The netlist is preferably resynthesized multiple times in an iterative loop to optimize the netlist according to the constraints.

Abstract: A method for removing the critical false paths takes place during logic optimization. It is based on a path-constrained redundancy removal algorithm. This path-constrained redundancy removal algorithm automatically finds that a path node does not affect the behavior of the path output and so determines a critical path. This method is iteratively repeated for as long as this critical path is false.

Abstract: Process for the processing of logic function specification data of an associated specific integrated circuit or ASIC for a graphical representation of said circuit. The process consists of associating with the specification data Boolean attributes as a function of aspects, characteristics and details which a user wishes to know with respect to the circuit and then constructing data representative of said characteristics. One representation of the circuit can then be displayed by associating graphical symbols with the constructed data.

Abstract: A computer aided design system and method for automatically modifying a specified Hardware Description Language (HDL) characterization of a circuit to reduce signal delays on critical paths of the circuit is described. The specified circuit is analyzed with a logic synthesizer including a novel cell-based timing verifier that determines if a circuit meets specified timing requirements. Timing requirements are tested by computing a slack value for each node of the circuit at the component (macrocell) level, where the slack value represents the difference between the required arrival time of a signal at each circuit node and the computed worst case signal arrival time for the node. The output node having the most negative slack value is identified as a critical node. The HDL description of the circuit corresponding to the critical node is modified with a synthesis directive to substitute the original datapath cell with a better cell in order to improve the circuit's timing performance.

Abstract: A computer aided design system automatically modifies a specified circuit netlist to reduce signal delays on critical signal paths. A critical signal path that does not meet specified timing constraints is identified by computing signal slack values for each node, where negative slack values indicate a failure to meeting timing requirements. Critical gates along the critical signal path that are candidates for duplication are identified by determining which critical gates have a fanout greater than one and can be represented by library cells compatible with the next circuit tree along the critical signal path. One such gate is selected and duplicated, with one copy of the duplicated output gate being used to generate only the signal on the critical signal path and the other copy of the duplicated output gate being used to drive all other fanouts of the selected gate. This generates a modified circuit netlist.