Abstract: Some embodiments of the invention provide a method for pre-tabulating sub-networks. This method (1) generates a sub-network that performs a function, (2) generates a parameter based on this function, and (3) stores the sub-network in a storage structure based on the generated parameter. In some embodiments, the generated sub-network has several circuit elements. Also, in some embodiments, the generated sub-network performs a set of two or more functions. Some embodiments store each generated sub-network in an encoded manner. Some embodiments provide a method for producing a circuit description of a design. This method (1) selects a candidate sub-network from the design, (2) identifies an output function performed by the sub-network, (3) based on the identified output function, identifies a replacement sub-network from a storage structure that stores replacement sub-networks, and (4) replaces the selected candidate sub-network with the identified replacement sub-network in certain conditions.

Abstract: A multiple-input follower amplifier is coupled through a configuration of switching devices to an upper reference voltage at a number of its inputs and to a lower reference voltage at the remaining number of its inputs to form a voltage interpolator. The output of the voltage interpolator is a voltage between the upper and lower reference voltages proportional to the number of inputs coupled to each reference voltage. The voltage interpolator may be constructed so that the interpolated voltage may be selected through a reduced number of signal lines, such as by a row/column selection scheme. A voltage reference circuit providing the upper and lower reference voltages may also implement a row/column selection mechanism, thereby allowing a decoding scheme common to both a voltage reference circuit and a voltage interpolator in a digital-to-analog converter.

Abstract: Concurrent engineering among multiple design groups is facilitated by maintaining design changes in a data model of a design being developed. Design changes for each group are made from a baseline design. Changes are tracked by maintaining change information from all but an owner of the original baseline design. Changes are synchronized by identifying owner and non-owner changes and merging the changes to produce a final design. Since non-owner changes are tracked, the baseline design is not needed in synchronization. Preferably the invention is applied to electronic designs made by multiple design groups at geographically diverse locations. The invention may also be applied to any system where configuration management of developed software, parts, or any design is needed.

Abstract: Provided are a method, article of manufacture, and apparatus for estimating delays of networks. An automated design system comprises a computer configured to identify a critical path in a network, calculate a delay for the technology-mapped version of the network, calculate a delay for the technology-independent version of the network, calculate a scale factor from the technology-mapped and technology-independent delays, and apply the scale factor to all the delays in the technology-independent network.

Abstract: Method and system for providing a signal with a controllable zero crossing time value. The system provides first and second two-sided triangular wave signals, identical but shifted by a selected fraction f·T of a period T of either triangular signal, and forms a weighted sum of the signals, weighted by A and 1−A, respectively, with 0≦A≦1. In each of two time regions within a period T, a zero crossing time of the sum varies linearly with choice of the value A.

Abstract: Provided are a method, article of manufacture, and apparatus for matching candidate clusters to cells in a technology library. An automated design system comprises a computer configured to use second order signatures in generating candidate permutations of each permutation group in a canonical form of the candidate function. The system selects first and second symmetric subgroups, determines a second order signature for the candidate function and the first and second symmetric subgroups, and compares the second order signature to a corresponding second order signature for a library cell function. If the signatures match, the permutation is continued with the first and second symmetric subgroups being included in an intermediate permutation. If not, the system produces no more intermediate permutations beginning with the first and second symmetric subgroups. Further symmetric subgroups are added to the intermediate permutation.

Abstract: Provided are a method, article of manufacture, and apparatus for identifying candidate clusters for matching to cells in a technology library. An automated design system comprises a computer configured to extract a portion of a circuit, levelize it, select a first node, identify the realizable clusters at the inputs of the first node, and combine the first node with realizable clusters at the inputs to produce candidate clusters. A dummy cluster is used at each input to represent using the input as a fanin. The system takes the cross product of the sets, and the first node is merged with each element of the cross product to produce a set of candidate clusters. The candidate clusters are then checked for realizability by comparing them to cells in the technology library, which includes dummy cells to facilitate mapping to large cells in the technology library. A set of realizable clusters is produced for the first node.