Abstract: Dual-structure clock tree synthesis (CTS) is described. Some embodiments can construct a set of upper-level clock trees, wherein each leaf of each upper-level clock tree is a root of a lower-level clock tree. Each upper-level clock tree can be optimized to reduce an impact of on-chip-variation and/or cross-corner variation on clock skew. Next, for each leaf of each upper-level clock tree, the embodiments can construct a lower-level clock tree to distribute a clock signal from the leaf of the upper-level clock tree to a set of clock sinks. The lower-level clock tree can be optimized to reduce latency, power consumption, and/or area.

Abstract: Dual-structure clock tree synthesis (CTS) is described. Some embodiments can construct a set of upper-level clock trees, wherein each leaf of each upper-level clock tree is a root of a lower-level clock tree. Each upper-level clock tree can be optimized to reduce an impact of on-chip-variation and/or cross-corner variation on clock skew. Next, for each leaf of each upper-level clock tree, the embodiments can construct a lower-level clock tree to distribute a clock signal from the leaf of the upper-level clock tree to a set of clock sinks. The lower-level clock tree can be optimized to reduce latency, power consumption, and/or area.

Abstract: Systems and techniques are described for automatically generating clock tree synthesis (CTS) exceptions. The process can use on one or more criteria to identify sequential circuit elements that can be ignored during clock skew minimization. For example, the process can identify sequential circuit elements whose clock skew cannot be balanced with other sequential circuit elements due to structural reasons, identify sequential timing elements that do not have a timing relationship with other sequential timing elements in the clock tree, and/or identify sequential circuit elements whose data pins have a sufficiently large slack so that clock skew is not expected to cause timing violations at any of the data pins. Next, the process can generate clock tree exceptions based on the identified sequential circuit elements.

Abstract: Systems and techniques are described for automatically generating clock tree synthesis (CTS) exceptions. The process can use on one or more criteria to identify sequential circuit elements that can be ignored during clock skew minimization. For example, the process can identify sequential circuit elements whose clock skew cannot be balanced with other sequential circuit elements due to structural reasons, identify sequential timing elements that do not have a timing relationship with other sequential timing elements in the clock tree, and/or identify sequential circuit elements whose data pins have a sufficiently large slack so that clock skew is not expected to cause timing violations at any of the data pins. Next, the process can generate clock tree exceptions based on the identified sequential circuit elements.

Abstract: A method and apparatus for shortening the time to emulation and user-friendliness of a hardware emulation system is disclosed that places adjustable delay elements at the inputs to each flip-flop in a design after the user's design has been compiled. The user selects the amount of delay to be programmed into the adjustable delay element.

Abstract: An apparatus and method for locating a good approximation of optimal Steiner tree routing in the presence of rectilinear obstacles, including finding a Steiner tree on an escape graph. The escape graph is constructed by forming lines from given points (pins) and obstacles. Obstacles and the segments of obstacles are provided with lines parallel to that segment at a given minimum distance S.sub.min from the obstacle is constructed until it reaches either a boundary of an obstacle or a boundary of the core. For pins which do belong to a boundary of an obstacle, a ray, perpendicular to the segment of the boundary on which the pin is located is constructed from the pin and out from the obstacle until it reaches another obstacle or a boundary of the core. For pins which do not belong to an obstacle, vertical and horizontal lines are constructed. A Steiner tree may then be found on the escape graph by using any number of algorithms such as algorithm S and algorithm M.

Abstract: The invention quickly produces a dense layout for an integrated circuit that enables a smaller die to be used to implement the integrated circuit than would otherwise be the case, resulting in a desirable size reduction in the final packaged integrated circuit. The invention combines routing space estimation and adjustment (a technique similar to channel-based global routing) with area-based detailed routing, resulting in an approach that provides the benefits of both channel-based and area-based layout techniques while minimizing the disadvantages of those techniques.

Abstract: A large number of microelectronic circuit cells that are interconnected by a set of wiring nets are optimally placed on an integrated circuit chip such that all interconnects can be routed and the total wirelength of the interconnects is minimized. Cells are first grouped into disjoint clusters by an optimization-driven clustering technique, which uses both local and global connectivity information among the cells. This technique uses Rent's rule for combining pairs of neighboring clusters, and selects among pairs of clusters having the same Rent's exponent using distance information derived from global optimization processing. Clusters are prevented from growing to an excessive size by limiting the number of cells per cluster and the maximum area per cluster to predetermined maximum values. After the clusters are generated, they are placed using an optimization-driven placement technique, preferably "Gordian".

Abstract: An apparatus and method for locating a good approximation of optimal Steiner tree routing in the presence of rectilinear obstacles, including finding a Steiner tree on an escape graph. The escape graph is constructed by forming lines from given points (pins) and obstacles. Obstacles and the segments of obstacles are provided with lines parallel to that segment at a given minimum distance s.sub.min from the. The lines are constructed until they reaches either a boundary of an obstacle or a boundary of the core. For pins which do belong to a boundary of an obstacle, a ray, perpendicular to the segment of the boundary on which the pin is located is constructed from the pin and out from the obstacle until it reaches another obstacle or a boundary of the core. For pins which do not belong to an obstacle, vertical and horizontal lines are constructed. A Steiner tree may then be found on the escape graph by using any number of algorithms such as algorithm S and algorithm M.

Abstract: An integrated circuit layout technique is described which employs an optimization-driven clustering technique to provide improved cell placement. The technique utilizes clustering of cells based upon Rent's rule, with global-optimization-derived inter-cell distances being used to break ties when identical Rent exponents are encountered. A constraint on the number of cells permitted to be in a cluster and a constraint on the maximum Rent exponent which to be considered for merging clusters minimize the "overgrowth" of clusters and serve to even out cluster size, ideally suiting the technique to conventional partitioning and placement schemes.

Abstract: An apparatus and method for locating a good approximation of optimal Steiner tree routing in the presence of rectilinear obstacles, including finding a Steiner tree on an escape graph. The escape graph is constructed by forming lines from given points (pins) and obstacles. Obstacles and the segments of obstacles are provided with lines parallel to that segment at a given minimum distance S.sub.min from the obstacle. The lines are constructed until they reach either a boundary of an obstacle or a boundary of the core. For pins which do belong to a boundary of an obstacle, a ray, perpendicular to the segment of the boundary on which the pin is located is constructed from the pin and out from the obstacle until it reaches another obstacle or a boundary of the core. For pins which do not belong to an obstacle, vertical and horizontal lines are constructed. A Steiner tree may then be found on the escape graph by using any number of algorithms such as algorithm S and algorithm M.