Cadence Design Systems, Inc.

Wen-Hao Liu

Zhuo Li

Charles Jay Alpert

Mehmet Can Yildiz

Gracieli Posser

Wing-Kai Chow

Derong Liu

Brian Wilson

Natarajan Viswanathan

Yi-Xiao Ding

Thomas Andrew Newton

Ruth Patricia Jackson

Wing Kai Chow

Various embodiments provide for routing a network of a circuit design based on at least one of a placement blockage or a layer-assigned network of a circuit design. For instance, some embodiments route a network of a circuit design (e.g., clock net, date net) by generating a congestion map based on modeling layer-assigned networks, considering (e.g., accounting for) routing congestion based on a placement blockage of the circuit design, or some combination of both.

Routing congestion based on layer-assigned net and placement blockage

Various embodiments provide for routing a net of a circuit design using multiple layer ranges. In particular, some embodiments route a net of a circuit design using multiple layer ranges by performing routing of the net over multiple iterations such that at each iteration, a layer bound of a layer range is gradually adjusted (e.g., relaxed) based on wirelength, wire detour, or congestion of a routing result of a prior iteration. For instance, some embodiments may gradually relax a layer bound of the layer range by increasing a layer upper bound or decreasing a layer lower bound.

Systems and methods for routing a clock net with multiple layer ranges

Systems, methods, media, and other such embodiments are described for routing track assignment in a circuit design. One embodiment involves accessing routing data for a circuit design, and a first wire of a plurality of wires in the routing data. A second wire is identified that is related to the first wire as a parent wire along a shared routing direction. A misalignment value is calculated for the first wire and the second wire, and a new routing placement is selected for the first wire based at least in part on the misalignment value. In some embodiments, all wires in various routings of a circuit design are checked for possible misalignment in order to improve slew performance via reduction of unnecessary vias.

Systems and methods for routing track assignment

Aspects of the present disclosure address improved systems and methods for routing based on enhanced routing topologies. Consistent with some embodiments, the method may include accessing a routing topology of an integrated circuit design and determining that a routing path of a net in the routing topology violates a routing constraint. In response to determining that the routing path violates the routing constraint, a routing guide is created to reroute the routing path. The routing path in the net is then rerouted using the routing guide, thereby producing an enhanced routing topology that reduces issues in detailed routing caused by the routing constraint violation.

Integrated circuit routing based on enhanced topology

Aspects of the present disclosure address improved systems and methods of partition-aware grid graph based routing for integrated circuit designs. Consistent with some embodiments, a method may include accessing a design layout that defines a layout of components of an integrated circuit design, and includes one or more partitions. The method may further include building a uniform grid graph by superimposing a uniform grid structure over the design layout and inserting additional grid lines into the grid structure such that each partition boundary is aligned with a grid line. The method may further include removing redundant grid lines from the non-uniform grid graph resulting from inserting the additional grid lines, the result of which is the partition-aware grid graph. The method further includes using the partition-aware grid graph to route the integrated circuit design.

Partition-aware grid graph based hierarchical global routing

Aspects of the present disclosure address improved systems and methods for resolving single-entry constraint violations in hierarchical integrated circuit designs. In routing multi-pin nets of IC designs, the system employs a partition-entry-aware search algorithm to identify single-entry-violation-free routing results for two-pin nets, which are then combined to form routed multi-pin nets. The search algorithm is 'entry-aware' in that it penalizes multiple entries into a single partition. Consistent with some embodiments, the system may further employ a post fix stage to remove extra partition entries for the multi-pin nets with single-entry violations by choosing a main entry to enter a partition and rerouting the paths that cause the violations such that the paths share the main entry.

Routing framework to resolve single-entry constraint violations for integrated circuit designs

Aspects of the present disclosure address improved systems and methods for routing topology generation. More specifically, the present disclosure addresses systems and methods for generating a routing topology using a spine-like tree structure. Consistent with some embodiments, given a Steiner-tree based routing topology as input, the system performs an iterative refinement process on the tree topology where at least a portion of subtrees are converted to spine subtrees as the system traverses the nodes of the tree in a particular traversal order. This process continues until all tree nodes have been processed. The result is a refined routing topology that has a spine-like structure.

Routing topology generation using spine-like tree structure

Aspects of the present disclosure address improved systems and methods for local cluster refinement during clock tree synthesis for integrated circuit designs. In accordance with some embodiments, the methods for local cluster refinement may include pin move refinement and local reclustering. With pin move refinement, pins are moved from clusters that fail to satisfy design rule constraints to nearby clusters that satisfy design rule constraints. With local reclustering, groups of neighboring clusters that fail or nearly fail to satisfy design rule constraints are dissolved and corresponding pins are regrouped to form new clusters that satisfy design rule constraints.

Local cluster refinement

Various embodiments provide for clustering pins of a circuit design for connection to a power-ground network (PG) of the circuit design using a nearest neighbor graph. Pin clustering, according to some embodiments, can minimize wirelength, minimize a number of vias, satisfy constraints relating to a pin count (e.g., maximum number of pins per power-ground access point), and satisfy constraints relating to a bounding box size.

Systems and methods for clustering pins for power

Methods and systems of optimization of and Integrated Circuit (IC) design disclosed herein result in a power efficient clustering of circuit devices. The methods may depart from the conventional geometric clustering using a nearest neighbor approach when wiring flops to local clock buffers. To reduce the number of clock-gaters, the methods in one embodiment use a grouping of flops wired to a common clock-gater to form nodes, which are then wired to the local clock buffers based on a load-balancing process. In another embodiment, the methods use a local cleanup process to rewire the nodes between neighboring clock buffers to further reduce the amount of clock-gaters.

Systems and methods for power efficient flop clustering

The present disclosure relates to a system and method for constructing spanning trees. Embodiments may include receiving, using at least one processor, a plurality of nodes associated with the integrated circuit design. In some embodiments, the plurality of node may be configured to be intercoupled by one or more combinations of edges. Embodiments may further include receiving a user-defined value at a graphical user interface. Embodiments may also include generating a routing graph with a subset of the one or more combinations of edges based upon, at least in part, the user-defined value and the position of each of the plurality of nodes. Embodiments may further include generating a spanning tree based upon, at least in part, at least one of: one or more wirelengths of the routing graph and one or more source-sink detour costs associated with the routing graph.

System and method for constructing spanning trees

Disclosed herein are systems and methods to construct a symmetric clock-distribution H-tree in upper layers of an integrated circuit (IC), which may have complicated routing and/or placement blockages. The systems and methods disclosed herein may implement concomitant bottom-up wiring and top-down rewiring to achieve a clock-distribution tree symmetrically balanced across all of the hierarchical levels while respecting the complicated routing and/or placement blockages. Such symmetrically balanced clock-tree ensures that a clock-signal reaches all of the clock-sinks simultaneously or near simultaneously thereby minimizing clock-skew across the clock-sinks. The minimal skew symmetric clock-distribution H-tree may therefore be used for higher performance and high speed ICs.

Systems and methods for symmetric H-tree construction with complicated routing blockages

The present disclosure relates to a system and method for evaluating spanning trees. Embodiments may include receiving, using at least one processor, a spanning tree including one or more sinks coupled by one or more edges. Embodiments may further include receiving a user-selected floating parameter. Embodiments may also include interchanging the one or more edges of the spanning tree based upon, at least in part, the user-selected floating parameter.

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Cedar Park, TX, United States of America

Wen-Hao Liu