Cadence Design Systems, Inc.

Gracieli Posser

Mehmet Can Yildiz

Zhuo Li

Wing-Kai Chow

Wen-Hao Liu

Derong Liu

Charles Jay Alpert

Natarajan Viswanathan

Yi-Xiao Ding

William Robert Reece

Andrew Mark Chapman

Ruth Patricia Jackson

Mateus Paiva Fogaça

Aspects of the present disclosure address systems and methods for density-aware layer assignment for integrated circuit (IC) designs. Data describing an IC design is accessed. The IC design comprises a net and a set of routing layers. Single-layer routing and an initial layer assignment is performed on the set of nets. The single-layer routing and the initial layer assignment comprises generating a route for a net from the set of nets and assigning the route to one or more layers from the set of layers. A multi-layer density map is generated based on the single-layer routing and the initial layer assignment on the set of nets. Incremental layer reassignment is performed on the set of nets based on the multi-layer density map. The incremental layer assignment comprises reassigning a segment of the route from the first layer to a second layer from the set of layers based on the density value.

Wire density-aware layer assignment

Various embodiments provide for routing a circuit design using routing congestion based on fractional via cost, via density, or both in view of one or more design rules. For instance, some embodiments model via cost based on one or more design rules to determine routing congestion, where routing demand (e.g., routing capacity occupied by) of a via is fractional to the amount of the track blocked by the via. Additionally, some embodiments apply via density modeling based on one or more design rules to determine a routing demand of a via for routing congestion.

Routing congestion based on fractional via cost and via density

Various embodiments provide for routing a net of a circuit design using rule-based routing blockage extension, which may be part of electronic design automation (EDA). In particular, some embodiments route a net of a circuit design by determining a dimension extension value based on a design rule of the circuit design and applying the dimension extension value to at least one existing routing blockage.

Routing using rule-based blockage extension

Various embodiments provide for routing a circuit design based on adjusting a routing demand. More specifically, some embodiments implement routing demand smoothing of a grid cell, routing overflow spreading of a grid cell, or some combination of both prior to detailed routing of a circuit design, which can result in improved detailed routing over conventional routing techniques.

Circuit design routing based on routing demand adjustment

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

Aspects of the present disclosure address systems and methods for fixing clock tree design constraint violations. An initial clock tree is generated. The generating of the initial clock tree comprises routing a clock net using an initial value for a parameter that controls a priority ratio between total route length and a maximum source-to-sink route length in each net of the clock tree. A violation to a clock tree design constraint is detected in the clock net in the clock tree, and based on detecting the violation, a rerouting candidate is generated by rerouting the clock net using an adjusted value for the parameter. A target clock tree is selected based on a comparison of timing characteristics of the rerouting candidate with the clock tree design constraint.

Modifying route topology to fix clock tree violations

Various embodiments provide for routing a network of a circuit design based on at least one of via spacing or pin density. For instance, some embodiments route a net of a circuit design (e.g., data nets, clock nets) by generating a congestion map based on modeling via spacing, modeling pin density, or some combination of both.

Routing congestion based on via spacing and pin density

Various embodiments provide for circuit design routing based on parallel run length (PRL) rules. In particular, a plurality of PRL rules is accessed and used to generate a set of additional routing blockages around an existing routing blockage of the circuit design. The additional routing blockages can be positioned relative to the existing routing blockage. During routing, the set of additional routing blockages can be modeled into a capacity map, which is then used by global to generate routing guide(s) between at least two nodes of the circuit design. In doing so, the various embodiments can assist in routing a wire while avoiding violation of the plurality of PRL rules with respect to the existing blockage, can speed up performance of global routing, can make it easier for detailed routing to honor routing guides produced by global routing, and can speed up performance of detailed routing in resolving DRC violations.

Circuit design routing based on parallel run length rules

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

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

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.

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Austin, TX, United States of America

Gracieli Posser