Cadence Design Systems, Inc.

Jhih-Rong Gao

Zhuo Li

Yi-Xiao Ding

Charles Jay Alpert

Mehmet Can Yildiz

Sheng-En David Lin

Thomas Andrew Newton

Derong Liu

Wen Hao Liu

Aspects of the present disclosure address systems and methods for driver resizing using a transition-based capacitance increase margin. An integrated circuit (IC) design stored in a database in memory is accessed. The IC design comprises a net comprising a set of driver cells. A capacitance increase margin for resizing an initial driver cell is determined based on a total capacitance of the net and transition time target associated with the initial driver cell. An alternative driver cell is selected from a library to resize the initial driver cell and is used to replace the initial driver cell in the net. The alternative driver is selected such that a pin capacitance of the alternative driver cell exceeds an initial pin capacitance corresponding to the initial driver cell by no more than the capacitance increase margin.

Driver resizing using a transition-based pin capacitance increase margin

A system includes a machine configured to perform operations including accessing an integrated circuit design including a buffer tree that interconnects a plurality of inputs and buffers. The buffer tree includes a baseline timing characteristic. The operations include identifying a set of candidate solutions for improving the baseline timing characteristic using an initial timing model and selecting a subset of candidate solutions that have a timing characteristic lower than the baseline timing characteristic. Then the subset of candidate solutions are evaluated using a detailed timing model and based on determining that at least one candidate solution in the subset has a timing characteristic that is better than the baseline timing characteristic, selecting a candidate solution from the set of candidate solutions, and updating the buffer tree based on the candidate solution.

Pruning redundant buffering solutions using fast timing models

A system includes one or more processors and a computer storage medium storing instructions that cause a machine to perform operations including accessing an integrated circuit (IC) design including an initial clock tree. The operations include selecting a first driver to evaluate for resizing, the first driver being a first size and having a first leakage current and determining a baseline power consumption measurement of clock tree based on the first size and the first leakage current of the first driver. The operations include identifying a plurality of replacement drivers to replace the first driver and determining a power consumption measurement for a second driver. Based on determining that the power consumption measurement for the second driver is less than the baseline power consumption measurement replacing the first driver with the second driver and generating a layout instance based on the second driver.

Switching power aware driver resizing by considering net activity in buffering algorithm

An integrated circuit (IC) design is accessed from a database in memory. The IC design comprises a route connecting a source to a sink. A set of buffering candidates for buffering are generated for the net. A timing improvement associated with a buffering candidate in the set of buffering candidates is determined using a first timing model. The buffering candidate is pruned from the set of buffering candidates based on the timing improvement and a cost associated with the buffering candidate. The pruned set of buffering candidates is evaluated using a second timing model, and a buffering solution for the net is selected from the pruned set of buffering candidates based on a result of the evaluating. The IC design is updated to include the buffering solution selected for the net.

Pruning of buffering candidates for improved efficiency of evaluation

An integrated circuit (IC) design is accessed from a database in memory. The IC design comprises a routing topology for a net comprising interconnections between a set of pins. The IC design further comprises a set of candidate locations for inserting buffers. A set of cells from a cell library in memory is accessed. A candidate location from the set of candidate locations is assessed to determine whether at least one cell in the set of cells fits at the location. Based on determining that at least one cell in the set of cells fits at the candidate location, the location is marked as bufferable. A largest cell width that fits at the candidate location is determined based on the set of cells and a buffering solution is generated for the net using the largest cell width as a constraint on buffer insertion performed at the candidate location.

Cell-width aware buffer insertion technique for narrow channels

An integrated circuit (IC) design is accessed from a database in memory. The IC design comprises an initial buffer tree for a net in the IC design. A maximum cost constraint for rebuffering the net is determined based on the initial buffer tree. A partial rebuffering solution is generated for net and a cost associated with the partial rebuffering solution is determined. Based on determining the cost of the partial rebuffering solution satisfies the maximum cost constraint, the partial rebuffering solution is saved in a set of partial rebuffering solutions for the net. A set of candidate rebuffering solutions for the net is generated based on the set of partial rebuffering solutions, and a rebuffering solution for the net is selected from the set of candidate rebuffering solutions. The database is updated to replace the initial buffer tree in the IC design with the rebuffering solution selected for the net.

Buffering algorithm with maximum cost constraint

Aspects of the present disclosure address improved systems and methods for buffer insertion in an integrated circuit (IC) design using a cost function that accounts for edge spacing and stack via constraints associated with cells in the IC design. An integrated circuit (IC) design comprising a routing topology for a net is accessed. A set of candidate insertion locations along the routing topology are identified. A set of buffering candidates is generated based on the candidate insertion locations. A buffering candidate comprises a cell inserted at a candidate insertion location along the routing topology. A cost associated with the buffering candidate is determined based on a number of potential edge spacing conflicts and a number of stack vias associated with the cell. A buffering solution for the net is selected from the buffering candidate based on the cost associated with the buffering candidate.

Buffer insertion technique to consider edge spacing and stack via design rules

Aspects of the present disclosure address improved systems and methods for rebuffering an integrated circuit (IC) design using a unified improvement scoring algorithm. A plurality of rebuffering candidates are generated based on an initial buffer tree in an integrated circuit (IC) design. A rebuffering candidate in the plurality of rebuffering candidates comprises a modified buffer tree based on the initial buffer tree. A buffering cost of each rebuffering candidate is determined. A reference buffer tree is selected from among the rebuffering candidates based on the buffering cost of each rebuffering candidate. An improvement score of each rebuffering candidate is determined based on the buffering cost of each rebuffering candidate relative to the reference buffer tree. A new buffer tree is selected from among the plurality of rebuffering candidates to replace the initial buffer tree based on the improvement score of each rebuffering candidate.

Unified improvement scoring calculation for rebuffering an integrated circuit design

Aspects of the present disclosure address improved systems and methods for layer assignment to improve timing in integrated circuit (IC) designs. An initial placement layout of a net of an IC design is accessed. A plurality of buffer insertion candidates is generated using multiple candidate buffer insertion points and multiple layer assignments from among multiple layers of the IC design. Timing characteristics of each buffer insertion candidate are determined, and timing improvements provided by each buffer insertion candidate are determined based on respective timing characteristics. A buffer insertion candidate is selected from the plurality of buffer insertion candidates based on the timing improvement provided by the buffer insertion candidate. A layout instance for the IC is generated based in part on the selected buffer insertion candidate.

Layer assignment technique to improve timing in integrated circuit design

Systems, methods, media, and other such embodiments described herein relate to generation of routing trees. One embodiment involves accessing a circuit design comprising a source, a plurality of sinks, and a skew threshold associated with the source and the plurality of sinks. An initial routing tree is generated between the source and the plurality of sinks, and then a first intermediate point is identified between the source and the plurality of sinks. The first intermediate point may be identified based on a median location of all sinks of the plurality of sinks, or other criteria. The first intermediate point is then used for an updated routing tree. In some embodiments, a process proceeds iteratively until the skew threshold is reached or a maximum wire length is exceeded.

Routing tree topology generation

Disclosed herein are systems and methods to reduce wirelength and congestion in an integrated circuit (IC) design. The systems and methods disclosed herein may be implemented during a detailed placement stage of IC design to identify and select a cell for relocation and determine an area of interest to which the cell can be relocated. The systems and methods may identify one or more potential locations within the area of interest where the cell can be relocated to, and then determine a cost based upon the wirelength and/or congestion for the selected cell, at each of the one or more potential locations. Upon determining that a potential location may have a lower cost compared to the original location of the selected cell, the systems and methods may relocate the selected cell to the potential location.

Growing community of inventors

Austin, TX, United States of America

Jhih-Rong Gao