International Business Machines Corporation

Manikandan Viswanath

Paul David Kartschoke

John J Reilly

Steven E Charlebois

Albert Manhee Chu

Samuel I Ward

Gi-Joon Nam

Thomas Edward Rosser

Eric D Johnson

William J Rensch

Timing for a critical path of a circuit design is optimized by splitting up the path so the synthesis effort to solve the path is appropriately apportioned. Selected nodes of the path are made visible, and internal timing constraints are applied to gates at the visible nodes. The internal timing constraints are translated into physical locations, and placement constraints are applied to the gates based on the physical locations, followed by timing-driven placement. The internal timing constraints can be required arrival times computed using a linear delay model. The placement constraints can include an attractive force between a given one of the selected gates and a corresponding one of the physical locations. The results are better stability control from run to run, and significant savings in power consumption due to less buffering and better gate sizing, with an optimum partition of the path for better routing.

Apportioning synthesis effort for better timing closure

Systems and methods for determining adjustable wafer acceptance criteria based on chip characteristics. The method includes measuring a density of at least one chip. The method further includes computing a difference in density between the density of the at least one chip and a density of at least one kerf structure. The method further includes calculating an offset value to modify a Wafer Acceptance Criteria (WAC) to match the density difference between the at least one chip and the at least one kerf structure. The method further includes applying the offset value to the WAC for a wafer level measurement in order to increase chip yield performance.

Systems and methods for determining adjustable wafer acceptance criteria based on chip characteristics

A netlist for an integrated circuit design is constrained by virtual or 'soft' pins to control or stabilize the placement of logic such as an architectural logic path. One soft pin is inserted at a fixed location proximate an input net of the path and is interconnected with the input net, and another is inserted at a fixed location proximate the output net and is interconnected with the output net. Cell placement is then optimized while maintaining the virtual pins at their fixed locations. More than two virtual pins may be inserted to bound a cluster of logic. The virtual pins may lie along the input/output nets. Pseudo-net weights are assigned to pseudo-nets formed between a cell and the virtual pins, and the pseudo-net weight can be increased for each placement iteration.

Soft pin insertion during physical design

Systems and methods are provided to optimize critical paths by modulating systemic process variations, such as regional timing variations in IC designs. A method includes determining a physical location of an element in the semiconductor chip design within the critical path. The method further includes modulating a systemic process variation of the semiconductor chip design to speed up the critical path based on a polysilicon conductor perimeter density associated with the element.

Optimizing timing critical paths by modulating systemic process variation

Spare cells are inserted in a region of an integrated circuit design based on a logic complexity of the region. The logic complexity can be computed based on the number of reachable states of digital logic in the region, and can be correlated to a desired spare cell insertion rate which is then compared to the actual spare cell utilization in the region. The target spare cell rate can further based on logic complexity values for neighboring regions with a proximity penalty.

Spare cell insertion based on reachable state analysis

A design structure that performs iterative synthesis of an integrated circuit design to attain power closure is described. In one embodiment, the design structure is embodied in a computer readable medium and has the capability to initially synthesized an integrated circuit design to satisfy timing and power constraints. Results from the initial synthesis are fed back into the synthesis process where specific nodes in the circuit design are targeted to satisfy the timing and power constraints. Selected nodes in the circuit design are worked on in an iterative manner until it has been determined that all of selected nodes have undergone evaluation for satisfying timing and power constraints. Once all of the selected nodes have undergone evaluation for satisfying timing and power constraints, then a final netlist representing the circuit design is generated.

Design structure for performing iterative synthesis of an integrated circuit design to attain power closure

Power gating logic cones is described. In one embodiment a method includes synthesizing logic for an integrated circuit (IC) design; identifying low switching nodes within the logic that switch less than a threshold; determining a potential power gating cone (PGC) based on the identified low switching nodes; determining a power gating logic expression for the potential PGC that includes a minimum set of inputs to the potential PGC that are least switching; determining whether energy savings using the power gating logic expression meets a criteria; and accepting the potential PGC in response to meeting the criteria.

Power gating logic cones

An approach that iteratively synthesizes an integrated circuit design to attain power closure is described. In one embodiment, the integrated circuit design is initially synthesized to satisfy timing and power constraints. Results from the initial synthesis are fed back into the synthesis process where specific nodes in the circuit design are targeted to satisfy the timing and power constraints. Selected nodes in the circuit design are worked on in an iterative manner until it has been determined that all of selected nodes have undergone evaluation for satisfying timing and power constraints. Once all of the selected nodes have undergone evaluation for satisfying timing and power constraints, then a final netlist representing the circuit design is generated.

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South Burlington, VT, United States of America

Manikandan Viswanath