International Business Machines Corporation

Alexander Itskovich

Cynthia Rae Eisner

Eli Arbel

Oded Fuhrmann

David J Levitt

Daniel Lawrence Stasiak

Nicolas Maeding

Dan Ramon

Israel Berger

Peter Hofstee

A novel method for optimizing the implementation of clock gating logic in digital circuits utilizing clock gating. The method over-approximates the clock gating function by removing the variable with the least influence on the resulting approximation function. Approximations of clock gating functions expressed in normal form are performed by removing an appropriate component from the function. Approximations of clock gating functions expressed in conjunctive normal form are performed by removing a clause from the function. Approximations of clock gating functions expressed in disjunctive normal form are performed by removing a literal from a clause in the function.

Over approximation of integrated circuit based clock gating logic

A novel method for optimizing the design of digital circuits containing clock gated memory elements. The method unclock gates memory elements by adding necessary feedback loops. Logic functions of memory element outputs in the circuit are viewed as a whole, rather than as separate functions for each input. Detection of duplicate unclock gated memory elements is then effected by identifying identical canonical representations of said unclock gated memory elements. Identified duplicate clock gated memory elements can then be eliminated from the original digital circuit. Further optimization can be accomplished by applying standard logic optimization algorithms to all unclock gated memory elements in said digital circuit. The resulting optimized circuit is clock gated and replaces the original clock gated circuit in said digital circuit.

Circuit design optimization of integrated circuit based clock gated memory elements

A system for clustering Boolean functions for clock gating according to various exemplary embodiments can include a computer configured to identify at least two small gating groups within a clock tree representative of an electrical network and at least two gating functions of the at least two small gating groups, wherein the at least two gating functions are Boolean functions; perform hierarchical clustering on the at least two gating functions using a similarity measure that describes a distance between the at least two gating functions such that the clustering forms a merge function of a cluster generated and displayed in a form of a dendrogram; assign to each gating domain a merit value according to a power consumption profile of the gating domain using a merit function; and partition the cluster into gating groups using the dendrogram to construct a directed acyclic graph to determine a partition which maximize the overall power saving.

Device to cluster Boolean functions for clock gating

Given a function F of a circuit having a data latching device and a feedback loop feeding an output Q of the device into logic which feeds the device, a method includes extracting at least one data independent case and clock-gating the device with the at least one data independent case. The method also includes eliminating the feedback loop if function F depends only on Q with a positive polarity or leaving the feedback loop if function F depends on Q in both positive and negative polarities.

Clock-gating through data independent logic

A method to cluster Boolean functions for clock gating according to various exemplary embodiments can include identifying at least two small gating groups within a clock tree representative of an electrical network and at least two gating functions of the at least two small gating groups, wherein the at least two gating functions are Boolean functions; performing hierarchical clustering on the at least two gating functions using a similarity measure that describes a distance between the at least two gating functions such that the clustering forms a merge function of a cluster generated and displayed in a form of a dendrogram; assigning to each gating domain a merit value according to a power consumption profile of the gating domain using a merit function; and partitioning the cluster into gating groups using the dendrogram to construct a directed acyclic graph to determine a partition which maximize the overall power saving.

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Yoqneam Ilit, Israel

Alexander Itskovich