System and method for inserting leakage reduction control in logic circuits
AssigneeInternational Business Machines Corporation
InventorsJohn M. Cohn, Alvar A. Dean, David J. Hathaway, Sebastian T. Ventrone
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Abstract
A method for reducing leakage power of a logic network comprising the steps of: using (observability) don't care information to identify “sleep states” for individual nets; determining based on probabilistic analysis at least one net in which expected power consumption will be reduced by forcing a net to a particular value during at least a portion of a “sleep state”; and forcing the determined net to the determined value determined portion of that “sleep state”.
Claims46
A method for reducing leakage power of a logic network comprising a plurality of nets, comprising the steps of:
- a) determining observability don't care (ODC) information for one or more first nets in said logic network, said ODC information representing a set of input values for which the values at said first nets have no influence on any output value of the logic network, said ODC information being used for identifying sleep states for first nets of said logic network;
- b) performing a simulation to force at least one selected net from said first nets to a particular value during at least a portion of at least one of said identified sleep states and performing a probabilistic analysis to determine at least one net in which expected power consumption will be reduced;
- and
- c) forcing said selected nets to said particular value for said portion of a sleep state when expected power consumption is reduced.
A method for reducing leakage power of a logic network comprising a plurality of nets, comprising the steps of:
- a) computing state, switching functions for nets in a logic network and probabilities thereof and, computing observability don't care (ODC) functions used for identifying sleep states for nets of said logic network and, probabilities thereof;
- b) calculating an initial power leakage calculation for one or more of said nets;
- c) determining one or more function preserving logical changes for at least one selected net of said one or more nets and, simulating said changes to force said selected net to a particular value during at least a portion of a sleep state;
- d) updating said state, switching functions and observability don't care (ODC) functions for chosen nets of said logic network and, updating said probabilities thereof in light of said changes;
- e) calculating power leakage changes for the chosen nets resulting from the forcing of said selected nets;
- and
- f) deciding whether to accept or reject the proposed function preserving logical changes in accordance with acceptable performance criteria.
A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for reducing leakage power of a logic network comprising a plurality of nets, the method comprising the steps of:
- a) determining observability don't care (ODC) information for one or more first nets in said logic network, said ODC information representing a set of input values for which the values at said first nets have no influence on any output value of the logic network, said ODC information being used for identifying sleep states for first nets of said logic network;
- b) performing a simulation to force at least one selected net from said first nets to a particular value during at least a portion of at least one of said identified sleep states and performing a probabilistic analysis to determine at least one net in which expected power consumption will be reduced;
- and
- c) forcing said selected nets to said particular value for said portion of a sleep state when expected power consumption is reduced.
An integrated circuit device of reduced power consumption comprising:
- a logic network comprising one or more nets capable of being placed in a sleep state wherein a set of input values at said nets have no influence on any output value of the logic network, at least one net capable of being forced to a particular value so as to exhibit reduced power consumption as previously determined by a probabilistic analysis;
- and
- a device in said logic network for forcing said selected net to said particular value during a sleep state when expected power consumption is reduced.
Dependencies are inferred from the claim text.