Statistical Design with Importance Sampling Reuse
First Claim
1. A method, in a data processing system, for determining failure rate of a device using importance sampling reuse, the method comprising:
- performing, by the data processing system, a uniform sampling over a random sample space for a performance metric for the device with respect to an origin to form a set of samples, wherein the origin represents nominal values for device parameters for a given design of the device, wherein the metric is an operational performance value of the device, and wherein the set of samples comprises one or more failing samples;
determining, by the data processing system, a center of gravity of the one or more failing samples with respect to the origin;
determining, by the data processing system, importance samples based on the center of gravity of the one or more failing samples;
selecting a new origin representing alternative values for device parameters corresponding to a process variation or design consideration;
recomputing, by the data processing system, new importance sampling weight ratios for the new origin; and
determining, by the data processing system, a failure rate for the device based on the new importance sampling weight ratios alternative values for device parameters or environmental parameters.
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Abstract
A mechanism is provided for reusing importance sampling for efficient cell failure rate estimation of process variations and other design considerations. First, the mechanism performs a search across circuit parameters to determine failures with respect to a set of performance variables. For a single failure region, the initial search may be a uniform sampling of the parameter space. Mixture importance sampling (MIS) efficiently may estimate the single failure region. The mechanism then finds a center of gravity for each metric and finds importance samples. Then, for each new origin corresponding to a process variation or other design consideration, the mechanism finds a suitable projection and recomputes new importance sampling (IS) ratios.
65 Citations
29 Claims
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1. A method, in a data processing system, for determining failure rate of a device using importance sampling reuse, the method comprising:
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performing, by the data processing system, a uniform sampling over a random sample space for a performance metric for the device with respect to an origin to form a set of samples, wherein the origin represents nominal values for device parameters for a given design of the device, wherein the metric is an operational performance value of the device, and wherein the set of samples comprises one or more failing samples; determining, by the data processing system, a center of gravity of the one or more failing samples with respect to the origin; determining, by the data processing system, importance samples based on the center of gravity of the one or more failing samples; selecting a new origin representing alternative values for device parameters corresponding to a process variation or design consideration; recomputing, by the data processing system, new importance sampling weight ratios for the new origin; and determining, by the data processing system, a failure rate for the device based on the new importance sampling weight ratios alternative values for device parameters or environmental parameters. - View Dependent Claims (2, 4, 7, 8, 27)
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3. (canceled)
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5. (canceled)
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6. (canceled)
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9. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to:
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perform a uniform sampling over a random sample space for a performance metric for a device with respect to an origin to form a set of samples, wherein the origin represents nominal values for device parameters for a given design of the device, wherein the metric is an operational performance value of the device, and wherein the set of samples comprises one or more failing samples; determine a center of gravity of the one or more failing samples with respect to the origin; determine importance samples based on the center of gravity of the one or more failing samples; recompute new importance sampling weight ratios for a selected new origin, wherein the new origin represents alternative values for device parameters corresponding to a process variation or design consideration; and determine a failure rate for the device based on the new importance sampling weight ratios alternative values for device parameters or environmental parameters. - View Dependent Claims (10, 12, 15, 16, 17, 18, 28)
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11. (canceled)
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13. (canceled)
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14. (canceled)
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19. An apparatus, comprising:
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a processor; and a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to; perform a uniform sampling over a random sample space for a performance metric for a device with respect to an origin to form a set of samples, wherein the origin represents nominal values for device parameters for a given design of the device, wherein the metric is an operational performance value of the device, and wherein the set of samples comprises one or more failing samples; determine a center of gravity of the one or more failing samples with respect to the origin; determine importance samples based on the center of gravity of the one or more failing samples; recompute new importance sampling weight ratios for a selected new origin, wherein the new origin represents alternative values for device parameters corresponding to a process variation or design consideration; and determine a failure rate for the device based on the new importance sampling weight ratios alternative values for device parameters or environmental parameters. - View Dependent Claims (20, 22, 25, 26, 29)
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21. (canceled)
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23. (canceled)
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24. (canceled)
Specification