Apparatus and method of LSI timing degradation simulation
First Claim
1. An LSI timing degradation simulation apparatus which predicts LSI degradation with time at a design stage and simulates an LSI operation after degradation, said LSI timing degradation simulation apparatus comprising:
- a cell delay degradation estimation means for estimating a delay degradation degree with time of each circuit cell where at least one of a plurality of circuit cells compose a target LSI, by referring to a reliability library which shows dependence of a property degradation degree of a circuit cell on predetermined operational conditions, based on values of said predetermined operational conditions about said circuit cell at an operation of said target LSI; and
an LSI timing degradation estimation means for estimating a delay of each circuit cell in said target LSI which has been degraded with time, based on the delay degradation degree of each circuit cell in said target LSI estimated by said cell delay degradation estimation means,wherein the operation of said target LSI after degradation is simulated based on the delay of each circuit cell in said degraded target LSI estimated by said LSI timing degradation estimation means,wherein said reliability library uses, as said property degradation degree of a circuit cell, a degradation degree of a signal propagation delay between an input terminal and an output terminal of said circuit cell,wherein said reliability library uses, as said predetermined operational conditions, the rise and fall times of the input signal, the output load capacitance, and the number of switching of the input signal of a circuit cell.
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Abstract
An apparatus and method of simulating the operation of an LSI after degradation is provided for predicting actual LSI degradation with time at the design stage, so as to prevent the LSI specification from becoming excessively reliable. A reliability library generation device drives a circuit reliability simulator and generates a reliability library which shows the dependence of the property degradation degree of each circuit cell on predetermined operational conditions. A cell delay degradation estimation means estimates the delay degradation degree with time of each circuit cell which composes a target LSI, by referring to the reliability library. An LSI timing degradation estimation means estimates the delay of each circuit cell in the target LSI which has been degraded with time, based on the delay degradation degree of each circuit cell, and generates an after-degradation LSI timing. A logic simulator simulates the operation of an LSI after degradation, based on the after-degradation LSI timing, so that the timing degradation of each signal path in the target LSI can be accurately expressed in conformation to real operation.
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Citations
17 Claims
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1. An LSI timing degradation simulation apparatus which predicts LSI degradation with time at a design stage and simulates an LSI operation after degradation, said LSI timing degradation simulation apparatus comprising:
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a cell delay degradation estimation means for estimating a delay degradation degree with time of each circuit cell where at least one of a plurality of circuit cells compose a target LSI, by referring to a reliability library which shows dependence of a property degradation degree of a circuit cell on predetermined operational conditions, based on values of said predetermined operational conditions about said circuit cell at an operation of said target LSI; and an LSI timing degradation estimation means for estimating a delay of each circuit cell in said target LSI which has been degraded with time, based on the delay degradation degree of each circuit cell in said target LSI estimated by said cell delay degradation estimation means, wherein the operation of said target LSI after degradation is simulated based on the delay of each circuit cell in said degraded target LSI estimated by said LSI timing degradation estimation means, wherein said reliability library uses, as said property degradation degree of a circuit cell, a degradation degree of a signal propagation delay between an input terminal and an output terminal of said circuit cell, wherein said reliability library uses, as said predetermined operational conditions, the rise and fall times of the input signal, the output load capacitance, and the number of switching of the input signal of a circuit cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of simulating an LSI operation after degradation by predicting LSI degradation with time at a design stage, said method comprising the steps of:
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estimating a delay degradation degree with time of each circuit cell which composes a target LSI, by referring to a reliability library which shows dependence of a property degradation degree of a circuit cell on predetermined operational conditions, based on values of said predetermined operational conditions about said circuit cell at the operation of said target LSI; estimating a delay of each circuit cell in said target LSI which has been degraded with time, based on said estimated delay degradation degree of each circuit cell in said target LSI; and simulating the operation of said target LSI after degradation, based on said estimated delay of each circuit cell in said degraded target LSI wherein said reliability library uses, as said property degradation degree of a circuit cell, a degradation degree of a signal propagation delay between an input terminal and an output terminal of said circuit cell, wherein said reliability library uses, as said predetermined operational conditions, the rise and fall times of he input signal, output load capacitance, and the number of switching of the input signal of a circuit cell. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification