Cell-library-for-statistical-timing-analysis creating apparatus and statistical-timing analyzing apparatus
First Claim
1. A cell-library-for-statistical-timing-analysis creating apparatus, comprising:
- a group determining unit that groups cells as statistical timing analysis targets into groups of cells each having same topology;
a representative-cell selecting unit that selects representative cells from the respective grouped cell groups;
a signal-transition-time-information determining unit that sets one or more kinds of signal transition time information based on output signal transition time as transition time of an output signal from a cell and input signal transition time as transition time of an input signal to the cell;
an output-load-capacitance/input-signal-transition-time determining unit that calculates, based on the set signal transition time information and a cell library for static timing analysis, for each of the selected representative cells, an output load capacitance and input signal transition time for each of the set kinds of signal transition time information to be used for circuit simulation;
a circuit-simulation executing unit that executes the circuit simulation using the calculated output load capacitance and input signal transition time and calculates a delay variation amount;
a delay-variation-information calculating unit that calculates delay variation information based on a delay average and the delay variation amount calculated by the circuit simulation; and
a library output unit that outputs, as a cell library for statistical timing analysis, association for each of the representative cells between the signal transition time information and the delay variation information.
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Abstract
A cell-library-for-statistical-timing-analysis creating apparatus includes: a unit that groups cells into groups of cells each having the same topology; a unit that selects representative cells from the respective grouped cell group; a unit that sets one or more kinds of signal transition time information based on output signal transition time and input signal transition time; a unit that calculates, for each of the representative cells, an output load capacitance and input signal transition time for each of kinds of signal transition time information; a unit that executes circuit simulation using the output load capacitance and the input signal transition time and calculates a delay variation amount; a unit that calculates delay variation information based on a delay average and the delay variation amount; and a unit that outputs association for each of the representative cells between the signal transition time information and the delay variation information.
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Citations
18 Claims
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1. A cell-library-for-statistical-timing-analysis creating apparatus, comprising:
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a group determining unit that groups cells as statistical timing analysis targets into groups of cells each having same topology; a representative-cell selecting unit that selects representative cells from the respective grouped cell groups; a signal-transition-time-information determining unit that sets one or more kinds of signal transition time information based on output signal transition time as transition time of an output signal from a cell and input signal transition time as transition time of an input signal to the cell; an output-load-capacitance/input-signal-transition-time determining unit that calculates, based on the set signal transition time information and a cell library for static timing analysis, for each of the selected representative cells, an output load capacitance and input signal transition time for each of the set kinds of signal transition time information to be used for circuit simulation; a circuit-simulation executing unit that executes the circuit simulation using the calculated output load capacitance and input signal transition time and calculates a delay variation amount; a delay-variation-information calculating unit that calculates delay variation information based on a delay average and the delay variation amount calculated by the circuit simulation; and a library output unit that outputs, as a cell library for statistical timing analysis, association for each of the representative cells between the signal transition time information and the delay variation information. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A statistical-timing analyzing apparatus, comprising:
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a net-delay analyzing unit that calculates, for each of nets forming a path, a delay average and a delay variation amount of a cell arranged in a pre-stage of the net; and a path-delay analyzing unit that calculates a path delay of the path based on the delay average and the delay variation amount calculated for each of the nets, wherein the net-delay analyzing unit includes; a net selecting unit that selects a net forming the path; a delay-average/output-signal-transition-time calculating unit that calculates a delay average and output signal transition time referring to a cell library for static timing analysis with input signal transition time to a cell arranged in a pre-stage of the selected net and an output load capacitance of the cell set as search keys; a signal-transition-time-ratio calculating unit that divides the calculated output signal transition time by the input signal transition time to calculate a signal transition time ratio; a delay-variation-ratio calculating unit that calculates a delay variation ratio referring to a cell library for statistical timing analysis with the calculated signal transition time ratio set as a search key; and a delay-variation-amount calculating unit that multiplies the calculated delay average and the calculated delay variation ratio together to calculate a delay variation amount, wherein the cell library for statistical timing analysis is created by a cell-library-for-statistical-timing-analysis creating apparatus including; a group determining unit that groups cells as statistical timing analysis targets into groups of cells each having same topology; a representative-cell selecting unit that selects representative cells from the respective grouped cell groups; a signal-transition-time-information determining unit that sets one or more signal transition time ratios as ratios of the input signal transition time and the output signal transition time; an output-load-capacitance/input-signal-transition-time determining unit that calculates, based on the signal transition time ratios set by the signal-transition-time-information determining unit and the cell library for static timing analysis, for each of the selected representative cells, an output load capacitance and input signal transition time for each of the set signal transition time ratios to be used for circuit simulation; a circuit-simulation executing unit that executes the circuit simulation using the output load capacitance and the input signal transition time calculated by the output-load-capacitance/input-signal-transition-time determining unit and calculates a delay variation amount; a delay-variation-information calculating unit that calculates a delay variation ratio as a ratio of the delay variation amount calculated by the circuit-simulation executing unit and the delay average; and a library output unit that outputs, as the cell library for statistical timing analysis, association for each of the representative cells between the signal transition time ratio and the delay variation ratio calculated by the delay-variation-information calculating unit. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A statistical-timing analyzing apparatus, comprising:
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a cell-library-for-statistical-timing-analysis creating unit that creates a first cell library for statistical timing analysis, which outputs a delay variation amount with the input signal transition time and the output load capacitance set as search keys, using a second cell library for statistical timing analysis created by a cell-library-for-statistical-timing-analysis including;
a group determining unit that groups cells as statistical timing analysis targets into groups of cells each having same topology;
a representative-cell selecting unit that selects representative cells from the respective grouped cell groups;
a signal-transition-time-information determining unit that sets one or more signal transition time ratios as ratios of input signal transition time as transition time of an input signal to a cell and output signal transition time of an output signal from the cell;
an output-load-capacitance/input-signal-transition-time determining unit that calculates, based on the set signal transition time ratios and a cell library for static timing analysis, for each of the selected representative cells, an output load capacitance and input signal transition time for each of the set signal transition time ratios to be used for circuit simulation;
a circuit-simulation executing unit that executes the circuit simulation using the calculated output load capacitance and input signal transition time and calculates a delay variation amount;
a delay-variation-information calculating unit that calculates a delay variation ratio as a ratio of the delay variation amount calculated by the circuit simulation and the delay average; and
a library output unit that outputs, as the second cell library for statistical timing analysis, association for each of the representative cells between the signal transition time ratio and the delay variation ratio; anda statistical-timing-analysis executing unit that executes statistical timing analysis based on the first cell library for statistical timing analysis, wherein the cell-library-for-statistical-timing-analysis creating unit includes; an input-signal-transition-time/output-load-capacitance setting unit that selects one input signal transition time and one output load capacitance out of a plurality of input signal transition times and a plurality of output load capacities, respectively; a delay-average/output-signal-transition-time calculating unit that calculates a delay average and output signal transition time referring to the cell library for static timing analysis with the input signal transition time and the output load capacitance selected by the input-signal-transition-time/output-load-capacitance setting unit set as search keys; a signal-transition-time-ratio calculating unit that divides the output signal transition time calculated by the delay-average/output-signal-transition-time calculating unit by the input signal transition time selected by the input-signal-transition-time/output-load-capacitance setting unit to calculate a signal transition time ratio; a delay-variation-ratio calculating unit that calculates a delay variation ratio referring to the second cell library for statistical timing analysis with the signal transition time ratio calculated by the signal-transition-time-ratio calculating unit set as a search key; and a delay-variation-amount calculating unit that multiplies the delay average calculated by the delay-average/output-signal-transition-time calculating unit and the delay variation ratio calculated by the delay-variation-ratio calculating unit together to calculate a delay variation amount. - View Dependent Claims (15, 16, 17, 18)
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Specification