System for estimating a terminal capacitance and for characterizing a circuit

A method for estimating a terminal capacitance at a determined operation point, the terminal capacitance associated with an input terminal of a cell of a digital circuit, the method comprising executing instructions stored on a computer storage device that cause a processor to:

• retrieve a first capacitance value associated with an upper bound on the terminal capacitance and a second capacitance value associated with a lower bound on the terminal capacitance;
• determine input pulse edge characteristics associated with the input terminal in a timing analysis of the digital circuit, wherein determining the input pulse edge characteristics comprise determining an input slew;
• determine output pulse edge characteristics associated with an output terminal of the cell in the timing analysis of the digital circuit;
• and
• estimate the terminal capacitance by interpolating between the first capacitance value and the second capacitance value based on the input pulse edge characteristics and the output edge characteristics, wherein the interpolating comprises comparing the input slew with a predefined slew value.

A method for characterizing a digital circuit, wherein the digital circuit includes a cell which includes a terminal, the terminal having a terminal capacitance, the method comprising executing instructions stored on a computer storage device that cause a processor to:

• retrieve a first capacitance value associated with an upper bound on the terminal capacitance and a second capacitance value associated with a lower bound on the terminal capacitance;
• analyze the digital circuit, wherein the terminal capacitance is approximated by one of the first capacitance value or the second capacitance value;
• determine a temporal overlap of a pulse edge of a terminal voltage associated with the terminal and of a pulse edge of a further terminal voltage associated with a further terminal of the cell;
• determine an estimation value for the terminal capacitance from a result of the analyzing, at least one of the first capacitance value and the second capacitance value, and the temporal overlap of the pulse edge of the terminal voltage and of the pulse edge of the further terminal voltage;
• and
• re-analyze the digital circuit, wherein the terminal capacitance is approximated by the estimation value.

A computer program product for estimating a terminal capacitance associated with a terminal of a cell of a digital circuit, the computer program product comprising a computer storage device comprising:

• computer-executable code means executable to provide a first capacitance value associated with an upper bound on the terminal capacitance and a second capacitance value associated with a lower bound on the terminal capacitance;
• computer-executable code means executable to provide results of a timing analysis of the digital circuit;
• computer-executable code means executable to determine a temporal overlap of a pulse edge of a terminal voltage associated with the terminal and of a pulse edge of a further terminal voltage associated with a further terminal of the cell;
• and
• computer-executable code means executable to determine an estimation value for the terminal capacitance based on the results of the timing analysis, at least one of the first capacitance value and the second capacitance value, and the temporal overlap of the pulse edge of the terminal voltage and of the pulse edge of the further terminal voltage.

A computer program product for characterizing a digital circuit, wherein the digital circuit includes a cell which includes a terminal, the terminal having a terminal capacitance, the computer program product comprising a computer storage device comprising:

• computer-executable code means executable to provide a first capacitance value associated with an upper bound on the terminal capacitance and a second capacitance value associated with a lower bound on the terminal capacitance;
• computer-executable code means executable to analyze the digital circuit, wherein the terminal capacitance is approximated by one of the first capacitance value or the second capacitance value;
• computer-executable code means executable to determine a temporal overlap of a pulse edge of a terminal voltage associated with the terminal and of a pulse edge of a further terminal voltage associated with a further terminal of the cell;
• computer-executable code means executable to determine an estimation value for the terminal capacitance from a result of the analyzing, at least one of the first capacitance value and the second capacitance value, and the temporal overlap of the pulse edge of the terminal voltage and of the pulse edge of the further terminal voltage;
• and
• computer-executable code means executable to re-analyze the digital circuit, wherein the terminal capacitance is approximated by the estimation value.

A system for estimating a terminal capacitance associated with a terminal of a cell of a digital circuit, the system comprising:

• storage means for storing a first capacitance value associated with an upper bound on the terminal capacitance and a second capacitance value associated with a lower bound on the terminal capacitance;
• analyzing means for analyzing the digital circuit and for providing a result of the analyzing;
• determining means for determining a temporal overlap of a pulse edge of a terminal voltage associated with the terminal and of a pulse edge of a further terminal voltage associated with a further terminal of the cell
• estimating means coupled to the storage means for retrieving the first capacitance value and the second capacitance value, coupled to the analyzing means for retrieving the result of the analyzing, and coupled to the determining means for retrieving the results of the determining, the estimating means estimating the terminal capacitance based on the result of the analyzing, at least one of the first capacitance value and the second capacitance value, and the temporal overlap.