Circuit and method for modeling I/O
First Claim
1. A method for creating a model of inputs and outputs of integrated circuits, comprising the steps of:
- representing in the model, the output characteristics of integrated circuit driver circuits by two types of elements, switching and non-switching;
tabulating the output characteristics for each of the elements by applying a DC voltage source on the output of the driver circuits and measuring the current through each element;
characterizing the switching elements represented as voltage-time controlled resistors by obtaining the product of DC impedance as a function of voltage and scalars that are functions of time; and
embedding in the model, equations that are functions of input edge arrival times and cycle time for each scalar in order to modify behavior of the switching and non-switching elements to fit their environment.
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Abstract
A behavioral modeling technique that captures driver delay. The output characteristics of a typical driver are represented by two basic element types: switching and non-switching. Switching elements are functions of both time-varying and non-time-varying parameters, and non-switching elements are functions of non-time-varying parameters only. The outputs of these elements are characterized and tabulated by applying a DC voltage on the output of the driver and measuring the current through each element. The time-varying switching element are represent by time-controlled resistors. The invention provides a methodology to account for variations in input transition rate, supply voltage(s) or temperature.
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Citations
28 Claims
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1. A method for creating a model of inputs and outputs of integrated circuits, comprising the steps of:
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representing in the model, the output characteristics of integrated circuit driver circuits by two types of elements, switching and non-switching; tabulating the output characteristics for each of the elements by applying a DC voltage source on the output of the driver circuits and measuring the current through each element; characterizing the switching elements represented as voltage-time controlled resistors by obtaining the product of DC impedance as a function of voltage and scalars that are functions of time; and embedding in the model, equations that are functions of input edge arrival times and cycle time for each scalar in order to modify behavior of the switching and non-switching elements to fit their environment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for creating a model of inputs and outputs of integrated circuits, comprising the steps of:
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representing in the model, the output characteristics of integrated circuit driver circuits by two types of elements, switching and non-switching; tabulating the output characteristics for each of the elements by applying a DC voltage source on the output of the driver circuits and measuring the current through each element; characterizing the switching elements represented as voltage-time controlled resistors by obtaining the product of DC conductance as a function of voltage and scalars that are functions of time; and embedding in the model, equations that are functions of input edge arrival times and cycle time for each scalar in order to modify behavior of the switching and non-switching elements to fit their environment. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for creating a model of inputs and outputs of integrated circuits, comprising the steps of:
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representing in the model, the output characteristics of integrated circuit driver circuits by two types of elements, switching and non-switching; tabulating the output characteristics for each of the elements by applying a DC voltage source on the output of the driver circuits and measuring the current through each element; characterizing the switching elements represented as voltage-time controlled resistors by obtaining the product of DC conductance or impedance as a function of voltage and scalars that are functions of time; accounting for variations in input slew rate, temperature, and supply voltages and their effects on the elements by using a modified local time; accounting for variations in temperature and supply voltages in the integrated, wherein the characteristics for the elements are obtained from a dc—
base impedance, according to the equation;
dc—
impedance or conductance=(1+D0)*dc—
base where D0 is a function of supply voltage and temperature; andembedding in the model, equations that are functions of input edge arrival times and cycle time for each scalar in order to modify behavior of the switching and non-switching elements to fit their environment.
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28. A program storage device readable by a machine, tangibly embodying a program of instruction executable by a machine, to perform method steps for creating a model of inputs and outputs of integrated circuits, the method comprising the steps of:
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representing in the model, the output characteristics of integrated circuit driver circuits by two types of elements, switching and non-switching; tabulating the output characteristics for each of the elements by applying a DC voltage source on the output of the driver circuits and measuring the current through each element, characterizing the switching elements as voltage-time controlled resistors by obtaining the product of either DC impedance or conductance as a function of voltage and scalars that are functions of time; and embedding in the model, equations that are functions of input edge arrival times and cycle time for each scalar in order to modify behavior of the switching and non-switching elements to fit their environment.
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Specification