Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
1999-01-05
2001-08-21
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C455S295000
Reexamination Certificate
active
06278951
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to crosstalk noise calculation methods and storage mediums, and more particularly to a crosstalk noise calculation method for calculating a crosstalk noise of an adjacent wiring and to a computer-readable storage medium which stores a program for causing a computer to calculate the crosstalk noise using such a crosstalk noise calculation method.
When wirings to be formed on an assembling board of a computer, printed circuit board, printed wiring board and the like are designed by computer aided design (CAD), a crosstalk noise between adjacent wirings may exceed a tolerable range due to an error in the design, an error in the wiring rule or the like. For this reason, it is necessary to finally determine the wirings by checking whether or not the crosstalk noise falls within the tolerable range. The crosstalk noise between the adjacent wirings can be obtained by simulation. But in the case of the assembling board of a personal computer, for example, there are more than 1000 wirings. Further, the number of wirings is more than ten times that of the assembling board of the personal computer, that is, more than 10000, in the case of the assembling board of a work station, super computer and the like. Hence, it takes too much time to obtain the crosstalk for all of the wirings by simulation.
Accordingly, the crosstalk noise of the wiring is obtained by calculation, and the wiring is determined so that the calculated crosstalk noise falls within the tolerable range.
FIG. 1
is a diagram for explaining a conventional crosstalk noise calculation method. In
FIG. 1
, the ordinate indicates a peak value of the crosstalk noise, and the abscissa indicates a length of parallel wirings (hereinafter referred to as a parallel wiring length).
As may be seen from
FIG. 1
, the crosstalk noise is conventionally calculated using a function F by assuming that the peak value of the crosstalk noise is simply proportional to the adjacent wiring length. In the conventional assembling board and the like, the density of the wirings is relatively low, the wiring length is relatively short, and a transfer rate of a signal flowing through the wirings is relatively low. For these reasons, the crosstalk noise calculated using the function F shown in
FIG. 1
was a relatively good approximation, and in addition, the calculation itself was also simple.
However, due to the increased operation speeds of CPUs and the development of high-speed memory elements, the wiring density on the assembling board and the like has recently increased, the wiring length has increased, and the transfer rate of the signal flowing through the wiring also has increased. As a result, when the crosstalk is calculated using the conventional method described above, even in a case where the crosstalk of 10% or less of the total number of wirings actually does not fall within the tolerable range, the check result obtained by the conventional method in an extreme case may indicate that the crosstalk of 50% or more of the total number of wirings does not fall within the tolerable range. When the check result is based on such an excessively strict checking, there is a problem in that the design efficiency of the wiring greatly deteriorates.
Such an excessively strict checking is made according to the conventional method because the peak value of the crosstalk noise is assumed to be simply proportional to the adjacent wiring length, even though the peak value of the crosstalk noise actually saturates and becomes approximately constant when a predetermined wiring length is exceeded as will be described later.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide a novel and useful crosstalk noise calculation method and storage medium, in which the problems described above are eliminated.
Another and more specific object of the present invention is to provide a crosstalk noise calculation method which can accurately calculate a crosstalk noise of an adjacent wiring and improve a design efficiency of the wiring by preventing an excessively strict checking, and to provide a computer-readable storage medium which stores a program for causing a computer to calculate the crosstalk noise using such a crosstalk noise calculation method.
Still another object of the present invention is to provide a crosstalk noise calculation method for calculating crosstalk noise among a plurality of wirings, comprising the steps of calculating a crosstalk noise using a function in which the crosstalk noise becomes approximately constant when a predetermined wiring length is exceeded. According to the crosstalk noise calculation method of the present invention, it is possible to accurately calculate the crosstalk noise of the adjacent wirings, and to improve the design efficiency of the wirings by preventing an excessively strict checking from being performed.
A further object of the present invention is to provide a computer-readable storage medium which stores a program for causing a computer to calculate crosstalk noise among a plurality of wirings on a substrate, comprising means for causing the computer to calculate a crosstalk noise using a function in which the crosstalk noise becomes approximately constant when a predetermined wiring length is exceeded. According to the computer-readable storage medium of the present invention, it is possible to accurately calculate the crosstalk noise of the adjacent wirings, and to improve the design efficiency of the wirings by preventing an excessively strict checking from being performed.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.
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Fujitsu Limited
Raymond Edward
Shah Kamini
Staas & Halsey , LLP
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