Return route search device, circuit design apparatus and circuit design program storage medium

Abstract

A return route search device includes a starting point/destination point setting section which accepts the setting of a starting point on a circuit from which a return current starts accompanied by a signal transmission on the circuit, and a setting of a destination point on the circuit to which the current flows. The return route search device further includes an easiness setting section which accepts a setting of easiness of conduction of the return current through each of portions on the circuit, and a return route search section which searches for a route when the return current flows from the starting point to the destination point on the basis of the easiness of conduction on the circuit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an external appearance of a computer to which an embodiment of the invention is applied;

FIG. 2 is a diagram showing a hardware configuration of the computer shown in FIG. 1;

FIG. 3 is a diagram showing a CD-ROM on which a CAD program corresponding to an embodiment of the circuit design program storage medium of the invention is stored;

FIG. 4 is a functional block diagram of a CAD apparatus corresponding to an embodiment of the circuit design apparatus of the invention;

FIG. 5 is schematic diagram showing signal transmission and a return current on a circuit;

FIG. 6 is a flowchart showing an operation of a return route search function section;

FIG. 7 is a schematic diagram showing parameter values set at each of portions on the circuit;

FIG. 8 is a schematic diagram showing the area of a loop;

FIG. 9 is a schematic diagram showing the relationship between the loop size and the difference between the route lengths; and

FIG. 10 is a diagram showing an example of a display produced by a display section.

Claims

1. A return route search device comprising: a starting point/destination point setting section that accepts a setting of a starting point on a circuit from which a return current starts accompanied by a signal transmission on the circuit, and a setting of a destination point on the circuit which the return current reaches;an easiness setting section that accepts a setting of easiness of conduction of the return current through each of portions on the circuit; anda return route search section that searches for a route when the return current flows from the starting point to the destination point on the basis of the easiness of conduction on the circuit.

2. The return route search device according to claim 1, further comprising a display section that displays the route obtained by the return route search section.

3. The return route search device according to claim 1, further comprising: a transmission route identification section that accepts identification of a route of the signal transmission on the circuit; anda setting reflection section that sets the starting point and the destination point in the starting point/destination point setting section on the basis of the route identified in the transmission route identification section and a predetermined setting rule, and that sets the easiness of conduction in the easiness setting section.

4. The return route search device according to claim 1, further comprising:a transmission route identification section that accepts identification of a route of the signal transmission on the circuit; anda first good-bad determination section that computes the area surrounded by a loop going through both the route identified in the transmission route identification section and the route obtained by the return route search section, and that determines whether or not the return current route is good on the basis of the area.

5. The return route search device according to claim 1, further comprising:a transmission route identification section that accepts identification of a route of the signal transmission on the circuit; anda second good-bad determination section that computes the difference between the length of the route identified in the transmission route identification section and the length of the route obtained by the return route search section, and that determines whether or not the return current route is good on the basis of the difference.

6. The return route search device according to claim 1, wherein the starting point/destination point setting section accepts the setting of a starting point and the setting of a destination point with respect to each of a plurality of return currents generated with each of a plurality of signal transmissions, the easiness setting section accepts the setting of easiness of conduction in correspondence with each of the plurality of signal transmissions,the return route search section searches for a plurality of routes corresponding to each of the plurality of return currents, andthe return route search device further comprises a concentration position search section that obtains a position at which the plurality of routes are concentrated on the circuit.

7. A circuit design apparatus comprising: a design section that designs a circuit in accordance with an operation;a starting point/destination point setting section that accepts a setting of a starting point on the circuit designed in the design section, from the starting point starting a return current generated with a signal transmission on the circuit, and a setting of a destination point on the circuit which the return current reaches;an easiness setting section that accepts a setting of easiness of conduction of the return current through each of portions on the circuit designed in the design section; anda return route search section that searches for a route when the return current flows from the starting point to the destination point on the basis of the easiness of conduction on the circuit.

8. A circuit design program storage medium storing a circuit design program that is incorporated in a computer and constructs on the computer: a design section that designs a circuit in accordance with an operation;a starting point/destination point setting section that accepts a setting of a starting point on the circuit designed in the design section, from the starting point starting a return current generated with a signal transmission on the circuit, and a setting of a destination point on the circuit which the return current reaches;an easiness setting section that accepts a setting of easiness of conduction of the return current through each of portions on the circuit designed in the design section; anda return route search section that searches for a route when the return current flows from the starting point to the destination point on the basis of the easiness of conduction on the circuit.