Computer-aided design and analysis of circuits and semiconductor – Nanotechnology related integrated circuit design
Reexamination Certificate
2002-08-08
2004-12-07
Siek, Vuthe (Department: 2825)
Computer-aided design and analysis of circuits and semiconductor
Nanotechnology related integrated circuit design
C716S030000, C716S030000, C716S030000, C716S030000
Reexamination Certificate
active
06829749
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a design support apparatus for a circuit diagram of a circuit including a directional coupler using crosstalk and for a circuit layout diagram of the same, a design support tool, a method of designing the circuit, and a circuit board.
As a technology for transferring data among a plurality of modules, a bus system used for data transfer in a computer has been known. In this bus system, the plurality of modules are connected by a common bus, and data is transferred time-divisionally among the modules by use of this bus as a data transmission line. Such a kind of bus is usually constituted by a wiring for an address signal, a wiring for a data signal, a wiring for a control signal and the like.
In the bus system, as a connection style of the bus and the module, the one in which the modules are coupled to the bus directly or through resistors and the one in which by use of crosstalk, the modules are coupled to the bus so as to be uncontacted with each other have been known. The style in which by use of the crosstalk, the modules are connected to the bus so as to be uncontacted with each other is described in Japanese Patent Application Laid-Open No. 2000-132290.
When the crosstalk is utilized, as shown in
FIG. 35
, for example, a driver signal line
3502
is coupled to a driver
3501
, a receiver signal line
3512
is coupled to a receiver
3511
, and a part
3504
of the driver signal line
3502
and a part
3514
of the receiver signal line
3512
are arranged in parallel with a constant interval. The parts in parallel with each other are a main line
3504
and a stub line
3514
, and a directional coupler (coupler)
3500
is constituted by these wirings. In this coupler
3500
, crosstalk is generated by a signal from the driver
3501
. In the crosstalk signal, there are rear crosstalk generated in the reverse direction to a signal direction in the main line
3504
and front crosstalk generated in the same direction as the signal direction in the main line
3504
. In the constitution shown in
FIG. 35
, the rear crosstalk is sent to the receiver
3511
via the stub line
3514
, and the front crosstalk is absorbed by a termination resistor
3513
coupled to the stub line
3514
. A waveform of a signal from the driver
3501
is absorbed by a termination resistor
3503
coupled to the main line
3504
. Thus, unnecessary crosstalk due to the reflection of a drive signal does not occur on the stub line
3514
.
In general, when crosstalk is generated between two ordinary wirings, the crosstalk becomes signal noise. Therefore, in order to prevent this crosstalk, the two wirings are made to be apart from each other with an interval more than a certain length. On the contrary, in the above described technologies, the interval between the two wirings is narrowed, and crosstalk is intentionally generated. A signal is transferred from one wiring to the other wiring without contacting them with each other.
By the way, a circuit diagram of a bus system utilizing the crosstalk was conventionally illustrated as shown in FIG.
36
.
In this circuit diagram, reference numerals
611
and
612
denote functional components. Terminals D
1
, D
2
and CLK are provided in the functional component
611
, and wirings
621
,
622
and
623
are provided so as to extend respectively from the terminals D
1
, D
2
and CLK. Terminals d
1
, d
2
and clk are provided also in the functional component
612
, and wirings
641
,
642
and
643
are provided so as to extend respectively from the terminals d
1
, d
2
and clk.
In
FIG. 36
, portions
3601
,
3602
and
3603
are respectively formed as couplers, and indirect connections of the terminals D
1
and d
1
, the terminals D
2
and d
2
, and the terminals CLK and clk are intended. In
FIG. 36
, though the coupler portions
3601
,
3602
and
3603
are surrounded by the circles, the circles are merely drawn for the sake of convenience to facilitate understanding of the positions of the coupler portions. In the conventional circuit diagram, the coupler is simply treated as two different wirings, and the coupler portion is not illustrated.
When a circuit layout diagram is illustrated by use of the above described circuit diagram, the circuit layout diagram as shown in
FIG. 37
is prepared in the prior art in such a manner that two wirings forming a coupler is anew selected among many wirings illustrated in the circuit diagram, and parts of the selected two wirings are arranged in parallel with a certain interval. Note that
FIG. 37
illustrates a layout diagram of the coupler portions
3601
,
3602
and
3603
in FIG.
36
.
However, in the foregoing prior art, since the couplers are treated as a mere wiring in the circuit diagram, that is, since illustrations of the coupler are not made in the circuit diagram, two wirings forming a coupler must be anew selected among many wirings illustrated in the circuit diagram when a circuit layout diagram is drawn with reference to this circuit diagram, and moreover recognition of a correlation between the circuit diagram and the circuit layout diagram takes a lot of trouble.
Particularly, when crosstalk is used in a bus line, the number of the couplers is equal to the product of a “bus width” and the “number of functional components”. For example, when the bus width is 64, and the number of the functional components is 9, the number of the couplers is as large as 512. Therefore, a lot of trouble is required to recognize the correlation between the circuit diagram and the circuit layout diagram.
Furthermore, normally, after the circuit layout diagram is once completed, intervals between many wirings are checked by use of a design support apparatus. If the contravention against a wiring rule is found out, the wiring layout is anew prepared. In this case, when a coupler
800
exists in the circuit layout diagram as shown in
FIG. 37
, an interval
3701
between two wirings forming the coupler
800
contravenes the wiring rule. Accordingly, when it is tried to check the interval
3701
visually without the use of the design support apparatus, labor for checking the interval
3701
is immense. Moreover, even when an interval
3702
between two wirings which do not constitute a coupler is narrow and crosstalk between these wirings occurs, there is a fear that the crosstalk cannot be found out.
In other words, the prior art has a problem that the preparation of the layout diagram of the circuit including the coupler takes a lot of trouble.
SUMMARY OF THE INVENTION
This application was made while focusing on the above described problems of the prior art, an end of this application is to provide the invention according to a design support apparatus for a circuit diagram and a layout diagram, which is capable of reducing the number of design steps for designing the layout diagram of a circuit including couplers, a system comprising the design support apparatus, a design support tool for operating a computer for a design support, and a design method of the same. This application provides also the invention according to a circuit board which is designed by the above-mentioned design support system or the design support tool.
A first design support apparatus for achieving the foregoing end is a design support apparatus for a circuit diagram which illustrates connections of components in a circuit including a directional coupler in which first and second signal lines are arranged partially in parallel with each other, the first signal line being coupled to a driver for outputting a signal and the second signal line being coupled to a receiver for receiving a crosstalk signal based on the signal from the driver, comprising:
symbol storage means for storing various symbols, each being previously determined for corresponding one of various components including the directional coupler;
symbol arrangement means for accepting a symbol to be arranged among various symbols stored in the symbol storage means and for accepting an arrangement position of the symbol to arrange the symbo
Komatsu Toyohiko
Osaka Hideki
Mattingly Stanger & Malur, P.C.
Renesas Technology Corp.
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