Electrical computers and digital data processing systems: input/ – Intrasystem connection
Reexamination Certificate
1999-10-28
2002-12-17
Auve, Glenn A. (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
C333S109000
Reexamination Certificate
active
06496886
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a technology to transfer data between elements of a multiprocessor, a memory, or the like in an information processing system, for example, between digital circuits or functional blocks thereof including complementary metal-oxide semiconductors (CMOS), and in particular, to a technology to increase transmission speed of a data transfer bus in which a plurality of elements are connected to one transmission line.
JP-A-5-2239807 (De Veer et al; U.S. Pat. No. 3,619,504) describes a non-contact bus wiring which is a bus method to transfer data at a high speed between many nodes, for example, in a multiprocessor system.
FIG. 3
shows a fundamental layout of the wiring in which data is transferred between two nodes using crosstalk, i.e., a directional coupler. That is, in this transfer technology, data is transferred between a bus master
10
-
1
and slaves
10
-
2
to
10
-
8
by means of crosstalk between two transmission lines, i.e., wiring
1
-
1
and
1
-
2
to
1
-
8
. In this diagram, Rtt indicates a termination resistor. This circuit configuration is suitable for data transfer between bus master
10
-
1
and slaves
10
-
2
to
10
-
8
, but is not suitable for data transfer between slaves
10
-
2
to
10
-
8
.
To solve the problem, JP-A-8-188366 (PCT/JP97/03922 filed Oct. 29, 1997) describes a gap coupling bus system.
FIG. 4
shows a basic circuit of this system. In the circuit configuration of this technology, data is transferred between nodes
11
to
16
by use of crosstalk signals in directional coupling sections (
1
-
4
to
5
-
6
) in which wiring lines
21
to
26
are coupled with each other as shown in FIG.
4
.
“Present State and Problems of Build-Up Multi-Layer Wiring Board Technology” written in pages 463 to 468 of the “Journal of the Society of Circuit Engineers of Japan” describes a technology of printed wiring boards in which via holes of pad-on-via type are implemented at a low cost to increase the wiring density.
In the wiring technology of the gap coupling bus system of JP-A-8-188366, one-bit slave-to-slave transfer routes are arranged in a lattice layout to couple all nodes with each other (in a multi-coupling wiring network). However, this network is not suitable to transfer multi-bit data for the following reasons. To construct a one-bit multi-coupling wiring network, the printed wiring board includes two signal layers arranged in a direction of thickness of the board to form a coupling network in a horizontal direction of the board. This increases the wiring width of each one-bit wiring. That is, to achieve a one-bit transfer using a multilayered printed wiring board, there are required four layers including two signal layers for each bit and two shield layers. For example, to simultaneously transfer data including one-byte, i.e., eight bits, there are required at least 23 layers including 16 signal layers (two layers×8 bits) and seven shield layers to decrease interference between the bits. Even a personal computer today has a data width of eight bytes. In some server apparatuses, the data width is 16 bytes. To implement such a server using the technology, there are required at least 184 layers (8 bytes×23 layers) for 8-byte data width and 368 layers (16 bytes×23 layers) for 16-byte data width. However, it is difficult to manufacture 100 or more layers at a low cost in the printed wiring board technology at present. Particularly, it is practically impossible to construct a printed wiring board at a low cost using material such as glass epoxy or aramid.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a data transmission technology in which multi-bit data is transferred between nodes via directional coupling (crosstalk) using a printed wiring board to thereby transfer data at a high speed.
Another object of the present invention to provide a data transmission technology in which differential signals from a directional coupler formed in a printed wiring board are compared with each other such that errors can be detected by demodulating an output signal resultant from the comparison.
To achieve the object in accordance with a concept of the present invention, since multi-bit data is transferred by directional coupling, when a one-bit multi-coupling wiring network is configured, using a multilayered printed wiring board, in a direction vertical to a board surface of the printed wiring board, a multi-bit configuration can be implemented with a minimized width of wiring for one bit in a wiring direction of the board.
The present invention has aspects as follows.
In accordance with a first aspect of the present invention, there is provided a directional coupling bus system including a bus connected to a plurality of modules each including an interface circuit to transfer digital data and a printed wiring board connected to the modules. The system further includes a termination resistor for impedance matching termination of each lead signal line from the modules and directional couplers in lead wiring ranging from a first one of the module to the termination resistor, the couplers including portions of lead wiring respectively from second and subsequent ones of the modules, the portions having a length of, for example, 30 mm. There is also included via holes of non-through type to connect the coupler between the modules to communicate data therebetween.
In accordance with a second aspect of the present invention, in the directional coupling bus system of the first aspect, the directional coupler includes two adjacent lines in one signal layer enclosed between ground planes or layers, and the coupler is connected via the via holes of non-though type.
In accordance with a third aspect of the present invention, in the directional coupler of the system of the first aspect, the digital signals from the modules are differential signals and the signal transmission from a functional element on one side to a functional element on another side is conducted by directional couplers of differential type.
In accordance with a fourth aspect of the present invention, there is provided a printed wiring board. In the bus system of the third aspect, the differential directional coupler includes two signal layers, layers
1
and
2
enclosed with power planes or layers of a printed wiring board. Differential signal (drive signal) lines from the functional element are arranged in layer
1
to be parallel to each other. Differential signal (receive signal) lines to the partner functional element are arranged in layer
2
to be at positions vertically associated with the differential drive signal lines in layer
1
.
In accordance with a fourth aspect of the present invention, there is provided a printed wiring board. The directional coupler of differential type in accordance with the third aspect includes one signal layer enclosed with power planes of a printed wiring board. Differential signal (drive signal) lines from the functional element are arranged in the signal layer to be parallel to each other. Differential signal (receive signal) lines to the partner functional element are arranged in another layer of the signal layer to be on both sides of the differential drive signal lines.
In accordance with a sixth aspect of the present invention, there is provided a printed board by using the printed wiring board of the fourth or fifth aspect in which n functional elements (n is equal to or more than two) are mounted on the board. There are arranged m signal layers, each of the layer includes two layers in pair or one layer to configure a directional coupler of differential type. Pairs of signal and ground planes are disposed on the board to set m=n−1.
There are further arranged P directional couplers to transfer data between the n modules, where P=n·(n−1)/2. The P directional couplers are alternately disposed in a direction of thickness of the board such that wiring from the modules configure one set of the P directional couplers for each
Kitano Masahiro
Komatsu Toyohiko
Kurihara Ryoichi
Osaka Hideki
Yamagiwa Akira
Antonelli Terry Stout & Kraus LLP
Auve Glenn A.
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