JPH0951207A - Microstrip transmission line board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the arrangement and the wiring by forming the board beneath a strip conductor with dielectric layers whose specific dielectric constants differ on a same plane as a layer structure so as to reduce a length difference among wires even when a propagation delay time is in existence in each transmission line. SOLUTION: The microstrip transmission line board is mad up of microstrip conductors 21, 22, dielectric boards 23, 24, and a board conductor 25 being a component of a microstrip transmission line. Each of the dielectric boards 23, 24 is formed as one board by adhering an alumina composite dielectric material 29 and an alumina composite dielectric material 30 whose thickness differs from each other with an adhesives to form a laminator structure. The side faces of the boards 23, 24 are adhered to each other by an adhesives to form them into one board. Then a copper foil is rolled and adhered to both sides of the board and the copper foil at the lower side is used for the board conductor 25. Thus, each characteristic impedance of the plural microstrip transmission lines is set optionally, then the line impedance is matched and a degree of freedom of the line is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip transmission line board, a method of manufacturing the same, and a module in which circuit elements and the like are mounted on the transmission line board, and more particularly to transmission of high-speed digital signals with high precision timing secured. The present invention relates to a suitable microstrip transmission line substrate, a method for manufacturing the same, and a module in which circuit elements and the like are mounted on the transmission line substrate.

[0002]

2. Description of the Related Art The basic structure of a conventional microstrip transmission line substrate is, for example, a transmission line design handbook "Transmission Line Design".
Handbook "by Brian C. Wadell, 1991 Artech Hous
e issue, pages 93-111, it is composed of a laminated structure in which strip conductors are formed on a single dielectric provided on a substrate conductor.

Further, the present invention relates to a planar antenna, which has a technical field different from that of the microstrip transmission line substrate of the present invention, but a part of the dielectric on the substrate conductor is made of another dielectric having a different dielectric constant. However, Japanese Patent Laid-Open No. 5-24380 discloses that the propagation speed on the strip conductor in that portion can be changed to cause a phase difference even with strip conductors of the same length.

[0004]

In signal connection between high speed digital circuits, it is necessary in timing design to accurately realize the absolute propagation delay time of a signal. For example,
The data width of the 2.4 Gb / s data signal is about 400 p
s (p ico s econd) only without the propagation delay time of the effective dielectric constant epsilon _r of 7.0 microstrip transmission line is about 88Ps / cm, the data by the wiring length difference of a few cm There is a possibility that the flip-flop circuit cannot be incorporated into the flip-flop circuit, and it is essential to accurately realize the absolute delay time of each microstrip transmission line required by the timing specifications between high-speed digital circuits.

Therefore, when there are a large number of signals and there is a large difference in the absolute propagation delay time required for each wiring, there is a difference in the wiring length, and long wiring and short wiring are mixed. The problem is that it is difficult to place and route high-speed digital circuits on a microstrip transmission line board.

Therefore, an object of the present invention is to eliminate the above-mentioned conventional problems, and a first object of the present invention is to provide different propagation to each transmission line when connecting circuit elements with a plurality of transmission lines. A second object of the present invention is to provide an improved microstrip transmission line substrate in which a difference in transmission line length with respect to a difference in propagation delay time is minimized even when a signal having a delay time is transmitted. And an improved microstrip transmission line board that can also achieve the above-mentioned matching, and a third object is to mount a plurality of circuit elements on these microstrip transmission line boards and to mount the transmission lines between these circuit elements. The purpose is to provide each circuit module connected by.

[0007]

To achieve the first object, in the present invention (hereinafter referred to as the first invention), a dielectric substrate disposed on at least a substrate conductor, and In a microstrip transmission line substrate having a plurality of strip conductors arranged adjacent to each other on the same plane of a dielectric substrate, the absolute propagation delay time of a signal transmitted through each of the strip conductors is long. When there is a difference in size, the dielectric substrate disposed directly below one of the strip conductors is used as a reference, and the dielectric substrate disposed directly below the other strip conductor is used as the dielectric substrate of the one of the dielectric substrates. Is a structure in which various dielectrics with different relative permittivities are laminated on the same plane so that they have different relative permittivities corresponding to the difference in absolute propagation delay time. The biography of Adjusting the delay time is obtained by a microstrip transmission line substrate comprising a means for controlling.

More specifically, in the microstrip transmission line substrate, in the wiring that is longer than the other wiring, that is, in the wiring in which the absolute value of the propagation delay time is large, the wiring length is maintained without changing the absolute propagation delay time. If it is necessary to shorten the difference in the wiring length with other wiring, make the dielectric substrate that constitutes the microstrip transmission line have a larger relative permittivity than the dielectric substrate directly under the other short wiring. As described above, in the dielectric substrate, various dielectrics having different relative permittivities are laminated on the same plane, and the propagation delay time per unit length is substantially increased to make the same propagation delay time relatively large. Make it possible to achieve with a short wiring length.

Contrary to the above case, in the case of a wire shorter than other wires, that is, a wire having a small absolute value of the propagation delay time, the absolute propagation delay time is left unchanged and the wire length is increased. If it is necessary to reduce the difference in the wiring length from the wiring of the above, the relative dielectric constant is different so that the dielectric that constitutes the microstrip transmission line has a smaller relative dielectric constant than the dielectric immediately below the other long wiring. Various dielectrics are laminated on the same plane and the propagation delay time per unit length is substantially reduced so that the same delay time can be realized with a relatively long wiring length.

In the above microstrip transmission line board, when connecting the microstrip transmission lines having different relative permittivities of the dielectric substrates constituting the transmission line,
When connecting the microstrip transmission line and the circuit element, the characteristic impedances of the microstrip transmission lines should be matched with each other, and the characteristic impedance between the microstrip transmission line and the circuit element should be matched with the input / output impedance of the circuit element. It is practically preferable to take it.

A second object of the present invention is to solve this problem. In the present invention (hereinafter referred to as the second invention), a microstrip in which the relative permittivity of a dielectric substrate forming a microstrip transmission line is changed is used. The characteristic impedance of the strip transmission line can be matched by any one of the following three characteristic impedance control means. That is, one of them is a control means for setting the distance d between the strip conductor of the microstrip transmission line and the substrate conductor to a predetermined value, and the other one is a width w of the strip conductor of the microstrip transmission line to a predetermined value. The control means is set to a value, and the other one is a combination of these control means, that is, the distance d between the strip conductor of the microstrip transmission line and the substrate conductor and the strip conductor width w of the microstrip transmission line. Both of
These are control means for setting predetermined values.

A third object of the present invention is to mount a plurality of high-speed digital circuit elements on the microstrip transmission line substrate, and connect these elements by the plurality of microstrip transmission lines. This is achieved by the circuit module (hereinafter referred to as the third invention).

That is, by using the microstrip transmission line substrate according to the first aspect of the invention, the wiring length can be shortened,
By utilizing the feature of the present invention that the size of the microstrip transmission line substrate can be reduced, a miniaturized microstrip transmission line substrate module can be realized. Further, by using the microstrip transmission line substrate according to the second aspect of the present invention, it is possible to realize a highly efficient microstrip transmission line substrate module in which the characteristic impedance of the microstrip transmission line is further matched.

[0014]

The principle of the microstrip transmission line board of the present invention having the above-mentioned structure is applied to a mounting wiring board of a digital signal multiplex circuit and a separation circuit in an ultrahigh-speed optical communication system with reference to FIGS. explain.

FIG. 1 is a schematic block diagram of an ultrahigh-speed optical communication system. In this system, a large number of input signals 1 are multiplexed by a digital signal multiplexing circuit 2, and this multiplexed signal 3
Is converted from an electric signal into an optical signal by the electro-optical conversion unit 4 and transmitted as a multiplexed optical signal by the optical fiber 5. The optical-electrical converter 6 receives the multiplexed optical signal, converts the optical signal into an electrical signal, and the multiplexed signal 7 is separated by the digital signal separation circuit 8 into a large number of output signals 9.

The speed of the output signal of the digital signal multiplexing circuit 2 and the input signal of the digital signal separating circuit 8 is several tens.
Gb / s is feasible, and in such a case, the number of input signals 1 and output signals 9 exceeds several tens with a signal of 600 Mb / s, and a high-speed digital circuit must meet the timing specifications. It is necessary to arrange elements and wire-connect between high-speed digital circuit elements.

FIG. 2 is a plan view of a conventional microstrip transmission line board shown for comparison. High-speed digital circuit elements (integrated circuit elements) 12 and 13 arranged on the microstrip transmission line board 11, A microstrip transmission line 1 is provided between these high-speed digital circuit elements.
An example of electrically connecting by 4 and 15 is shown. In this case, since there is a large difference in absolute delay time between the signals transmitted by the two transmission lines 14 and 15, there is a large difference in the wiring length between the two as shown in the figure. Then, as shown in the figure, the increase in the area of the microstrip transmission line substrate is a problem even if wiring is possible.

As shown in FIG. 3 which will be described later as an example of the present invention, this is because the microstrip transmission lines 142 and 152 between the high-speed digital circuit elements 122 and 132 arranged on the microstrip transmission line substrate 112. It is obvious by comparing the area of the microstrip transmission line substrate 112 and the area of the microstrip transmission line substrate 11 of FIG. 2 when the wiring lengths are the same.

In the case where there is a large difference between the wiring lengths in FIG. 2 and the long wirings and the short wirings are mixed between the high speed digital circuit elements 12 and 13, there are many wirings between these high speed digital circuit elements. When doing so, it is a big problem that the placement and wiring becomes difficult.

FIG. 3 is a plan view showing an example of the microstrip transmission line board according to the first invention of the present invention, which is a high-speed digital circuit element (integrated circuit element) 122 and 132 mounted on the board 112. The transmission lines 142 and 152 having the same wiring length are connected to each other.

FIG. 4 is a sectional view taken along the line AA 'of FIG. 3, showing the microstrip transmission lines 142, 1 of FIG.
52 is a strip conductor 2 having the same line width w in FIG.
1 and 22, dielectric substrates 23 and 24 having different relative permittivity εr, and a substrate conductor 25. FIG.
The structure of the dielectric substrate 23 is shown, and includes a dielectric 29, a dielectric 30, and a dielectric 31. FIG. 6 shows the structure of the dielectric substrate 24, which includes the dielectric 32 and the dielectric 3.
3 and a dielectric 34. Dielectric substrate 23, 2
Both 4 are formed by stacking dielectrics having different relative permittivity εr.

It is generally known that the delay time tpd per unit length of the microstrip transmission line is proportional to the magnitude of the relative permittivity εr of the dielectric substrate as shown in the following equation (1). That is, as the relative permittivity εr of the dielectric substrate increases, the delay time tpd per unit length increases.
It can be seen that Note that in the formula (1), C
Indicates the speed of light.

[0023]

[Equation 1]

Further, the relative permittivity εr and the permittivity ε have the relationship shown in the following equation (2). In the equation, ε ₀ is the dielectric constant in vacuum.

[0025]

[Equation 2]

Therefore, for example, when the absolute delay time required for the strip conductor 21 constituting the microstrip transmission line is larger than the absolute delay time required for the strip conductor 22, in order to reduce the difference in wiring length. Is the relative permittivity εr of the dielectric substrate 23 between the strip conductor 21 and the substrate conductor 25.
The various dielectrics that form the laminated structure of the dielectric substrate 23 and the dielectric substrate 24 are selected so as to be larger than the relative permittivity εr of the dielectric substrate 24 between the substrate conductor 25 and the substrate conductor 25. The strip transmission line board may be configured. This makes it possible to satisfy the absolute delay time required for the strip conductor 21 and the strip conductor 22 that form the microstrip transmission line, and reduce the difference in wiring length between them.

Contrary to the above case, when the absolute delay time required for the strip conductor 21 constituting the microstrip transmission line is smaller than the absolute delay time required for the strip conductor 22, the difference in wiring length is caused. In order to reduce the relative dielectric constant εr of the dielectric substrate 23 between the strip conductor 21 and the substrate conductor 25, the relative dielectric constant εr of the dielectric substrate 24 between the strip conductor 22 and the substrate conductor 25 can be reduced. A microstrip transmission line substrate may be configured by selecting various dielectrics that form a laminated structure that configures the dielectric substrate 23 and the dielectric substrate 24 so as to be smaller than εr. This makes it possible to satisfy the absolute delay time required for the strip conductor 21 and the strip conductor 22 that form the microstrip transmission line, and reduce the difference in wiring length between them.

There are various types of dielectric materials used, and a typical material typically used is, for example, polytetrafluoroethylene (2.
4), glass epoxy (4.4 to 5.0), alumina composite (5.0 to 10.0), alumina ceramic (9.0 to 10.0) and the like. The numerical value in parentheses indicates the relative dielectric constant (representative value) εr. Further, as the strip conductors 21 and 22, and the substrate conductor 25, for example, a conductor layer of copper, nickel or the like that can be easily formed by a well-known film forming technique such as plating, sputtering, vapor deposition or the like is used.

Next, the characteristic impedance matching means of the second invention will be described. In FIG. 4, the relative dielectric constant εr of the dielectric substrate 23 between the strip conductor 21 and the substrate conductor 25 and the dielectric substrate between the strip conductor 22 and the substrate conductor 25 in order to reduce the difference in wiring length. Since the relative permittivity εr of 24 has different values, the characteristic impedances of these microstrip transmission lines have different values. This generally means that
Characteristic impedance Z _{0 of the} microstrip transmission line
Is clearly inversely proportional to the dielectric constant ε as shown in the following equation (3). In the equation, μ is the magnetic permeability, W is the width of the strip conductor, and d is the distance between the strip conductor and the substrate conductor (corresponding to the thickness of the dielectric).

[0030]

(Equation 3)

From the equation (3), the characteristic impedance Z ₀ of the microstrip transmission line is proportional to the distance d between the strip conductor and the substrate conductor, that is, the width W of the strip conductor and the distance between the strip conductor and the substrate conductor. It can be seen that the characteristic impedance Z ₀ also changes depending on the ratio with d. Therefore, in the second invention, the strip conductor is required to be improved by controlling the width W of the strip conductor, the distance d between the strip conductor and the substrate conductor, or both of them by further improving the first invention. It is also possible to match the characteristic impedances.

A third aspect of the present invention is a microstrip transmission line substrate module, wherein when the absolute delay time of the microstrip transmission line is fixed according to the specifications and the wiring length of the microstrip transmission line loses flexibility, By shortening the wiring length by changing the relative permittivity εr of the dielectric material just below the strip transmission line, the wiring length between each digital element can be shortened, so the dimensions of the microstrip transmission line board on which the digital elements are mounted can be reduced. Has a working effect.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. It is to be noted that an effective target for carrying out the present invention is a mounting wiring board of a digital signal multiplex circuit and a separation circuit in an ultrahigh-speed optical communication system. ,
An example of a microstrip transmission line board as a mounted wiring circuit board used in an ultrahigh-speed optical communication system will be described.

<Embodiment 1> FIG. 3 shows high-speed digital circuit elements (integrated circuits) 122 and 132 mounted on a microstrip transmission line substrate 112 of the present invention, and two transmission lines are provided between these circuit elements. FIG. 4 is a plan view showing an example of a circuit module connected by 142 and 152, and FIG.
Microstrip transmission line 14 showing -A 'cross section
2 is a cross-sectional view of a transmission line substrate 112 showing the main part configuration of 2, 152. FIG.

The structure, manufacturing method, and performance test results of the microstrip transmission line board will be sequentially described below with reference to FIGS.

(1) Structure of Microstrip Transmission Line Substrate As shown in the figure, the microstrip transmission line substrate is composed of strip conductors 21 and 22 constituting the transmission line, dielectric substrates 23 and 24, and a microstrip transmission line. It is composed of a substrate conductor 25 constituting the same. Strip conductors 21, 2
A copper foil 2 has a thickness of 18 μm, a conductor width of 0.66 mm, and a wiring length of 3 cm. As shown in FIG. 5, the dielectric substrate 23 includes an alumina composite dielectric 29 having a thickness of 0.0794 mm and a relative permittivity εr of 9.0 and an alumina composite dielectric 29 having a thickness of 0.0794 mm and a relative permittivity εr of 5.0. A laminated structure is formed by the body 30, and it has been experimentally confirmed that various values of the relative dielectric constant can be obtained by combining the relative dielectric constants of the individual dielectrics. Therefore, in this case, the relative dielectric constant is about 8.0. As shown in FIG. 6, the dielectric substrate 24 has a thickness of 0.0794 mm and an alumina composite dielectric 32 having a relative permittivity εr of 5.0 and a thickness of 0.0794 m.
A laminated structure is formed by the alumina composite dielectric 33 having a relative permittivity εr of 2.0 of 2.0, and similarly, the relative permittivity is about 4.0. In addition, the dielectric substrate 23 at this time,
The thickness of each 24 is 0.635 mm.

(2) Manufacturing Method The dielectric substrates 23 and 24 are formed as a single substrate by joining the alumina composite dielectric 29 and the alumina composite dielectric 30 with an adhesive and forming a laminated structure in the same manner. Form. The side surfaces of the dielectric substrate 23 and the dielectric substrate 24 manufactured as described above are bonded with an adhesive to form one substrate, and then the thickness of 18 μm is formed on both surfaces of the substrate.
m copper foil is rolled and adhered, and the lower copper foil is used as the substrate conductor 25. Further, a photoresist film is formed on the copper foil on the upper surface of the substrate, and the strip conductor pattern (width 0.66 mm, length 3
A resist pattern is formed by exposing and developing through a mask on which a wiring pattern (cm cm) is formed. Using this resist pattern as an etching mask, the exposed copper foil is selectively etched to transfer and form a strip conductor pattern. Instead of rolling and adhering copper foil to both sides of the dielectric substrate, apply a plating catalyst such as palladium to the substrate and perform electroless copper plating, or, if more thickness is desired, use this electroless copper plating. May be used as a base for electrolytic plating.

(3) Performance test result The signal transmitted through the strip conductor 21 is tpd = 76.9.
Clock signal of ps / cm, strip conductor 22
Is a data signal of tpd = 56.9 ps / cm. In the case of this embodiment, the strip conductors 21 and 22 both have a wiring length of 3 cm, and the data signal time width and the clock signal period are 120 ps. Further, the rising timings of the data signal input to the strip conductor 22 and the clock signal input to the strip conductor 21 are the same. Therefore, the data signal transmitted through the strip conductor 22 is transmitted to the strip conductor 21.
To take in at the output side by the clock signal transmitting
The clock signal needs to be delayed from the data signal by half the time width of the data signal, and the clock signal transmitted through the strip conductor 21 needs to be delayed by 60 ps from the signal transmitted through the strip conductor 22. Therefore, by setting the relative permittivity εr of the dielectric substrate 23 directly below the strip conductor 21 to 8.0 and the relative permittivity εr of the dielectric substrate 24 directly below the strip conductor 22 to 4.0, the wiring length is 3 cm. In this case, a difference of 60 ps could be achieved, and as a result, normal operating characteristics could be obtained.

Further, when the size of the substrate for obtaining the same characteristics is compared with the size of the conventional microstrip transmission line substrate shown in FIG. 2 (125 mm × 120 mm), the case of this embodiment is shown in FIG. Thus, the area was 80 mm × 120 mm, and the area could be reduced by 36%.

Although alumina composite is used as the dielectric material in this embodiment, other suitable materials can be selected according to the characteristics of the signal to be transmitted and the environment in which it is used. A typical dielectric material and its relative dielectric constant (typical value) are Teflon (2.4):
Glass epoxy (4.4 to 5.0): Alumina ceramic (9.0 to 10.0).

<Embodiment 2> In the case of Embodiment 1, the absolute delay time required for the strip conductor 21 constituting the microstrip transmission line is the absolute delay time required for the strip conductor 22 constituting the microstrip transmission line. In order to reduce the difference in the wiring length when it is larger than the above, the relative permittivity εr of the dielectric substrate 23 between the strip conductor 21 and the substrate conductor 25 and the strip conductor 22 and the substrate conductor 2 are
Since the relative permittivity εr of the dielectric substrate 24 between 5 and 5 has different values, the characteristic impedances of these microstrip transmission lines have different values.

The present embodiment describes an example of a microstrip transmission line substrate in which the different characteristic impedances are matched, and FIG. 7 shows a sectional view of the transmission line substrate.

(1) Structure of Microstrip Transmission Line Substrate As shown in FIG. 7, the structure is basically the same as that of FIG. 4, but the dielectric substrate 24 immediately below the strip conductor 22 for transmitting a data signal. The thickness is reduced from 0.635 mm to 0.381 mm for impedance matching, and
Along with this, the only difference is that the shape of the board conductor 25 is deformed into a crank shape in cross section.

As shown in the above equation (3), the characteristic impedance Z ₀ is proportional to the distance d between the strip conductor and the substrate conductor and inversely proportional to the width W of the strip conductor (the relative permittivity εr of the dielectric material). In this embodiment, the characteristic impedance Z ₀ of both transmission lines is matched by adjusting the thickness of the dielectric substrate 24 without changing the width W of the strip conductor.

That is, from the equations (2) and (3), the characteristic impedance Z ₀ of the transmission line constituted by the strip conductor 21, the dielectric substrate 23, and the substrate conductor 25 is 50Ω, and the strip conductor 22 and the dielectric substrate. Characteristic impedance Z of the transmission line composed of 24 and substrate conductor 25
_In order to match ₀ with this value, it is necessary to compensate for the difference in relative permittivity εr of both dielectrics. The difference (8.0-4.0 = 4.0) in the relative permittivity εr is used as the strip conductor 22.
The characteristic impedance Z of this transmission line is adjusted by adjusting the distance d between the substrate conductor 25 and the substrate conductor 25, that is, the thickness of the dielectric substrate 24 from 0.635 mm to 0.381 mm.
_{0 is set} to 50Ω.

(2) Manufacturing Method Since the dielectric substrate 24 on one side is made thin, the method of forming the substrate conductor 25 is basically the same as that of the first embodiment except that copper plating is used instead of roll bonding. It was manufactured in the same process.

(3) Performance test result The same signal as that of the first embodiment (the signal transmitted through the strip conductor 21 is a clock signal of tpd = 76.9 ps / cm: the signal transmitted through the strip conductor 22 is tpd = 62.2 ps).
(Data signal of / cm) is transmitted to each transmission line, the characteristic impedance Z _{0 of} both is matched, so that the characteristic is improved as compared with the case of the first embodiment, and the signal transmission loss is significantly reduced. However, it was possible to transmit efficiently.

<Embodiment 3> As in Embodiment 2, this embodiment improves the difference in characteristic impedance between the two transmission lines caused by the difference in relative permittivity εr of the dielectric substrates 23 and 24 of Embodiment 1. An example of a microstrip transmission line substrate in which the characteristic impedance is matched by adjusting the width W of the strip conductor in this embodiment, instead of adjusting the distance d and matching in Embodiment 2 8 is a sectional view of the transmission line substrate.

(1) Structure of Microstrip Transmission Line Substrate As shown in FIG. 8, the structure is basically the same as that of the first embodiment shown in FIG. The width W is set to 0.
The structural difference is that the width is widened from 66 mm to 1.08 mm.

As shown in the above equation (3), the characteristic impedance Z ₀ is proportional to the distance d between the strip conductor and the substrate conductor and inversely proportional to the width W of the strip conductor (the relative permittivity εr of the dielectric material εr). However, in this embodiment, the strip conductor 2 is not changed in thickness.
Adjust the width W of 2 and set the characteristic impedance Z of both transmission lines.
_It is a match of ₀ .

That is, from the equations (2) and (3), the characteristic impedance Z ₀ of the transmission line constituted by the strip conductor 21, the dielectric substrate 23, and the substrate conductor 25 is 50Ω, and the strip conductor 22 and the dielectric substrate. Characteristic impedance Z of the transmission line composed of 24 and substrate conductor 25
_In order to match ₀ with this value, it is necessary to compensate for the difference in relative permittivity εr of both dielectrics. The difference (9.0-5.0 = 4.0) in the relative permittivity εr is used as the strip conductor 22.
By adjusting the width W from 0.66mm to 1.08 mm, the characteristic impedance Z ₀ of the transmission line 50
Ω.

(2) Manufacturing Method Basically, the same process as in Example 1 was carried out. However, as shown in the figure, only the pattern width of the photoresist mask forming one strip conductor 22 is widened to a width of 1.0.
An 8 mm strip conductor 22 was formed. The width of the other strip conductor 21 was fixed at 0.66 mm as in Example 1.

(3) Performance test result The same signal as in Example 1 (the signal transmitted through the strip conductor 21 is a clock signal of tpd = 76.9 ps / cm: the signal transmitted through the strip conductor 22 is tpd = 62.2 ps)
(Data signal of / cm) is transmitted to each transmission line, the characteristic impedance Z _{0 of} both is matched, so that the characteristic is improved as compared with the case of the first embodiment, and the signal transmission loss is significantly reduced. However, it was possible to transmit efficiently.

<Embodiment 4> This embodiment also matches the characteristic impedance Z ₀ and adjusts the distance d between the strip conductor and the substrate conductor of the embodiment 2 and the strip conductor of the embodiment 3. The width W is adjusted and both are combined. FIG. 9 shows a sectional view of the configuration example.

As shown, the width W of the strip conductor 21.
And the width W'of the strip conductor 22 and the strip conductor 2
1 and the distance d ′ between the board conductor 25 and the strip conductor 2
Both the distance 2 between the substrate 2 and the substrate conductor 25 are arbitrarily set according to the characteristic impedance Z ₀ required for each microstrip transmission line. As a result, the strip conductor 21 forming the microstrip transmission line and the strip conductor 2 forming the microstrip transmission line
It is possible to satisfy the absolute delay time required for No. 2 and to reduce the difference between these wiring lengths. Furthermore, the strip conductor 2 which constitutes the microstrip transmission line can be achieved.
1. The characteristic impedance Z ₀ required for the strip conductor 22 that constitutes the microstrip transmission line can be satisfied.

Here, one width of the strip conductor and
The configuration of the microstrip transmission line substrate and the signal applied to the transmission line are the same as in the first embodiment, except that one thickness of the dielectric is changed to a predetermined value. That is, the line widths of the strip conductor 21 and the strip conductor 22 are the same as those in the third embodiment shown in FIG. 6, and the width W of the strip conductor 21 is W = 0.66 mm and the width W ′ of the strip conductor 22 is 1. The thickness of the dielectric is such that the thickness of the dielectric 23 is d ′ = 0.381 mm, and the thickness of the dielectric 24 is d = 0.635 mm.
As a result, in addition to the effect similar to that of the first embodiment, the characteristic impedance Z of both transmission lines is obtained as in the second and third embodiments.
_Since both _0s are matched with 50Ω, a transmission line substrate with less transmission loss can be realized.

<Embodiment 5> FIG. 11 is a plan view of a multiple circuit module of the present invention. 8: 1 multiplex IC
(MUX1, MUX2) and 2: 1 multiplex IC (MUX
3), a microstrip transmission line substrate 119, microstrip transmission lines 106, 10
7, 108, 104 and 105.

This multiplex circuit module outputs 8 data signals from the microstrip transmission lines 104 and 105, respectively, to an 8: 1 multiplex IC (MUX1, MUX2).
8: 1 data input, 8: 1 multiplex IC
The data signals multiplexed by (MUX1, MUX2) are input to the two data inputs of the 2: 1 multiplex IC (MUX3) by the microstrip transmission lines 106 and 107, respectively, and the data signals of the 2: 1 multiplex IC (MUX3) are input. 1 from output
It has a function of taking out a 6: 1 multiplexed data signal from the microstrip transmission line 108.

FIG. 10 is a plan view of a comparative multiple circuit module having the same function as that of FIG. This module is also an 8: 1 multiplex IC (MUX1, MUX
2) A circuit element formed of a 2: 1 multiplex IC (MUX3), a microstrip transmission line substrate 109, microstrip transmission lines 106, 107, 108, 104,
And 105.

The multiplexing circuit module shown in FIG. 10 receives the data signal multiplexed by the 8: 1 multiplexing IC (MUX1, MUX2) from the microstrip transmission line 106,
Data is input to two data inputs of the 2: 1 multiplex IC (MUX3) by 107, and the data input timing of these two data is 10 μs.
6 and 107, and depending on the timing specifications, microstrip transmission lines 106, 1
As the length of 07 increases, 8: 1 multiplex IC (M
UX1, MUX2), 2: 1 multiplex IC (MUX3) There is a case where the degree of freedom in the arrangement of the circuit elements is lost, and the size of the microstrip transmission line substrate 109 cannot be reduced. In the comparative example of FIG. However, the size of the entire substrate becomes 10 cm × 15 cm. This is because the dielectric material of the microstrip transmission line substrate 109 is the same in all areas of the microstrip transmission line substrate.
That is, the dielectric substrates constituting the microstrip transmission line have the same relative permittivity (set to εr = 2.2) in the entire area of the microstrip transmission line substrate.

Therefore, in this embodiment, as shown in FIG. 11, the wiring lengths of the microstrip transmission lines 106 and 107 are made shorter than the wiring length in FIG. 10, and the delay time is respectively set in the microstrip transmission lines in FIG. In order to make them the same as 106 and 107, the substantial relative permittivity of the dielectric substrate between the strip conductors and the substrate conductor which form the microstrip transmission lines 106 and 107 is determined as follows. 1
The combination of the dielectrics forming the laminated structure of the dielectric substrate is selected so as to be larger than the substantial relative permittivity of the dielectric substrate between the strip conductor and the substrate conductor constituting 07 (εr = 10 0.0)), and the microstrip transmission line substrates 106 and 107 were configured.

That is, in the case of the comparative example of FIG. 10, the transmission lines 106 and 107 have a wiring length of 6 cm, the dielectric substrate is an alumina composite, and εr = 2.2, tpd = 44.8p.
It is s / cm, and the delay time required for this wiring is 268.8 ps. On the other hand, in the case of FIG. 11 of this embodiment, only the dielectric substrate immediately below the transmission lines 106 and 107 is εr.
= 10.0 and tpd = 89.6 ps / cm to obtain the same delay time of 268.8 ps with a wiring length of 3 cm, the total size of the transmission line substrate 109 is 8 cm.
cm × 12 cm, and the area could be reduced by 30.7% compared with the module of Comparative Example FIG.

Further, at this time, as in the second to third embodiments, either the width of the strip conductor or the distance between the strip conductor and the substrate conductor or both of them is set to the characteristic impedance required for each microstrip transmission line. According to the setting, the characteristic impedances can be matched, the absolute delay times required for the microstrip transmission lines 106 and 107 can be satisfied, and the wiring lengths of these can be shortened.

[0064]

As described above in detail, according to the present invention, the intended purpose can be achieved. That is, even if there is a difference in the propagation delay time required for each microstrip transmission line among the plurality of microstrip transmission lines between the high-speed digital circuit elements, it becomes possible to reduce the difference in the wiring length. This has the effect of facilitating the placement and wiring of elements.

Further, in this case, the characteristic impedance of each microstrip transmission line of the plurality of microstrip transmission lines between the high-speed digital circuit elements can be arbitrarily set, so that between the microstrip transmission line and the high-speed digital circuit elements and between the plurality of high-speed digital circuit elements. There is an effect that the characteristic impedance between the microstrip transmission lines can be matched.

Further, since the degree of freedom of wiring of the microstrip transmission line is increased, there is an effect that the size of the microstrip transmission line substrate module on which the digital element is mounted can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an ultrahigh-speed optical transmission system.

FIG. 2 is a plan view when high-speed digital circuit elements are connected by a conventional microstrip transmission line substrate.

FIG. 3 is a plan view for explaining the principle of the invention in which high-speed digital circuit elements are connected by a microstrip transmission line substrate of the invention.

FIG. 4 is a cross-sectional view of the first embodiment which also serves as a principle explanation of the microstrip transmission line substrate of the present invention.

FIG. 5 is a cross-sectional view of the dielectric substrate according to the first embodiment, which also serves to explain the principle of the microstrip transmission line substrate of the present invention.

FIG. 6 is a cross-sectional view of a dielectric substrate of Example 1 which also serves to explain the principle of the microstrip transmission line substrate of the present invention.

FIG. 7 is a sectional view of the microstrip transmission line substrate shown in the second embodiment.

FIG. 8 is a sectional view of the microstrip transmission line substrate shown in the third embodiment.

FIG. 9 is a sectional view of the microstrip transmission line substrate shown in the fourth embodiment.

FIG. 10 is a schematic plan view of a multiple circuit module using a conventional microstrip transmission line substrate as a comparative example.

FIG. 11 is a schematic plan view of a multiple circuit module using the microstrip transmission line substrate shown in the ninth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input signal, 2 ... Digital signal multiplex circuit, 3, 7 ... Multiplexed signal, 4 ... Electric-optical conversion part, 5 ... Optical fiber, 6 ... Optical-electrical conversion part, 8 ... Digital signal separation circuit, 12, 13, 122, 132 ... Integrated circuit element (high-speed digital circuit element), 14, 15, 106, 107, 108, 142, 152
... Microstrip transmission line, 21, 22, ... strip conductor, 23, 24, 131, ... dielectric, 25, 123, 133 ... substrate conductor, 29, 30, 31, 32 ... alumina composite dielectric, 109, 112 ... Microstrip transmission line substrate, MUX1, MUX2 ... Integrated circuit device (8: 1 multiplex I
C), MUX3 ... Integrated circuit element (2: 1 multiplex IC).

Claims (9)

[Claims] 1. A microstrip transmission line comprising at least a dielectric substrate arranged on a substrate conductor, and a plurality of strip conductors arranged adjacent to each other on the same plane of the dielectric substrate. When the absolute propagation delay time of a signal transmitted through each of the strip conductors is large or small, the dielectric substrate disposed directly below one of the strip conductors is used as a reference. , The dielectric substrate disposed directly below the other strip conductor is constituted by a dielectric substrate having a relative dielectric constant different from that of the one dielectric substrate by an amount corresponding to a difference in absolute propagation delay time. The dielectric substrate has a means for adjusting and controlling the propagation delay time per unit length of the strip conductor, and as a means for realizing an arbitrary relative permittivity of the dielectric substrate directly below the strip conductor, Difference in rate Various microstrip transmission line substrate comprising a dielectric formed into a laminated structure on the same plane that. 2. A microstrip transmission line substrate comprising at least a dielectric substrate arranged on a substrate conductor and a plurality of strip conductors arranged adjacent to each other on the same plane of the dielectric substrate. When the absolute propagation delay time of the signal transmitted through the strip conductor has a difference in magnitude, the dielectric substrate directly below the one strip conductor having a large absolute propagation delay time is set to the absolute propagation delay time. As a means for realizing an arbitrary relative permittivity of the dielectric substrate arranged directly below the strip conductor, the dielectric substrate is formed of a dielectric substrate having a relative permittivity larger than that of the other small strip conductor. A microstrip transmission line substrate in which various dielectrics having different relative dielectric constants are formed in a laminated structure on the same plane. 3. A microstrip transmission line substrate comprising at least a dielectric substrate disposed on a substrate conductor and a plurality of strip conductors disposed adjacent to each other on the same plane of the dielectric substrate. When the absolute propagation delay time of a signal transmitted through the strip conductor has a large or small difference, the dielectric substrate directly below one of the strip conductors having a small absolute propagation delay time is set to the absolute propagation delay time. As a means for realizing an arbitrary relative permittivity of the dielectric substrate arranged directly below the strip conductor, the dielectric substrate is formed of a dielectric substrate having a smaller relative permittivity than the dielectric substrate directly below the other large strip conductor. A microstrip transmission line substrate in which various dielectrics having different relative dielectric constants are formed in a laminated structure on the same plane. 4. A microstrip transmission line substrate comprising at least a dielectric substrate disposed on a substrate conductor and a plurality of strip conductors disposed adjacent to each other on the same plane of the dielectric substrate. When there is a large or small difference in the length of the absolute propagation delay time of the transmitted signal, the type of the dielectric material directly under the strip conductor of the microstrip transmission line is selected, and only the amount corresponding to the difference is selected. A means for adjusting and controlling the propagation delay time per unit length of the strip conductor, which is composed of dielectric substrates having different relative permittivities, and a distance between the strip conductor and the substrate conductor for controlling the difference in relative permittivity. And a means for matching the characteristic impedance of the microstrip transmission line generated on the basis of, and as a means for realizing an arbitrary relative permittivity of the dielectric material disposed immediately below the strip conductor, Microstrip transmission line substrate comprising a conductor substrate a dielectric constant different variety of dielectric to form a laminated structure on the same plane. 5. A microstrip transmission line substrate comprising at least a dielectric substrate arranged on a substrate conductor and a plurality of strip conductors arranged adjacent to each other on the same plane of the dielectric substrate. When there is a large or small difference in the length of the absolute propagation delay time of the transmitted signal, the type of the dielectric material directly under the strip conductor of the microstrip transmission line is selected, and only the amount corresponding to the difference is selected. A means for adjusting and controlling the propagation delay time per unit length of the strip conductor, which is composed of dielectric substrates having different relative permittivities, and a line width of the strip conductor is controlled, based on the difference in the relative permittivity. And a means for matching the characteristic impedance of the generated microstrip transmission line, and as a means for realizing an arbitrary relative permittivity of the dielectric material disposed directly under the strip conductor, a dielectric substrate is used. Microstrip transmission line substrate made various dielectric having different dielectric constants to form a multilayer structure on the same plane. 6. A microstrip transmission line substrate comprising at least a dielectric substrate disposed on a substrate conductor and a plurality of strip conductors disposed adjacent to each other on the same plane of the dielectric substrate. When there is a large or small difference in the length of the absolute propagation delay time of the transmitted signal, the type of the dielectric material directly under the strip conductor of the microstrip transmission line is selected, and only the amount corresponding to the difference is selected. A means for adjusting and controlling the propagation delay time per unit length of the strip conductor, which is composed of dielectric substrates having different relative dielectric constants, and for controlling the distance between the strip conductor and the substrate conductor and the line width of the strip conductor. And a means for matching the characteristic impedance of the microstrip transmission line generated on the basis of the difference in relative permittivity, and an arbitrary dielectric substrate disposed immediately below the strip conductor. Ratio as a means to achieve a dielectric constant, a microstrip transmission line substrate obtained by forming various dielectrics different dielectric substrate having a relative dielectric constant of the laminated structure on the same plane. 7. The dielectric substrate as claimed in any one of claims 1 to 6 is provided with various dielectrics having different relative dielectric constants as means for realizing an arbitrary relative dielectric constant of the dielectric substrate arranged directly below the strip conductor. When forming a laminated structure on the same plane, in order to obtain a relative dielectric constant of 8.0, a thickness of 0.0794 mm, a relative dielectric constant of 9.0 and a thickness of 0.0794 mm, a relative dielectric constant of 5.
0 dielectrics are alternately formed in a laminated structure on the same plane, and in order to obtain a relative dielectric constant of 4.0, a thickness of 0.0794 mm, a relative dielectric constant of 5.0 and a thickness of 0.0794 mm, A microstrip transmission line substrate formed by alternately laminating dielectrics having a dielectric constant of 2.0 on the same plane. 8. A means for realizing an arbitrary relative permittivity of a dielectric substrate having a different relative permittivity directly below the strip conductors of a plurality of microstrip transmission lines, which is formed by controlling the thickness of the strip conductors. The microstrip transmission line substrate according to any one of claims 1 to 6, 9. A microstrip transmission line comprising at least a dielectric substrate arranged on a substrate conductor and a plurality of strip conductors arranged adjacent to each other on the same plane of the dielectric substrate. 8. A circuit module in which a plurality of digital circuit elements are mounted on a substrate, and the respective circuit elements are connected by the microstrip transmission line, wherein the microstrip transmission line substrate comprises:
A circuit module comprising the microstrip transmission line substrate according to any one of the above.