JPH10322106A - Packaging structure for coplanar transmission line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the transmission characteristic in a wider range of bands by securing an opposite placement with spaces of each prescribed distance between the end faces of coplanar lines of a photoconductor and the corresponding end faces of strip lines of microstrip lines and ensuring the ground reinforcement between the ground conductors of a metallic container, placed immediately under the said spaces and the ground conductors placed on a half-insulated substrate of the photoconductor. SOLUTION: For the placement of microstrips 200, the end faces of strip lines 211 to 213 of the microstrips 200 are set opposite to the end faces of coplanar lines 111 and 112 of a photoconductor via the grounding metallic parts respectively, so as to secure spaces 71 to 73 of each prescribed distance. The ground conductors 250 of a metallic container placed immediately under the spaces 71 to 73 are connected to the ground conductors 121 to 123, which are placed on a half-insulated substrate of the photoconductor via bonding wires 350b to 370b. With such a constitution, a flat region extends even to a band region higher compared with a conventional case, and accordingly the transmission characteristic is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a mounting structure of a coplanar transmission line for realizing a wider band of the coplanar transmission line.

[0002]

2. Description of the Related Art A prior art example will be described with reference to a front mounting diagram of a transmission line using a photoconductor (photoconductive element) shown in FIG. 4, an enlarged view thereof, and a pass band characteristic diagram of FIG.
As a configuration example using a photoconductor, there is a “reflection point measuring device” of Japanese Patent Application No. 7-35172.

[0003] An example of a mounting structure shown in FIG.
Three coaxial connectors, a photoconductor 100, a microstrip 200, and a number of bonding wires 350 to 370 connecting between lines and between grounds;
It consists of grounding hardware. Representative photoconductor 100
Are formed on a semi-insulating substrate of InP (indium phosphorus) doped with Fe (iron), for example, as shown in FIG.
112, a ground conductor 121 to 123, and a pair of gap electrodes 130 formed by an extremely fine gap at the T branch point of the T-shaped coplanar line.
When an ultra-short pulse light beam of sub-picoseconds to several picoseconds is irradiated onto the gap electrode 130, an ultra-high-speed optical switching action follows the light beam, and the detection signal is transmitted through the microstrip strip line 213. Transmitted to the outside.

The arrangement of the microstrip 200 is shown in FIG.
As shown in (b), the end faces of the strip lines 211 to 213 of the microstrip 200 are
The end faces of the 00 coplanar lines 111 and 112 are arranged so as to be in contact with each other so that there are no gaps 71 to 73. The other end surfaces of the strip lines 211 to 213 are connected to the center conductor of the external connector. Signals are input / output via this external connector. These strip lines 211 to 213
The ground conductors on both sides are grounded and fixed to the ground conductor 250 of the metal container using grounding hardware. The characteristic impedance of these transmission lines is formed so as to accurately match 50Ω so as not to cause signal reflection and amplitude fluctuation, and is used for use.

[0005] The bonding wire includes a wire for electrically connecting a signal line between the photoconductor 100 and the microstrip 200 and a grounding wire for grounding so as to have a predetermined characteristic impedance over the entire transmission line at high frequencies. There is a wire. First, the coplanar lines 111 to 112 of the photoconductor 100 are connected to the corresponding strip lines 211 to 213 of the microstrip 200. In addition, a large number of bonding wires 350, 360, 370 are connected to the ground conductor 250 of the nearest metal container so as to be equivalent to the ground potential in high frequency. As described above, in the related art, the photoconductor 100 and the microstrip 200 are arranged in contact with the shortest distance and are electrically connected.

[0006]

By the way, an electric field is generated between the signal line and the ground with the propagation of the high frequency signal.
This electric field is naturally concentrated near the coplanar lines 111 to 112 of the photoconductor 100 and the strip lines 211 to 213 of the microstrip. However, in the mounting structure shown in FIG. 4B, a strong electric field is generated at the position 90 of the ground conductors 121 to 123 on the photoconductor 100, but the ground conductor 250 of the metal container is formed.
, Which has an undesirable effect on the transmission characteristics of high-frequency signals. FIG. 5 shows the pass band characteristics in this mounting structure. As shown in this characteristic diagram, there is a problem that the dip 82 occurs at a frequency of about 15 GHz. Although the photoconductor 100 itself can operate as an ultra-high-speed switch of several hundred GHz or more, there is a problem in that a structure in which the photoconductor 100 is mounted has a non-flat portion in transmission characteristics in the frequency band of the dip 82.

An object of the present invention is to provide a mounting structure of a coplanar transmission line having a wider transmission characteristic in a photoconductor mounting structure.

[0008]

FIG. 1 shows a solution according to the present invention. First, in order to solve the above-described problem, in the configuration of the present invention, a gap 71 with a predetermined interval is provided between the end faces of the coplanar lines 111 and 112 of the photoconductor 100 and the corresponding end faces of the strip lines 211 to 213 of the microstrip 200. And a plurality of bonding wires between the ground conductor 250 of the metal container immediately below the gaps 71 to 73 at predetermined intervals and the ground conductors 121 to 123 on the semi-insulating substrate of the photoconductor 100. The photoconductor 1 includes means for connecting at 350b to 370b to reinforce the ground, and the photoconductor 1 corresponding to the ends of the strip lines 211 to 213 of the microstrip 200.
A plurality of bonding wires 310 to 330 are provided between the ends of the coplanar lines 111 and 112 on the semi-insulating substrate 00.
It is a configuration means provided with a means for connecting with. Thereby, the transmission characteristics are improved in the mounting structure of the coplanar transmission path in which the photoconductor 100 having the metal film line formed on the semi-insulating substrate and the input / output coaxial connector are connected by the microstrip 200 and housed in the metal container. Further, a mounting structure of a coplanar transmission line having a wider band can be realized.

FIG. 3 shows a solution according to the present invention. Further, on the coplanar line 112 at the optical switch signal output end on the semi-insulating substrate of the photoconductor 100, the reinforcing means for connecting the ground conductors 122 to 123 on both sides of the coplanar line with a plurality of bonding wires 410 is provided. There is a mounting structure additionally provided in the transmission path. In this case, a mounting structure of a coplanar transmission path with a wider band can be realized.

Further, a photoconductor 100 having a T-shaped coplanar line formed on a semi-insulating substrate and a gap electrode 130 at an extremely fine interval formed at the T branch point, and a micro-conductor arranged opposite to an end of the coplanar line. There is a mounting structure of a broadband coplanar transmission line having a T-shaped electrode structure as the strip 200.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings together with embodiments.

An embodiment of the present invention will be described with reference to an enlarged front view of a transmission line using the photoconductor of FIG. 1 and a passband characteristic diagram of FIG. Elements corresponding to the conventional configuration are denoted by the same reference numerals. The configuration of the present invention is the same as the conventional one, except for the arrangement of the microstrip 200 and the connection of the bonding wires.

The arrangement of the microstrip 200 is shown in FIG.
As shown in FIG. 3, the strip lines 21 of the microstrip 200 are provided so as to provide gaps 71 to 73 at predetermined intervals.
The end faces 1 to 213 are opposed to the end faces of the coplanar lines 111 and 112 of the photoconductor 100, and are fixed to the ground by metal grounding fittings. Predetermined gap 7 due to the above arrangement
1 to 73 and the ground conductors 121 to 121 on the semi-insulating substrate of the photoconductor 100.
A plurality of bonding wires 350b to 350b-3
The connection is grounded at 70b. As a result, the effect of reinforcing and strengthening the nearby ground along the strip lines 211 to 213, which is a conventional difficulty, can be obtained. FIG. 2A shows the pass band characteristics in this mounting structure. As shown in the characteristic diagram, it can be seen that the flat region extends to a higher region as compared with the related art, and the advantage of improving the transmission characteristics is obtained.

However, as shown in FIG. 2A, an undesired dip 84 is observed around a high frequency of 20 GHz. Therefore, an improved mounting structure is shown in an enlarged front mounting view of another transmission line using the photoconductor of FIG. This mounting structure is a mounting structure in which an air bridge wiring is added in addition to the mounting structure described above. That is, on the coplanar line 112 on the semi-insulating substrate of the photoconductor 100, an air bridge wiring (crossover connection) is made between the ground conductors 122 to 123 on both sides of the coplanar line by a plurality of bonding wires 410. According to this structure, FIG.
As shown in the transmission characteristic diagram, the effect of eliminating the dip and flattening to a higher frequency range can be obtained. As a result, there is obtained an advantage that a mounting structure of a coplanar transmission line that can be used up to a higher frequency band is realized.

In the description of the above embodiment, a specific example of the photoconductor 100 having a coplanar line formed in a T-shape on a semi-insulating substrate has been described. However, a plurality of photoconductive elements are provided on the semi-insulating substrate. There are elements to be formed. Corresponding to the arrangement of the coaxial connector for input / output corresponding to this, a predetermined gap is provided as in the above-mentioned embodiment, and a plurality of ground conductors 250 of the metal container immediately below this and the ground conductor on the semi-insulating substrate are provided. There is another mounting structure that is connected by a bonding wire to reinforce grounding, and it is clear that the effect of improving the transmission characteristics can be obtained in the same manner as described above.

[0016]

According to the present invention, the following effects can be obtained from the above description. According to the configuration of the above-described invention, the strip lines 211 to 21 of the microstrip 200
3, the coplanar line 111 of the photoconductor 100,
A predetermined gap 71-73 is provided between the metal conductors 112 and the ground conductor 250 and the photoconductor 100 of the metal container immediately below the gaps.
Between the grounding conductors 121 to 123
By grounding with the wires 350b to 370b, the grounding at the ends of the coplanar lines 111 and 112 can be reinforced and strengthened, so that the advantage of improving the transmission characteristics up to a higher frequency range than before can be obtained.

When a plurality of bonding wires 410 are used to connect (crossover) the plurality of bonding wires 410 between the ground conductors 122 to 123 on both sides of the coplanar line of the photoconductor 100, there is an advantage of improving the transmission characteristics up to a higher frequency range. can get.

[Brief description of the drawings]

FIG. 1 is an enlarged front view of a transmission path using a photoconductor according to the present invention.

FIG. 2 is a diagram showing pass band characteristics of the present invention.

FIG. 3 is another enlarged front view of a transmission path using a photoconductor of the present invention.

FIG. 4 is a front mounting view of a conventional transmission line using a photoconductor and an enlarged view thereof.

FIG. 5 is a conventional passband characteristic diagram.

[Explanation of symbols]

71 to 73 Gap 100 Photoconductor 111, 112 Coplanar line 121 to 123 Ground conductor 130 Gap electrode 200 Microstrip 211 to 213 Strip line 250 Ground conductor of metal container 310, 320, 330, 350, 360, 370, 3
50b-370b, 410 Bonding wire

Claims (3)

[Claims] 1. A mounting structure for a coplanar transmission line in which a photoconductor having a metal film line formed on a semi-insulating substrate and an input / output coaxial connector are connected by a microstrip line and housed in a metal container. The end face of the coplanar line of the conductor and the corresponding end face of the strip line of the microstrip are arranged facing each other with a predetermined gap therebetween, and the ground conductor of the metal container immediately below the predetermined gap and the photoconductor Means for reinforcing the ground between the ground conductors on the semi-insulating substrate, and means for connecting the ends of the strip lines of the microstrip and the corresponding ends of the coplanar lines on the semi-insulating substrate of the photoconductor. A mounting structure of a coplanar transmission line, comprising: 2. The coplanar device according to claim 1, further comprising: means for connecting the ground conductors on both sides of the coplanar line on the coplanar line on the semi-insulating substrate of the photoconductor. Transmission path mounting structure. 3. A T-shaped coplanar line formed on a semi-insulating substrate and a T-shaped microstrip structure corresponding thereto.
3. The mounting structure for a coplanar transmission line according to claim 1, wherein the mounting structure is a die mounting structure.