JP3259738B2 - Transversal filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high-frequency filter .
More particularly, the present invention relates to a transversal filter as a seed, and more particularly, to a configuration of a signal line of a transversal filter using a directional coupler.

[0002]

2. Description of the Related Art Dielectric resonator filters have greatly contributed to the miniaturization of mobile communication devices. However, as the frequency of mobile communication devices has become higher (millimeter wave band) and miniaturization (MMIC), they have been improved. It has been difficult to practically use the used dielectric resonator filter due to problems such as a large loss of the resonator and extremely strict dimensional and material constant accuracy.

Therefore, a transversal filter using a directional coupler has been considered as a filter for these mobile communication devices. The directional coupler used in this transversal filter has the properties of both a delay element and a weighting element. By connecting a plurality of directional couplers having different coupling coefficients, an appropriate bandpass A type of filter can be configured.

FIG. 5 shows a transversal filter using a directional coupler, which is realized as an MMIC by multi-layering. Connection line 2 made of Ag or Cu conductor on dielectric substrate 21 made of low-temperature sintered ceramic material
When the signal lines 22 and 23 are formed so as to approach and separate from each other on the substrate 21, a directional coupler is formed in the vicinity of the line, and if the approach and separation of the signal lines are repeated, This means that many directional couplers are connected.

The substrates 21 are laminated as necessary to form a multilayer structure, and the connecting lines 22 and 23 of the upper and lower substrates 21 and 21 are connected.
Are electrically connected by through holes 24 to form a filter. A transversal filter having a required bandwidth can be obtained by variously selecting and varying the coupling degrees of the plurality of directional couplers.

[0006]

By the way, the degree of coupling of the directional coupler is greatly influenced by the line spacing in the vicinity of the two lines 22 and 23, and depending on the degree of coupling, several tens μm to 2 μm.
Although a line spacing of about 0 μm is required, the line spacing that can be stably obtained is at least about 100 μm due to the limit of processing accuracy for forming the line, and it is difficult to obtain a line spacing smaller than that. Therefore, there is a limit to the improvement of the filter characteristics due to the improvement of the coupling degree.

[0007] The present application is to solve the above problems, tiger
An object of the present invention is to obtain a high-performance and highly reliable transversal filter by increasing the degree of freedom of the degree of coupling by improving the limit of the degree of coupling of the directional coupler that constitutes the versatile filter.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a plurality of directional couplers formed by two signal lines formed on a substrate being closely adjacent to each other. In the connected transversal filter, two signal lines are formed on different planes, and
By repeating the approach and separation, at least 5 steps are performed, and at least one of the adjacent portions opposes in the thickness direction of the substrate,
A plurality of directional couplers having different coupling coefficients are connected in series, and the directional coupler is
Transformer characterized by being used as an element and a delay element
It is a versal filter.

[0009]

Since the coupling lines running in parallel with each other are formed on different planes, the substrate can be sandwiched between the two lines and the thickness of the substrate can be selected to adjust the degree of coupling. In addition, since the minimum value corresponding to the thickness of the substrate material can be stably obtained in this proximity portion, the degree of coupling of the directional coupler can be increased, and the transversal composed of these directional couplers can be obtained. > The filter characteristics and design flexibility are improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

[0011] As shown in FIGS. 1 and 2, this Toransuba
The Saru filter, there is a first signal line 1 and the output side of the second signal line 2 of the input side inside made of a dielectric material, the proximity and away each run parallel to the longitudinal direction 5 This is a five-stage filter that performs stages.

The two signal lines 1 and 2 are on different planes, and the signal line 1 is on the upper side and the signal line 2 is on the lower side.
Are formed, and a directional coupler is formed in the proximity portion 3 of both lines so as to face up and down in the thickness direction.

As shown in the sectional views of FIGS. 3A and 3B,
The configuration of this transversal filter includes a first ground electrode substrate 5 provided with a ground electrode 4 on the surface, an intermediate substrate 6, a second coupled line substrate 7 provided with a second coupled line 2 on the upper surface, A first signal line substrate 8 provided with the first signal line 1 on the upper surface, an intermediate substrate 9, and a ground electrode 1 on the surface;
0 provided second ground electrode substrate 11 and protection substrate 12
Are laminated and fired to form a chip.

Each of the above-mentioned substrates is formed of a low-temperature sintered ceramic sheet, and after forming each signal line, is stacked and fired under pressure to form an integrated dielectric laminate. Therefore, the ground electrode 10, the first coupling line 1, the second coupling line 2, and the ground electrode 4 are opposed to each other with the dielectric substrate material interposed therebetween. Further, on the outer surface of the chip-type laminate, external electrodes that are conductive for each signal line are formed when the ceramic sheets are stacked or after the laminate is fired (not shown).

The signal lines 1 and 2 are formed on separate substrates 8 and 7 using a conductor having excellent conductivity such as Ag or Cu as a material, and exist on different planes. The portion 3 is opposed in the thickness direction with the substrate 8 interposed therebetween as shown in FIG.

The directional coupler is formed in a plurality of adjacent portions 3 of the coupling line 1 and 2, the degree of coupling changes the inter-line distance of the proximity portion 3, transformer by changing the degree of coupling
Although the characteristics of the versal filter can be adjusted, the line interval (coupling degree) of the adjacent portion 3 can be adjusted by appropriately setting the thickness of the substrate 8.

To select the degree of coupling, the line spacing can be changed by shifting the upper and lower signal lines 1 and 2 in a plane, in addition to the thickness of the substrate. Since the minimum value can be set, the degree of coupling can be improved without depending on the printing accuracy of the signal line as in the related art.

In the above embodiment, the substrates having the coupling lines formed on the upper surface are sequentially laminated, but the transformer
Saru filter is not limited thereto, it can be practiced with modification shape and number such appropriate signal lines. Although not shown, an external connection electrode electrically connected to the signal lines 1 and 2 and the ground electrodes 4 and 10 is formed on the outer surface of the filter.

FIG. 4 shows a truck according to another embodiment of the present invention.
Is a perspective view showing a Nsubasaru filter, chip-Doo
On one end face of the Ransubasaru filter, the ground terminal electrode 13 as an electrode for external connection, the first signal line terminal electrode 14 (in the drawings do not crack current), the ground terminal electrodes 13 on the opposing end surfaces, and a 2 signal line terminal electrodes 1
5 are formed.

The first signal line electrode 14 is electrically connected to one of the signal lines formed on the upper side in the filter.
The second signal line electrode 15 is electrically connected to the other signal line formed on the lower side in the filter.
The length of 4, 15 is shortened to a necessary minimum to reduce the loss.

As shown in the figure, the signal line terminal electrodes 14,
By setting the length 15 to the minimum length that can be connected to the signal line, it is possible to minimize the influence of reflection and the like at the input and output terminals and obtain good characteristics. In addition, it is preferable in terms of characteristics if the external extraction electrodes of the signal lines 1 and 2 are extracted in a direction orthogonal to the longitudinal direction of each line.

[0022]

As described above, according to the present invention, the opposing signal lines are formed on different planes so as to oppose each other in the thickness direction. it is possible to adjust the degree of coupling, it is possible to increase the coupling coefficient of the directional coupler as a result, the tiger
The degree of freedom in designing a universal filter is increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of a transversal filter of the present invention.

FIG. 2 is a plan view of the transversal filter of the present invention.

FIG. 3 is a cross-sectional view of the transversal filter of the present invention, in which (A) is a cross-sectional view taken along line AA of FIG. 2;
(B) is sectional drawing which follows the BB line | wire.

FIG. 4 is a perspective view of a transversal filter according to another embodiment of the present invention.

FIG. 5 is a perspective view of a conventional transversal filter.

[Explanation of symbols]

 1,2 signal line 3proximity

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-99749 (JP, A) JP-A-60-149012 (JP, A) JP-A-52-26140 (JP, A) JP-A-53-997 44149 (JP, A) JP-A-4-26201 (JP, A) JP-A-60-247304 (JP, A) JP-A-59-169207 (JP, A) Japanese Utility Model Laid-open No. 64-11002 (JP, U) Japanese Utility Model Showa 59-119608 (JP, U) Japanese Utility Model Showa 54-173233 (JP, U) Japanese Utility Model Showa 46-35635 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03H 15/00 H01P 5/18

Claims (1)

(57) [Claims] 1. A transversal filter comprising a plurality of directional couplers formed by two signal lines formed on a substrate being closely opposed to each other, wherein the two signal lines are on different planes. And a plurality of directional couplers, each having a different coupling coefficient, are connected in series by repeating at least five steps by repeating the approach and separation, and at least one of the adjacent portions is opposed in the thickness direction of the substrate. And the directional coupler is connected to a weighting element and a delay element.
A transversal filter used as an extension element .