JPH06350302A - Strip line filter - Google Patents

Abstract

PURPOSE:To obtain a strip line filter in which dispersion in a residual inductance produced to a ground terminal electrode is less. CONSTITUTION:A couple of strip lines are provided for a strip line filter 15 and a common ground electrode is provided at a bottom face. Soldering use ground terminal electrodes 10, 12, 13, 14 connecting to the common ground electrode are provided on an face of the filter 15. Then relay ground terminal electrodes 9, 11 connecting each trip line and the common ground electrode are provided on an end face of the filter 15 apart from the soldering use ground terminal electrode 10. When the filter 15 is mounted on a printed circuit board or the like, solder is applied to the soldering use ground terminal electrodes 10, 12, 13, 14 except the relay ground terminal electrodes 9, 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stripline filter used by being incorporated in a communication circuit or the like.

[0002]

2. Description of the Related Art As shown in FIG. 8, a conventional stripline filter 49 is provided with input / output terminal electrodes 50 and 51 on its left and right end faces, and has a ground on its front and back end faces, respectively. The terminal electrodes 52 and 53 were provided. The ground terminal electrodes 52 and 53 are used for the filter 4
9 is for connecting the strip line disposed inside 9 and the common ground electrode disposed on the bottom surface of the filter 49, and is an electrode having such a wide area that substantially covers the front and rear end surfaces. there were. This stripline filter 49
Are surface-mounted on the printed wiring board 55. That is, the input / output terminal electrode 51 and the ground terminal electrode 52 are electrically connected and fixed to the circuit conductors 56 and 57 provided on the surface of the printed wiring board 55 by the solders 60 and 61, respectively. The input / output terminal electrode 50 and the ground terminal electrode 53 are also
Similarly, they are electrically connected and fixed to the circuit conductors provided on the surface of the printed wiring board 55 by soldering.

On the other hand, this strip line filter 49
Is used in the high frequency band, the ground terminal electrode 52,
Residual inductance occurs at 53. The value of the residual inductance varies depending on the amount of the solder 61 and the spread area of the solder 61. By the way, since the ground terminal electrodes 52 and 53 are electrodes having a large area, the amount of the solder 61 and the spread area of the solder 61 vary greatly. Therefore, the conventional stripline filter 49 has a problem that the value of the residual inductance generated in the ground terminal electrodes 52 and 53 is greatly changed and the filter characteristics are greatly varied.

Therefore, an object of the present invention is to provide a stripline filter in which variations in residual inductance generated in the ground terminal electrode are small.

[0005]

In order to solve the above problems, the stripline filter according to the present invention is
(A) at least two resonators, (b) a soldering ground terminal electrode connected to a common ground electrode of the resonator is provided on a filter end face, (c) a strip line of the resonator and the common ground At least two relay ground terminal electrodes connected to the electrodes are provided on the filter end face so as to be separated from the soldering ground terminal electrodes.

In the above structure, the ground terminal electrodes are of two types, that is, the soldering ground terminal electrode and the relaying ground terminal electrode, and when the stripline filter is surface-mounted on a printed wiring board or the like, the soldering ground terminal is used. The electrode is soldered to the circuit conductor provided on the surface of the printed wiring board, and solder for mounting is not attached to the relay ground terminal electrode. The electrode area of the soldering ground terminal electrode is reduced by setting the electrode width to a predetermined value. Therefore, the amount of solder and the spread area of the solder are smaller than those of the conventional filter. The value of the residual inductance generated in the ground terminal electrode is the distance from the common ground electrode to the strip line via the relay ground terminal electrode because there is no solder adhesion on the relay ground terminal electrode for mounting. Determined by

[0007]

Embodiments of the stripline filter according to the present invention will be described below with reference to the accompanying drawings. [First Embodiment, FIGS. 1 to 5] A first embodiment is a microstripline filter having two resonators on a dielectric substrate, and a microstripline filter that functions as a bandpass filter will be described.

As shown in FIG. 1, a pair of strip lines 2 and 3 are formed on the upper surface of the dielectric substrate 1. The lead-out portion 2a of the strip line 2 is exposed at the left side edge portion of the dielectric substrate 1, and the lead-out portion 2b is exposed at the left side position of the front side edge portion of the dielectric substrate 1. The lead-out portion 3a of the strip line 3 is exposed at the right side edge portion of the dielectric substrate 1, and the lead-out portion 3b is exposed at the right side position of the front side edge portion of the dielectric substrate 1. A common ground electrode 4 is formed on substantially the entire lower surface of the dielectric substrate 1. The lead-out portions 4a, 4b, 4c of the common ground electrode 4 are exposed at the left side position, the center position, and the right side position of the front side edge of the dielectric substrate 1, respectively. Furthermore, the lead-out portion 4 of the common ground electrode 4
d, 4e, and 4f are exposed at the left side position, the center position, and the right side position of the back side edge of the dielectric substrate 1, respectively. The strip lines 2 and 3 and the common ground electrode 4 are
For example, applying a paste such as Ag or Cu by a printing method,
It may be formed by drying, or may be formed by a thin film method such as sputtering or photolithography. The dielectric substrate 6 is integrally attached to the upper surface of the dielectric substrate 1 with an adhesive to form a stripline filter 15.

As shown in FIG. 2, the strip line filter 15 has an input / output terminal electrode 7 in a state in which it is electrically connected to the lead-out portion 2a of the strip line 2 on the left end face portion.
Is provided. Similarly, an input / output terminal electrode 8 is provided on the right end face portion while being electrically connected to the lead-out portion 3a of the strip line 3. A relay ground terminal electrode 9 is provided at a position on the left side of the end face portion on the front side in a state of being electrically connected to the lead-out portion 2b of the strip line 2 and the lead-out portion 4a of the common ground electrode 4, and at the center position. The soldering ground terminal electrode 10 is provided in a state of being electrically connected to the lead-out portion 4b of the common ground electrode 4, and the lead-out portion 3b of the strip line 3 is provided at a position on the right side.
Also, the relay ground terminal electrode 11 is provided in a state of being electrically connected to the lead portion 4c of the common ground electrode 4. Further, a soldering ground terminal electrode 12 is provided in a position on the left side of the end face portion on the back side in a state of being electrically connected to the lead-out portion 4d of the common ground electrode 4, and a common ground electrode 4 is provided at a central position. The soldering ground terminal electrode 13 is provided in a state of being electrically connected to the lead-out portion 4e, and the lead-out portion 4 of the common ground electrode 4 is provided at a position on the right side.
The ground terminal electrode 14 for soldering is provided in a state of being electrically connected to f. Therefore, the strip lines 2 and 3 are electrically connected to the common ground electrode 4 via the relay ground terminal electrodes 9 and 11, respectively. The terminal electrodes 7 to 14 may be formed, for example, by applying a paste such as Ag or Ag-Pd by a printing method and drying the paste, or by using a thin film method such as sputtering or photolithography. When the thin film method is adopted, it is possible to form electrodes with higher accuracy, and variations in the amount of solder and the spread area of the solder during soldering become smaller.

The stripline filter 15 thus obtained is, for example, as shown in FIG. 3, a printed wiring board 20.
Surface mounted and used. That is, the input / output terminal electrode 8 and the soldering ground terminal electrode 10 are circuit conductors 21 and 22 provided on the surface of the printed wiring board 20, respectively.
Are electrically connected to and fixed by solders 24 and 26. Similarly, the input / output terminal electrode 7 and the soldering ground terminal electrodes 12, 13, and 14 are also printed wiring boards 20 respectively.
Is electrically connected and fixed to a circuit conductor provided on the surface of the substrate by soldering.

Ground terminal electrodes 10, 12 for soldering,
Since the electrodes 13 and 14 have a small electrode area, variations in the amount of the solder 26 and the spread area of the solder 26 are smaller than those in the conventional filter. Further, in the filter 15, since the relay ground terminal electrodes 9 and 11 do not have solder adhered for mounting on the printed wiring board, the strip line is formed from the common ground electrode 4 through the relay ground terminal electrodes 9 and 11. Two
A residual inductance is generated which is determined by the distance to reach 3. Therefore, the value of the residual inductance can be easily predicted at the time of designing, and the residual inductance can be taken in as a circuit component when designing the filter.

FIG. 4 is an equivalent electric circuit diagram of the stripline filter 15. The inductance L1 of the strip line 2 and the capacitance C1 formed between the strip line 2 and the common ground electrode 4 constitute one resonator, and the inductance L2 and the strip line 3 of the strip line 3 and the common ground electrode 4 are formed. The capacitance C2 formed therebetween constitutes the other resonator. The two resonators are electrically coupled by a mutual inductance M. L3 and L4 are residual inductances determined by the size from the common ground electrode 4 to the strip lines 2 and 3 via the relay ground terminal electrodes 9 and 11.

FIG. 5 is a band characteristic diagram of the stripline filter 15 having the above configuration. Solid line A in the figure
1 and A3 are in a standard state (1.2 mm on the circuit conductor of the printed wiring board 20 using a mask having a thickness of 0.10 mm).
The attenuation amount and the insertion loss of the filter 15 in a state where the filter 15 is soldered after applying the solder paste to the area of × 1.5 mm are displayed. The solid line A2 is for comparison (using a mask with a thickness of 0.35 mm, a thick solder paste was applied to an area of 1.2 mm × 1.5 mm on the circuit conductor of the printed wiring board 20, and then the filter 15 was soldered. The attenuation amount of the filter 15 (state) is displayed. For comparison, band characteristics of a conventional filter having a wide area for the ground terminal electrode are also shown by dotted lines B1, B2, and B3. Dotted line B
Reference numerals 1 and B3 respectively indicate the attenuation amount and insertion loss of the filter in the reference state, and the dotted line B2 indicates the attenuation amount of the filter in the comparison state. Based on this FIG. 5, the following Table 1 is obtained. Table 1 shows the difference from the filter characteristic in the comparison state with the filter characteristic in the reference state as a reference.

[0014]

[Table 1]

In the filter 15 of the first embodiment, the poles a and b located on both sides of the pass band are 10 to 1 depending on the amount of solder.
Only 5 MHz is deviated (attenuation is 1.0 to 1.5
difference in dB). On the other hand, in the filter of the conventional example, the poles a and b located on both sides of the pass band are deviated by 40 to 50 MHz (the difference in attenuation is 3.5 to 5.0 dB). Therefore,
The filter 15 of the first embodiment can suppress variations in filter characteristics to about 30% of the conventional filter.

[Second Embodiment, FIGS. 6 and 7] As shown in FIG. 6, a stripline filter 31 according to the second embodiment has a dielectric green sheet 32 having a pair of striplines 35 and 36 provided on the surface thereof. The dielectric green sheet 33 provided with the common ground electrode 37 on the surface and the dielectric green sheet 34 are stacked, then pressed and fired to be integrated.

The lead-out portion 35a of the strip line 35 is exposed at the left side edge portion of the dielectric green sheet 32, and the lead-out portion 35b is exposed at the left side position of the front side edge portion of the dielectric green sheet 32. The lead-out portion 36a of the strip line 36 is exposed at the right side edge portion of the dielectric green sheet 32, and the lead-out portion 36b is exposed at the right side position of the front side edge portion of the dielectric green sheet 32. The lead portions 37a, 37b, 37c of the common ground electrode 37 are exposed at the left side position, the center position, and the right side position of the front side edge of the dielectric green sheet 33, respectively. Further, the lead portions 37d, 37e, 3 of the common ground electrode 4 are
7f are exposed at the left side position, the center position, and the right side position of the inner edge of the dielectric green sheet 33, respectively.

As shown in FIG. 7, the integrated stripline filter 31 is provided with an input / output terminal electrode 39 on the left end face in a state of being electrically connected to the lead portion 35a. Similarly, an input / output terminal electrode 40 is provided on the right end surface portion while being electrically connected to the lead portion 36a. Drawer 3 at the position near the left end of the front end
The relay ground terminal electrode 41 is provided in a state of being electrically connected to the 5b and 37a, and the lead-out portion 3 is provided at the center position.
7b is provided with a soldering ground terminal electrode 42 in a state of being electrically connected to 7b, and a lead-out portion 36 is provided at a position on the right side.
The relay ground terminal electrode 43 is provided in a state of being electrically connected to b and 37c. Further, a soldering ground terminal electrode 44 is provided in a position on the far left side of the end face portion on the left side in a state of being electrically connected to the lead-out portion 37d, and in a central position thereof is electrically connected to the lead-out portion 37e. The soldering ground terminal electrode 45 is provided in this state, and the soldering ground terminal electrode 46 is provided at a position on the right side while being electrically connected to the lead portion 37f. Therefore, the strip lines 35 and 36 are connected to the common ground electrode 37 via the relay ground terminal electrodes 41 and 43, respectively.
Electrically connected to.

The stripline filter 31 having the above structure has the same operation as the filter 15 of the first embodiment.
Produce an effect. [Other Embodiments] The strip line filter according to the present invention is not limited to the above embodiments, but can be variously modified within the scope of the gist thereof.

Two or more or three or more soldering ground terminal electrodes and relay ground terminal electrodes may be provided on the end surface of the filter. Alternatively, the surface of the relay ground terminal electrode may be covered with an insulating material so that the solder does not reliably adhere to the relay ground terminal electrode.

[0021]

As is apparent from the above description, according to the present invention, the ground terminal electrode is of two types, that is, the soldering ground terminal electrode and the relay ground terminal electrode. Therefore, the strip line filter is the printed wiring board. For surface mounting on a printed circuit board or the like, the soldering ground terminal electrode is soldered to the circuit conductor provided on the surface of the printed wiring board to be electrically connected and fixed. Since the grounding terminal electrode for soldering has a small electrode area, it is possible to reduce the amount of solder and the spreading area of the solder as compared with the conventional filter. Since solder for mounting does not adhere to the relay ground terminal electrode in this filter, the residual inductance value determined by the distance from the common ground electrode to the strip line via the relay ground terminal electrode is can get. From the above results, it is possible to obtain a stripline filter in which the residual inductance generated in the ground terminal electrode has less variation.

[Brief description of drawings]

FIG. 1 is a first stripline filter according to the present invention.
The assembly perspective view which shows an Example.

FIG. 2 is a perspective view showing an appearance of the stripline filter shown in FIG.

FIG. 3 is a perspective view showing a state in which the stripline filter shown in FIG. 2 is surface-mounted on a printed wiring board.

4 is an equivalent electric circuit diagram of the stripline filter shown in FIG.

FIG. 5 is a graph showing band characteristics of the stripline filter after surface mounting.

FIG. 6 is a second stripline filter according to the present invention.
The assembly perspective view which shows an Example.

FIG. 7 is a perspective view showing the appearance of the stripline filter shown in FIG.

FIG. 8 is a perspective view showing a conventional example.

[Explanation of symbols]

 1, 6 ... Dielectric substrate 2, 3 ... Strip line 4 ... Common ground electrode 9, 11 ... Relay ground terminal electrode 10, 12, 13, 14 ... Soldering ground terminal electrode 15 ... Strip line filter 31 ... Strip line Filters 32, 33, 34 ... Dielectric sheets 35, 36 ... Strip lines 37 ... Common ground electrodes 41, 43 ... Relay ground terminal electrodes 42, 44, 45, 46 ... Soldering ground terminal electrodes

Claims (1)

[Claims] 1. A soldering ground terminal electrode, which comprises at least two resonators and is connected to a common ground electrode of the resonator, is provided on a filter end surface, and a strip line of the resonator is connected to the common ground electrode. The stripline filter, wherein at least two relay ground terminal electrodes are provided on the filter end face so as to be separated from the soldering ground terminal electrodes.