JP2869912B2 - Stripline filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip line filter used in a communication circuit or the like.

[0002]

2. Description of the Related Art As shown in FIG. 8, a conventional stripline filter 49 has input / output terminal electrodes 50 and 51 provided on left and right end faces, respectively, and grounds on front and back end faces, respectively. Terminal electrodes 52 and 53 were provided. The ground terminal electrodes 52 and 53 are connected to the filter 4
9 and a common ground electrode provided on the bottom surface of the filter 49. The electrode has a wide area enough to cover the front and rear end surfaces substantially entirely. 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 to 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 also
Similarly, they are electrically connected and fixed by solder to circuit conductors provided on the surface of the printed wiring board 55, respectively.

On the other hand, this strip line filter 49
Is used in the high frequency band, the ground terminal electrode 52,
53 generates a residual inductance. The value of this residual inductance varies depending on the amount of the solder 61 and the spread area of the solder 61. Since the ground terminal electrodes 52 and 53 are wide-area electrodes, the amount of the solder 61 and the spread area of the solder 61 greatly vary. 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 fluctuates greatly, causing a large variation in filter characteristics.

An object of the present invention is to provide a strip line filter in which a variation in residual inductance generated in a ground terminal electrode is small.

[0005]

In order to solve the above problems, a strip line filter according to the present invention comprises:
Comprising at least two resonators, each of said resonators
Of the strip line corresponds to the common ground electrode of the resonator.
And direction, are connected to a common ground electrode of the resonator and before
A ground terminal electrode for soldering, which is not connected to the strip line of the resonator, is provided on the end face of the filter, and is separated from the ground terminal electrode for soldering on the end face of the filter .
A plurality of relay ground terminal electrodes, which are terminals, are provided.
One end of the strip line of the vibrator is
Electrically to the common ground electrode via a ground terminal electrode.
It is characterized by being connected .

In the above configuration, two types of ground terminal electrodes, a ground terminal electrode for soldering and a ground terminal electrode for relay, are used. When the strip line filter is surface-mounted on a printed wiring board or the like, the ground terminal for soldering is used. soldered to the circuit conductor provided with electrodes on the surface of the printed wiring board, non
The relay ground terminal electrode is mounting terminals not adhere solder for mounting. 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. In addition, 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 no solder adheres to the relay ground terminal electrode for mounting. Is determined by

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a strip line filter according to the present invention will be described below with reference to the accompanying drawings. [First Embodiment, FIGS. 1 to 5] The first embodiment is a microstrip line filter having two resonators on a dielectric substrate, and a description will be given of a filter functioning as a bandpass filter.

As shown in FIG. 1, a pair of strip lines 2 and 3 are formed on the upper surface of a dielectric substrate 1. The lead portion 2a of the strip line 2 is exposed at the left edge of the dielectric substrate 1, and the lead portion 2b is exposed at a position on the left side of the front edge of the dielectric substrate 1. The lead portion 3a of the strip line 3 is exposed at the right edge of the dielectric substrate 1, and the lead portion 3b is exposed at a position on the right side of the front edge 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 portions 4a, 4b, 4c of the common ground electrode 4 are exposed at the left, center, and right positions of the front edge of the dielectric substrate 1, respectively. Furthermore, the lead portion 4 of the common ground electrode 4
d, 4e, and 4f are exposed at the left, center, and right positions of the back edge of the dielectric substrate 1, respectively. The strip lines 2 and 3 and the common ground electrode 4
For example, a paste such as Ag or Cu is applied 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 adhered to the upper surface of the dielectric substrate 1 with an adhesive to form a strip line filter 15.

As shown in FIG. 2, the strip line filter 15 has an input / output terminal electrode 7 which is electrically connected to the lead 2a of the strip line 2 on the left end face.
Is provided. Similarly, an input / output terminal electrode 8 is provided on the right end face portion while being electrically connected to the lead portion 3a of the strip line 3. A relay ground terminal electrode 9 is provided at a position closer to the left side of the end face on the front side while being electrically connected to the lead portion 2b of the strip line 2 and the lead portion 4a of the common ground electrode 4, and at the center position A grounding terminal electrode for soldering 10 is provided in a state electrically connected to a lead-out portion 4b of the common ground electrode 4, and a lead-out portion 3b of the strip line 3 is provided at a position on the right side.
The relay ground terminal electrode 11 is provided in a state where the relay ground terminal electrode 11 is electrically connected to the lead portion 4c of the common ground electrode 4. Further, a soldering ground terminal electrode 12 is provided at a position on the left side of the end face on the left side, electrically connected to the lead portion 4 d of the common ground electrode 4, and a common ground electrode 4 is provided at the center position. A ground terminal electrode 13 for soldering is provided in a state electrically connected to the lead portion 4e, and the lead portion 4 of the common ground electrode 4 is provided at a position on the right side.
A ground terminal electrode for soldering 14 is provided in a state electrically connected to the terminal 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 by applying and drying a paste of, for example, Ag or Ag-Pd by a printing method, or may be formed 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 precision, and the amount of solder and the spread area of solder at the time of soldering become smaller.

The strip line filter 15 thus obtained is, for example, as shown in FIG.
Used for surface mounting. That is, the input / output terminal electrodes 8 and the ground terminal electrodes 10 for soldering are connected to the circuit conductors 21 and 22 provided on the surface of the printed wiring board 20, respectively.
Are electrically connected to each other by solders 24 and 26 and fixed. Similarly, the input / output terminal electrode 7 and the ground terminal electrodes 12, 13, and 14 for soldering are printed wiring board 20 respectively.
Are electrically connected and fixed to the circuit conductor provided on the surface of the substrate by soldering.

The ground terminal electrodes for soldering 10, 12,.
Since the electrodes 13 and 14 have a small electrode area, the variation in the amount of the solder 26 and the spread area of the solder 26 is small as compared with the conventional filter. Further, since the filter 15 does not have solder attached to the relay ground terminal electrodes 9 and 11 for mounting on the printed wiring board, the filter 15 uses the strip line from the common ground electrode 4 via the relay ground terminal electrodes 9 and 11. 2,
Residual inductance is determined depending on the distance up to 3. Therefore, the value of the residual inductance can be easily predicted at the time of designing, and this residual inductance can be taken in as a circuit component when designing a filter.

FIG. 4 is an equivalent electric circuit diagram of the strip line 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 of the strip line 3 and the inductance of the strip line 3 and the common ground electrode 4 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 dimensions 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 strip line filter 15 having the above configuration. In the figure, solid line A
1 and A3 are each in a reference state (1.2 mm on a circuit conductor of the printed wiring board 20 using a mask having a thickness of 0.10 mm).
(A state where the solder paste is applied to an area of 1.5 mm and the filter 15 is soldered.) The attenuation and insertion loss of the filter 15 are shown. The solid line A2 indicates a comparative state (a thick paste of solder paste is applied to an area of 1.2 mm × 1.5 mm on the circuit conductor of the printed wiring board 20 using a 0.35 mm thick mask, and then the filter 15 is soldered. The state (attenuation) of the filter 15 is displayed. For comparison, the band characteristics of a conventional filter having a large ground terminal electrode are also indicated by dotted lines B1, B2, and B3. Dotted line B
Reference numerals 1 and B3 indicate the attenuation and insertion loss of the filter in the reference state, respectively, and the dotted line B2 indicates the attenuation of the filter in the comparison state. Based on FIG. 5, Table 1 shown below is obtained. Table 1 shows the difference between the filter characteristic in the comparison state and the filter characteristic in the reference state.

[0014]

[Table 1]

In the filter 15 of the first embodiment, the poles a and b located on both sides of the pass band have a difference of 10 to 1 depending on the amount of solder.
It is shifted only by 5 MHz (the attenuation is 1.0 to 1.5
dB difference). 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 shifted by 40 to 50 MHz (a difference of 3.5 to 5.0 dB in attenuation). Therefore,
The filter 15 of the first embodiment can suppress the variation of the filter characteristics to about 30% of the conventional filter.

[Second Embodiment, FIGS. 6 and 7] As shown in FIG. 6, the strip line filter 31 of the second embodiment has a dielectric green sheet 32 having a pair of strip lines 35 and 36 provided on the surface. And a dielectric green sheet 33 provided with a common ground electrode 37 on the surface and a dielectric green sheet 34, stacked, pressed, fired and integrated.

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

As shown in FIG. 7, the integrated strip line 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-out portion 35a. Similarly, an input / output terminal electrode 40 is provided on the right end face in a state of being electrically connected to the lead portion 36a. A drawer 3 is located at the left side of the front end
The relay ground terminal electrode 41 is provided in a state electrically connected to the lead portions 5b and 37a.
A ground terminal electrode for soldering 42 is provided in a state of being electrically connected to 7b, and a lead portion 36 is provided at a position on the right side.
A relay ground terminal electrode 43 is provided in a state electrically connected to the terminals b and 37c. Further, a ground terminal electrode 44 for soldering is provided at a position closer to the left side of the end face on the back side while being electrically connected to the lead-out portion 37d, and is electrically connected to the lead-out portion 37e at a central position. A ground terminal electrode 45 for soldering is provided in this state, and a ground terminal electrode 46 for soldering 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.
Is electrically connected to

The strip line filter 31 having the above-described configuration operates similarly to the filter 15 of the first embodiment.
It works. [Other Embodiments] The strip line filter according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist.

The ground terminal electrode for soldering and the ground terminal electrode for relay may be provided at two or more or three or more at the end face of the filter. Also, the surface of the relay ground terminal electrode may be coated 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, since the ground terminal electrodes are of two types, a ground terminal electrode for soldering and a ground terminal electrode for relay, the strip line filter can be used as a printed wiring board. When surface mounting is performed, the ground terminal electrode for soldering is soldered to a circuit conductor provided on the surface of the printed wiring board to be electrically connected and fixed. Since the ground terminal electrode for soldering has a small electrode area, the amount of solder and the spread area of the solder can be reduced as compared with a conventional filter. In this filter , since the solder for mounting does not adhere to the relay ground terminal electrode which is a non-mounting terminal, it depends on the distance from the common ground electrode to the strip line via the relay ground terminal electrode. The determined residual inductance value is obtained. Based on the above results, a strip line filter with little variation in residual inductance generated in the ground terminal electrode can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a stripline filter according to the present invention.
FIG. 2 is an assembled perspective view showing the embodiment.

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

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

FIG. 4 is an equivalent electric circuit diagram of the strip line filter shown in FIG. 2;

FIG. 5 is a graph showing band characteristics of a strip line filter after surface mounting.

FIG. 6 shows a second example of the stripline filter according to the present invention.
FIG. 2 is an assembled perspective view showing the embodiment.

FIG. 7 is an exemplary perspective view showing the appearance of the stripline filter shown in FIG. 6;

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

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-306003 (JP, A) JP-A-4-306004 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01P 1/203 H01P 1/205 H03H 7/01-075

Claims (1)

(57) [Claims] 1. A semiconductor device comprising : at least two resonators;
Each strip line of the vibrator is connected to the common group of the resonator.
A ground terminal electrode for soldering , which is opposed to the land electrode, is connected to the common ground electrode of the resonator and is not connected to the strip line of the resonator, is provided on the filter end face, and the solder is provided on the filter end face. The relay ground terminal electrode, which is a non-mounting terminal, is separated from the mounting ground terminal electrode.
One end of the strip line of the resonator
The common ground via the relay ground terminal electrode
A stripline filter electrically connected to an electrode .