JPH10290103A - Dielectric lamination filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the attenuation characteristic at the outside of a pass band by placing a band pass filter and a notch filter in the dielectric lamination filter. SOLUTION: A band pass filter is formed by strip line resonator electrodes 11a, 11b formed on a ceramic sheet 10a, and a notch filter is formed by a notch use strip line resonator electrode 11c. An attenuation pole is formed with a simple structure by adjusting a frequency of the attenuation pole of the notch filter so as to improve the attenuation characteristic at the outside of the filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric laminated filter mainly used for high frequency radio equipment such as a portable telephone.

[0002]

2. Description of the Related Art In recent years, a large number of dielectric filters have been used in wireless devices such as mobile phones, and further reductions in size and performance have been demanded. Hereinafter, an example of the above-described conventional dielectric filter will be described with reference to the drawings.

FIG. 13 is an exploded perspective view of a conventional laminated dielectric filter. In FIG. 13, the ceramic sheet 2
0a are strip line resonator electrodes 21a and 21b.
Are formed on the ceramic sheet 20b.
2a, 22b, 22c and a loading capacitance electrode 22d are formed.

[0004] Strip line resonator electrodes 21a, 21
b is grounded at one end through a common ground electrode 26.
The first strip line resonator electrode 21a includes a first transmission line section 27a having a high characteristic impedance and a second transmission line section 28 having one end opened and having a low characteristic impedance.
a, and the second strip line resonator electrode 21b includes a first transmission line portion 27b having a high characteristic impedance and a second transmission line portion 28b having one end opened and having a low characteristic impedance. Cascade connection. With such a configuration, the entire line length is shorter than a quarter wavelength SIR (Stepped impedance Resonator)
It has a structure.

The first transmission lines 27a and 27b and the second transmission lines 28a and 28b are electromagnetically coupled to each other. Also, the second transmission line 28a,
28b is capacitively coupled via the capacitance electrode 22b. The short-circuit ends of the first transmission lines 27a and 27b are grounded via a common ground electrode 26.

The stripline resonator electrode 21a is capacitively coupled to the capacitance electrode 22a at the open end of the transmission line 28a, and the capacitance electrode 22a is connected to the input / output terminal 24a. The stripline resonator electrode 21b is capacitively coupled to the capacitance electrode 22c at the open end of the transmission line 28b, and the capacitance electrode 22c is connected to the input / output terminal 24b. The stripline resonator electrodes 21a and 21b form a capacitance between the second transmission line portions 28a and 28b and the loading capacitance electrode 22d.

[0007] Shield electrodes 23a and 23b are formed on the dielectric sheets 20c and 20d, respectively. The shield electrodes 23a and 23b, the loading capacitance electrode 22d, and the common ground electrode 26 are grounded by ground terminals 25a and 25b formed by side electrodes. The ceramic sheet 20e for protecting the electrodes and the ceramic sheets 20c, 20a, 20b, 20d on which the respective electrodes are formed are stacked in the order shown in the figure, and the whole is laminated and integrally fired.

FIG. 14 shows an equivalent circuit diagram of a conventional dielectric laminated filter configured as described above. In FIG. 14, an input terminal IN is connected to an open end of the first strip line resonator L1 having a low characteristic impedance via an input / output capacitance Co, is grounded by a loading capacitance CL, and has an inter-stage coupling capacitance. Cc is connected to the open end of the second stripline resonator L2. This connection point is also grounded by the loading capacitance CL and the input / output capacitance C
and o to the output terminal OUT. The other ends of the first and second stripline resonators L1 and L2 having a high characteristic impedance are grounded.

[0009]

However, in such a conventional dielectric multilayer filter, as shown in the transmission characteristic diagram of FIG. 15, only a small amount of attenuation can be obtained by the attenuating pole due to polarization. On the other hand, filters are required to further increase the amount of attenuation outside the passband due to interference from other communication systems, narrowing of transmission / reception intervals of communication systems, and the like.

SUMMARY OF THE INVENTION The present invention has been made to provide a dielectric laminated filter which pursues further attenuation in response to the above requirements.

[0011]

According to a first aspect of the present invention, there is provided a dielectric laminated filter according to the present invention, wherein a band-pass filter and a notch filter are provided in the dielectric laminated filter. It works to improve the damping characteristics. Further, according to claim 2, a cascade connection of a first transmission line portion forming one end of the band-pass filter and having a grounded end and a second transmission line portion having one end opened and having a lower characteristic impedance than the first transmission line portion. Two or more sets of stripline resonators configured and coupled by capacitance between adjacent second transmission lines, a first transmission line portion forming a notch filter, one end of which is grounded, and a first transmission line whose one end is open. One of the stripline resonators for a band-pass filter, which is configured by cascade connection with a second transmission line having a lower characteristic impedance than the line, and is adjacent to the second transmission line.
This configuration includes a set of notch stripline resonators that are coupled to a set of second transmission lines by capacitance.

In this configuration, the first transmission line and the second transmission line of the two or more sets of strip line resonators are respectively electromagnetically coupled to each other, and a capacitance electrode is formed between the second transmission lines. A bandpass filter is formed using capacitive coupling. Further, the bandpass filter is configured such that attenuation poles formed by notch stripline resonators adjacent to the two or more sets of stripline resonators forming the bandpass filter are generated near the pass band of the bandpass filter. It works to improve the out-of-band attenuation characteristics. In the dielectric laminated filter according to the present invention, the attenuation pole of the notch filter is provided near the pass band to improve the attenuation characteristic of the filter. Further, in the dielectric laminated filter of the present invention, in claim 4, any or all of the second transmission line portions of the strip line resonator are grounded by a capacitor to shorten the resonator length. In the dielectric laminated filter according to the present invention, the resonance frequency of the notch stripline resonator is set to an arbitrary frequency, and the frequency of the notch is set to be above or below the pass band to improve the attenuation characteristic outside the band. I have.

Further, the laminated dielectric filter according to the present invention has a configuration in which two sets of notch stripline resonators are provided, and this configuration generates a plurality of attenuation poles due to the notch near the pass band of the filter. And the attenuation outside the pass band can be further increased.

Further, according to the seventh and eighth aspects of the dielectric laminated filter of the present invention, in the configuration of the sixth aspect, the resonance frequency of the notch stripline resonator is arbitrarily set to thereby provide attenuation characteristics outside the pass band. Is a configuration in which the desired characteristics can be obtained. With this configuration, a high-performance dielectric laminated filter can be obtained.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is an exploded perspective view of a dielectric laminated filter according to Embodiment 1 of the present invention, FIG. 2 is an equivalent circuit diagram thereof, and FIG. 3 includes a notch printed on a ceramic sheet. FIG. 4 is a pattern diagram of a strip line resonator electrode, FIG. 4 is a diagram of a capacitor electrode pattern printed on a ceramic sheet, and FIG. In FIG. 1, a strip line resonator electrode 1 is provided on a ceramic sheet 10a.
1a and 11b and a notch stripline resonator electrode 11c are formed, and capacitance electrodes 12a, 12b and 12c and a loading capacitance electrode 12d are formed on the ceramic sheet 10b.

As in the prior art, the strip line resonator electrodes 11a and 11b are grounded at one end through a common ground electrode 16, and are connected to the first strip line resonator electrode 11a.
Is a first transmission line section 17a having a high characteristic impedance.
And the second strip line resonator electrode 11b is connected to the first transmission line portion 17b having a high characteristic impedance and the second transmission line portion 17b having a high characteristic impedance. Are open and are connected in cascade with the second transmission line section 18b having a low characteristic impedance. With such a configuration, the total line length is shorter than a quarter wavelength SIR (Stepped impedance R
esonator) structure.

The first transmission lines 17a and 17b and the second transmission lines 18a and 18b are electromagnetically coupled to each other. Also, the second transmission line 18a,
18b is capacitively coupled via the capacitance electrode 12b. By grounding the short-circuit ends of the first transmission lines 17a and 17b via the common ground electrode 16, it is possible to reduce variations in resonance frequency due to a cutting error when cutting the dielectric sheet.

The strip line resonator electrode 11a is capacitively coupled to the capacitance electrode 12a on the transmission line 18a on the open end side, the capacitance electrode 12a is connected to the input / output terminal 14a, and the strip line resonator electrode 11b is Is capacitively coupled to the capacitance electrode 12c by the transmission line 18b on the open end side, and the capacitance electrode 12c is connected to the input / output terminal 14b.

Stripline resonator electrodes 11a, 11
"b" forms a capacitance between the second transmission line portions 18a and 18b and the loading capacitance electrode 12d. This loading capacitance causes the stripline resonator electrode 11
The lengths of a and 11b can be reduced.

The dielectric multilayer filter of the present invention is different from the prior art in that the notch stripline resonator electrode 11c has a high characteristic impedance from the common ground electrode 16 to the first transmission line section 17c and one end. Are open and the cascade connection with the second transmission line section 18c having a low characteristic impedance is made. The notch stripline resonator electrode 11c is connected to the input / output terminal 1 via the capacitor electrode 12c on the second transmission line 18c on the open end side.
4b and a capacitive coupling electrode 12
and d.

Shield electrodes 13a and 13b are formed on the dielectric sheets 10c and 10d, respectively. The shield electrodes 13a and 13b, the loading capacitance electrode 12d, and the common ground electrode 16 are grounded by ground terminals 15a and 15b formed by side electrodes. The ceramic sheet 10e for protecting the electrodes and the ceramic sheets 10c, 10a, 10b, 10d on which the respective electrodes are formed are stacked in the order shown in the figure, and the whole is laminated and integrally fired.

The ceramic sheet is formed by stacking a plurality of green sheets each having a thickness of several tens of microns, for example, a Bi-Ca-Nb-O-based ceramic or the like as a dielectric material to a required thickness. In FIG. 1, the ceramic sheet 10
a was 0.05 mm, 10b was 0.45 mm, 10c was 0.5 mm, 10d and 10e were each 0.1 mm. The electrode pattern is printed with a highly conductive metal paste such as silver, copper, or gold.

FIG. 2 shows an equivalent circuit diagram of the dielectric laminated filter having such a configuration. In FIG. 2, the input terminal IN is
The loading capacitance CL is connected to the open end of the first strip line resonator L1 via the input / output capacitance Co.
, And is connected to the open end side of the second strip line resonator L2 by an interstage coupling capacitance Cc.
This connection point is also grounded by the loading capacitance CL and connected to the output terminal OUT by the input / output capacitance Co.
The notch capacitance C is connected to the output terminal OUT side of the input / output capacitance Co.
A notch resonator N is connected via n and grounded by a notch loading capacitance CLn. The length of the notch stripline resonator electrode can be shortened by the notch loading capacitance CLn.

The pattern of the strip line resonator electrode including the notch printed on the ceramic sheet 10a of FIG. 3 and the capacitance electrode pattern printed on the ceramic sheet 10b of FIG. 4 were also printed to the dimensions as shown. The dashed line in FIG. 4 shows the pattern of the strip line resonator electrode including the notch.

As a result of the trial production under the above conditions, the input / output capacitance Co was 3.4 pF, and the interstage coupling capacitance Cc was 0.9 pF.
F, loading capacitance CL is 2.2 pF, notch capacitance C
n was 1.8 pF, and the notch loading capacitance CLn was 2.2 pF.

In FIG. 3, the pattern of the three strip line resonators has the same dimensions, but the notch capacitance Cn is interposed in series so that the resonance frequency of the notch strip line resonator is lower than the pass band of the band-pass filter. As a result, the attenuation outside the band of the dielectric multilayer filter can be further increased by the attenuation pole of the notch.

FIG. 5 is a graph showing the transmission characteristics of the dielectric laminated filter of the above embodiment. Compared to FIG. 15 of the conventional example, in FIG. 5, the dip of the attenuation pole due to the notch near 1600 MHz is larger, and it can be seen that the effect of the notch circuit occurs. The loss of f0 at the point of 1,870 MHz is 2.7d.
B, the attenuation pole due to the polarization of the band-pass filter is 1,50
At 2 MHz, the attenuation pole due to the notch was 1,572 MHz.

As described above, according to the present embodiment, the notch stripline resonator electrode 11c is connected to the two-stage band-pass filter including the first stripline resonator electrode 11a and the second stripline resonator electrode 11b. In addition, by making the attenuation pole of this notch stripline resonator close to the attenuation pole of the filter, a dielectric multilayer filter that has a steeper and larger attenuation characteristic than the conventional dielectric multilayer filter can achieve is obtained. Can be obtained.

(Embodiment 2) FIG. 6 shows an equivalent circuit diagram of a dielectric laminated filter according to Embodiment 2 of the present invention, and FIG. 7 shows a pass characteristic diagram thereof. 6 differs from FIG. 2 of the equivalent circuit diagram of the first embodiment in that the notch loading capacitance CLn is not provided, and the pattern shape of the notch resonator N and the loading capacitance CLn of the notch resonator N The frequency of the attenuation pole can be arbitrarily controlled. As a result, as shown in FIG. 7, it is possible to change the band to be on the high frequency side outside the pass band. The attenuation pole of the band-pass filter by the first and second strip line resonators L1 and L2 and the notch strip line The attenuation pole by the resonator N can be provided on the lower side and the upper side of the pass band. The attenuation pole is also adjusted only by adjusting the frequency of the attenuation pole of the notch stripline resonator, and the attenuation is also provided on the higher side of the pass band of the band pass filter. A pole can be formed. Thereby, attenuation poles can be formed on both sides of the pass band of the filter with a simple structure, and the attenuation characteristics outside the pass band can be further improved.

(Embodiment 3) FIG. 8 is an exploded perspective view of a dielectric laminated filter according to Embodiment 3 of the present invention, and FIG. 9 is an equivalent circuit diagram of the dielectric laminated filter of Embodiment 3 of the present invention. FIG. 10 shows the transmission characteristic diagram. In FIG. 9, the second input terminal IN of the equivalent circuit diagram of FIG.
The notch stripline resonator N2 is added, and the resonance is made at a higher frequency than the first notch stripline resonator N1 to further increase the attenuation at a frequency higher than the pass band as shown in FIG. be able to.

(Embodiment 4) FIG. 11 is an equivalent circuit diagram of a dielectric laminated filter according to Embodiment 4 of the present invention, and FIG. 12 is a transmission characteristic diagram thereof. In FIG. 11, a second notch strip line resonator N2 is further added to the input terminal IN of FIG. 2 of the equivalent circuit diagram of the first embodiment.
The notch stripline resonator N1 has an attenuation pole on the lower frequency side than the passband as in the first embodiment due to the notch loading capacitance CLn, and the second notch stripline resonator N2 has a higher frequency than the passband. Since there is an attenuation pole on the side, the amount of attenuation above and below the pass band can be further increased as shown in FIG.

As described above, the attenuation pole due to the notch is provided on the side different from the attenuation pole due to the band-pass filter of the second embodiment, and the number of notch stripline resonators is reduced as in the third and fourth embodiments. By increasing it, the attenuation characteristics outside the pass band can be further improved.

As can be seen from the above embodiments, the notch stripline resonator may be arbitrarily determined as to whether or not a loading capacitance is individually loaded as necessary. The same applies to two or more sets of stripline resonators to be formed.

Although two sets of stripline resonators forming the bandpass filter have been exemplified, three or more sets may be provided. Similarly, two or more sets of notch stripline resonators may be provided as needed. In addition, the numerical values, materials, processing conditions, pattern shapes, and the like illustrated in each embodiment are merely examples, and the present invention is not limited thereto.

[0036]

As described above, according to the dielectric laminated filter of the present invention, the bandpass filter and the notch filter are provided in the dielectric laminated filter to improve the attenuation characteristic outside the pass band. doing. It can be easily realized by using the configuration of the strip line according to the second aspect. According to the third aspect, the attenuation pole by the notch stripline resonator is provided near the pass band of the band-pass filter, and the attenuation characteristic outside the pass band can be improved without increasing the loss of the pass band of the filter.

In the dielectric laminated filter according to the present invention, the resonance frequency of the filter can be reduced without changing the resonator length.

In the dielectric laminated filter according to the present invention, the attenuation pole can be easily set at a desired frequency by controlling the resonance frequency of the notch stripline resonator.

Further, in the laminated dielectric filter of the present invention, by providing two notch stripline resonators, a laminated dielectric filter having further excellent attenuation characteristics can be constructed.

Further, by providing two notch stripline resonators as in claim 7 or claim 8, a plurality of attenuation poles due to the notch can be generated near the pass band of the filter, and the outside of the pass band can be generated. The attenuation characteristics can be improved.

As described above, according to the present invention, a dielectric laminated filter having a simple structure and excellent attenuation characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a dielectric laminated filter according to a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of the same.

FIG. 3 is a pattern diagram of a stripline resonator electrode including a notch printed on a ceramic sheet.

FIG. 4 is a diagram of a capacitor electrode pattern similarly printed on a ceramic sheet.

FIG. 5 is a transmission characteristic diagram of the same dielectric laminated filter.

FIG. 6 is an equivalent circuit diagram of the dielectric laminated filter according to the second embodiment of the present invention.

FIG. 7 is a transmission characteristic diagram of the dielectric multilayer filter according to the second embodiment of the present invention.

FIG. 8 is an exploded perspective view of a dielectric laminated filter according to Embodiment 3 of the present invention.

FIG. 9 is an equivalent circuit diagram of Embodiment 3.

FIG. 10 is a graph showing transmission characteristics according to the third embodiment.

FIG. 11 is an equivalent circuit diagram of a dielectric laminated filter according to a fourth embodiment of the present invention.

FIG. 12 is a graph showing the transmission characteristics of a dielectric multilayer filter according to a fourth embodiment of the present invention.

FIG. 13 is an exploded perspective view of a conventional dielectric laminated filter.

FIG. 14 is an equivalent circuit diagram of the same.

FIG. 15 is a transmission characteristic diagram of the same.

[Explanation of symbols]

10a, 10b, 10c, 10d, 10e Ceramic sheet 11a, 11b Stripline resonator electrode 11c, 11d Notch stripline resonator electrode 12a, 12b, 12c Capacitance electrode 12d Loading capacitance electrode 13a, 13b Shield electrode 14a, 14b Input / output Terminals 15a, 15b Ground terminal 16 Common ground electrode 17a, 17b, 17c, 17d First transmission line section 18a, 18b, 18c, 18d Second transmission line section Co Input / output capacitance Cc Interstage coupling capacitance CL Loading capacitance Cn notch Capacitance CLn Notch loading capacitance L1 Stripline resonator for first filter L2 Stripline resonator for second filter N Notch stripline resonator N1 First notch stripline resonator N2 Strip line resonator for the notch

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hideaki Nakakubo 55-12 Osumi Oji, Tanabe-cho, Tanabe-gun, Kyoto Prefecture Matsushita Nitto Denki Co., Ltd. (72) Inventor Makoto Fujikawa, Tanabe-cho, Kyoto Osumi small character beach 55-12 Matsushita Nitto Electric Co., Ltd.

Claims (8)

[Claims] A resonator forming a band-pass filter and a notch resonator forming a notch filter are provided in a dielectric laminated filter, and a target out-of-band attenuation characteristic of the band-pass filter is the following. A dielectric laminated filter obtained by an attenuation pole by a notch filter. 2. A first transmission line section having one end grounded;
Two or more sets of stripline resonators each having an open end and a cascade connection with a second transmission line unit having a characteristic impedance lower than that of the first transmission line unit; The second transmission lines are electromagnetically coupled to each other, and the adjacent second transmission lines are coupled by a capacitance to form a band-pass filter, and another first transmission line having one end grounded. A set of notch stripline resonances constituting a notch filter constituted by a cascade connection of a line portion and another second transmission line portion having one end opened and having a lower characteristic impedance than the another first transmission line. A second transmission line of the notch stripline resonator, and a second set of two or more sets of stripline resonators forming the bandpass filter. Dielectric laminated filter and transmission line is equal to or bound by volume. 3. The notch stripline resonator according to claim 1, wherein an attenuation pole of the notch stripline resonator is generated near a pass band of a band-pass filter including the two or more sets of stripline resonators. 3. The dielectric laminated filter according to 2. 4. The second transmission line section of any one or all of the two or more sets of stripline resonators and the notch stripline resonator is grounded by a capacitor. Item 3. The dielectric laminated filter according to Item 2. 5. A band-pass filter comprising two or more sets of stripline resonators, wherein the notch stripline resonator is provided with an attenuation pole on a high band side or a low band side thereof. The laminated dielectric filter according to claim 2. 6. A first transmission line section having one end grounded;
One or more sets of stripline resonators each having an open end and a cascade connection with a second transmission line unit having a lower characteristic impedance than the first transmission line unit;
And the second transmission line are electromagnetically coupled to each other, and the adjacent second transmission lines are coupled by a capacitance to form a band-pass filter. Two sets of notches forming a notch filter constituted by a cascade connection of one transmission line portion and another second transmission line portion having one end opened and having a lower characteristic impedance than the another first transmission line. A laminated dielectric filter comprising a stripline resonator. 7. The two notch stripline resonators are provided adjacent to the two or more stripline resonators, respectively, and the one notch stripline resonator is provided with the two or more stripline resonators. 7. The dielectric multilayer filter according to claim 6, wherein an attenuation pole is provided on a low band side of a pass band of the filter including the resonator, and another attenuation pole is provided on a high band side. 8. The two or more sets of stripline resonators are provided adjacent to the two or more sets of stripline resonators, respectively, and the attenuation poles of the notch stripline resonators are provided in the two or more sets of striplines. 7. The filter according to claim 6, wherein the filter comprises a line resonator and is provided on a lower side of a pass band or an attenuation pole is provided on a higher side.
3. The dielectric laminate filter according to item 1.