JP3823409B2 - Multilayer filter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer filter used in a high-frequency circuit unit of a mobile phone.
[0002]
[Prior art]
Conventionally, the pass characteristic of this type of multilayer filter has two pass bands, that is, a low-pass band 1 and a high-pass band 2, as shown in FIG. In addition, in order to achieve impedance matching of the high-pass band 2, bandpass filters 31 and 32 shown in FIG. 7 are designed, and only impedance matching is performed so that the respective passbands do not affect each other. The band 3 between the low-pass band 1 and the high-pass band 2 was not considered.
[0003]
[Problems to be solved by the invention]
The problem in the above configuration is that only impedance matching between the low-pass band 1 and the high-pass band 2 is taken into account, and therefore, between the low-pass band 1 and the high-pass band 2. In the band 3, there is a problem that the attenuation of the high frequency circuit portion of the mobile phone occurs because a sufficient amount of attenuation cannot be obtained.
[0004]
Therefore, the present invention attenuates the band 3 between the low-pass band 1 and the high-pass band 2 without deteriorating the insertion loss of the low-pass band 1 and the high-pass band 2 of the filter. The purpose is to obtain a sufficient amount.
[0005]
[Means for Solving the Problems]
In order to achieve this object, the present invention forms an attenuation pole 4 in a band 3 between the low-pass band 1 and the high-pass band 2 so that a larger attenuation can be obtained. Is.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention is a multilayer filter having an attenuation pole in a band between two or more pass bands, and attenuation outside the pass band without deteriorating insertion loss in the pass band. It has the effect that a sufficient amount can be obtained.
[0007]
The invention according to claim 2 is a multilayer filter having two or more pass bands, and has an attenuation pole in the vicinity of the low band side of the low band side pass band to degrade the insertion loss in the pass band. And has an effect that a sufficient attenuation outside the passband can be obtained.
[0008]
The invention according to claim 3 is a multilayer filter having two or more pass bands, and has an attenuation pole in the vicinity of the high band side of the high band side pass band, and deteriorates the insertion loss in the pass band. And has an effect that a sufficient attenuation outside the passband can be obtained.
[0009]
According to a fourth aspect of the present invention, there is provided a dielectric layer having an input / output capacitance pattern having a dielectric having a plurality of strip lines between dielectrics having a plurality of shield patterns and a coupling portion facing the plurality of strip lines. And an end face electrode connected to the input / output capacitance pattern is formed, and a connection pattern for connecting the ground portion of the strip line and the ground electrode is formed, and the direction perpendicular to the strip line length direction of the connection pattern is formed The line width is less than the minimum line width of the strip line, an inductance component is formed between the resonator ground and the ground, the admittance between two or more passbands is set to 0, and an attenuation pole is obtained to obtain an attenuation amount. Is sufficiently obtained.
[0010]
According to a fifth aspect of the present invention, the shape of the ground electrode is set to be equal to or smaller than the minimum line width of the strip line perpendicular to the strip line length direction, an inductance component is formed between the resonator ground portion and the ground, and two or more The admittance between the two passbands is set to 0, and an attenuation pole is obtained to obtain a sufficient attenuation.
[0011]
(Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, 3, and 4.
[0012]
FIG. 1 shows the pass characteristics of a filter in one embodiment of the present invention, FIG. 2 shows a perspective view of the filter in the embodiment, FIG. 3 shows an exploded perspective view thereof, and FIG. 4 shows an equivalent circuit thereof. Yes.
[0013]
As shown in FIG. 3, the present embodiment has a configuration in which ten dielectric layers 10 to 19 are laminated, and shield patterns 11A, 16A, 19A is provided. An input / output capacitance pattern 12A and a loading capacitance pattern 12B are provided on the upper surface of the dielectric 12, an input / output capacitance pattern 14A and an interstage capacitance pattern 14B are provided on the upper surface of the dielectric 14, respectively. Are provided with strip lines 13A and 13D constituting the resonators A and B, respectively. As shown in FIG. 2, end electrodes 20A and 20B connected to the input / output capacitance patterns 12A and 14A are provided on both side surfaces of the multilayer filter.
[0014]
Here, the input / output capacitance patterns 12A and 14A are provided opposite to the strip lines 13A and 13D via the dielectric 12 and the dielectric 13, and constitute the input / output capacitor C1 shown in the equivalent circuit of FIG. Yes. Similarly, the loading capacitance pattern 12B is opposed to the strip lines 13A and 13D via the dielectric 12, thereby forming a loading capacitor C2. Further, the interstage capacitance pattern 14B is interposed via the strip lines 13A and 13D and the dielectric 13. Therefore, the interstage capacitor C3 and the strip lines 13A and 13D are coupled between the lines to constitute an electromagnetic field coupling M.
[0015]
That is, the input / output capacitance patterns 12A and 14A, the strip lines 13A and 13D, the loading capacitance pattern 12B, and the interstage capacitance pattern 14B constitute a band pass filter 21 that forms the low-pass band 1 and similarly on the dielectric 17 The band-pass filter 22 forming the high-pass band 2 is constituted by the input / output capacitance pattern 17A and the loading capacitance pattern 17B, the interstage capacitance pattern 17C, and the strip lines 18A and 18B provided on the dielectric 18. ing.
[0016]
Next, FIG. 1 shows the pass characteristics of a filter according to an embodiment of the present invention. In the band 3 between the low-pass band 1 and the high-pass band 2 that are two pass bands, the attenuation pole is shown. 4 is formed. Further, an attenuation pole 6 is also formed in the low band side vicinity band 5 of the low band side pass band 1 and an attenuation pole 8 is also formed in the high band side vicinity band 7 of the high band side pass band 2. Attenuation amounts are obtained in the bands 3, 5, and 7 other than the band-side passband 1 and the high-band passband 2.
[0017]
Here, the line width in the direction perpendicular to the strip line length direction of the connection pattern 13C connecting the ground portion 13B of the strip lines 13A and 13D constituting the resonators A and B and the ground electrode 20 is set to the minimum of the strip lines 13A and 13D. By making the line width equal to or smaller than the line width, the line impedance of the connection pattern 13C can be increased. Therefore, an inductance L1 as shown in FIG. 4 can be formed, and admittance is generated in the band 3 as shown in FIG. The attenuation pole 4 can be formed by generating a point 23 that becomes inductive from capacitive, that is, a point where the admittance becomes 0, and a larger attenuation amount can be obtained. Moreover, the same effect is acquired by making the shape of the ground electrode 20 of stripline 13A, 13D into the shape which has the dimension below the minimum line | wire width of stripline 13A, 13D.
[0018]
In the present embodiment, a multilayer filter having two pass bands has been described. However, a multilayer filter having a plurality of pass bands can be similarly realized.
[0019]
【The invention's effect】
As described above, the present invention is a multilayer filter having two or more passbands, and has an attenuation pole in a band between the plurality of passbands.
[0020]
With the above configuration, a large amount of attenuation between the passbands can be obtained, so that the signal selectivity is improved and the filter performance can be improved without deteriorating the insertion loss in the passband.
[Brief description of the drawings]
FIG. 1 is a diagram showing pass characteristics in an embodiment of the present invention. FIG. 2 is a perspective view of the embodiment. FIG. 3 is an exploded perspective view of the embodiment. 5] Diagram showing its admittance characteristics [Fig. 6] Diagram showing conventional pass characteristics [Fig. 7] Its equivalent circuit diagram [Explanation of symbols]
1 Low-pass band 2 High-pass band 3 Band 4 Attenuation pole 5 Near-low band 6 Attenuation pole 7 Near-high band 8 Attenuation pole

Claims (2)

A low-pass bandpass filter that forms a low-pass band, and a high-pass band that is connected in parallel with the low-pass bandpass filter and forms a high-pass band that is higher than the low-pass band. A low-frequency bandpass filter including a signal-side end face electrode and a signal-output end face disposed on an end face of the multi-layer filter. An electrode, a plurality of resonators disposed on an arbitrary dielectric layer and having an open end connected to the signal input end surface electrode and the signal output end surface electrode in high frequency, and the optional dielectric layer And an inductive connection pattern connected to the short-circuit end side of the plurality of resonators so as to combine the plurality of resonators, and disposed on the end face of the multilayer filter and the front A ground electrode connected to a connection pattern, and the line width of the connection pattern is different from the line width on the short-circuit end side of the resonator and the line width on the open end side of the resonator. A multilayer filter having a line width equal to or smaller than the minimum line width. A low-pass bandpass filter that forms a low-pass band, and a high-pass band that is connected in parallel with the low-pass bandpass filter and forms a high-pass band that is higher than the low-pass band. A low-frequency bandpass filter including a signal-side end face electrode and a signal-output end face disposed on an end face of the multi-layer filter. An electrode, a plurality of resonators disposed on an arbitrary dielectric layer and having an open end connected to the signal input end surface electrode and the signal output end surface electrode in high frequency, and the optional dielectric layer And a connection pattern connected to a short-circuit end side of the plurality of resonators so as to combine the plurality of resonators, and an end face of the multilayer filter and the connection pattern. An inductive ground electrode connected to the ground, and the line width on the short-circuit end side of the resonator is different from the line width on the open end side of the resonator, and the line width of the ground electrode is The multilayer filter which is below the minimum line width among the line widths of the resonator.

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