JP2012209826A - Multiple frequency band passing filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple frequency band passing filter which has small size and good attenuation characteristics, and facilitates manufacturing.SOLUTION: First and second band passing filter portions 4A and 4B which are configured by using a block 2 of a dielectric are included. The first band passing filter portion includes: a first through-hole group 40A formed from a first surface 21 to a second surface 22, and arranged along a third surface 23; a first inner conductor 42A; an outer conductor 43 formed on an outer surface of the block; and a first coupling electrode 44A. So does the second band passing filter portion. On the first surface, first and second common electrodes 61 and 62 respectively coupled to resonators of one end portion and the other end portion of the first and second band passing filter portions are formed. On the block, a slit 8 interposed between the first and second through-hole groups, formed from the first surface to the second surface, and extending generally in parallel with the third surface and a forth surface 24 is formed. On an inner surface of the slit, a shield conductor 9 connected to the outer conductor formed on the second surface is formed.

Description

  The present invention relates to a bandpass filter used in a high frequency band such as a microwave band, in which a plurality of resonators are formed in a dielectric block. More specifically, the present invention relates to a multi-frequency bandpass filter that is inserted between a set of input / output terminals and passes a plurality of frequency bands.

  The multi-frequency bandpass filter of the present invention is suitable as a two-frequency bandpass filter connected to a two-frequency band antenna of a mobile phone, for example.

  2. Description of the Related Art Conventionally, mobile communication devices such as mobile phones are configured so that signals transmitted and received by an antenna can be transmitted and received only in a desired frequency band through a filter such as a band pass filter.

  In recent years, mobile phones capable of supporting a plurality of communication systems have been proposed. In such a mobile phone, a plurality of high frequency bands can be transmitted and received by one antenna, and a desired frequency band is selected and used as necessary using a filter.

  Regarding filters for multiple frequency bands, there is the following technical background. That is, in recent years, with the development of electronic equipment, the characteristics of amplifiers have become very wide, and for example, two frequency bands can be amplified with the same amplifier. Therefore, in communication equipment using such an amplifier, if the same kind of parts used in different frequency bands can be shared, the number of parts constituting the communication equipment can be reduced, and at the same time, the size of the communication equipment can be reduced. Is preferable.

  In order to adapt to two frequency band systems and independently perform signal processing on different frequency bands, it is necessary to satisfactorily attenuate frequency bands outside the desired frequency band. A structure as described in Patent Document 1 has been proposed as a band-pass filter that enables signal processing by separating two frequency bands.

  A structure as described in Patent Document 2 has been proposed as another bandpass filter that enables signal processing by separating two frequency bands.

JP-A-8-237003 JP 2002-252501 A

  However, the technique described in Patent Document 1 that uses a waveguide or a cavity resonator has a complicated structure and becomes large in size, and thus there has been a demand for downsizing in mobile communication devices such as mobile phones in recent years. I can't meet. On the other hand, in the technique described in Patent Document 1 and using a microstrip line, both filters are coupled to each other, and good attenuation cannot be obtained.

  Further, in the technique described in Patent Document 2 in which a dielectric is filled between the inner conductor and the outer conductor in order to reduce the size of the structure, a partition plate for partitioning the two band pass portions is disposed. As a result, the number of parts increases. Moreover, when manufacturing the bandpass filter described in Patent Document 2, the ceramics and organic materials are filled and solidified between the inner conductor and the outer conductor, or a plurality of ceramic green sheets are pressed. A complicated process such as sintering is required, which makes the manufacturing complicated and increases the cost. That is, the technique described in Patent Document 2 cannot use an inexpensive and low-loss dielectric block.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-frequency bandpass filter that is small in size, good in attenuation characteristics, and easy to manufacture.

According to the present invention, the object as described above is achieved.
A first surface and a second surface that are substantially parallel to each other; and an outer surface that includes a third surface and a fourth surface that are substantially orthogonal to the first surface and the second surface and substantially parallel to each other. Having a dielectric block;
A first bandpass filter unit and a second bandpass filter unit configured using the dielectric block;
A multi-frequency bandpass filter comprising
The first band pass filter unit is:
A first through hole group comprising a plurality of first through holes formed in the dielectric block from the first surface to the second surface and arranged along the third surface;
A first inner conductor formed on the inner surface of the first through hole;
An outer conductor formed on an outer surface of the dielectric block excluding the first surface;
A first coupling electrode extending from the first inner conductor on the first surface and coupling resonators formed corresponding to the first through holes;
Comprising
The second bandpass filter unit is
A second through hole group comprising a plurality of second through holes formed in the dielectric block from the first surface to the second surface and arranged along the fourth surface;
A second inner conductor formed on the inner surface of the second through hole;
An outer conductor formed on an outer surface of the dielectric block excluding the first surface;
A second coupling electrode extending from the second inner conductor on the first surface and coupling resonators formed corresponding to the second through holes;
Comprising
The first surface includes a first common electrode coupled to a resonator at one end of the first bandpass filter unit and a resonator at one end of the second bandpass filter unit, and the first band. A resonator at the other end of the pass filter section and a second common electrode coupled to the resonator at the other end of the second band pass filter section are formed,
The dielectric block is interposed between the first through-hole group and the second through-hole group and is formed from the first surface to the second surface, and the third surface and the second surface A slit extending substantially parallel to the surface of 4 is formed,
On the inner surface of the slit, a shield conductor connected to the outer conductor formed on the second surface is formed.
A multi-frequency bandpass filter, characterized by
Is provided.

  In one aspect of the present invention, the dielectric block has the same cross-sectional shape substantially parallel to the first surface and the second surface from the first surface to the second surface. . In one aspect of the present invention, the dielectric block is made of a dielectric ceramic. In one aspect of the present invention, an electromagnetic shield cover is provided so as to substantially cover the first surface.

  According to the present invention, there is provided a multi-frequency bandpass filter that is small, has good attenuation characteristics, and is easy to manufacture.

1 is a schematic perspective view showing a first embodiment of a multi-frequency bandpass filter according to the present invention. It is a typical sectional view of a multiple frequency band pass filter of a 1st embodiment. It is a typical perspective view which shows 2nd Embodiment of the multiple frequency bandpass filter by this invention. It is a typical disassembled perspective view of the multiple frequency bandpass filter of 2nd Embodiment. FIG. 4 is a schematic partial cross-sectional view taken along arrow A in FIG. 3. FIG. 4 is a schematic cross-sectional view taken in the direction of arrow B in FIG. 3. It is a figure which shows an example of the frequency characteristic of the multiple frequency bandpass filter of 2nd Embodiment.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic perspective view showing a first embodiment of a multi-frequency bandpass filter according to the present invention. FIG. 2 is a schematic cross-sectional view of the multi-frequency bandpass filter of the present embodiment. In the present embodiment, the multiple frequency bandpass filter is a two-frequency bandpass filter.

The two-frequency bandpass filter of this embodiment has a dielectric block 2. The material of the dielectric block 2, for example, can use a dielectric ceramic, in particular a relative dielectric constant epsilon _r can be used forsterite ceramic of about 10.

  The dielectric block 2 has a first surface 21 and a second surface 22 that are substantially parallel to each other. The dielectric block 2 further includes a third surface 23 and a fourth surface 24 that are substantially orthogonal to the first surface 21 and the second surface 22 and substantially parallel to each other. The dielectric block 2 further includes a fifth surface 25 and a sixth surface that are substantially orthogonal to the first surface 21 and the second surface 22 and the third surface 23 and the fourth surface 24 and substantially parallel to each other. 26. Thus, the outer surface of the dielectric block 2 includes the first surface 21 to the sixth surface 26.

  The first surface 21 is an upper surface. The second surface 22 is a lower surface, and is located opposite to and substantially parallel to the first surface 21 with a distance (height) H from the first surface 21. The third surface 23 and the fourth surface 24 are a pair of side surfaces and are located in opposite directions with a distance (width) W therebetween. The fifth surface 25 and the sixth surface 26 are a pair of end surfaces, and are located in opposite directions with a distance (length) L therebetween. The dimensions of the dielectric block 2 can be appropriately set according to required characteristics. For example, H is 4 mm to 25 mm, L is 60 mm to 130 mm, and W is 25 mm to 60 mm. L is preferably within 3W. For example, the length L is about 70 mm, the width W is about 35 mm, and the height H is about 9 mm.

  The two-frequency bandpass filter includes a first bandpass filter unit 4A and a second bandpass filter unit 4B configured using the dielectric block 2.

  The first band pass filter portion 4A is formed in the dielectric block 2 from the first surface 21 to the second surface 22 and includes a plurality of first through holes 41A arranged along the third surface 23. A first through hole group 40A, a first inner conductor 42A formed on the inner surface of the first through hole 41A, an outer conductor 43 formed on the outer surface of the dielectric block 2 excluding the first surface 21, A first coupling electrode 44A extending from the first inner conductor 42A on the first surface 21 and coupling quarter-wave resonators formed corresponding to the first through holes 41A. .

  Similarly, the second band-pass filter portion 4B is formed in the dielectric block 2 from the first surface 21 to the second surface 22, and has a plurality of second through holes arranged along the fourth surface 24. A second through hole group 40B composed of 41B, a second inner conductor 42B formed on the inner surface of the second through hole 41B, and an outer conductor 43 formed on the outer surface of the dielectric block 2 excluding the first surface 21. And a second coupling electrode 44B extending from the second inner conductor 42B on the first surface 21 and coupling quarter-wave resonators formed corresponding to the second through holes 41B. Comprising.

  In the dielectric block 2, a slit 8 is formed between the first through hole group 40A and the second through hole group 40B and formed from the first surface 21 to the second surface 22. The slit 8 extends substantially in parallel with the third surface 23 and the fourth surface 24 and has a through-hole shape having a width D as a whole. The width D can be set as appropriate, and is, for example, 3 mm to 15 mm. As an example, the width D is 4 mm. A shield conductor 9 connected to the outer conductor 43 formed on the second surface 22 is formed on the inner surface of the slit 8. The longitudinal direction of the slit 8 (the arrangement direction of the first through holes 41A arranged along the third surface 23: the arrangement direction of the second through holes 41B arranged along the fourth surface 24) The length (L ′) is, for example, 50 mm to 115 mm.

  The slit 8 has a resonator (a resonator at a non-end portion) excluding the resonators at one end and the other end of the first through-hole group 40A in the length direction of the dielectric block 2, and the second through-hole group 40B. In order to prevent coupling with the other resonators, the resonators excluding the resonators at one end and the other end of the second through-hole group 40B in the longitudinal direction of the dielectric block 2 (non-end portions) Of the first through-hole group 40A is prevented from being coupled with the resonator. That is, the slit 8 is disposed so as to completely include a length direction region covering the resonators at the non-end portions of the first through hole group 40A and the second through hole group 40B.

  The dielectric block 2 has the same cross-sectional shape substantially parallel to the first surface 21 and the second surface 22 from the first surface 21 to the second surface 22, and is shown in FIG. Become. Such a dielectric block 2 can be manufactured by compressing and firing ceramic powder in a mold. The shape of the cross section substantially parallel to the first surface 21 and the second surface 22 is the same from the first surface 21 to the second surface 22, so that the dielectric block can be easily formed by uniaxial compression molding. 2 can be manufactured.

  Note that a coupling adjustment electrode connected to the outer conductor 43 and / or the shield conductor 9 may be attached to the first surface 21 of the dielectric block 2. In the first bandpass filter unit 4A, the first coupling electrode 44A and the coupling adjustment electrode provide the required coupling between the resonators adjacent to each other, thereby forming a first bandpass filter. Similarly, in the second band-pass filter unit 4B, the required coupling between the resonators adjacent to each other is achieved by the second coupling electrode 44B and the coupling adjustment electrode, thereby forming a second band-pass filter.

  The first band pass filter unit 4A and the second band pass filter unit 4B formed as described above pass different frequency bands. Specifically, by forming the first coupling electrode 44A larger than the second coupling electrode 44B, the first band-pass filter unit 4A is a low-pass filter and the second band-pass filter unit 4B is a high-pass filter. It can be.

  The first surface 21 includes a first common electrode 61 coupled to a resonator at one end of the first bandpass filter unit 4A and a resonator at one end of the second bandpass filter unit 4B, and a first band A second common electrode 62 coupled to the resonator at the other end of the pass filter unit 4A and the resonator at the other end of the second band pass filter unit 4B is formed. These first common electrode 61 and second common electrode 62 are each connected to a set of input / output terminals of an external circuit.

  According to this embodiment, since a dielectric block is used, it is possible to provide an integrated multi-frequency bandpass filter that is easy to downsize, has good attenuation characteristics, is easy to manufacture, and is low in cost. it can.

  FIG. 3 is a schematic perspective view showing a second embodiment of the multi-frequency bandpass filter according to the present invention. FIG. 4 is a schematic exploded perspective view of the multi-frequency bandpass filter of the present embodiment. FIG. 5 is a schematic partial cross-sectional view taken along arrow A in FIG. 6 is a schematic cross-sectional view taken in the direction of arrow B in FIG. In the present embodiment, the multiple frequency bandpass filter is a two-frequency bandpass filter. 3 to 6, the same members or parts as those in FIGS. 1 and 2 are denoted by the same reference numerals.

  This embodiment is basically the same as the first embodiment except that an electromagnetic shield cover is provided.

  However, a connection conductor 91 extending from the shield conductor 9 is formed on the first surface 21 of the dielectric block 2.

  The electromagnetic shield cover 10 is disposed so as to substantially cover the first surface 21 of the dielectric block 2. Specifically, the electromagnetic shield cover 10 is arranged so as to be separated from the open region (region part where no conductor is formed) of the first surface 21 of the dielectric block 2 and to cover the open region, For example, it consists of a metal plate having a thickness of about 0.3 mm to 0.8 mm. The electromagnetic shield cover 10 may be made of a conductive material. For example, iron-based metal, particularly iron whose surface is tin-plated can be used. The electromagnetic shield cover 10 is joined to the outer conductor 43 attached to the third surface 23 to the sixth surface 26 of the dielectric block 2 and the connection conductor 91 attached to the first surface 21 of the dielectric block 2. ing. For this joining, for example, solder or a conductive adhesive is used. Thereby, the electromagnetic wave leakage from the 1st surface (open area) 21 is suppressed, the favorable electromagnetic shielding effect is exhibited, and a much higher electrical characteristic can be acquired.

  Furthermore, since the electromagnetic shield cover 10 is joined via the connection conductor 91, attachment is easy even when the width D of the slit 8 is narrow, contributing to downsizing. Of course, when the slit width D has a margin, the electromagnetic shield cover 10 may be directly joined to the shield conductor 9.

  As shown in FIG. 5, the inner conductor of the coaxial connection cable 12 is connected to the first common electrode 61, and the two-frequency bandpass filter is connected to the first input / output circuit by the connection cable 12. Connected to terminal. The outer conductor of the connection cable 12 is connected to, for example, the electromagnetic shield cover 10. The same applies to the second common electrode 62.

  The method for connecting the two-frequency bandpass filter and the external circuit is not limited to the above, and other known methods may be used as necessary, using a coaxial connector or using a lead pin. What was there is good.

  FIG. 7 shows an example of frequency characteristics of the multi-frequency bandpass filter of the present embodiment. The horizontal axis represents frequency and the vertical axis represents attenuation. The pass band (4A ′) of the low-pass filter configured by the first band-pass filter unit 4A is approximately 1.7 GHz to 1.8 GHz, and the high-pass filter configured by the second band-pass filter unit 4B. The passband (4B ′) is about 1.9 GHz to 2 GHz. From FIG. 7, it can be seen that in the frequency bands other than these pass bands, radio waves leaking from the first surface 21 are suppressed and attenuated satisfactorily.

  Although the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the number of resonators and the arrangement interval constituting the first band pass filter unit 4A and the second band pass filter unit 4B can be changed as appropriate. The number of resonators and the cross-sectional shape of the through hole may be different between the first band pass filter unit 4A and the second band pass filter unit 4B. The material of each member is not limited to that described in the embodiment.

2 Dielectric block 21 1st surface 22 2nd surface 23 3rd surface 24 4th surface 25 5th surface 26 6th surface 4A 1st bandpass filter part 40A 1st through-hole group 41A 1st Through hole 42A first inner conductor 43 outer conductor 44A first coupling electrode 4B second bandpass filter section 40B second through hole group 41B second through hole 42B second inner conductor 44B second coupling electrode 61 first common electrode 62 Second common electrode 8 Slit 9 Shield conductor 91 Connection conductor 10 Electromagnetic shield cover 12 Coaxial connection cable

Claims (4)

A first surface and a second surface that are substantially parallel to each other; and an outer surface that includes a third surface and a fourth surface that are substantially orthogonal to the first surface and the second surface and substantially parallel to each other. Having a dielectric block;
A first bandpass filter unit and a second bandpass filter unit configured using the dielectric block;
A multi-frequency bandpass filter comprising
The first band pass filter unit is:
A first through hole group comprising a plurality of first through holes formed in the dielectric block from the first surface to the second surface and arranged along the third surface;
A first inner conductor formed on the inner surface of the first through hole;
An outer conductor formed on an outer surface of the dielectric block excluding the first surface;
A first coupling electrode extending from the first inner conductor on the first surface and coupling resonators formed corresponding to the first through holes;
Comprising
The second bandpass filter unit is
A second through hole group comprising a plurality of second through holes formed in the dielectric block from the first surface to the second surface and arranged along the fourth surface;
A second inner conductor formed on the inner surface of the second through hole;
An outer conductor formed on an outer surface of the dielectric block excluding the first surface;
A second coupling electrode extending from the second inner conductor on the first surface and coupling resonators formed corresponding to the second through holes;
Comprising
The first surface includes a first common electrode coupled to a resonator at one end of the first bandpass filter unit and a resonator at one end of the second bandpass filter unit, and the first band. A resonator at the other end of the pass filter section and a second common electrode coupled to the resonator at the other end of the second band pass filter section are formed,
The dielectric block is interposed between the first through-hole group and the second through-hole group and is formed from the first surface to the second surface, and the third surface and the second surface A slit extending substantially parallel to the surface of 4 is formed,
On the inner surface of the slit, a shield conductor connected to the outer conductor formed on the second surface is formed.
A multi-frequency bandpass filter characterized by the above.   The dielectric block has the same cross-sectional shape substantially parallel to the first surface and the second surface from the first surface to the second surface. The multi-frequency bandpass filter according to 1.   The multi-frequency bandpass filter according to claim 1 or 2, wherein the dielectric block is made of a dielectric ceramic.   The multi-frequency bandpass filter according to any one of claims 1 to 3, further comprising an electromagnetic shield cover arranged to substantially cover the first surface.

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