JP2010199899A - Filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter that broadens a passband without being subject to restriction in respect of manufacture. <P>SOLUTION: The filter is equipped with: a dielectric substrate 1 having a grounding conductors 2a, 2b on both surfaces in a thickness direction; a plurality of conductor pieces 3 that are disposed in parallel with the grounding conductors 2a, 2b and coupled with each other in electromagnetic coupling manner; a power feeding section 4 formed on a conductor piece 31; an output section 5 formed on a conductor piece 36; and grounding through-holes 6 formed in ends of the conductor pieces, of ends of the conductor pieces 3, opposed to each other in pieces adjacent in the juxtapositional direction in an orthogonal direction relative to the juxtapositional direction of the conductor pieces 3, which connects the conductor pieces 3 to the grounding conductors 2a, 2b. The conductor pieces 3 are disposed on two planes having different positions in a thickness direction within the dielectric substrate 1 and being parallel with the grounding conductors 2a, 2b. The planes on which the conductor pieces 3 are disposed are planes adjacent in a thickness direction with respect to the planes on which the conductor pieces adjacent in the juxtapositional direction are formed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an interdigital filter.

  FIG. 11 shows a configuration of a conventional filter. This filter has a thin-film conductor 310 formed on the back surface of a dielectric substrate 1a on which a ground conductor 2a is placed, and the dielectric substrate 1b It has a stripline structure in which the back surface thereof is placed on the conductor portion 310 so as to face the back surface of the dielectric substrate 1a, and the ground conductor 2b is placed on the surface of the dielectric substrate 1b. Here, the dielectric substrate 1 is composed of the dielectric substrates 1a and 1b, and the conductor portion 310 is formed in parallel to the ground conductors 2a and 2b in the dielectric substrate 1.

  The thin-film conductor 310 is composed of rectangular conductor pieces 301 to 304 formed on a plane parallel to the ground conductors 2a and 2b between the dielectric substrates 1a and 1b. ... To 304 are arranged in parallel at predetermined intervals in the width direction of the conductor pieces. The conductor pieces 301 to 304 that are adjacent in the juxtaposed direction are coupled to each other by electromagnetic coupling, and the power feeding portion 4 extends from the conductor piece 301 at one end in the juxtaposed direction, and from the conductor piece 304 at the other end in the juxtaposed direction. The output unit 5 is extended.

  The conductor pieces 301 to 304 are each provided with a grounding through hole 6 at one end in the length direction of the conductor pieces orthogonal to the juxtaposed direction. The conductor pieces 301 to 304 are provided with the grounding through hole 6. Are electrically connected to the ground conductors 2a and 2b. The conductor pieces 301 to 304 have the grounding through hole 6 at the end opposite to the adjacent conductor piece. For example, if the conductor piece 301 forms the grounding through hole 6 at one end, The conductor piece 302 has a grounding through hole 6 at the other end, the conductor piece 303 has a grounding through hole 6 at one end, and the conductor piece 304 has a grounding through hole 6 at the other end. Form. The ends of the conductor pieces 301 to 304 that are not provided with the grounding through hole 6 are open.

  The conductor pieces 301 to 304 operate as a resonator, and are arranged in an interdigital manner with adjacent conductor pieces and electromagnetically coupled to each other, so that the output of the output unit 5 with respect to the input of the power feeding unit 4 passes only in a predetermined frequency band. The band pass filter is configured (see, for example, Patent Document 1).

  FIG. 12 shows pass characteristics of the band-pass filter according to the conventional technique. In FIG. 12, the horizontal axis represents the frequency, the vertical axis represents the attenuation, and shows the characteristics of the bandpass filter with the center frequency f0 = 4 GHz and the original passband B11. In addition, let the range until attenuation falls by 3 dB from the peak value in a center frequency be a pass band.

  FIG. 13 shows a detailed view of the conductor piece 300 (hereinafter referred to as the conductor piece 300 when the conductor pieces 301 to 304 are not distinguished from each other), and the relationship between the dimensions of the conductor piece 300 and the characteristics of the band-pass filter. Is a band-pass filter where the length and width of the rectangular conductor piece 300 and the gap between adjacent conductor pieces are L, W, and G, respectively, and the frequency at which the length L of the conductor piece 300 is ¼ wavelength is obtained. The width W of the conductor piece 300 and the gap G (hereinafter referred to as the horizontal gap G) determine the passband B11.

Japanese Examined Patent Publication No. 61-19122

  In the band-pass filter according to the above-described prior art, as the horizontal gap G is narrowed and the degree of coupling between the conductor pieces 300 is increased, the pass characteristic Y11 spreads from B11a to B11b as shown in FIG. . However, when a general electronic circuit board, LTCC (Low Temperature Co-fired Ceramics) board or the like is used for the dielectric substrate 1, the minimum value of the horizontal gap G is limited to about 0.05 mm due to manufacturing restrictions. It was difficult to further widen the passband.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to provide a filter capable of widening the passband without being restricted in manufacturing.

  According to the first aspect of the present invention, there are provided a dielectric plate having ground conductors on both sides in the thickness direction, and a plurality of conductors arranged in parallel in the dielectric plate in a direction parallel to the ground conductor and coupled to each other by electromagnetic coupling. Each of the plurality of conductor pieces, a power feeding portion formed on one conductor piece in the juxtaposed direction, an output portion formed on the other conductor piece in the juxtaposed direction, and each conductor. Grounding that is formed at the end opposite to the conductor piece adjacent in the juxtaposed direction among both ends of the piece in the direction perpendicular to the juxtaposed direction, and connects each conductor piece to the ground conductors on both sides of the dielectric plate Each conductor piece is disposed on a plurality of surfaces that are different from each other in the thickness direction in the dielectric plate and parallel to the ground conductor, and the surfaces on which the conductor pieces are disposed are arranged in parallel. It is a surface which adjoins the thickness direction with respect to the surface in which the conductor piece adjacent to the direction was formed.

  According to the present invention, the horizontal gap between the conductor pieces can be narrowed not only to a “positive” value but also to a “0” or “negative” value. It is possible to increase the degree of coupling between the two to increase the passband.

  A second aspect of the invention is characterized in that, in the first aspect, the conductor pieces adjacent to each other in the juxtaposed direction are partially overlapped when viewed from the thickness direction.

  According to this invention, the degree of coupling between the conductor pieces can be made stronger, and the passband can be widened.

  According to a third aspect of the present invention, in the first or second aspect, each conductor piece has an end portion where the ground coupling portion of the conductor piece is formed to form the ground coupling portion of the conductor piece adjacent in the parallel arrangement direction. It is shifted and arrange | positioned on each surface in the orthogonal direction with respect to the said parallel arrangement direction so that it may leave | separate from the edge part which is not.

  According to this invention, even if the area where adjacent conductor pieces overlap each other is enlarged, the ground coupling portion at the end of the conductor piece does not interfere with the end of the adjacent conductor piece, and the adjacent conductor The electromagnetic coupling between the pieces can be further strengthened to greatly increase the passband.

  As described above, according to the present invention, there is an effect that it is possible to widen the pass band without being restricted in manufacturing.

FIG. 3 is a partially exploded perspective view showing the configuration of the filter according to the first embodiment. It is side surface sectional drawing which shows a structure same as the above. It is a top view which shows the structure of the conductor piece same as the above. It is a side view which shows the structure of the conductor piece same as the above. (A) (b) It is a top view which shows the case where the horizontal gap between the conductor pieces same as the above is "0" "negative". It is a figure which shows the change of an attenuation characteristic same as the above. (A) (b) It is a perspective view which shows the state where the horizontal gap between adjacent conductor pieces is large. (A) (b) It is a perspective view which shows the state which narrowed the horizontal gap between adjacent conductor pieces. It is a perspective view which shows a partial structure of the filter of Embodiment 2. It is a top view which shows the structure of the conductor piece same as the above. It is a partially exploded perspective view which shows the structure of the conventional filter. It is a figure which shows an attenuation characteristic same as the above. It is a top view which shows the structure of the conductor piece same as the above. It is a figure which shows the change of an attenuation characteristic same as the above.

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

(Embodiment 1)
FIG. 1 and FIG. 2 show the configuration of the filter of the present embodiment. This filter has a thin film in a dielectric substrate 1 in which a ground conductor 2a is placed on one surface and a ground conductor 2b is placed on the other surface. The conductor portion 30 is formed in parallel with the ground conductors 2 a and 2 b in the dielectric substrate 1. Here, FIG. 1 shows a state in which the dielectric substrate 1 is cut in the surface direction. The dielectric substrate 1 has a single-layer structure in which one surface side and the other surface side are integrally formed, or a plurality of layers are stacked. Any of the laminated structure combined may be sufficient.

  The thin film-like conductor portion 30 is composed of rectangular conductor pieces 31 to 36 formed in the dielectric substrate 1, and the conductor pieces 31 to 36 are arranged in the thickness direction of the dielectric substrate 1 (surface of the dielectric substrate 1. As viewed from the normal direction), the conductor pieces are arranged at predetermined intervals in the width direction of the conductor pieces. The conductor pieces 31 to 36 adjacent in the juxtaposed direction are coupled to each other by electromagnetic coupling, and the power feeding portion 4 extends from the conductor piece 31 at one end in the juxtaposed direction, and from the conductor piece 36 at the other end in the juxtaposed direction. The output unit 5 is extended.

  Further, in the dielectric substrate 1, two surfaces S1 and S2 that are parallel to the surfaces of the ground conductors 2a and 2b and have different positions (levels) in the thickness direction in the dielectric substrate 1 (FIG. 2). Is virtually provided. The two surfaces S1 and S2 are separated by a gap D (hereinafter referred to as a vertical gap D) in the thickness direction in the dielectric substrate 1, and the conductor pieces 32, 34, and 36 are dielectrics on which the ground conductor 2a is placed. The conductor pieces 31, 33, and 35 are disposed on the surface S2 located on the other surface side of the dielectric substrate 1 on which the ground conductor 2b is placed. Yes. That is, the conductor pieces 31 to 36 are juxtaposed in the surface direction in the dielectric substrate 1 while being alternately shifted in the thickness direction of the substrate at a vertical gap D interval.

  The conductor pieces 31 to 36 are each provided with a grounding through hole 6 (ground coupling portion) at one end in the length direction of the conductor pieces orthogonal to the parallel arrangement direction. The dielectric substrate 1 is inserted in the thickness direction and connected to the ground conductors 2a and 2b, and the conductor pieces 31 to 36 are electrically connected to the ground conductors 2a and 2b through the grounding through holes 6. . The conductor pieces 31 to 36 have a grounding through hole 6 at the end opposite to the adjacent conductor piece. For example, if the conductor piece 31 has the grounding through hole 6 at one end, The conductor piece 32 forms the grounding through hole 6 at the other end, the conductor piece 33 forms the grounding through hole 6 at one end, and the conductor piece 34 forms the grounding through hole 6 at the other end. The conductor piece 35 forms the grounding through hole 6 at one end, and the conductor piece 36 forms the grounding through hole 6 at the other end. The ends of the conductor pieces 31 to 36 where the grounding through hole 6 is not provided are open.

  The conductor pieces 31 to 36 operate as a resonator and are arranged in an interdigital manner with adjacent conductor pieces so as to be electromagnetically coupled to each other so that the output of the output unit 5 with respect to the input of the power feeding unit 4 passes only in a predetermined frequency band. A band pass filter is configured.

  FIG. 3 shows a detailed view of the conductor piece 3 (hereinafter referred to as the conductor piece 3 when the conductor pieces 31 to 36 are not distinguished from each other). The relationship between the dimensions of the conductor piece 3 and the characteristics of the bandpass filter is as follows. When the length and width of the rectangular conductor piece 3 and the gap between adjacent conductor pieces are L, W, and G, the frequency at which the length L of the conductor piece 3 is ¼ wavelength is the center of the bandpass filter. The frequency f0 and the width W of the conductor piece 3 and the gap G (hereinafter referred to as the horizontal gap G) determine the passband B1.

  Then, the narrower the horizontal gap G and the stronger the coupling degree between the conductor pieces 3, the wider the pass band B1. However, when a general electronic circuit board, LTCC (Low Temperature Co-fired Ceramics) board or the like is used for the dielectric substrate 1, the minimum value of the horizontal gap G is limited to about 0.05 mm due to manufacturing restrictions. The limit of the horizontal gap G has been the limit of the conventional passband.

  However, in the present embodiment, as shown in FIG. 4, the arrangement of the conductor pieces 3 when viewed from the surface direction of the dielectric substrate 1 is alternately shifted in the thickness direction of the dielectric substrate 1 by the vertical gap D interval. In this configuration, the electromagnetic coupling between the adjacent conductor pieces 3 is made stronger.

  Specifically, as shown in FIGS. 5A and 5B, the horizontal gap G between the conductor pieces 3 may be narrowed not only to a “positive” value but also to a “0” or “negative” value. Is possible. If the horizontal gap G between the conductor pieces 3 is set in the negative direction and the adjacent conductor pieces 3 overlap each other when viewed from the thickness direction of the dielectric substrate 1, the larger this overlapping region, the stronger the electromagnetic coupling. The pass band B1 can be made wider. FIG. 6 shows the pass characteristic Y1 of the band-pass filter of the present embodiment when the horizontal gap G is changed from “0” to a “negative” value. The horizontal gap G changes in the negative direction. As the region where the adjacent conductor pieces 3 overlap each other as viewed from the thickness direction of the dielectric substrate 1 increases, the degree of coupling increases, and the passband B1 extends to B1a to B1b, resulting in a wider band. In addition, although the pass characteristic Y11 obtained by narrowing the horizontal gap G between the conductor pieces 3 by the conventional band pass filter is also shown in FIG. 6, it has a narrower band than the pass characteristic Y1 of this embodiment. Yes.

  Thus, in the filter of this embodiment, the horizontal gap G between the adjacent conductor pieces 3 can be made narrower than the conventional one without being restricted in manufacturing, and the degree of coupling between the conductor pieces 3 can be made stronger. The passband is widened.

(Embodiment 2)
In the filter of the first embodiment, the horizontal gap G between the adjacent conductor pieces 3 is set in the negative direction, and the pass band B1 becomes larger as the region where the adjacent conductor pieces 3 overlap each other when viewed from the thickness direction of the dielectric substrate 1 is larger. Become wider. However, when the area where the adjacent conductor pieces 3 overlap each other is enlarged, there is a problem that the grounding through hole 6 at the end of the conductor piece 3 interferes with the end of the adjacent conductor piece 3 at a certain time. To do.

  For example, as shown in FIGS. 7A and 7B, when the horizontal gap G between the adjacent conductor pieces 3 is large and the overlapping area of the conductor pieces 3 is small, the grounding through at the end of the conductor piece 3 is used. There is no possibility that the hole 6 interferes with the end portion of the adjacent conductor piece 3. However, as shown in FIGS. 8A and 8B, when the horizontal gap G between the adjacent conductor pieces 3 is narrowed and the overlapping area of the conductor pieces 3 is increased, the grounding through at the end of the conductor piece 3 is increased. The hole 6 interferes with the end portion of the adjacent conductor piece 3.

  Therefore, in this embodiment, as shown in FIGS. 9 and 10, each conductor piece 3 has an end portion where the grounding through hole 6 of the conductor piece is formed, and the grounding through hole 6 of the adjacent conductor piece 3. Are arranged to be shifted in the direction orthogonal to the juxtaposition direction (the length direction of the conductor pieces 3) so as to be away from the end where the conductors are not formed.

  Specifically, the conductor pieces 31, 33, and 35 are arranged so as to be shifted to one end side where the grounding through-hole 6 is formed on the surface S 2, and the conductor pieces 32, 34, and 36 are arranged on the surface S 1. The grounding through-hole 6 is arranged so as to be shifted to the other end side where the grounding through-hole 6 is formed, and the grounding through-hole 6 of the conductor pieces 31, 33, and 35 and the grounding through-hole 6 of the conductor pieces 32, 34, and 36 are arranged. The conductor pieces 31 to 36 are arranged so as to deviate from each other.

  Therefore, even if the area where the adjacent conductor pieces 3 overlap each other is enlarged, the grounding through hole 6 at the end of the conductor piece 3 does not interfere with the end of the adjacent conductor piece 3 and is adjacent. The electromagnetic coupling between the conductor pieces 3 can be further strengthened, and the pass band can be greatly widened.

  In the present embodiment, the length L ′ at which the adjacent conductor pieces 3 overlap each other determines the center frequency f0 of the bandpass filter, and the frequency at which the length L ′ is a quarter wavelength is the bandpass filter. Becomes the center frequency f0. Note that the width W of the conductor piece 3 and the horizontal gap G determine the passband B1 as in the first embodiment.

DESCRIPTION OF SYMBOLS 1 Dielectric board 2a, 2b Grounding conductor 3 (31-36) Conductor piece 4 Feeding part 5 Output part 6 Grounding through hole

Claims (3)

A dielectric plate with ground conductors on both sides in the thickness direction;
A plurality of conductor pieces arranged in parallel in a dielectric plate in a direction parallel to the ground conductor and coupled to each other by electromagnetic coupling;
A power feeding portion formed on one end of the plurality of conductor pieces in the juxtaposed direction,
An output portion formed on the conductor piece at the other end in the juxtaposition direction among the plurality of conductor pieces;
Of the two ends of each conductor piece in the direction perpendicular to the parallel arrangement direction, it is formed at the end opposite to the conductor piece adjacent to the parallel arrangement direction, and each conductor piece is connected to the ground conductors on both sides of the dielectric plate And a ground joint
Each conductor piece is disposed on a plurality of surfaces that are different from each other in the thickness direction in the dielectric plate and parallel to the ground conductor, and the surface on which each conductor piece is disposed is an adjacent conductor piece in the juxtaposition direction. A filter that is adjacent to the surface on which the is formed in the thickness direction.   2. The filter according to claim 1, wherein the conductor pieces adjacent to each other in the juxtaposed direction overlap each other as viewed from the thickness direction.   Each conductor piece has the end on which the ground coupling portion of the conductor piece is formed on each surface so that the end of the conductor piece adjacent to the parallel arrangement direction is away from the end on which the ground coupling portion is not formed. The filter according to claim 1 or 2, wherein the filter is arranged so as to be shifted in a direction orthogonal to the juxtaposed direction.

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