JP5480037B2 - BANDPASS FILTER, RADIO COMMUNICATION MODULE HAVING THE SAME, AND RADIO COMMUNICATION DEVICE - Google Patents

Description

  The present invention relates to a band-pass filter, and more particularly to a band-pass filter having two pass bands, a wireless communication module and a wireless communication device including the same.

  In the field of wireless communication, for example, in a radio wave transmitter / receiver, it is necessary to effectively extract radio waves to be transmitted and radio waves to be received, and characteristics of a filter that allows a signal in a specific frequency band to pass from an input high frequency signal Is important. In addition, radio waves used for wireless communication are not limited and can be used. For example, a frequency band that can be used for each application is set. A filter is an indispensable element for using a high-frequency signal in a set frequency band. In order to make maximum use of the usable frequency band, a steep characteristic change is required at the boundary between the frequency band to be passed and the frequency band not to be passed. This steep characteristic change is obtained by attenuating the signal intensity in a frequency band that is not allowed to pass. The wider the frequency band (pass band) to be passed, the more difficult it is to attenuate sharply outside the pass band.

  One of the wireless communication systems that use a wide frequency band, that is, a wide pass band for the filter, is a UWB (Ultra wide band) system. In addition to being able to perform ultrahigh-speed communication at a short distance, the UWB system can effectively realize many applications such as position measurement and radar. However, since the pass band is wide, the filter used requires high performance. Furthermore, in the UWB system, the usable frequency band is separated into a relatively low frequency band and a relatively high frequency band. Therefore, in order to use all the frequency bands, the low frequency band is passed. There are two types of band-pass filters: a band-pass filter and a band-pass filter for passing a high frequency band.

  Since the UWB system is a short-range communication, it is indispensable to be mounted on a so-called mobile device. In the mobile device, a filter element capable of supporting two wide frequency bands with one filter element is required due to the limitation of the number of parts. .

  In the bandpass filter described in Patent Document 1, a plurality of single resonance electrodes and a plurality of composite resonance electrodes are arranged so as to be orthogonal to each other when viewed from the stacking direction. By resonating and the plurality of composite resonance electrodes resonate at a relatively high frequency, it is possible to cope with two wide frequency bands.

JP 2009-290430 A

  Even in the wireless communication of the same system, the usable frequency band is set for each country, and the pass band changes when the country to be used changes, so the design of the filter element must be changed. In addition, if there are overlapping bands in a plurality of countries among usable frequency bands, and a filter characteristic having the overlapping band as a pass band is obtained, a filter element usable in a plurality of countries can be realized.

  The band-pass filter described in Patent Document 1 exhibits sufficient filter characteristics when used only in one country. However, there is still room for improvement in the attenuation characteristics in the high frequency band when considering filters that can be used in a plurality of countries, for example, aiming for higher performance filters.

  An object of the present invention is to provide a band-pass filter that can further improve attenuation characteristics on the high-frequency side of a pass band, a wireless communication module and a wireless communication device including the band-pass filter.

The present invention is a single resonator comprising a plurality of strip electrodes provided in parallel with each other at a predetermined interval, and one of the end portions in the extending direction of the strip electrodes is connected to a ground electrode, and connected A single resonator configured to have different ends that are alternately different in the plurality of strip electrodes;
A composite resonator comprising a plurality of branch electrodes each composed of an electrode base and a plurality of parallel electrode fingers branched from the electrode base and extending in one direction, opposite to the side on which the electrode fingers are provided. A branching electrode connected to the ground electrode at the end on the side, and a composite resonator configured such that a direction in which the electrode finger extends from the electrode base is opposite,
The single resonator and the composite resonator are stacked such that the extending direction of the strip electrode and the extending direction of the electrode finger are orthogonal to each other,
Of the plurality of electrode fingers provided in the composite resonator, two electrode fingers arranged on the outermost sides have a bent portion that is parallel to the extending direction of the belt-like electrode when viewed from the stacking direction. Is a bandpass filter characterized by

  In the invention, it is preferable that the bent portion is provided at the tips of the two electrode fingers arranged on the outermost side.

  The present invention also provides electrode wiring stacked on a side of the single resonator that is different from the composite resonator, wherein one end portion and the other end portion are respectively provided in the single resonator. An electrode wiring is further provided, which is configured to be magnetically coupled to the two outermost band-shaped electrodes among the band-shaped electrodes.

  The present invention also provides a reaction resonator electrode disposed so as to be electromagnetically coupled to at least one of the belt-like electrodes, wherein a reaction resonator electrode having one end connected to the ground electrode and the other end being an open end is provided. It is characterized by having.

  The present invention is also a wireless communication module comprising the bandpass filter.

The present invention also includes an RF unit including the bandpass filter;
A baseband unit connected to the RF unit;
A wireless communication device comprising an antenna connected to the RF unit.

  According to the bandpass filter of the present embodiment, the bandpass filter includes a single resonator and a composite resonator, and is laminated so that the extending direction of the band-shaped electrode and the extending direction of the electrode finger are orthogonal to each other. A single resonator has a relatively low frequency as a passband, and a composite resonator has a relatively high frequency as a passband.

  The single resonator and the composite resonator are stacked such that the extending direction of the strip electrode and the extending direction of the electrode finger are orthogonal to each other, and among the plurality of electrode fingers provided in the composite resonator The two electrode fingers arranged on the outermost sides have a bent portion that is parallel to the extending direction of the strip electrode when viewed from the stacking direction.

  The bent portion is magnetically coupled to the band electrode of the single resonator, and the two outermost electrode fingers are jump-coupled via the band electrode of the single resonator. Thereby, an attenuation pole is generated on the high frequency side of the pass band, and the attenuation characteristic in the high frequency band can be further improved.

  Further, according to the wireless communication module and the wireless communication device of the present embodiment, the bandpass filter is used for filtering the transmission signal and the reception signal by using a bandpass filter with a small loss of a signal passing over the entire communication band. Since the attenuation of the reception signal and transmission signal passing through the channel is reduced, the reception sensitivity is improved. Further, since the amplification degree of the transmission signal and the reception signal can be reduced, power consumption in the amplifier circuit is reduced.

  Therefore, a high-performance wireless communication module and wireless communication device with high reception sensitivity and low power consumption can be obtained. Furthermore, two communication bands can be handled with one filter. In addition, a wireless communication module and a wireless communication device that are small in size and low in manufacturing cost can be obtained by using a band-pass filter that can obtain good filter characteristics even if it is thin.

It is a perspective view which shows the external appearance of the band pass filter 1 which is embodiment of this invention. It is sectional drawing of the band pass filter 1 in cut surface line AA of FIG. 2 is an exploded plan view showing the configuration of the bandpass filter 1. FIG. 2 is an exploded plan view showing the configuration of the bandpass filter 1. FIG. 2 is an exploded plan view showing the configuration of the bandpass filter 1. FIG. 2 is an exploded plan view showing the configuration of the bandpass filter 1. FIG. 2 is an exploded plan view showing the configuration of the bandpass filter 1. FIG. 2 is an exploded plan view showing the configuration of the bandpass filter 1. FIG. 2 is an exploded plan view showing the configuration of the bandpass filter 1. FIG. It is a figure which shows the positional relationship of the bending parts 26a and 31a of the branch electrodes 22a and 27a, and the strip | belt-shaped electrodes 23d and 24d. 5 is a graph showing filter characteristics when θ1 and θ2 are 0 ° and 20 °. 6 is a graph showing filter characteristics when θ1 and θ2 are 0 ° and 10 °. It is an exploded top view showing electrode layer 20a of other embodiments. It is an exploded top view showing electrode layer 20a of other embodiments. It is an exploded top view showing electrode layer 20a of other embodiments. It is a top view which shows the dielectric material layer 10g and the electrode layer 20f provided in the upper surface. 2 is a block diagram showing a configuration of a wireless communication module 80 and a wireless communication device 85 using the bandpass filter 1. FIG.

  The bandpass filter of the present embodiment has two non-overlapping passbands. A low band using a relatively low frequency band, for example, a band of about 3.1 to 4.7 GHz, and a high band using a relatively high frequency band, for example, a band of about 6.6 GHz to 8.7 GHz ( High pass band). In particular, the attenuation characteristic at 5.3 GHz between the two bands and the attenuation characteristic at 9 GHz, which is a higher frequency region than the high band, are important.

  The bandpass filter of this embodiment includes a single resonator as a resonator corresponding to the low band. The single resonator includes a plurality of strip electrodes, and the strip electrodes are provided in parallel to each other at a predetermined interval in a direction orthogonal to the extending direction. The strip electrodes adjacent to each other are connected to the ground electrode on one side of the extending direction end portions, and the connected end portions are alternately different for the strip electrodes. The strip electrode is configured so that the electrical length is about ¼ of the wavelength of the center frequency (low side frequency) in the low band frequency band, and functions as a ¼ wavelength resonator.

  The bandpass filter of this embodiment includes a composite resonator as a resonator corresponding to the high band. The composite resonator includes a plurality of branch electrodes. The branch electrode includes an electrode base and a plurality of parallel electrode fingers extending in one direction from the electrode base. The plurality of branch electrodes are provided at predetermined intervals in a direction orthogonal to the extending direction of the electrode fingers. In the branch electrode, the end of the electrode base opposite to the side where the electrode fingers are provided is connected to the ground electrode, and the branch electrodes adjacent to each other have the opposite directions in which the electrode fingers extend from the electrode base. It is provided as follows. The electrode base and the electrode finger resonate at a relatively low frequency (high-side first frequency) in the high-band frequency band in which the sum of the electrical length of the electrode finger and the electrical length of the electrode base in the extending direction of the electrode finger. In addition, the electrical length of the electrode finger in the extending direction of the electrode finger is configured to resonate at a relatively high frequency (high side second frequency) in the high band frequency band.

  In the band-pass filter of the present embodiment, a single resonator and a composite resonator are provided in the inner layer of the laminated structure, the extending direction in which the band-like electrode of the single resonator extends, and the branch electrode of the composite resonator The extending direction in which the electrode fingers extend is provided so as to be orthogonal when viewed from the stacking direction.

  Furthermore, in the composite resonator, of the electrode fingers provided on all the branch electrodes, the two outermost electrode fingers are part of the single resonator when viewed from the stacking direction. The strip electrode is bent and provided so as to be parallel to the extending direction. By providing the bent parallel portion in the composite resonator, an attenuation pole is generated on the high frequency side of the high band, and the attenuation characteristic is improved. As a result, a band-pass filter with further improved filter characteristics can be realized.

  FIG. 1 is a perspective view showing an appearance of a bandpass filter 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the bandpass filter 1 taken along section line AA in FIG. 3A to 3G are exploded plan views showing the configuration of the bandpass filter 1.

  The bandpass filter 1 is a filter element having a rectangular parallelepiped shape, for example, connected between an antenna and a transmission / reception semiconductor element and having two specific types of passbands. The bandpass filter 1 is formed by laminating a plurality of dielectric layers 10 and an electrode layer 20 that is an inner layer between dielectric layers, and a solid ground electrode layer 60 is provided on the outermost side in the laminating direction. The electrode layers 20 are electrically connected to each other through a through conductor 40 that penetrates the dielectric layer 10. For input / output of high frequency signals to / from the outside of the filter, a part of the outermost ground electrode layer 60 is cut out to provide an input / output terminal 50, and the input / output terminal 50 and the electrode layer 20 are connected via the through conductor 40. Connect electrically. In the following, as shown in FIGS. 1 to 3, the side on which the input / output terminal 50 is provided is described as an upper surface. However, when mounting on the circuit board, the input / output terminal is determined depending on the positional relationship with the terminal on the board side. The side provided with 50 is not limited to the upper surface, and the side provided with the input / output terminal 50 may be the lower surface.

  In the present embodiment, for example, the dielectric layer 10 includes six dielectric layers 10a, 10b, 10c, 10d, 10e, and 10f, and the electrode layer 20 includes five electrode layers 20a, 20b, 20c, and 20d. 20e, and the ground electrode layer 60 is composed of ground electrode layers 60a and 60b. The input / output terminal 50 includes an input terminal 50a and an output terminal 50b.

  As shown in the cross-sectional view of FIG. 2, the dielectric layer 10 is formed by laminating dielectric layers 10a, 10b, 10c, 10d, 10e, and 10f in this order from the top. A ground electrode layer 60a is provided on the upper surface of the dielectric layer 10a, and an input terminal 50a and an output terminal 50b are provided by cutting the ground electrode layer 60a. A ground electrode layer 60b is provided on the lower surface of the dielectric layer 10f.

  An electrode layer 20a is provided between the dielectric layer 10a and the dielectric layer 10b, and an electrode layer 20b is provided between the dielectric layer 10b and the dielectric layer 10c, and the dielectric layer 10c and the dielectric layer The electrode layer 20c is provided between the dielectric layer 10d and the dielectric layer 10e, and the electrode layer 20d is provided between the dielectric layer 10e and the dielectric layer 10f. 20e is provided.

  The input terminal 50a and the output terminal 50b are electrically connected to the electrode layer 20c through the through conductor 40a. The through conductor 40a is provided so as to penetrate the dielectric layers 10a, 10b, and 10c. The electrode layer 20b is electrically connected to the electrode layer 20c through the through conductor 40b. The through conductor 40b is provided so as to penetrate the dielectric layer 10c. The electrode layer 20d is electrically connected to the electrode layer 20e through the through conductor 40c. The through conductor 40c is provided so as to penetrate the dielectric layer 10e.

  FIG. 3A is an exploded plan view showing the dielectric layer 10a and the ground electrode layer 60a provided on the upper surface thereof. The ground electrode layer 60a is provided in a solid shape on the surface of the dielectric layer 10a, and a rectangular cutout hole is provided in one end and the other end on the opposite side, and the ground electrode layer 60a is provided in the cutout hole. An input terminal 50a and an output terminal 50b are provided so as not to contact with each other. The input terminal 50a and the output terminal 50b are connected to the through conductor 40a.

  FIG. 3B is an exploded plan view showing the dielectric layer 10b and the electrode layer 20a provided on the upper surface thereof. The electrode layer 20a includes an annular ground electrode 21a and branch electrodes 22a and 27a, and constitutes a composite resonator corresponding to the high band. The annular ground electrode 21a is an annular electrode provided along the four sides of the dielectric layer 10b, and has a ground potential by being connected to a ground potential wiring (not shown).

  The branch electrode 22a is composed of an electrode base 23a and a plurality of parallel electrode fingers 24a and 25a extending in one direction from the electrode base 23a, and the branch electrode 27a is a plurality of parallel electrodes extending in one direction from the electrode base 28a and the electrode base 28a. It consists of electrode fingers 29a and 30a. The extending direction in which the electrode fingers 24a and 25a of the branch electrode 22a extend and the extending direction in which the electrode fingers 29a and 30a of the branch electrode 27a extend are parallel to each other.

  The annular ground electrode 21a and the branch electrodes 22a and 27a are connected only by the electrode bases 23a and 28a, and the end of the electrode bases 23a and 28a opposite to the side where the electrode fingers are provided is the annular ground electrode 21a. Connected to. The branch electrodes 22a and 27a are provided at predetermined intervals in a direction orthogonal to the extending direction of the electrode fingers 24a, 25a, 29a, and 30a. Since the branch electrodes 22a and 27a are formed to be rotated on the dielectric layer 10b, the features common to both the branch electrodes 22a and 27a will be described below using the branch electrode 22a as an example.

  The electrical length from the connection position with the annular ground electrode 21a to the connection position with the electrode fingers 24a and 25a in the electrode base 23a (hereinafter referred to as “base electrical length”), the electrode base 23a in the electrode fingers 24a and 25a, The electrical length from the connecting position to the opposite end thereof (hereinafter referred to as “electrode finger electrical length”) is the sum of the base electrical length and the electrode finger electrical length at the first high frequency (for example, 6.8 GHz). ) To resonate. Furthermore, the electrode finger electrical length is configured to resonate at a high-side second frequency (for example, 8.9 GHz).

  Of the electrode fingers 24a and 25a of the branch electrode 22a, the electrode fingers 24a arranged on the outside and the electrode fingers 25a arranged on the inside have the same electrical length but different physical lengths. The electrode finger 24a is shorter than the electrode finger 25a. The electrical length of the electrode fingers is determined not only by the physical length but also by the interaction with other electrodes, that is, the electromagnetic coupling state with the other electrodes. Since the inner electrode finger 25a is coupled to the outer electrode finger 24a and the inner electrode finger 30a of the branch electrode 27a, the interaction between the inner electrode finger 25a and the other electrode is strong. Is weaker than the inner electrode finger 25a. Therefore, in order to make the electrical lengths of the inner electrode finger 25a and the outer electrode finger 24a the same, the actual length of the outer electrode finger 24a may be made shorter than that of the electrode finger 25a.

  Although details of the single resonator will be described later, in the band-pass filter 1 of the present embodiment, the extending direction of the electrode fingers included in the branch electrode and the extending direction of the band-shaped electrode of the single resonator are from the stacking direction. Orthogonal when viewed. In the band pass filter 1 of the present embodiment, of the electrode fingers 24a, 25a, 29a, 30a provided in the two branch electrodes 22a, 27a, the two electrode fingers 24a, 29a arranged on the outermost side are in the stacking direction. When viewed from the above, a part thereof is bent and provided so as to be parallel to the extending direction in which the band-like electrode of the single resonator extends.

  A part of the electrode finger 24a, which is a part of the bent portion 26a parallel to the extending direction of the band-shaped electrode of the single resonator and the part of the electrode finger 29a, and is parallel to the extending direction of the band-shaped electrode of the single resonator Each of the bent portions 31a is magnetically coupled to the band-like electrode of the single resonator. Since the strip electrodes are coupled to each other, the bent portion 26a and the bent portion 31a are indirectly coupled via the strip electrode. In the composite resonator, so-called jump coupling occurs in which the two outermost electrode fingers of the branch electrode are coupled. The inventors of the present invention have found that the damping characteristic on the high frequency side in the composite resonator is improved by strengthening the interlaced coupling. As a preceding stage, a description will be given of the reduction of the interlaced coupling due to the reduction in the height of the bandpass filter 1. In order to reduce the height of the bandpass filter 1, it is necessary to reduce the overall thickness of the filter, thereby reducing the distance between the electrode layers of the bandpass filter 1. When the distance between the electrode layers is reduced, the distance between the composite resonator and the single resonator is reduced. As a result, the coupling between the composite resonator and the single resonator is strengthened, and the inter-electrode coupling between the electrode fingers of the composite resonator is increased. Will be weakened.

  When the inventors of the present invention exclude the influence of a single resonator and look at the pass characteristic of only the composite resonator, the attenuation pole approaches the pass band as the jump coupling becomes stronger, that is, the steeper attenuation characteristic. Based on this knowledge, we actively use the coupling between the electrode finger of the composite resonator and the band electrode of the single resonator, and strengthen the jump coupling between the electrode fingers. Tried. Specifically, in consideration of the influence of the single resonator, the single resonator and the electrode finger are coupled by providing the bent portion 26a and the bent portion 31a at the tip of the electrode finger. As a result, an attenuation pole was generated on the high frequency side, and this tendency showed the same tendency as the improvement of the attenuation characteristic due to the strong jump coupling.

  FIG. 3C is an exploded plan view showing the dielectric layer 10c and the electrode layer 20b provided on the upper surface thereof. FIG. 3D is an exploded plan view showing the dielectric layer 10d and the electrode layer 20c provided on the upper surface thereof. The electrode layer 20b includes electrode wirings 21b and 22b, and is coupled to the composite resonator. The electrode layer 20c includes electrode wirings 21c and 22c, and the electrode wirings 21c and 22c are connected to the input terminal 50a and the output terminal 50b through the through conductor 40a. The electrode wirings 21c and 22c are connected to the electrode wirings 21b and 22b through the through conductors 40b.

  Here, the flow of the high frequency signal in the band pass filter 1 will be described. The high frequency signal input from the input terminal 50a reaches the electrode wiring 22c through the through conductor 40a. The high-frequency signal transmitted along the electrode wiring 22c reaches the electrode wiring 22b through the through conductor 40b. Due to the magnetic coupling between the electrode wiring 22b and the outer electrode finger 29a of the branch electrode 27a, a high frequency signal is input to the outer electrode finger 29a of the branch electrode 27a. The input high-frequency signal propagates from the outer electrode finger 29a of the branch electrode 27a to the outer electrode finger 24a of the branch electrode 22a, and is branched by magnetic coupling between the electrode wiring 21b and the outer electrode finger 24a of the branch electrode 22a. Output from the outer electrode finger 24a of the electrode 22a. The output high-frequency signal becomes a signal that has passed through the high-band frequency band, and reaches the electrode wiring 21c through the through conductor 40b. The high frequency signal is transmitted along the electrode wiring 21c, and is output from the output terminal 50b to the outside of the filter through the through conductor 40a.

  FIG. 3E is an exploded plan view showing the dielectric layer 10e and the electrode layer 20d provided on the upper surface thereof. FIG. 3F is an exploded plan view showing the dielectric layer 10f and the electrode layer 20e provided on the upper surface thereof.

  The electrode layer 20d includes an annular ground electrode 21d and strip electrodes 22d, 23d, 24d, and 25d, and constitutes a single resonator corresponding to the low band. The annular ground electrode 21d is an annular electrode provided along the four sides of the dielectric layer 10e, and has a ground potential by being connected to a ground potential wiring (not shown).

  The strip electrodes 22d, 23d, 24d, and 25d are provided in parallel to each other at a predetermined interval in a direction orthogonal to the extending direction. The strip electrodes 22d, 23d, 24d, and 25d are connected to the annular ground electrode 21d at one end in the extending direction, the strip electrode 22d is connected to the annular ground electrode 21d, and the strip electrode 23d is annular grounded. The end connected to the electrode 21d is an end on a different side. Similarly, the strip electrodes 24d and 25d are connected to the annular ground electrode 21d, and the strip electrodes 22d and 24d and the strip electrodes 23d and 25d are respectively formed in a comb shape, and are arranged so as to mesh with each other. A so-called interdigital resonator is formed. The band-like electrodes 22d, 23d, 24d, and 25d are not only the physical length but also the interaction with other electrodes, that is, the electromagnetic coupling state with the other electrodes, like the electrode fingers of the composite resonator. The electrical length is determined. For example, if the electrical length is made the same, the physical length of the strip electrodes 23d and 24d is longer than that of the charging electrodes 22d and 25d. The strip electrodes 22d, 23d, 24d, and 25d may be configured so that the electrical length is about ¼ of the wavelength of the low-side frequency.

  The electrode layer 20e includes an electrode wiring 21e and an electrode wiring 23e, and an electrode wiring 22e that connects them. The electrode wiring 21e and the electrode wiring 23e extend in parallel with the extending direction of the band-shaped electrode of the single resonator, and are arranged with an interval in both the extending direction and the direction orthogonal to the extending direction. The electrode wiring 22e includes an end on the side close to the electrode wiring 23e in the extending direction end of the electrode wiring 21e, and an end on the side close to the electrode wiring 21e in the extending direction end of the electrode wiring 23e. Connect. The end of the electrode wiring 21e opposite to the side connected to the electrode wiring 22e is electrically connected to the annular ground electrode 21d through the through conductor 40c penetrating the dielectric layer 10e. Of the end portions of the electrode wiring 23e, the end opposite to the side connected to the electrode wiring 22e is electrically connected to the annular ground electrode 21d through the through conductor 40c penetrating the dielectric layer 10e. The electrode wiring 21e is magnetically coupled to the band-shaped electrode 22d of the single resonator, and the electrode wiring 23e is magnetically coupled to the band-shaped electrode 25d of the single resonator. By connecting the electrode wiring 21e and the electrode wiring 23e via the electrode wiring 22e, inductive coupling occurs between the band-shaped electrode 22d and the band-shaped electrode 25d of the single resonator.

  The band-shaped electrodes 22d, 23d, 24d, and 25d of the single resonator have capacitive coupling between adjacent band-shaped electrodes, and a high-frequency signal that propagates through the band-shaped electrodes 22d, 23d, 24d, and 25d by capacitive coupling. The high-frequency signals propagating through the electrode wirings 21e, 22e, and 23e by inductive coupling are different in phase by 180 °, so that these two high-frequency signals cancel each other and generate a large attenuation pole in the vicinity of the low-band pass region. And attenuation characteristics are improved.

  FIG. 3G is a plan view showing the ground electrode layer 60b. The ground electrode layer 60b is formed in a solid form on the entire surface.

  In the present embodiment, for example, the dielectric layer 10 includes six dielectric layers 10a, 10b, 10c, 10d, 10e, and 10f, and the electrode layer 20 includes five electrode layers 20a, 20b, 20c, and 20d. 20e, and the ground electrode layer 60 is composed of ground electrode layers 60a and 60b. The input / output terminal 50 includes an input terminal 50a and an output terminal 50b.

  The bandpass filter 1 of the present embodiment is characterized by the composite resonator as described above, and is one of the two electrode fingers 24a and 29a arranged on the outermost side among the electrode fingers of the branch electrodes 22a and 27a. The portion is bent so as to be parallel to the band-shaped electrode of the single resonator.

  Here, the parallel means that the extending direction of the bent portion of the electrode finger matches the extending direction of the strip electrode, that is, the extended portion of the bent portion of the electrode finger when viewed from the stacking direction of the bandpass filter. If the positional relationship is such that the bent portion of the electrode finger and the strip electrode are magnetically coupled, not only when the angle between the direction and the extending direction of the strip electrode is 0 °, This is included in the parallel concept.

  FIG. 4 is a diagram showing the positional relationship between the bent portions 26a and 31a of the branch electrodes 22a and 27a and the strip electrodes 23d and 24d. In FIG. 4, each electrode of the electrode layer 20a is indicated by a solid line, and a part of the belt-like electrode (band-like electrode 23d) of the electrode layer 20d which is a separate layer is indicated by a broken line.

  When the angle formed by the extending direction of the strip electrode 23d and the extending direction of the bent portion 26a is θ1, the range of the angle θ1 is −20 ° to 20 °. When the angle formed by the extending direction of the strip electrode 24d and the extending direction of the bent portion 31a is θ2, the range of the angle θ2 is set to −20 ° or more and 20 ° or less similarly to θ1. It is preferable that the angles θ1 and θ2 are 0 ° because the highest effect can be obtained. θ1 and θ2 are preferably the same angle, but need not be the same angle, and may be different angles as long as they are within the above range.

  FIG. 5A is a graph showing filter characteristics when θ1 and θ2 are 0 ° and 20 °. FIG. 5B is a graph showing filter characteristics when θ1 and θ2 are 0 ° and 10 °. The horizontal axis represents frequency (GHz) and the vertical axis represents attenuation (dB). Graph A shows the case of θ1 = θ2 = 0 °, Graph B shows the case of θ1 = θ2 = 20 °, and Graph C shows the case of θ1 = θ2 = 10 °. The graph D shows the case of the conventional structure which does not have a bending part as a comparison object.

  These filter characteristics are results obtained by simulation. The bandpass filter model used for the simulation will be described. The layer configuration and each electrode layer are the same as the cross-sectional view shown in FIG. 2 and the plan views shown in FIGS. 3A to 3G.

The layer thickness is 175 μm for the dielectric layer 10a, 25 μm for the dielectric layer 10b, 75 μm for the dielectric layer 10c, 25 μm for the dielectric layer 10d, 125 μm for the dielectric layer 10e, The body layer 10f is 75 μm. As the material of the dielectric layer, glass ceramics was assumed, the relative dielectric constant εr was 7.5, and the dielectric loss tangent (tan δ) was 0.001. The conductive material of the electrode wiring was assumed to be copper, and the conductivity was 4.5 × 10 ⁷ (siemens / m). The external dimensions of the bandpass filter were 4 mm in length, 5 mm in width, and 0.5 mm in height.

  The ground electrode layer 60a has a solid shape of 4 mm in length and 5 mm in width, provided with two 0.5 mm square notch holes, and provided with 0.2 mm square input terminals 50 a and output terminals 50 b. Regarding the electrode layer 20a, the electrode base portion 23a of the branch electrode 22a has an electrode finger extending direction length of 0.7 mm and a width of 0.62 mm. The electrode finger 24a has a width of 0.25 mm and an overall length of 1.65 mm, and the bent portion 26a has a length of 0.3 mm. The electrode finger 25a has a width of 0.25 mm and an overall length of 2.7 mm, and the distance between the electrode finger 24a and the electrode finger 25a is 0.12 mm. The branch electrode 27a is the same as the branch electrode 22a. As for the electrode layer 20b, both the electrode wirings 21b and 22b have a width of 0.25 mm and a length of 0.58 mm.

  As for the electrode layer 20c, both the electrode wirings 21c and 22c have a width of 0.15 mm and a length of 4.375 mm. Regarding the electrode layer 20d, the strip electrodes 22d, 03d, 24c, and 25d have a width of 0.175 mm and a length of 4.05 mm, the distance between the strip electrode 22d and the strip electrode 23d, and the strip electrode 24d and the strip electrode 25d, Is 0.075 mm, and the distance between the strip electrode 23 d and the strip electrode 24 d is 0.085 mm. Regarding the electrode layer 20e, both the electrode wirings 21e and 23e have a width of 0.1 mm, the length is 1.65 mm, and the distance between the ends of the electrode wirings 21e and 23e (lateral direction) is 1.3 mm. The distance (vertical direction) between the end portions of the electrode wirings 21e and 23e is 0.775 mm. The ground electrode layer 60b has a solid shape with a length of 4 mm and a width of 5 mm.

The through conductors 40a, 40b, and 40c all have a diameter of 0.075 mm.
In the conventional configuration having no bent portion, as shown in the graph D, attenuation is performed on the high-frequency side of the high band, but the attenuation is insufficient to meet strict required characteristics. As shown in graphs A to C, the band pass filter of this embodiment having a bent portion in the branch electrode has improved attenuation characteristics on the high frequency side of the high band, and θ1 and θ2 are 20 °, 10 °, As the angle reaches 0 °, the attenuation pole approaches the high-band passband. Although not shown in the graph, the same results were obtained when θ1 and θ2 were −20 ° and −10 °, respectively, when they were 20 ° and 10 °, respectively.

  Further, the length of the bent portion of the branch electrode parallel to the band electrode of the single resonator is not limited as long as it can be magnetically coupled to the band electrode. Further, the position of the bent portion in the electrode finger does not have to be the tip of the electrode finger, and may be an intermediate portion as long as it is a part of the electrode finger. The length and position of the bent portion can be appropriately set as long as the electrode finger electrical length is the same.

  6A to 6C are exploded plan views showing electrode layers 20a of other embodiments. As other embodiment of this invention, there exists a thing of the structure from which the shape of a bending part differs in branch electrode 22a, 27a of the electrode layer 20a. Since the configuration other than the electrode layer 20a is the same as that in the above embodiment, the description thereof is omitted.

  In the electrode layer 20a shown in FIG. 6A, the lengths of the bent portions 32a and 33a are longer than the bent portions 26a and 31a in the electrode fingers 24a and 29a of the branch electrodes 22a and 27a. Since the electrode finger electrical length is the same, when the length of the bent portion is increased, the position of the corner portion is closer to the electrode base portions 23a and 28a.

  In the electrode layer 20a shown in FIG. 6B, the bent portions 34a and 35a are located in the middle portions of the electrode fingers 24a and 29a of the branch electrodes 22a and 27a. The electrode fingers 24a and 29a are stepped or cranked as a whole.

  In the electrode layer 20a shown in FIG. 6C, the bent portions 36a and 37a are located in the middle portions of the electrode fingers 24a and 29a of the branch electrodes 22a and 27a. The electrode fingers 24a and 29a have a needle shape as a whole.

  Next, a bandpass filter including a reaction resonator electrode will be described as still another embodiment of the present invention.

  In the present embodiment, there is provided a reaction resonator electrode disposed so as to be electromagnetically coupled to at least one of the strip electrodes 22d, 23d, 24d, and 25d except between the plurality of strip electrodes. FIG. 7 is a plan view showing the dielectric layer 10g and the electrode layer 20f provided on the upper surface thereof. For example, a dielectric layer 10g is further provided between the dielectric layer 10f and the ground electrode layer 60b, and an electrode layer 20f is provided on the upper surface of the dielectric layer 10g. The electrode layer 20f has reaction resonator electrodes 21f and 22f.

  The reaction resonator electrode 21f includes a rectangular resonance electrode 23f and a connection electrode 24f extending inward from one side of the resonance electrode 23f to connect to the ground electrode layer 60b. The reaction resonator electrode 22f is rectangular. The resonance electrode 25f has a shape and a connection electrode 26f that extends inward from one side of the resonance electrode 25f and is connected to the ground electrode layer 60b.

  One end of the reaction resonator electrode 21f is connected to the ground electrode layer 60b via the connection electrode 24f and the through conductor, and the other end is an open end. The reaction resonator electrode 22f has the same configuration.

  By providing the reaction resonator electrodes 21f and 22f, an attenuation pole that functions as a reaction resonator (notch filter) can be further formed in the harmonics (11.2 GHz) due to the strip electrodes 22d, 23d, 24d, and 25d. Thus, it is possible to provide a band-pass filter that removes unnecessary signals in a specific frequency (high frequency band) and further improves characteristics.

  The thicknesses of the dielectric layers 10 a, 10 b, 10 c, 10 d, 10 e, and 10 f affect the coupling state between the electrode layers 20 arranged above and below the dielectric layer 10. When the layer thickness is small, the bonding between the electrode layers 20 arranged above and below becomes strong, and when the layer thickness is large, the bonding between the electrode layers 20 arranged above and below becomes weak. Therefore, when the bonding between the electrode layers 20 is to be strengthened, the layer thickness of the dielectric layer between them is relatively small, and when the bonding between the electrode layers 20 is to be weakened, the layer thickness of the dielectric layer between them is reduced. Should be relatively large. When a plurality of electrodes are provided in the electrode layer 20, the coupling between the electrodes in the same electrode layer 20 and the coupling with another electrode layer 20 via the dielectric layer occur. When it is desired to bond other electrodes 20 while maintaining the bonding between the electrodes in the same electrode layer 20, the layer thickness should be as small as possible with a layer thickness that is at least the distance between the electrodes in the same electrode layer 20. Good. If the layer thickness is too small, the bond with the other electrode layer 20 is too strong and the bond between the electrodes in the same electrode layer 20 is weakened.

  In the band-pass filter 1 of the present embodiment, for example, it is preferable to increase the coupling between the electrode layers 20, that is, it is preferable to make the dielectric layer 10 relatively thin. The electrode layers 20 a and 20 b And a dielectric layer 10d between the electrode layer 20c and the electrode layer 20d. These dielectric layers 10b and 10d are made relatively thin so that the branch electrodes 22a and 27a are coupled to the electrode lines 21b and 22b of the composite resonator, and the electrode lines 21c and 22c are single-resonant. It is possible to strengthen the coupling with the strip electrodes 22d and 25d.

  In addition, since it is preferable that the coupling between the electrodes of the composite resonator and the single resonator and the electrodes other than the electrode wiring to be coupled is weak, for example, the dielectric layer 10a and the dielectric layer 10e have relatively thin layer thicknesses. It is thick.

  The bond strength between the electrode layers 20 when the dielectric layer 10 is interposed therebetween is the relative dielectric constant of the dielectric layer 10 in addition to the thickness of the dielectric layer 10 as described above, that is, the distance between the electrode layers 20. Also affected. Therefore, the dielectric layer 10 may be appropriately selected in consideration of the overall filter characteristics and the layer thickness may be set.

In the band-pass filter 1 of the present embodiment, as a material of the dielectric layer 10, for example, an organic material such as an epoxy resin or a ceramic material such as a dielectric ceramic can be used. Examples of the ceramic material include a dielectric ceramic material such as BaTiO ₃ , Pb ₄ Fe ₂ Nb ₂ O ₁₂ and TiO ₂ and a glass material such as B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ and ZnO. A glass-ceramic material that can be fired at a relatively low temperature of about 800 to 1200 ° C. is preferably used. In addition, the thickness of the dielectric layer 10 is set to about 10 μm to 200 μm, for example.

  As the material of the electrode and the through conductor, for example, a conductive material mainly composed of an Ag alloy such as Ag, Ag-Pd, or Ag-Pt, a Cu-based, W-based, Mo-based, or Pd-based conductive material is preferable. Used. The thickness of the various electrodes is set to 1 μm to 200 μm, for example. The diameter of the through conductor is set to, for example, 25 μm to 100 μm.

  The bandpass filter of this embodiment can be manufactured as follows, for example. First, an appropriate organic solvent is added to the ceramic raw material powder, and these are mixed to produce a slurry, and a ceramic green sheet having a predetermined thickness is formed by a doctor blade method.

  Next, a through hole for forming a through conductor is formed on the obtained ceramic green sheet using a punching machine or the like, and a conductive paste containing a conductive material such as Ag, Ag-Pd, Au, Cu is filled. Further, the same conductive paste as described above is applied to the surface of the ceramic green sheet by using a printing method to produce a ceramic green sheet with a conductive paste. Next, these ceramic green sheets with conductor paste are laminated in a predetermined order, and are pressure-bonded using a hot press apparatus, and are fired at a peak temperature of about 800 ° C. to 1050 ° C.

  FIG. 8 is a block diagram illustrating a configuration of the wireless communication module 80 and the wireless communication device 85 using the bandpass filter 1.

  The wireless communication module 80 according to another embodiment of the present invention includes, for example, a baseband unit 81 where a baseband signal is processed, and an RF (Radio) after being connected to the baseband unit 81 and before modulation of the baseband signal. Frequency) signal is processed. The RF unit 82 is provided with a band pass filter 821 having the same configuration as the band pass filter 1 of the present embodiment, and an RF signal obtained by modulating a baseband signal or a communication band other than the communication band in the received RF signal. The signal is attenuated by a band-pass filter 821, and a signal having a frequency in a necessary band is passed.

Specifically, the baseband unit 81 includes a baseband IC (Integrated).
Circuit) 811 is arranged, and the RF unit 82 is arranged between the band pass filter 821 and the baseband unit 81 in the RF unit 82. Note that another circuit may be interposed between these circuits. Then, by connecting the antenna 84 to the bandpass filter 821 of the wireless communication module 80, a wireless communication device 85 capable of transmitting and receiving RF signals is configured.

  According to the wireless communication module 80 and the wireless communication device 85 having such a configuration, the transmission signal and the reception signal are filtered through the band-pass filter 821 in which the loss of a signal passing through the entire frequency band used for wireless communication is small. As a result, the attenuation of the reception signal and the transmission signal passing through the band-pass filter 821 is reduced, so that the reception sensitivity is improved and the amplification degree of the transmission signal and the reception signal can be reduced. Less. Therefore, it is possible to obtain a high-performance wireless communication module 80 and a wireless communication device 85 with high reception sensitivity and low power consumption. Further, by using the band-pass filter 821 that can cover two communication bands with one filter and can obtain a good filter characteristic even if the filter is thinned, the wireless communication module 80 and the wireless device that are small in size and low in manufacturing cost can be obtained. A communication device 85 can be obtained.

1 Band pass filter 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g Dielectric layer 20, 20a, 20b, 20c, 20d, 20e, 20f Electrode layer 21a, 21d Annular ground electrode 21b, 21c, 21e, 22b , 22c, 22e, 23e Electrode wiring 22a, 27a Branch electrode 22d, 23d, 24d, 25d Strip electrode 23a, 28a Electrode base 24a, 25a, 29a, 30a Electrode finger 26a, 31a, 32a, 34a, 36a Bending part 40, 40a , 40b, 40c Through conductor 50 Input / output terminal 50a Input terminal 50b Output terminal 60, 60a, 60b Ground electrode layer 80 Wireless communication module 81 Baseband section 82 RF section 84 Antenna 85 Wireless communication equipment 821 Bandpass filter 822 RFIC

Claims (6)

A single resonator comprising a plurality of strip electrodes provided in parallel with each other at a predetermined interval, wherein one of the end portions in the extending direction of the strip electrodes is connected to the ground electrode, and the connected end portion A single resonator configured to be alternately different in the plurality of strip electrodes;
A composite resonator comprising a plurality of branch electrodes each composed of an electrode base and a plurality of parallel electrode fingers branched from the electrode base and extending in one direction, opposite to the side on which the electrode fingers are provided. A branching electrode connected to the ground electrode at the end on the side, and a composite resonator configured such that a direction in which the electrode finger extends from the electrode base is opposite,
The single resonator and the composite resonator are stacked such that the extending direction of the strip electrode and the extending direction of the electrode finger are orthogonal to each other,
Of the plurality of electrode fingers provided in the composite resonator, two electrode fingers arranged on the outermost sides have a bent portion that is parallel to the extending direction of the belt-like electrode when viewed from the stacking direction. A bandpass filter characterized by   The band-pass filter according to claim 1, wherein the bent portion is provided at a tip of the two electrode fingers arranged on the outermost side.   It is an electrode wiring layered on a side different from the composite resonator of the single resonator, and one end portion and the other end portion are respectively a plurality of strip electrodes provided in the single resonator. The band-pass filter according to claim 1 or 2, further comprising an electrode wiring configured to be magnetically coupled to the two outermost strip electrodes.   A reaction resonator electrode disposed so as to be electromagnetically coupled to at least one of the belt-like electrodes, wherein the reaction resonator electrode has one end connected to a ground electrode and the other end being an open end. The band pass filter according to any one of claims 1 to 3.   A wireless communication module comprising the bandpass filter according to claim 1. An RF unit including the bandpass filter according to claim 1;
A baseband unit connected to the RF unit;
A wireless communication device comprising: an antenna connected to the RF unit.

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