JP2006311492A - Filter and filtering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter and filtering apparatus allowing reduction of the increase of the characteristic impedance of a line due to band-widening for the filter and size reduction. <P>SOLUTION: The filter is provided with: first and second input/output terminals 1, 2; a reference node 3 to which a reference potential is supplied; a first parallel resonant line A1 connected between the first input/output terminal 1 and the reference node 3; second-fourth parallel resonant lines A2-A4 which are connected in serial between the first input/output terminal 1 and the second input/output terminal 2 and in each of which a signal outputted from a pre-stage is inputted to a post-stage; and a fifth parallel resonant line A5 connected between the second input/output terminal 2 and the reference node 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a filter device used in, for example, a wireless communication device such as a mobile phone and a wireless LAN, and other various communication devices.

  2. Description of the Related Art In recent years, filter devices used in mobile communication devices such as mobile phones have been distributed from a filter using a dielectric coaxial resonator to meet demands for thinning and miniaturization of mobile communication devices. Progress has been made in laminated stripline filters used in resonators.

  Also, these multilayer stripline filters have sharp band pass characteristics with attenuation poles in the low frequency side and high frequency side attenuation bands of the pass frequency band, respectively. Is used in order to allow high-quality communication by selectively passing only the low-frequency side and the high-frequency side of the pass band and preventing unwanted signals from being mixed in the signal band close to the high-frequency side.

  As such a conventional multilayer stripline filter, for example, there is one disclosed in Patent Document 1 below. A conventional multilayer stripline filter disclosed in Patent Document 1 is shown as a circuit configuration diagram in FIG. 9, a perspective plan view in FIG. 10, and a sectional view in FIG.

  As shown in FIG. 9, the conventional multilayer stripline filter is composed of tip short-circuit lines 111 to 115 and tip open lines 121 to 125. And the parallel resonance line B1 is formed by connecting the front end short circuit line 111 and the front end open line 121 in parallel. Moreover, the one end short-circuit termination line 112 and the open end line 122 are connected in parallel to form a parallel resonance line B2. Moreover, the tip short circuit line 113 and the tip open line 123 are connected in parallel to form a parallel resonance line B3. Moreover, the tip short circuit line 114 and the tip open line 124 are connected in parallel to form a parallel resonance line B4. Further, the tip short-circuit line 115 and the tip open line 125 are connected in parallel to form a parallel resonance line B5.

  One terminal of the parallel resonant line B2 is grounded via the parallel resonant line B1, and one of the input / output terminals is connected, and the other terminal of the parallel resonant line B2 is connected via the parallel resonant line B3. While being grounded, one terminal of the parallel resonant line B4 is connected, and the other terminal of the parallel resonant line B4 is grounded via the parallel resonant line B5, and the other input / output terminal is connected to the filter. It is composed.

  In this configuration, in general, in order to narrow the pass band of the filter, the characteristic impedances ZL1b, ZL3b, ZL5b of the short-circuited ends 111, 113, 115 forming the grounded parallel resonant lines B1, B3, B5 and The characteristic impedances of the open-ended short lines 112, 114 forming the parallel resonant lines B2, B4 connected in series between the input / output terminals are reduced, or the characteristic impedances ZC1b, ZC3b, ZC5b of the open-ended lines 121, 123, 125 are reduced. It is necessary to reduce the characteristic impedances ZC2b and ZC4b of the impedances ZL2b and ZL4b and the open-ended lines 122 and 124.

  However, in order to move the attenuation poles f1 and f2 in the vicinity of the narrow pass band closer to the pass frequency band, the characteristic impedance of the grounded parallel resonant lines B1, B3, and B5 is increased or the input / output is increased. It is necessary to reduce the characteristic impedance of the parallel resonant lines B2, B4 connected in series between the terminals, and the characteristic impedance of the grounded parallel resonant lines B1, B3, B5 tends to conflict with the narrowing of the band.

Therefore, in order to realize a narrow band with an attenuation pole in the vicinity while securing the necessary pass band, the parallel resonant line in which the characteristic impedance of the grounded parallel resonant line is also connected in series between the input and output terminals Both of the characteristic impedances of the filter circuit are made small, and their size is made sufficiently smaller than the input / output impedance of the filter circuit, thereby realizing a narrow band filter having a steep attenuation pole in the vicinity of the pass band.
JP-A-10-276005

  However, with an increase in information transmission capacity in recent years, wireless communication devices have become insufficient in the conventional frequency band, and the use bandwidth has been expanded and the information transmission capacity has been secured by increasing the frequency and bandwidth. Therefore, a filter having a wide pass band and having an attenuation pole in the vicinity of the pass band has been demanded.

  In such a situation, in the conventional multilayer stripline filter, in order to widen the pass band and obtain an attenuation pole in the vicinity, it is necessary to increase the characteristic impedance of the grounded parallel resonant line. In order to increase the characteristic impedance of the grounded parallel resonant line, it is necessary to increase the thickness of the dielectric layers 131 and 133.

  FIG. 7 shows the relationship between the characteristic impedance Z0 of the grounded line, the ratio of the line width W and the dielectric thickness h. When the characteristic impedance of the line constituting the resonator is increased, there is a problem that the thickness of the constituting line is increased and the thickness of the multilayer substrate is increased.

  The present invention has been devised in view of the above problems, and has an object of having a first attenuation pole in the vicinity of the low frequency side of the passband and a second attenuation pole in the vicinity of the high frequency side. In a filter with frequency band characteristics, the characteristic impedance of the line to be constructed tends to increase due to the broadening of the filter band, but the increase in the characteristic impedance of the line is reduced compared to the conventional structure, resulting in an increase in thickness. It is an object to provide a filter and a filter device that can be easily reduced in size.

  The filter of the present invention is a filter having a frequency band characteristic having a first attenuation pole in the vicinity of the low frequency side of the pass band and a second attenuation pole in the vicinity of the high frequency side. An input / output terminal; a reference node to which a reference potential is supplied; a first parallel resonant line connected between the first input / output terminal and the reference node; the first input / output terminal; A second to fourth parallel resonant line connected in series with the second input / output terminal, and a signal output from the previous stage is input to the subsequent stage, and the second input / output terminal and the reference node And a fifth parallel resonant line connected between them.

  In the filter of the present invention, the first input / output terminal and the second input / output terminal are preferably connected via a capacitor.

  The filter device of the present invention is a filter device in which the filter having the above-described configuration is formed. Preferably, the filter device is laminated between the first and second ground electrodes arranged to face each other and the first and second ground electrodes. First to fifth dielectric layers formed between the first to fifth dielectric layers and electrically connected to the first and second ground electrodes and open to the first and fifth dielectric layers. And the first parallel resonant line is formed between the first ground electrode and the first conductor pattern, and the second to fourth conductor patterns are provided between the first ground electrode and the first conductor pattern. A parallel resonant line is formed between the conductor patterns of the first to fourth conductor patterns, and the second parallel resonant line is formed between the second ground electrode and the fourth conductor pattern. It is characterized by being.

  The filter device of the present invention preferably has the length of the first to fifth parallel resonant lines or the length from the short-circuit end to the open end of the first to fourth conductor patterns in the above configuration. Is not more than ½ of the wavelength of the center frequency of the passband.

  In the filter device of the present invention, preferably, the first and fourth conductor patterns are arranged so as to overlap the second and third conductor patterns in a plan view, and It is characterized by being wider than the second and third conductor patterns.

  In the filter device of the above-described configuration, preferably, the first and second ground electrodes and the short-circuit ends of the first to fourth conductor patterns are the first to fifth filters. It is electrically connected by a through conductor formed in the dielectric layer or a side conductor formed on the side surface of the first to fifth dielectric layers.

  The filter of the present invention is connected in series between the first parallel resonant line connected between the first input / output terminal and the reference node, and between the first input / output terminal and the second input / output terminal. The second to fourth parallel resonant lines to which the signal output from the previous stage is input to the subsequent stage, and the fifth parallel resonant line connected between the second input / output terminal and the reference node. Therefore, it is possible to reduce the increase in characteristic impedance of the line due to the increase in bandwidth, and as a result, it is possible to provide a filter device that can reduce the increase in thickness and can be easily downsized.

  Further, the filter of the present invention connects the first input / output terminal and the second input / output terminal via a capacitor, so that the signal transmitted between the first and second input / output terminals is connected. The phase can be advanced by the connected capacitor. Therefore, since the phase can be changed abruptly at a frequency higher than the pass band, the second attenuation pole can be provided closer to the high frequency side of the pass band. From this, the increase in the characteristic impedance of the line, which occurs when the passband and the second attenuation pole on the high band side approach each other due to the broadening of the band (the steepness increases), can be further reduced. It is possible to provide a filter device that can reduce the increase more effectively and can be easily further reduced in size.

  In the filter device of the present invention, the first parallel resonance line is formed between the first ground electrode and the first conductor pattern, and the second to fourth parallel resonance lines are the first to fourth conductor patterns. By forming the fifth parallel resonance line between the second ground electrode and the fourth conductor pattern, it is possible to provide a filter device that can be easily reduced in size. .

  In the filter device of the present invention, the length of the first to fifth parallel resonant lines or the length from the short-circuit end to the open end of the first to fourth conductor patterns is the center frequency of the passband. Since it is 1/2 or less of the wavelength, it is possible to provide a filter and a filter device that can be easily downsized.

  In the filter device of the present invention, the first and fourth conductor patterns are arranged so as to overlap the second and third conductor patterns in plan view, and moreover than the second and third conductor patterns. Since the width is wide, the stray capacitance causing the characteristic deterioration can be reduced, and a high-performance filter device can be provided.

  In the filter device according to the present invention, the first and second ground electrodes and the short-circuit ends of the first to fourth conductor patterns are formed in the first through fifth dielectric layers or the first through fifth conductor layers. By being electrically connected by the side conductor formed on the side surface of the fifth dielectric layer, the degree of freedom in designing the filter device formed inside the plurality of stacked dielectric layers is improved, and the size is reduced. And a high-performance filter device can be provided.

  The filter and filter device of the present invention will be described in detail below. FIG. 1 is a circuit configuration diagram showing an embodiment of a filter of the present invention. 2 to 4 show an example of an embodiment of a filter device in which the filter of FIG. 5 and 6 are examples of other embodiments of the filter device in which the filter of FIG. 2 is a perspective view of the filter device as an example of the embodiment, FIG. 3 is a perspective plan view of the filter device as an example of the embodiment (viewed from the stacking direction), and FIG. FIG. 4B is a cross-sectional view taken along the line bb ′ in FIG. 3. FIG. 5 is a perspective plan view of a filter device as an example of another embodiment (viewed from the stacking direction), FIG. 6A is a cross-sectional view taken along the line aa ′ in FIG. 4, and FIG. FIG. 5 is a sectional view taken along line bb ′ in FIG. 4.

  In FIG. 1, 11 to 15 are first to fifth tip short-circuited lines, 21 to 25 are first to fifth tip-opened lines, and a first tip short-circuited line 11 and a first tip-opened line 21. Are connected in parallel to form the first parallel resonant line A1, and the second tip short-circuited line 12 and the second tip-opened line 22 are connected in parallel to form the second parallel resonant line A2. The third tip short-circuit line 13 and the third tip open line 23 are connected in parallel to form the third parallel resonant line A3, and the fourth tip short-circuit line 14 and the fourth tip open line are formed. The line 24 is connected in parallel to form a fourth parallel resonant line A4, and the fifth tip short-circuited line 15 and the fifth tip open line 25 are connected in parallel to form a fifth parallel resonant line A5. Is formed.

  Reference numerals 1 and 2 denote first and second input / output terminals, and reference numeral 3 denotes a reference node to which a reference potential is supplied. The reference potential is, for example, the ground potential GND.

  The filter of the present invention includes a first parallel resonant line A1 connected between the first input / output terminal 1 and the reference node 3, a first input / output terminal 1 and a second input / output terminal 2. The second to fourth parallel resonant lines A2 to A4 are connected in series, and the signal output from the previous stage is input to the subsequent stage, and is connected between the second input / output terminal 2 and the reference node 3. And a fifth parallel resonant line A5. The filter of the present invention is electrically connected to an external circuit via a transmission line, and high frequency signals are input / output from the first input / output terminal 1 and the second input / output terminal 2.

  The first and second input / output terminals 1 and 2 may be used as input and output terminals for high-frequency signals, or may be used for either input or output. When the first and second input / output terminals 1 and 2 are used for either input or output, for example, a high frequency signal is input from the first input / output terminal 1 and the second input / output terminal 2 is input. A signal is output from

  2 to 4, 31 is a first dielectric layer, 32 is a second dielectric layer laminated on the first dielectric layer 31, and 33 is a second dielectric layer. A third dielectric layer laminated on the layer 32; 34 a fourth dielectric layer laminated on the third dielectric layer 33; and 35 a laminate on the fourth dielectric layer. A fifth dielectric layer. 41 is a first ground electrode disposed on the lower surface of the first dielectric layer 31, and 51 and 61 are first tip short-circuit electrodes disposed between the first and second dielectric layers 31, 32, respectively. And first and second tip open electrodes 52 and 62 are respectively disposed between the second and third dielectric layers 32 and 33. The second tip short-circuit electrode and the second tip open electrode 53 and 63 are respectively disposed between the second and third dielectric layers 32 and 33. A third tip short-circuited electrode and a third tip-open electrode 54 and 64 arranged between the third and fourth dielectric layers 33 and 34 are respectively formed on the fourth and fifth dielectric layers 34 and 35. A fourth tip short-circuited electrode and a fourth tip-open electrode 42 disposed between them are a second ground electrode disposed on the upper surface of the fifth dielectric layer 35.

  The first ground electrode 41 and the second ground electrode 42 correspond to the reference node 3 of the filter of the present invention. The tips of the first to fourth tip short-circuit electrodes 51 to 54 are electrically connected to the first and second ground electrodes 41 and 42 via via conductors, side conductors, and the like.

  A first input / output terminal is connected to a connection portion between the first tip short-circuit electrode 51 and the first tip open electrode 61, and the fourth tip short-circuit electrode 54 and the fourth tip open electrode 64 are connected to each other. A second input / output terminal is connected to the connection portion.

  And the 1st tip short circuit electrode 51 and the 1st tip open electrode 61 are connected, the 1st conductor pattern M1 which has a short circuit end and an open end is formed, the 2nd tip short circuit electrode 52, A first open-circuit electrode 62 is connected to form a second conductor pattern M2 having a short-circuited end and an open-end, and a third-end short-circuited electrode 53 and a third front-end open electrode 63 are connected to form a short-circuited end. And a fourth conductor pattern M4 having a short-circuited end and an open end to which a fourth tip short-circuit electrode 54 and a fourth tip-open electrode 64 are connected. Is formed.

  The first parallel resonant line A1 shown in FIG. 1 is formed between the first ground electrode 41 and the first conductor pattern M1, and the fifth parallel resonant line A5 is connected to the second ground electrode 42 and It is formed between the fourth conductor patterns M4. Also, the second to fourth parallel resonant lines A2 to A4 shown in FIG. 1 are formed between the conductor patterns of the first to fourth conductor patterns M1 to M4. Specifically, the second parallel resonance line A2 is formed between the first conductor pattern M1 and the second conductor pattern M2, and the third parallel resonance line A3 is the second conductor pattern M2 and the third conductor pattern. A fourth parallel resonance line A4 is formed between the third conductor pattern M3 and the fourth conductor pattern M4.

  Then, the first ground electrode 41 and the first tip short-circuit electrode 51 are arranged in parallel so as to overlap in plan view with the first dielectric layer 31 interposed therebetween, and constitute the first tip short-circuit line 11. The first and second tip short-circuit electrodes 51 and 52 are arranged in parallel so as to overlap in plan view across the second dielectric layer 32 to constitute the second tip short-circuit line 12, and the second and second The three short-circuited electrodes 52 and 53 are arranged in parallel so as to overlap in plan view with the third dielectric layer 33 interposed therebetween to form the third short-circuited short-circuit line 13, and the third and fourth short-circuited short-circuited electrodes. The electrodes 53 and 54 are arranged in parallel so as to overlap in a plan view across the fourth dielectric layer 34 to constitute the fourth tip short-circuit line 14, and the second ground electrode 42 and the fourth tip short-circuit are formed. The electrodes 54 are arranged in parallel so as to overlap in plan view with the fifth dielectric layer 35 interposed therebetween. It constitutes a tip short-circuited line 15.

  Also, the first ground electrode 41 and the first open end electrode 61 are arranged in parallel so as to overlap in plan view across the first dielectric layer 31 to constitute the first open end line 21, The first and second open-ended electrodes 61 and 62 are arranged in parallel so as to overlap in plan view with the second dielectric layer 32 in between, forming the second open-ended line 22, and the second and second The third open end electrodes 62 and 63 are arranged in parallel so as to overlap in plan view with the third dielectric layer 33 interposed therebetween to form the third open end line 23, and the third and fourth open end electrodes The electrodes 63 and 64 are arranged in parallel so as to overlap in a plan view across the fourth dielectric layer 34 to constitute a fourth tip open line 24, and the second ground electrode 42 and the fourth tip open. The electrodes 64 are arranged in parallel so as to overlap in plan view with the fifth dielectric layer 35 interposed therebetween, Constitute the end open line 25.

  In FIG. 3, the first and second grounding electrodes 41 and 42 are shown in the drawing in order to show the configuration of the first to fourth tip short-circuit electrodes 51 to 54 and the first to fourth tip open electrodes 61 to 64. Omitting.

  The length of the first to fifth parallel resonant lines A1 to A5 or the length from the short-circuited end to the open end of the first to fourth conductor patterns M1 to M4 is the wavelength of the center frequency of the passband. Or less.

  Further, the first and fourth conductor patterns M1 and M4 are arranged so as to overlap the second and third conductor patterns M2 and M3 in plan view, and moreover than the second and third conductor patterns. The width is widened.

  In the filter and filter device of the present invention having such a configuration, the first and second ground electrodes 41 and 42 and the short-circuit ends of the first to fourth conductor patterns M1 to M4 are connected to the first to fifth dielectrics. By using the through conductors formed in the body layers 31 to 34 or the side conductors (not shown) formed on the side surfaces of the first to fifth dielectric layers 31 to 34, three-dimensional Wiring design is possible, and the degree of freedom in designing a filter device formed inside a plurality of stacked dielectric layers is improved, so that a small and high-performance filter device is obtained.

The characteristic impedances ZL1a, ZC1a of the lines 11, 21 of the filter circuit configuration of the present invention, the characteristic impedances ZL1b, ZC1b, ZL5b, ZC5b of the lines 111, 121, 115, 125 of the conventional filter circuit configuration, The relationship between the frequencies f−1 and f + 1 of the high frequency side passband and the frequencies f−∞ and f + ∞ of the attenuation pole is shown in the following equation.

  According to the filter and the filter device (first filter and filter device) of the present invention, the characteristic impedances ZL1a and ZC1a of the lines 11 and 21 of the circuit configuration pass as shown by the equations (1) and (2). It increases in proportion to the wideband degree fw1 / ft (≈g / 2) of the band, and also increases as the steepness fw∞ / fw1 (≈q) of the attenuation band becomes higher. The characteristic impedances ZL1b, ZC1b, ZL5b, and ZC5b of the lines 111, 121, 115, and 125 having the circuit configuration of the conventional filter are expressed by equations (3) to (6).

  As a result, as shown by the equation (7), the characteristic impedance ZL1a of the line 11 having the circuit configuration of the filter of the present invention is smaller than the characteristic impedances ZL1b and ZL5b of the lines 111 and 115 having the circuit configuration of the conventional filter. Similarly, the characteristic impedance ZC1a of the line 21 having the circuit configuration of the filter of the present invention is smaller than the characteristic impedances ZC1b and ZC5b of the lines 121 and 125 having the circuit configuration of the conventional filter. In particular, the characteristic impedance ZL1b of the line 111 of the circuit configuration of the conventional filter is divided by the square term of Ω−1 with respect to the characteristic impedance ZL1a of the line 11 of the circuit configuration of the filter of the present invention. As the value increases, the difference tends to increase rapidly.

  Further, the square term of Ω−1 forms a frequency f−1 on the low frequency side of the pass band as the resonance frequency of the parallel resonant line B1 formed of the lines 111 and 121 in the circuit configuration of the conventional filter. Therefore, it is divided by the expression of the characteristic impedance ZL1b of the line 111. On the other hand, in the circuit configuration of the present invention, the resonance frequency of the parallel resonant line A1 formed by the lines 11 and 21 is 2 in the characteristic impedance ZL1a of the line 11 in order to form the center frequency ft of the pass band. This will form a power term. However, since the square of Ωt is 1, the equation (1) is obtained, and the characteristic impedance ZL1a of the line 11 is larger than the characteristic impedance ZL1b of the line 111 by at least the square of Ω−1. It can be reduced. This effect becomes more prominent as the bandwidth increases.

  5 and 6 which are examples of other embodiments will be described. Compared with FIG. 2 and FIG. 3 which are examples of the previous embodiment, the dielectric layer, the ground electrode, and the tip open electrode are divided in the stacking direction.

31′a and 31′b are dielectric layers obtained by dividing the first dielectric layer 31, 35′a and 35′b are dielectric layers obtained by dividing the fifth dielectric layer 35, and 33′a and 33 ′. Reference numerals b and 33 ′ c denote dielectric layers obtained by dividing the third dielectric layer 33. 41'a and 41'b are ground electrodes obtained by dividing the first ground electrode 41, and 42'a and 42'b are ground electrodes obtained by dividing the second ground electrode. Reference numerals 62 ′ a and 62 ′ b are open end electrodes that are obtained by dividing the second open end electrode 62, and reference numerals 63 ′ a and 63 ′ b are open end electrodes that are obtained by dividing the third open end electrode 63.

  The ground electrodes 41′a and 41′b obtained by dividing the first ground electrode 41 are connected by a through conductor (not shown) formed inside the dielectric layer 31′a to form the ground electrode 41 ′. The ground electrodes 42'a and 42'b obtained by dividing the second ground electrode 42 are connected by a through conductor (not shown) formed inside the dielectric layer 35'a, and the ground electrode 42 is connected. Is forming. Further, the open end electrodes 62′a and 62′b obtained by dividing the second open end electrode 62 are connected by a through conductor (not shown) formed inside the dielectric layer 33′a so that the open end is opened. The electrode 62 ′ is formed, and the tip open electrodes 63′a and 63′b obtained by dividing the third tip open electrode 63 are through conductors (not shown) formed inside the dielectric layer 33′c. Connected to form an open-ended electrode 63 ′.

  With such a configuration, the filter device of the present invention improves the design freedom of the filter device formed inside the plurality of stacked dielectric layers, and thus can be a small and high-performance filter device.

  As the first to fifth dielectric layers 31 to 35 used in the filter device of the present invention, for example, ceramic materials such as alumina ceramics and mullite ceramics, inorganic materials such as glass ceramics, or tetrafluoroethylene resin (polyethylene Tetrafluoroethylene (PTFE), tetrafluoroethylene-ethylene copolymer resin (tetrafluoroethylene-ethylene copolymer resin; ETFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (tetrafluoroethylene-perfluteroalkyl) Fluorine resin such as vinyl ether copolymer resin (PFA), glass epoxy resin, resin material such as polyimide, or the like is used. The shapes and dimensions (thickness, width, length) of the first to third dielectric layers 21 to 23 made of these materials are set according to the frequency used, the application, and the like.

  In the filter device of the present invention, the first and second ground electrodes 41 and 42, the first to fourth conductor patterns M1 to M4, and the through conductor are conductive layers of a metal material for high-frequency signal transmission, such as a Cu layer, Mo -Ni plated layer and Au plated layer deposited on Mn metallized layer, Ni plated layer and Au plated layer deposited on W metallized layer, Cr-Cu alloy layer, Cr-Cu Ni plating layer and Au plating layer deposited on alloy layer, Ni—Cr alloy layer and Au plating layer deposited on Ta2N layer, Pt layer and Au plating layer coated on Ti layer It is formed by a thick film printing method, various thin film forming methods, plating methods, or the like using a deposited material or a material in which a Pt layer and an Au plating layer are deposited on a Ni—Cr alloy layer. The thickness and width are also set according to the frequency and application of the high-frequency signal transmitted.

  In forming the first to fifth dielectric layers 31 to 35 used in the filter device of the present invention, for example, when the dielectric layer is made of glass ceramics, first, a glass ceramic green sheet to be a dielectric layer is used. After preparing a predetermined punching process to form a through hole to be a through conductor, the through hole is filled with a conductive paste such as Cu by a screen printing method, and a predetermined transmission line pattern and other conductor layers The pattern is printed and applied. Next, baking is performed at 850 to 1000 ° C., and finally Ni plating and Au plating are performed on the conductor layer exposed on the outer surface.

  FIG. 7 shows a representative example of the filter characteristics of the filter device of the present invention having the configuration shown in FIGS. FIG. 12 shows the filter characteristics obtained in the conventional filters shown in FIGS.

  In FIG. 7, the horizontal axis indicates the frequency normalized by the center frequency of the passband, the vertical axis indicates the insertion loss (unit: dB), f−1 and f + 1 indicate the frequencies of the low-frequency and high-frequency passbands, f -∞ and f + ∞ represent the frequencies of the low-frequency and high-frequency attenuation poles, fw1 represents the passband width, and fw∞ represents the width between the attenuation poles. Compared to FIG. 12, which is a filter characteristic diagram of a conventional filter device, it has a wide band characteristic.

  In the case of the filter and filter device of the present invention configured as shown in FIG. 1 to FIG. 4, the characteristic impedance of the line to be configured tends to increase due to the wide band, but the resonance frequency of the grounded parallel resonant line is In the configuration, f−1 is formed, but in order to form the center frequency ft of the pass band, the square term of Ω−1 is not divided into the characteristic impedance equation. Therefore, an increase in characteristic impedance of the line can be reduced as compared with the conventional configuration, and as a result, an increase in thickness can be reduced and a filter and a filter device that can be easily downsized can be provided.

  In the filter and filter device of the present invention, the first and second input / output terminals 1 and 2 are preferably connected via a capacitor 26 as shown in FIG.

  Since the first input / output terminal 1 and the second input / output terminal 2 are connected by the capacitor 26, the connected capacitor is connected to the signal transmitted between the first and second input / output terminals 1 and 2. 26 can advance the phase. Therefore, since the phase can be changed abruptly at a frequency higher than the pass band, the second attenuation pole can be provided closer to the high frequency side of the pass band. From this, the increase in the characteristic impedance of the line, which occurs when the passband and the second attenuation pole on the high band side approach each other due to the broadening of the band (the steepness increases), can be further reduced. It is possible to provide a filter device that can reduce the increase more effectively and can be easily further reduced in size.

  An example of an embodiment of this filter in which the first and second input / output terminals 1 and 2 are connected by a capacitor 26 will be described with reference to FIGS. 13 and 14. FIG. 13 is a circuit configuration diagram showing another embodiment of the filter of the present invention. In FIG. 13, a capacitor 26 for connecting the first and second input / output terminals 1 and 2 is added to the circuit configuration diagram shown in FIG. 1, and the input high-frequency signal passes through the capacitor 26. Is also output.

  Further, in FIG. 14, the broken line is an example of filter characteristics showing another embodiment of the filter of the present invention having the configuration shown in FIG. 1, and the solid line is shown in FIG. 1 having the filter characteristics shown by the broken line shown in FIG. This is an example of filter characteristics in which first and second input / output terminals 1 and 2 are connected by a capacitor 26 to the circuit configuration of another embodiment of the filter of the present invention having the configuration shown. In FIG. 14, the horizontal axis represents frequency (unit: GHz), and the vertical axis represents insertion loss (unit: dB). 14 to FIG. 13, the second embodiment of the filter of the present invention shown in FIG. 13 has a higher second attenuation pole closer to the passband than the embodiment of the filter of the present invention shown in FIG. It can be seen that it can be provided. This makes it possible to further reduce the increase in characteristic impedance of the line that occurs when the passband and the second attenuation pole on the high band side approach each other due to the broadening of the band (the steepness increases), and increase the thickness by increasing the impedance. Thus, it is possible to provide a filter device that can be easily reduced in size.

  The filter device of the present invention having the filter of FIG. 13 is configured such that the first input / output terminal 1 and the second input / output terminal 2 of the filter device of the present invention configured as shown in FIG. 1 are connected via a capacitor. Consists of. For example, as shown in FIG. 15, such a capacitor forms a built-in capacitor by forming a pair of electrodes 73 between dielectric layers constituting the filter device and sandwiching the dielectric layer between the pair of electrodes 73. Each electrode of the capacitor can be provided by being electrically connected to the first and second input / output terminals 71 and 72 via wiring conductors, via conductors, and the like. The capacitor may not be a built-in capacitor using a dielectric layer, and a chip capacitor may be provided on the surface of the filter device or embedded in the filter device.

  In the filter device according to the present invention, the first and second ground electrodes 41 and 42 and the short-circuit ends of the first to fourth conductor patterns M1 to M4 preferably include the first to fifth electrodes. It is a through conductor formed in the dielectric layers 31 to 34 or a side conductor formed on the side surfaces of the first to fifth dielectric layers 31 to 34, and is thus laminated. In addition, the degree of freedom in designing the filter device formed inside the plurality of dielectric layers is improved, and the filter device is small and has a high performance.

It is a circuit block diagram which shows embodiment of the filter apparatus of this invention. It is a see-through | perspective perspective view which shows an example of embodiment of the filter apparatus of this invention. It is a see-through plan view showing an example of an embodiment of a filter device of the present invention. It is sectional drawing of an example of embodiment of the filter apparatus of this invention shown in FIG. 3, (a) is a sectional view on the a-a 'line, (b) is sectional drawing on the b-b' line. It is a perspective top view which shows an example of other embodiment of the filter apparatus of this invention. It is sectional drawing of an example of embodiment of the filter apparatus of this invention shown in FIG. 5, (a) is a sectional view on the a-a 'line, (b) is sectional drawing on the b-b' line. It is a diagram which shows the example of the insertion loss in the filter apparatus of this invention. FIG. 5 is a relationship diagram of a characteristic impedance Z0, a line width W, and a ratio of a dielectric thickness h of a grounded line. It is a circuit block diagram which shows the example of the conventional filter apparatus. It is a perspective top view which shows the example of the conventional filter apparatus. It is sectional drawing which shows the example of the conventional filter apparatus shown in FIG. 10, (a) is a sectional view on the a-a 'line, (b) is sectional drawing on the b-b' line. It is a diagram which shows the example of the insertion loss in the conventional filter apparatus. It is a circuit block diagram which shows other embodiment of the filter apparatus of this invention. It is a diagram which shows the example of the insertion loss in FIG. 1 and FIG. It is a see-through | perspective perspective view which shows the other example of embodiment of the filter apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ...... 1st input / output terminal 2 ... 2nd input / output terminal 3 ... Reference node 11 ... 1st tip short circuit line 12 ... 2nd tip short circuit line 13 3rd tip short-circuit line 14 ... 4th tip short-circuit line 15 ... 5th tip short-circuit line 21 ... 1st tip open line 22 ... 2nd tip short-circuit line 23 3rd open end line 24 4th open end line 25 5th open end line 26 capacitor A1 1st parallel resonant line A2 2nd Parallel resonant line A3 ... third parallel resonant line A4 ... fourth parallel resonant line A5 ... fifth parallel resonant line

Claims (6)

First and second input / output terminals, a reference node to which a reference potential is supplied, a first parallel resonant line connected between the first input / output terminal and the reference node, and the first The second to fourth parallel resonant lines are connected in series between the input / output terminal and the second input / output terminal, and the signal output from the previous stage is input to the subsequent stage, and the second input / output terminal. And a fifth parallel resonant line connected between the reference node and the reference node. The filter according to claim 1, wherein the first input / output terminal and the second input / output terminal are connected via a capacitor. First and second ground electrodes arranged to face each other, first to fifth dielectric layers stacked between the first and second ground electrodes, and the first to fifth dielectric layers A first to a fourth conductor pattern having a short-circuit end and an open end formed between the body layers and electrically connected to the first and second ground electrodes, respectively. 3. The second to fourth parallel resonant lines according to claim 1, wherein the first parallel resonant line according to claim 2 is formed between the first ground electrode and the first conductor pattern. Is formed between the conductor patterns of the first to fourth conductor patterns, and the fifth parallel resonant line according to claim 1 is formed between the second ground electrode and the fourth conductor pattern. The filter apparatus characterized by the above-mentioned. The length of the first to fifth parallel resonant lines or the length from the short-circuit end to the open end of the first to fourth conductor patterns is less than or equal to ½ of the wavelength of the center frequency of the pass band. The filter device according to claim 3, wherein the filter device is provided. The first and fourth conductor patterns are arranged so as to overlap the second and third conductor patterns in plan view, and are wider than the second and third conductor patterns. The filter device according to claim 3 or 4. The first and second ground electrodes and the short-circuit ends of the first to fourth conductor patterns are through conductors formed in the first to fifth dielectric layers or the first to fifth conductors. The filter device according to claim 3, wherein the filter device is electrically connected by a side conductor formed on a side surface of the dielectric layer.

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