JP2016092525A - Bandpass filter and multiplexer/demultiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and wide-band bandpass filter having a microwave band, and a multiplexer/demultiplexer.SOLUTION: A bandpass filter comprises: a first parallel resonator arranged on a signal transmission path between a first terminal and a second terminal; a second parallel resonator arranged between the first parallel resonator and the second terminal; a third parallel resonator arranged between the second parallel resonator and the second terminal; a first capacitor in which a first electrode is connected between the first parallel resonator and the second parallel resonator, and a second electrode is connected to a reference potential node; a second capacitor arranged between the second parallel resonator and the second terminal and connected in series to the third parallel resonator; a series resonator connected between a connection node between the second parallel resonator and the third parallel resonator and the reference potential node; and a fourth parallel resonator connected between the connection node between the second parallel resonator and the third parallel resonator and the prescribed reference potential node.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a band-pass filter and a multiplexer / demultiplexer that pass a signal component of a desired frequency band.

  In recent years, various wireless communication systems using a microwave band such as a mobile phone and a wireless local area network (LAN) have become widespread. In a wireless device or terminal of such a wireless communication system, a band pass filter for suppressing unnecessary signals and noise components is essential.

  As a band pass filter in the microwave band, a SAW (Surface Acoustic Wave) filter (surface acoustic wave filter) is used for a mobile phone or the like. The SAW filter is a filter suitable for a radio system having a relatively narrow frequency bandwidth. According to the SAW filter, an electrical signal in a specific frequency band is taken out by a comb-shaped electrode formed on a piezoelectric thin film or a substrate. When the SAW filter is used, there is a problem that it is difficult to extract a high frequency of 5 GHz or more because of its structure.

  When extracting a frequency higher than that of the SAW filter, a filter using a bulk acoustic wave called an FBAR filter (Film Bulk Acoustic Resonator filter) is used. However, there are few choices of the piezoelectric material that can be used for the FBAR filter, the applicable frequency band is limited at present, and the manufacturing process is more complicated than that of the SAW filter. (Non-Patent Document 1).

  On the other hand, in a wireless system that requires a wide bandwidth, such as a 5 GHz wireless LAN or UWB (Ultra Wide Band) using a frequency band from 3 GHz to 10.6 GHz, a distribution formed by transmission lines on a dielectric substrate. A filter using a constant line is used. As this type of filter, a filter using a ¼ wavelength type or ½ wavelength type uniform line resonator according to the line length of the distributed constant line is mainly used. However, according to a filter using a distributed constant line, there is a problem that it is difficult to reduce the size of the filter because the line length of the transmission line is generally long (Non-patent Document 2).

  In recent years, LTCC (Low Temperature Co-fired Ceramics) process technology has been established, and a small band-pass filter has been used by multilayer wiring using the process technology. According to the band-pass filter using the LTCC process technology, the influence of the parasitic capacitance between the multilayer wirings becomes large particularly at a frequency of the microwave band or higher. In order to reduce the influence of such parasitic capacitance, design methods such as reducing the number of wires and securing the distance between lines are used (Non-patent Document 3).

Kenya Hashimoto, “Functional high-frequency acoustic wave devices: present and future”, IEICE Fundamentals Review Vol.4, No.3, pp.192-197, January. 2011. Koji Wada, “Recent Microwave Filter Technology Broadband Filter and Its Application to Demultiplexer”, Shimada Rika Technical Report, No.22, p2-8, 2012. S. Oshima, K. Wada, R. Murata, and Y. Shimakata, “A study on a multilayer diplexer using LTCC technology for ultra-wideband wireless modules,” IEICE Electronics Express vol.8, no.11, pp. 848- 853, June 2011.

  However, according to the above-described prior art, when realizing a broadband microwave band-pass filter using a multilayer substrate such as LTCC, in order to reduce the influence of parasitic capacitance, designing with a distributed constant line or Therefore, it is necessary to increase the thickness of each dielectric layer and to secure the interval between the wirings. For this reason, there exists a problem that size reduction is difficult.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a bandpass filter and a multiplexer / demultiplexer having a small and wide pass frequency bandwidth.

  In order to solve the above-described problem, one aspect of the present invention provides a first parallel resonator disposed on a signal transmission path between a first terminal and a second terminal, the first parallel resonator, and the first parallel resonator. A second parallel resonator disposed on the signal transmission path between the second terminal and a third parallel disposed on the signal transmission path between the second parallel resonator and the second terminal; A first capacitor having a first electrode connected between the resonator, the first parallel resonator and the second parallel resonator, and a second electrode connected to a predetermined reference potential node; and the second parallel A second capacitor disposed on the signal transmission path between the resonator and the second terminal and connected in series with the third parallel resonator; the second parallel resonator; and the third parallel resonator; A series resonator connected between a connection node between the first reference potential node and the predetermined reference potential node; A connection node between a column resonator and the third parallel resonator, and a fourth parallel resonator connected between the predetermined reference potential node, and a resonance frequency of the first parallel resonator Is F11, the resonance frequency of the second parallel resonator is F12, the resonance frequency of the third parallel resonator is F15, the resonance frequency of the series resonator is F13, and the resonance frequency of the fourth parallel resonator. Is F14, F11, F12, F13, F14, and F15 have a configuration of a band-pass filter that satisfies the condition of F13, F11> F14> F15> F12.

  One aspect of the present invention is the bandpass filter, wherein the bandpass filter is formed on a dielectric substrate having a multilayer wiring, and the first parallel resonator, the second parallel resonator, and the third A part of or all of the parallel resonator and the fourth parallel resonator have a configuration of a band-pass filter that is realized by utilizing self-resonance of the multilayer inductor of the dielectric substrate.

  One aspect of the present invention is the bandpass filter, wherein the bandpass filter is formed over a dielectric substrate having a multilayer wiring, and the series resonator connects between the multilayer wirings of the dielectric substrate. It has a configuration of a band pass filter that is realized by using a parasitic inductor formed by vias.

  One aspect of the present invention is the bandpass filter, wherein the second capacitor is between the third parallel resonator and the second terminal or between the second parallel resonator and the third parallel resonance. A band-pass filter characterized in that it is disposed between the filter and the filter.

  One aspect of the present invention includes a low-pass bandpass filter having the same topology as the bandpass filter with respect to input and output, and a high-passband pass filter having a topology opposite to the bandpass filter with respect to input and output. It has the structure of the provided multiplexer / demultiplexer.

  In order to solve the above-described problem, according to the present invention, in a bandpass filter formed on a dielectric substrate having a multilayer wiring, a parallel resonator 11 and a parallel resonator 12 are connected in series, and the parallel resonator A shunt capacitor C1 is connected to a connection terminal between the parallel resonator 12 and the parallel resonator 12, and a series resonator 13, a parallel resonator 14 and a parallel resonator 15 are connected to the other terminal of the parallel resonator 12, and the series resonance is performed. The other terminals of the resonator 13 and the parallel resonator 14 are grounded, and the other terminal of the parallel resonator 15 is connected to one terminal of the capacitor C2. In addition, when the resonance frequencies for generating the attenuation poles of the parallel resonators 11, 12, 15 and the series resonator 13 are F11, F12, F15, and F13, respectively, F13, F11> F14> F15> F12. This is a characteristic band-pass filter circuit. Either the frequency of F13 or F11 may be high.

  Further, according to the present invention, in a branching circuit composed of two bandpass filters formed on a dielectric substrate having a multilayer wiring, the low-pass bandpass filter is composed of a parallel resonator 11L and a parallel resonator 12L in series. A shunt capacitor CL1 is connected to a connection terminal between the parallel resonator 11L and the parallel resonator 12L, and the series resonator 13L, the parallel resonator 14L, and the parallel resonance are connected to the other terminal of the parallel resonator 12L. 15L is connected, the other terminal of the series resonator 13L and the parallel resonator 14L is grounded, the other terminal of the parallel resonator 15L is connected to one terminal of the capacitor CL2, and the other terminal of the capacitor CL2 Is connected to the terminal TB, the other terminal of the parallel resonator 11L is connected to the terminal TA, and the high-frequency band-pass filter is connected in parallel. A vibrator 21H and a parallel resonator 22H are connected in series, a shunt capacitor CH3 is connected to a connection terminal between the parallel resonator 21H and the parallel resonator 22H, and a series resonance is made at the other terminal of the parallel resonator 22H. 23H, parallel resonator 24H and parallel resonator 25H are connected, the other terminal of the series resonator 23H and the parallel resonator 24H is grounded, and the other terminal of the parallel resonator 25H is one of the capacitors CH4. A terminal is connected, the other terminal of the capacitor CH4 is connected to a terminal TA, and the other terminal of the parallel resonator 21H is connected to a terminal TC. The resonance frequencies for generating the attenuation poles of the parallel resonators 11L, 12L, 15L and the series resonator 13L inside the low-pass bandpass filter are F11, F12, F15, and F13, respectively. When the resonance frequencies of the parallel resonators 21H, 22H, and 25H and the series resonator 23H are F21, F22, F25, and F23, respectively, F11, F13> F14> F15> F12, and F23, F21> F24> F25> F22. , And the frequency relationship of F24> F14 is satisfied. Either the frequency of F13 or F11 may be high. Moreover, whichever is higher also about the frequency of F23 and F21.

  The present invention is also the bandpass filter circuit and the demultiplexing circuit described above, wherein a part or all of the parallel resonator is realized by self-resonance of the multilayer inductor.

  The present invention is the above-described band-pass filter circuit and branching circuit, wherein the inductor constituting the series resonator is realized by a via (VIA) connecting between the multilayer wirings.

  According to the present invention, a small and wide bandpass filter and multiplexer / demultiplexer can be realized. In addition, it is possible to reduce the price at the time of mass production at LTCC and to reduce the mounting area of the wireless communication module.

It is a block diagram of the bandpass filter by the 1st Embodiment of this invention. 1 is a circuit diagram of a bandpass filter according to a first embodiment of the present invention. FIG. It is a characteristic view of the band pass filter by the 1st Embodiment of this invention, and is a figure which shows an example of the characteristic obtained as a calculation result in a circuit simulator. It is a block diagram of the multiplexer / demultiplexer by the 2nd Embodiment of this invention. It is a circuit diagram of the multiplexer / demultiplexer by the 2nd Embodiment of this invention. It is a characteristic view of the multiplexer / demultiplexer by the 2nd Embodiment of this invention, and is a figure which shows an example of the calculation result by a circuit simulator. It is a characteristic view of the multiplexer / demultiplexer by the 2nd Embodiment of this invention, and is a figure which shows an example of the input impedance calculation result (0.9-1.8 GHz) by a circuit simulator. It is a characteristic view of the multiplexer / demultiplexer by the 2nd Embodiment of this invention, and is a figure which shows an example of the input impedance calculation result (2.4-4.5 GHz) by a circuit simulator. It is a figure which shows the example of mounting to the LTCC of the multiplexer / demultiplexer by the 2nd Embodiment of this invention. It is a characteristic figure of the multiplexer / demultiplexer by the 2nd Embodiment of this invention, and is a figure which shows an example of the calculation result by an electromagnetic field simulator.

Embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
First, a first embodiment of the present invention will be described.
FIG. 1 is a block diagram illustrating a configuration example of a bandpass filter 100 according to the first embodiment. In the figure, a band pass filter 100 includes a first terminal TA, a second terminal TB, a parallel resonator 11 (first parallel resonator), a parallel resonator 12 (second parallel resonator), a series resonator 13, and a parallel resonator. A resonator 14 (fourth parallel resonator), a parallel resonator 15 (third parallel resonator), a shunt capacitor C1 (first capacitor), and a series capacitor C2 (second capacitor) are included.
In the first embodiment, the first terminal TA is used as the input terminal of the bandpass filter 100, and the second terminal TB is used as the output terminal of the bandpass filter 100. However, the present invention is not limited to this example, and the first terminal TA may be an output terminal and the second terminal TB may be an input terminal.
In the first embodiment, the present invention is expressed as a bandpass filter, but may be expressed as a bandpass filter circuit, a bandpass filter device, a filter, or the like.

  The band-pass filter 100 has one first terminal TA as an input terminal and one second terminal TB as an output terminal, and a signal in a desired frequency band among signals input from the first terminal TA. Only through the second terminal with low loss. The parallel resonator 11 is disposed on the signal transmission path between the first terminal TA and the second terminal TB, and is connected to the first end of the parallel resonator 11 (in this example, the input portion of the parallel resonator 11). ) Is connected to the first terminal TA. The parallel resonator 12 is disposed on the signal transmission path between the parallel resonator 11 and the second terminal TB, and the first end of the parallel resonator 12 (in this example, the input portion of the parallel resonator 12). Is connected to the second end of the parallel resonator 11 (in this example, the output of the parallel resonator 11). The parallel resonator 15 is disposed on the signal transmission path between the parallel resonator 12 and the second terminal TB, and the first end of the parallel resonator 15 (in this example, the input portion of the parallel resonator 15). Is connected to the second end of the parallel resonator 12 (in this example, the output of the parallel resonator 12).

  A first electrode of the shunt capacitor C1 is connected between the parallel resonator 11 and the parallel resonator 12, and a second electrode of the shunt capacitor C1 is connected to a ground that is a predetermined reference potential node. The series capacitor C2 is disposed on the signal transmission path between the parallel resonator 12 and the second terminal TB, and is connected in series with the parallel resonator 15. Specifically, the first electrode of the series capacitor C2 is connected to the second end of the parallel resonator 15 (in this example, the output of the parallel resonator 15), and the second electrode of the series capacitor C2 is the second terminal. Connected to TB. However, the arrangement positions of the parallel resonator 15 and the series capacitor C2 may be reversed. In this case, the first electrode of the series capacitor C2 is connected to the second end of the parallel resonator 12 (in this example, the output of the parallel resonator 12), and the second electrode of the series capacitor C2 is connected to the parallel resonator 15. The first end (in this example, the input of the parallel resonator 15) is connected, and the second end of the parallel resonator 15 (in this example, the output of the parallel resonator 15) is connected to the second terminal TB. Is done.

  The series resonator 13 is connected between a connection node MA between the second parallel resonator and the third parallel resonator and a ground which is a predetermined reference potential node. The parallel resonator 14 is also connected between a connection node MA between the second parallel resonator and the third parallel resonator and a ground which is a predetermined reference potential node. That is, the series resonator 13 and the parallel resonator 14 are connected in parallel between the connection node MA and the ground.

  The parallel resonators 11, 12, 15 and the series resonator 13 have a role of resonating at a frequency desired to be attenuated in the pass characteristic and generating an attenuation pole. The series capacitor C2 mainly has a role of removing low frequency components and a role of expanding a passband bandwidth for impedance matching by causing series resonance with the internal inductor of the parallel resonator 15. The parallel resonator 14 is set to have a resonance frequency mainly in the passband frequency band. The shunt capacitor C1 has a role of adjusting as impedance matching of the pass band, and has a role of adjusting flatness of the pass band.

  In the first embodiment, the resonance frequency of the parallel resonator 11 is F11, the resonance frequency of the parallel resonator 12 is F12, the resonance frequency of the parallel resonator 15 is F15, and the resonance frequency of the series resonator 13 is F13. When the resonance frequency of the parallel resonator 14 is F14, F11, F12, F13, F14, and F15 satisfy the conditions of F11, F13> F14> F15> F12. That is, the resonance frequencies F11 and F13 are higher than the resonance frequency F14, the resonance frequency F14 is higher than the resonance frequency F15, and the resonance frequency F15 is higher than the resonance frequency F12. The magnitude relationship between the resonance frequency F11 and the resonance frequency F13 is arbitrary. That is, the resonance frequency F11 may be higher than the resonance frequency F13, and conversely, the resonance frequency F13 may be higher than the resonance frequency F11. Therefore, the F11, F12, F13, F14, and F15 may satisfy the condition of F11> F14> F15> F12 and the condition of F13> F14> F15> F12.

  The frequency of the high frequency band to be attenuated is set by the resonance frequency F11 of the parallel resonator 11 and the resonance frequency F13 of the series resonator 13. The low frequency band to be attenuated is set by the resonance frequency F15 of the parallel resonator 15 and the resonance frequency F12 of the parallel resonator 12.

  FIG. 2 is a circuit diagram of the band-pass filter 100 according to the first embodiment of the present invention. The circuit example of FIG. 2 shows a design example of a band-pass filter when each resonator is expressed by an equivalent circuit of one inductor and one capacitor. The parallel resonator 11 includes a capacitor C11 and an inductor L11 connected in parallel. The parallel resonator 12 includes a capacitor C12 and an inductor L12 connected in parallel. The series resonator 13 includes a capacitor C13 and an inductor L13 connected in series. The parallel resonator 14 includes a capacitor C14 and an inductor L14 connected in parallel. The parallel resonator 15 includes a capacitor C15 and an inductor L15 connected in parallel.

  The parameters of each element shown in FIG. 2 are as follows: C11 = 0.1 pF, C1 = 0.7 pF, C12 = 7 pF, C13 = 2 pF, C14 = 0.4 pF, C15 = 0.6 pF, C2 = 1.8 pF, L11 = 4.5nH, L12 = 7.5nH, L13 = 0.6nH, L14 = 5.5nH, L15 = 5.7nH. However, the present invention is not limited to this example, and the parameters of each element can be arbitrarily set as long as the above conditions are satisfied.

FIG. 3 is a characteristic diagram of the band-pass filter 100 according to the first embodiment of the present invention, and is a diagram illustrating an example of characteristics obtained as a calculation result in the circuit simulator. As can be understood from FIG. 4, the pass band of the band pass filter 100 has a bandwidth of 900 MHz in a section from 0.9 GHz to 1.8 GHz, and has a wide band pass characteristic of 66% in a specific band. A band pass filter is realized.
Therefore, according to the band pass filter 100 according to the first embodiment, a small and wide band pass filter can be realized. In addition, it is possible to reduce the price at the time of mass production at LTCC and to reduce the mounting area of the wireless communication module.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
In the second embodiment, a multiplexer / demultiplexer including a high-frequency band-pass filter and a low-frequency band-pass filter using the topology of the band-pass filter 100 of the first embodiment described above is realized.
In the second embodiment, when the band pass filter 100 of the first embodiment is used as a high band side band pass filter of the multiplexer / demultiplexer, as will be described in detail below, the first terminal TA and the band pass filter are used. The terminal of the series capacitor C2 of the filter 100 is connected. In the multiplexer / demultiplexer according to the second embodiment of the present invention, the imaginary part of the input impedance of the common port in each pass band is canceled using the out-of-band characteristics of the combined low-pass and high-pass filters. Such a design enables matching in a wide band while eliminating the matching circuit.
In the second embodiment, the present invention is expressed as a multiplexer / demultiplexer, but the multiplexer / demultiplexer, the multiplexer / demultiplexer, the demultiplexer, the demultiplexer, the demultiplexer, the multiplexer, and the multiplexer It can also be expressed as a multiplexing device, a filter, a filter circuit, a filter device, or the like.

FIG. 4 is a block diagram showing the configuration of the multiplexer / demultiplexer 300 according to the second embodiment of the present invention. The multiplexer / demultiplexer 300 includes a first terminal TA, a second terminal TB, a third terminal TC, a low-frequency band-pass filter 300L, and a high-frequency band-pass filter 300H.
In the second embodiment, the first terminal TA is an input terminal of the multiplexer / demultiplexer 300, and the second terminal TB and the third terminal TC are the output terminals of the multiplexer / demultiplexer 300. In this case, the multiplexer / demultiplexer 300 functions as a demultiplexer. When functioning the multiplexer / demultiplexer 300 as a multiplexer, the first terminal TA may be used as an output terminal, and the second terminal TB and the third terminal TC may be used as input terminals.

  The low-pass band-pass filter 300L has the same circuit topology in terms of input and output as the band-pass filter 100 according to the first embodiment shown in FIG. That is, the low-frequency side bandpass filter 300L has the same connection relationship of circuit components between the input terminal TA and the output terminal TB as the low-frequency side bandpass filter 100 according to the first embodiment. The parallel resonator 11L, the parallel resonator 12L, the parallel resonator 14L, the parallel resonator 15L, and the series resonator 13L, which are constituent elements of 300L, are respectively a parallel resonator 11 and a parallel resonance of the bandpass filter 100 shown in FIG. This element corresponds to the resonator 12, the parallel resonator 14, the parallel resonator 15, and the series resonator 13. However, the circuit constants are different. The low-frequency band-pass filter 300L passes only a signal in a desired low-frequency band in the signal input from the first terminal TA with low loss, and outputs it from the second terminal TB.

  On the other hand, the high-pass bandpass filter 300H has a reverse circuit topology in which the topology of the bandpass filter 100 according to the first embodiment shown in FIG. Specifically, the high-frequency band-pass filter 300H includes a parallel resonator 21H, a parallel resonator 22H, a series resonator 23H, a parallel resonator 24H, a parallel resonator 25H, a shunt capacitor CH3, and a series capacitor CH4. .

  The parallel resonator 21H is disposed on the signal transmission path between the first terminal TA and the third terminal TC, and is connected to the second end of the parallel resonator 21H (in this example, the output portion of the parallel resonator 21H). ) Is connected to the third terminal TC. The parallel resonator 22H is disposed on the signal transmission path between the parallel resonator 21H and the first terminal TA, and the second end of the parallel resonator 22H (in this example, the output portion of the parallel resonator 22H). Is connected to the first end of the parallel resonator 21H (in this example, the input of the parallel resonator 21H). The parallel resonator 25H is disposed on the signal transmission path between the parallel resonator 22H and the first terminal TA, and the second end of the parallel resonator 25H (in this example, the output portion of the parallel resonator 25H). Is connected to the first end of the parallel resonator 22H (in this example, the input of the parallel resonator 22H).

  A first electrode of the shunt capacitor CH3 is connected between the parallel resonator 21H and the parallel resonator 22H, and a second electrode of the shunt capacitor CH3 is connected to the ground which is a predetermined reference potential node. The series capacitor CH4 is disposed on the signal transmission path between the parallel resonator 22H and the first terminal TA, and is connected in series with the parallel resonator 25H. Specifically, the first electrode of the series capacitor CH4 is connected to the first end of the parallel resonator 25H (in this example, the input portion of the parallel resonator 25H), and the second electrode of the series capacitor CH4 is the first terminal. Connected to TA. However, the arrangement positions of the parallel resonator 25H and the series capacitor CH4 may be reversed. In this case, the first end portion of the parallel resonator 25H (in this example, the input portion of the parallel resonator 25H) is connected to the first terminal TA, and the second end portion of the parallel resonator 25H (in this example, parallel resonance). The second electrode of the series capacitor CH4 is connected to the output of the capacitor 25H, and the first electrode of the series capacitor CH4 is connected to the first end of the parallel resonator 22H (in this example, the input of the parallel resonator 22H). Connected.

  The series resonator 23H is connected between a connection node MB between the parallel resonator 22H and the parallel resonator 25H and a ground which is a predetermined reference potential node. The parallel resonator 24H is also connected between a connection node MB between the parallel resonator 22H and the parallel resonator 25H and a ground which is a predetermined reference potential node. That is, the series resonator 23H and the parallel resonator 24H are connected in parallel between the connection node MB and the ground.

  The parallel resonators 21H, 22H, 25H and the series resonator 23H resonate at a frequency desired to be attenuated in the pass characteristic and have a role of generating an attenuation pole. The series capacitor CH4 mainly has a role of removing low frequency components and a role of expanding a passband bandwidth for impedance matching by causing series resonance with the internal inductor of the parallel resonator 25H. The parallel resonator 24H is set to have a resonance frequency mainly in the passband frequency band. The shunt capacitor CH3 has a role of adjusting as impedance matching of the pass band, and has a role of adjusting flatness of the pass band.

  In the second embodiment, the condition of the resonance frequency of each resonator of the low-frequency side bandpass filter 300L is the same as that in the first embodiment. That is, the resonance frequency of the parallel resonator 11L is F11L, the resonance frequency of the parallel resonator 12L is F12L, the resonance frequency of the parallel resonator 15L is F15L, the resonance frequency of the series resonator 13L is F13L, and the parallel resonator 14L F11L, F12L, F13L, F14L, and F15L satisfy the following conditions: F11L, F13L> F14L> F15L> F12L. That is, the resonance frequencies F11L and F13L are higher than the resonance frequency F14L, the resonance frequency F14L is higher than the resonance frequency F15L, and the resonance frequency F15L is higher than the resonance frequency F12L. Note that the magnitude relationship between the resonance frequency F11L and the resonance frequency F13L is arbitrary. That is, the resonance frequency F11L may be higher than the resonance frequency F13L, and conversely, the resonance frequency F13L may be higher than the resonance frequency F11L.

  In the second embodiment, the resonance frequency of the parallel resonator 21H is F21H, the resonance frequency of the parallel resonator 22H is F22H, the resonance frequency of the parallel resonator 25H is F25H, and the resonance frequency of the series resonator 23H is When F23H is set and the resonance frequency of the parallel resonator 24H is F24H, the F21H, F22H, F23H, F24H, and F25H satisfy the following conditions: F23H, F21H> F24H> F25H> F22H. That is, the resonance frequencies F21H and F23H are higher than the resonance frequency F24H, the resonance frequency F24H is higher than the resonance frequency F25H, and the resonance frequency F25H is higher than the resonance frequency F22H. Further, the passband frequency of the low-pass bandpass filter 300L is substantially equal to the resonance frequency F14H, and the passband frequency of the high-pass bandpass filter 300H is substantially equal to the resonance frequency F24H. The resonance frequency F24H is higher than the resonance frequency F14H (that is, F24H> F14H). Note that the magnitude relationship between the resonance frequency F21H and the resonance frequency F23H is arbitrary. That is, the resonance frequency F21H may be higher than the resonance frequency F23H, and conversely, the resonance frequency F23H may be higher than the resonance frequency F21H.

  The frequency of the high frequency band to be attenuated is set by the resonance frequency F21H of the parallel resonator 21H and the resonance frequency F23H of the series resonator 23H. The low frequency band to be attenuated is set by the resonance frequency F25H of the parallel resonator 25H and the resonance frequency F22H of the parallel resonator 22H.

  FIG. 5 is a circuit diagram of the multiplexer / demultiplexer 300 according to the second embodiment of the present invention. The circuit example of FIG. 5 shows a design example of the multiplexer / demultiplexer when each resonator is expressed by an equivalent circuit of one inductor and one capacitor. The parallel resonator 11L includes a capacitor CL11 and an inductor LL11 connected in parallel. The parallel resonator 12L includes a capacitor CL12 and an inductor LL12 connected in parallel. The series resonator 13L includes a capacitor CL13 and an inductor LL13 connected in series. The parallel resonator 14L includes a capacitor CL14 and an inductor LL14 connected in parallel. The parallel resonator 15L includes a capacitor CL15 and an inductor LL15 connected in parallel. The parallel resonator 21H is composed of a capacitor CH21 and an inductor LH21 connected in parallel. The parallel resonator 22H includes a capacitor CH22 and an inductor LH22 connected in parallel. The series resonator 23H includes a capacitor CH23 and an inductor LH23 connected in series. The parallel resonator 24H includes a capacitor CH24 and an inductor LH24 connected in parallel. The parallel resonator 25H includes a capacitor CH25 and an inductor LH25 connected in parallel.

  The parameters of each element of the low-pass bandpass filter 300L shown in FIG. 5 are CL11 = 0.15 pF, CL1 = 0.7 pF, CL12 = 7 pF, CL13 = 2 pF, CL14 = 0.4 pF, CL15 = 0.6 pF, CL2 = 1.8 pF, LL11 = 6 nH, LL12 = 7.5 nH, LL13 = 0.6 nH, LL14 = 5.5 nH, LL15 = 5.7 nH. The parameters of each element of the high-frequency side bandpass filter 300H are, for example, CH4 = 0.75 pF, CH25 = 0.3 pF, CH23 = 0.4 pF, CH24 = 0.7 pF, CH22 = 3 pF, CH3 = 0. 1 pF, CH21 = 0.05 pF, LH25 = 1.7 nH, LH23 = 1.8 nH, LH24 = 0.3 nH, LH22 = 3 nH, LH21 = 1.5 nH. However, the present invention is not limited to this example, and the parameters of each element can be arbitrarily set as long as the above conditions are satisfied.

FIG. 6 is a characteristic diagram of the multiplexer / demultiplexer 300 according to the second embodiment of the present invention, and is a diagram illustrating an example of characteristics obtained as a calculation result in the circuit simulator. As can be seen from FIG. 6, the pass band from the first terminal TA to the second terminal TB has a wide bandwidth characteristic of 900 MHz and a specific band of 66.6% in a section from 0.9 GHz to 1.8 GHz. Has been realized. In addition, the pass band from the first terminal TA to the third terminal TC realizes a bandwidth of 2.1 GHz and a specific band of about 60.8% in a section from 2.4 GHz to 4.5 GHz.
Therefore, according to the multiplexer / demultiplexer 300 according to the second embodiment, a small-sized and broadband multiplexer / demultiplexer can be realized. In addition, it is possible to reduce the price at the time of mass production at LTCC and to reduce the mounting area of the wireless communication module.

  FIG. 7 and FIG. 8 show the input side impedances of the high band side band pass filter (300H), the low band side band pass filter (300L), and the branch circuit constituting the multiplexer / demultiplexer (300) shown in FIG. . FIG. 7 is a characteristic diagram of the multiplexer / demultiplexer 300 according to the second embodiment of the present invention, and shows an example of the input impedance calculation result (0.9 to 1.8 GHz) by the circuit simulator. FIG. 8 is a characteristic diagram of the multiplexer / demultiplexer 300 according to the second embodiment of the present invention, and shows an example of the input impedance calculation result (2.4 to 4.5 GHz) by the circuit simulator.

Considering the imaginary part of the out-of-band characteristics of the low-pass and high-pass bandpass filters 300H, the matching circuit is eliminated by designing to cancel the imaginary part of the input impedance of the common port in each passband However, wideband matching was achieved.
For example, in FIG. 7, the input impedance in the 0.9 to 1.8 GHz band of the high-frequency band-pass filter 300H is located in the right region of the lower semicircle in the Smith chart. On the other hand, the input impedance in the 0.9 to 1.8 GHz band of the low-frequency band-pass filter 300L is located in the left region from the center of the upper semicircle in the Smith chart. The input impedance when the multiplexer / demultiplexer 300 is configured by connecting these high-frequency and low-frequency bandpass filters is as shown in FIG. In this case, the imaginary parts cancel each other out and are located at the center on the Smith chart. The calculation results of the input impedance in the 2.4 to 4.5 GHz band shown in FIG. 8 are the same.

  The bandpass filter 100 according to the first embodiment and the multiplexer / demultiplexer 300 according to the second embodiment are suitable for using a multilayer inductor or multilayer capacitor using LTCC multilayer wiring. Since the multilayer inductor and the multilayer capacitor have parasitic capacitance and parasitic inductance, respectively, they self-resonate at a certain frequency. In the above-described embodiment, the self-resonance is positively utilized for the resonator, thereby realizing further miniaturization of the circuit of the band pass filter and the multiplexer / demultiplexer.

  FIG. 9 is a diagram illustrating an implementation example of the multiplexer / demultiplexer 300 according to the second embodiment of the present invention in the LTCC. In FIG. 9, an example of the branching circuit of the present invention (circuit shown in FIG. 5) designed by an electromagnetic field simulator in an LTCC in which ground conductors are provided on the upper and lower sides and an 8-layer metal layer is provided inside the substrate. Show. In the circuit configuration shown in this example, four capacitors (for example, CH25, CH22, CL1, and CL14) and two inductors (for example, LH23 and LL13) use parasitic components generated by a three-dimensional structure. The size reduction is achieved.

Further, in this example, for example, four capacitors (for example, CH25, CH22, CL1, CL14) do not use MIM capacitors, but as shown in FIG. Parasitic capacitance is used. Further, as shown in FIG. 9C, the two inductors (for example, LH23 and LL13) also use vias (VIA) in which multilayer wirings are connected toward the lower ground plane. This via has a small inductance value. By using this via, the inductance can be realized with a very small area. The dimensions of the branching circuit shown in the example of FIG. 9 are as small as 5.0 × 3.0 × 0.552 mm ³ .

  FIG. 10 is a characteristic diagram of the multiplexer / demultiplexer 300 according to the second embodiment of the present invention, and is a diagram illustrating an example of a calculation result by the electromagnetic field simulator. As shown in FIG. 10, the result of the electromagnetic field design also almost coincides with the predicted value in the circuit simulator.

  Further, in the band pass filter 100 of the present invention, the same characteristics as in the above example can be obtained even with a configuration in which the arrangement of the parallel resonator 15 and the capacitor C2 is replaced. The same applies to the multiplexer / demultiplexer 300 of the present invention. That is, in the multiplexer / demultiplexer 300, the same characteristics can be obtained even in a configuration in which the arrangement of the parallel resonator 15L and the capacitor CL2 is replaced or a configuration in which the arrangement of the parallel resonator 25H and the capacitor CH4 is replaced. In this case, the capacitors C2, CL2, and CH4, which are series capacitors, and the inductors in the parallel resonators 15, 15L, and 25H act as a series resonance circuit. This is possible even if the arrangement order of the capacitors and the inductors is changed. This is because the impedance becomes equivalent.

As described above, the bandpass filter 100 is formed on a dielectric substrate having a multilayer wiring, and includes parallel resonators 11, 11L, 21H, parallel resonators 12, 12L, 22H, parallel resonators 14, 14L, 24H, Some or all of the parallel resonators 15, 15L, and 25H are realized by utilizing the self-resonance of the multilayer inductor on the dielectric substrate.
In the band pass filter 100, the series resonators 13, 13L, and 23H are realized by using, for example, parasitic inductors formed by vias (VIA) that connect the multilayer wirings of the dielectric substrate.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and arbitrary modifications and corrections can be made without departing from the gist of the present invention.

  100: band pass filter, 11, 12, 14, 15, 11L, 12L, 14L, 15L, 21H, 22H, 24H, 25H ... parallel resonator, 13, 13L, 23H ... series resonator, C1, CL1, CH3 ... Shunt capacitors, C2, CL2, CH4 ... series capacitors, 300 ... multiplexer / demultiplexer, 300L ... low-pass bandpass filter, 300H ... high-pass bandpass filter.

Claims (5)

A first parallel resonator disposed on a signal transmission path between the first terminal and the second terminal;
A second parallel resonator disposed on the signal transmission path between the first parallel resonator and the second terminal;
A third parallel resonator disposed on the signal transmission path between the second parallel resonator and the second terminal;
A first capacitor having a first electrode connected between the first parallel resonator and the second parallel resonator and having a second electrode connected to a predetermined reference potential node;
A second capacitor disposed on the signal transmission path between the second parallel resonator and the second terminal and connected in series with the third parallel resonator;
A series resonator connected between a connection node between the second parallel resonator and the third parallel resonator, and the predetermined reference potential node;
A fourth parallel resonator connected between a connection node between the second parallel resonator and the third parallel resonator, and the predetermined reference potential node;
With
The resonance frequency of the first parallel resonator is F11, the resonance frequency of the second parallel resonator is F12, the resonance frequency of the third parallel resonator is F15, and the resonance frequency of the series resonator is F13. When the resonance frequency of the fourth parallel resonator is F14,
F11, F12, F13, F14, and F15 are
A band-pass filter that satisfies the following conditions: F11, F13>F14>F15> F12. The bandpass filter according to claim 1,
The band pass filter is formed on a dielectric substrate having a multilayer wiring,
A part or all of the first parallel resonator, the second parallel resonator, the third parallel resonator, and the fourth parallel resonator use self-resonance of the multilayer inductor of the dielectric substrate. A band-pass filter characterized by being realized. The bandpass filter according to claim 1 or 2,
The band pass filter is formed on a dielectric substrate having a multilayer wiring,
The band pass filter according to claim 1, wherein the series resonator is realized by using a parasitic inductor formed by vias connecting the multilayer wirings of the dielectric substrate. The band-pass filter according to any one of claims 1 to 3,
The second capacitor is disposed between the third parallel resonator and the second terminal or between the second parallel resonator and the third parallel resonator. filter. A low-pass bandpass filter having the same topology as the bandpass filter according to any one of claims 1 to 4 in terms of input and output;
A high-frequency bandpass filter having a topology opposite to that of the bandpass filter according to any one of claims 1 to 4 in terms of input and output;
A multiplexer / demultiplexer with

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