Band-pass filter and high-frequency front-end circuit having the same

Abstract

The band-pass filter (100) of the present application is provided with a dielectric substrate (110), conductor plates (P1, P2), a ground via (VG), waveguide resonators (R1 to R7), and a trap resonator (RT). The conductor plates (P1, P2) are disposed inside the dielectric substrate and are arranged opposite to each other. The ground via (VG) connects the conductor plates (P1, P2). The waveguide resonators are coupled in series along a main coupling path from an input terminal (T1) to an output terminal (T2) in a space sandwiched by the conductor plates (P1, P2). The waveguide resonators adjacent along the main coupling path are inductive coupled to each other. The trap resonator (RT) couples two groups of waveguide resonators included in the waveguide resonators by skipping a part of the main coupling path, and capacitive couples the waveguide resonators included in each group to each other.

Description

Technical Field

[0001] This disclosure relates to bandpass filters and high-frequency front-end circuits, and more particularly, to techniques for improving the characteristics of dielectric waveguide filters. Background Technology

[0002] International Patent Publication No. 2018 / 012294 (Patent Document 1) discloses a dielectric waveguide filter having multiple dielectric waveguide resonators. In the dielectric waveguide filter, the multiple dielectric waveguide resonators are configured to be coupled in series along the main path of the propagating signal.

[0003] In such a dielectric waveguide filter, adjacent dielectric waveguide resonators are coupled along the main path, and a secondary path can be formed in which the dielectric waveguide resonators are coupled to each other by skipping a portion of the main path. Furthermore, in the following description, the coupling state of the dielectric waveguide resonators that is coupled to each other by skipping a portion of the main path, such as the secondary path, is also referred to as "skip coupling".

[0004] Patent Document 1: International Publication No. 2018 / 012294

[0005] The aforementioned dielectric waveguide filter functions as a bandpass filter by connecting multiple dielectric waveguide resonators in series. In a bandpass filter, it is generally necessary to allow signals to pass through with low loss in the desired passband and to effectively attenuate signals in the non-passband outside that passband.

[0006] In dielectric waveguide filters, increasing the number of stages of the dielectric waveguide resonator is a known method to ensure attenuation in the non-passband. However, increasing the number of stages of the dielectric waveguide resonator increases the insertion loss in the passband, potentially reducing signal transmission efficiency. Furthermore, as the number of stages of the dielectric waveguide resonator increases, the overall size of the device also increases, making it impossible to achieve the desired specifications when miniaturization is required.

[0007] For such problems, there are methods that improve the attenuation characteristics in the non-passband by generating attenuation poles on the higher or lower frequency side than the passband through the aforementioned "jump coupling" between dielectric waveguide resonators.

[0008] On the other hand, in recent years, with the increase in communication standards and the expansion of frequency bands used, there are instances of adjacent frequency bands being used with very narrow spacing. Therefore, higher attenuation characteristics are required in both the non-passband and bandpass filters. Summary of the Invention

[0009] This disclosure was made to solve the aforementioned problems, and its purpose is to suppress the increase in device size and improve the attenuation characteristics in the non-passband in a bandpass filter equipped with a dielectric waveguide resonator.

[0010] The bandpass filter disclosed herein includes a dielectric substrate, a first conductor plate and a second conductor plate, a first connecting conductor, a plurality of waveguide resonators, and a notch resonator. The dielectric substrate has a first surface and a second surface facing each other, and a side surface connecting the outer edges of the first surface and the outer edges of the second surface. The first conductor plate and the second conductor plate are disposed inside the dielectric substrate and are arranged facing each other. The first connecting conductor connects the first conductor plate and the second conductor plate. The plurality of waveguide resonators are coupled in series along a main coupling path from an input terminal to an output terminal within a space sandwiched between the first conductor plate and the second conductor plate. Among the plurality of waveguide resonators, adjacent waveguide resonators along the main coupling path are inductively coupled to each other. For the notch resonator, two sets of waveguide resonators included in the plurality of waveguide resonators are coupled by the notch resonator skipping a portion of the main coupling path, capacitively coupling the waveguide resonators included in each set to each other.

[0011] In the bandpass filter of this disclosure, two sets of waveguide resonators comprising multiple dielectric waveguide resonators constituting the filter are coupled by a notch resonator that skips a portion of the main coupling path. By adopting such a structure, more than two attenuation poles are generated in the non-passband on the lower frequency side and / or higher frequency side than the passband without increasing the number of orders of the dielectric waveguide resonators along the main coupling path. Therefore, in the bandpass filter, it is possible to suppress the increase in device size and improve the attenuation characteristics in the non-passband. Attached Figure Description

[0012] Figure 1 This is a block diagram of a communication device having a high-frequency front-end circuit with a bandpass filter according to embodiment 1.

[0013] Figure 2 This is a three-dimensional view of the bandpass filter according to Embodiment 1.

[0014] Figure 3 It means Figure 2 The diagram shows the resonators in the bandpass filter.

[0015] Figure 4 yes Figure 2 A top view of a bandpass filter.

[0016] Figure 5 This is a diagram showing the internal conductors contained in each resonator.

[0017] Figure 6 It means Figure 2 A diagram showing the coupling structure of each resonator in a bandpass filter.

[0018] Figure 7 It means Figure 2 The diagram shows the pass-through characteristics of the bandpass filter.

[0019] Figure 8 This is a graph showing the pass-through characteristics of the bandpass filter in the comparative example.

[0020] Figure 9 This is a three-dimensional view of the bandpass filter in Implementation Method 2.

[0021] Figure 10 It means Figure 8 The diagram shows the resonators in the bandpass filter.

[0022] Figure 11 yes Figure 8 A top view of a bandpass filter.

[0023] Figure 12 It means Figure 8 A diagram showing the coupling structure of each resonator in a bandpass filter.

[0024] Figure 13 It means Figure 8 The diagram shows the pass-through characteristics of the bandpass filter.

[0025] Figure 14 This is a top view of the bandpass filter in Variation Example 1.

[0026] Figure 15 This is a top view of the bandpass filter in variation example 2.

[0027] Figure 16 This is a top view of the bandpass filter in variation example 3.

[0028] Figure 17 This is a top view of the bandpass filter in variation example 4.

[0029] Figure 18 This is a top view of the bandpass filter in variation 5.

[0030] Figure 19 This is a top view of the bandpass filter in variation 6.

[0031] Figure 20 This is a top view of the bandpass filter in variation 7. Detailed Implementation

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be labeled with the same reference numerals, and their description will not be repeated.

[0033] [Implementation Method 1]

[0034] (Basic structure of a communication device)

[0035] Figure 1 This is a block diagram of a communication device 10 having a high-frequency front-end circuit 20 with a bandpass filter according to embodiment 1. The communication device 10 is, for example, a mobile phone base station.

[0036] Reference Figure 1 The communication device 10 includes an antenna 12, a high-frequency front-end circuit 20, a mixer 30, a local oscillator 32, a D / A converter (DAC) 40, and an RF circuit 50. Furthermore, the high-frequency front-end circuit 20 includes bandpass filters 22 and 28, an amplifier 24, and an attenuator 26. Additionally, in... Figure 1 In this description, the high-frequency front-end circuit 20 includes a transmitting circuit that transmits high-frequency signals from the antenna 12. However, the high-frequency front-end circuit 20 may also include a receiving circuit that transmits high-frequency signals received through the antenna 12.

[0037] The communication device 10 up-converts the transmit signal from the RF circuit 50 into a high-frequency signal and emits it from the antenna 12. The transmit signal output from the RF circuit 50, i.e., the modulated digital signal, is converted into an analog signal by the D / A converter 40. The mixer 30 mixes the transmit signal, converted from digital to analog by the D / A converter 40, with the oscillation signal from the local oscillator 32 and up-converts it into a high-frequency signal. The bandpass filter 28 removes unwanted waves generated by the up-conversion, extracting only the transmit signal of the desired frequency band. The attenuator 26 adjusts the strength of the transmit signal. The amplifier 24 amplifies the power of the transmit signal passing through the attenuator 26 to a specified level. The bandpass filter 22 removes unwanted waves generated during amplification and allows only the signal components of the frequency band specified in the communication standard to pass through. The transmit signal passing through the bandpass filter 22 is emitted via the antenna 12.

[0038] The bandpass filters 22 and 28 in the communication device 10 described above can be bandpass filters corresponding to those disclosed herein.

[0039] (Structure of a bandpass filter)

[0040] Next, use Figures 2-4 The detailed structure of the bandpass filter 100 in Embodiment 1 will be described. Figure 2 and Figure 3 This is a perspective view showing the internal structure of the bandpass filter 100 in Embodiment 1. Figure 4 This is a top view of bandpass filter 100.

[0041] The bandpass filter 100 is a dielectric waveguide filter formed by connecting multiple dielectric waveguide resonators in series. The bandpass filter 100 includes a cuboid or approximately cuboid dielectric substrate 110 formed by stacking multiple dielectric layers along a predetermined direction. In the dielectric substrate 110, the direction in which the multiple dielectric layers are stacked is defined as the stacking direction. Each dielectric layer in the dielectric substrate 110 is formed, for example, of a dielectric ceramic such as low-temperature co-fired ceramics (LTCC), or a dielectric material such as quartz or resin. Inside the dielectric substrate 110, multiple conductor plates and multiple vias constitute the dielectric waveguide resonators. Furthermore, in this specification, a "via" refers to a conductor provided on the dielectric substrate for connecting multiple conductor plates and electrodes located at different positions along the stacking direction. Vias are formed, for example, of conductive paste, plating, and / or metal pins.

[0042] In the following description, the stacking direction of the dielectric substrate 110 is referred to as the "Z-axis direction", the direction perpendicular to the Z-axis direction and along the long side of the dielectric substrate 110 is referred to as the "X-axis direction", and the direction along the short side of the dielectric substrate 110 is referred to as the "Y-axis direction". In addition, in the following, the positive direction of the Z-axis in each figure is referred to as the upper side and the negative direction is referred to as the lower side.

[0043] In addition, Figures 2-4 And the following Figures 9-11 , Figures 14-20 In order to show the internal structure, the dielectric of the dielectric substrate 110 is omitted, and only the conductor plate, through holes and terminals disposed inside are shown.

[0044] Reference Figures 2-4 The dielectric substrate 110 has an upper surface 111 (first surface) and a lower surface 112 (second surface), as well as side surfaces 113 to 116 connecting the outer edges of the upper surface 111 and the lower surface 112. An input terminal T1, an output terminal T2, and a ground electrode GND are provided on the lower surface 112 of the dielectric substrate 110. The input terminal T1, the output terminal T2, and the ground electrode GND are each flat and function as external terminals for connecting the bandpass filter 100 and external devices.

[0045] A flat conductor plate P1 with a generally rectangular shape is disposed on the dielectric layer near the upper surface 111 of the dielectric substrate 110. Furthermore, in Figure 2 and Figure 3 In order to show the internal structure, the conductor plate P1 is represented by a dashed line.

[0046] A flat conductor plate P2 is disposed between the conductor plate P1 and the ground electrode GND, in the dielectric layer near the ground electrode GND. That is, conductor plates P1 and P2 are disposed inside the dielectric substrate 110, and are arranged opposite to the upper surface 111 and lower surface 112 in the normal direction (Z-axis direction). Partial cutouts are provided on the short sides of each long side of the conductor plate P2 near the side surface 113. Similarly, partial cutouts are provided on the short sides of each long side of the ground electrode GND near the side surface 113. Figure 4 As shown, when viewed from the normal direction (Z-axis direction) of the dielectric substrate 110, an input terminal T1 and an output terminal T2 are provided at positions on the lower surface 112 corresponding to the cutout of the conductor plate P2 and the cutout of the ground electrode GND.

[0047] On conductor plate P2, a flat plate electrode P2A is provided in a cutout on the long side of side 116, and a flat plate electrode P2B is provided in a cutout on the long side of side 114. Flat plate electrodes P2A and P2B protrude in the Y-axis direction. Flat plate electrode P2A is connected to input terminal T1 through a through-hole V1. Flat plate electrode P2B is connected to output terminal T2 through a through-hole (not shown).

[0048] Multiple grounding vias VG are disposed along the sides 113-116 of the dielectric substrate 110. Each grounding via VG is a columnar conductor extending along the stacking direction (Z-axis direction) and connecting conductor plates P1 and P2 to the ground electrode GND. Additionally, multiple vias V20 connecting conductor plates P1 and P2 are disposed between plate electrodes P2A and P2B inside the dielectric substrate 110. A dielectric waveguide resonant space is formed through the space sandwiched between conductor plates P1 and P2, i.e., the space formed by conductor plates P1 and P2, the ground electrode GND, the grounding vias VG, and the vias V20. Alternatively, instead of the grounding vias VG, plate-shaped electrodes disposed on the sides 113-116 of the dielectric substrate 110 can be used to connect conductor plates P1 and P2 to the ground electrode GND.

[0049] Figure 3 The dashed lines in the figure represent the virtual boundaries of the dielectric waveguide resonator (hereinafter also referred to as "waveguide resonator" or simply "resonator") constructed inside the dielectric substrate 110. Figure 3 As shown, seven resonators R1 to R7 are formed on the dielectric substrate 110. In addition, a resonator RT1, which is a waveguide resonator used as a notch filter resonator, is formed between resonators R2 and R6 and between resonators R3 and R5.

[0050] Resonator R1 is coupled to input terminal T1, and resonator R7 is coupled to output terminal T2. Resonators R1 to R4 are arranged sequentially along the positive X-axis, and resonators R4 to R7 are arranged sequentially along the negative X-axis. Furthermore, resonators R1 and R7, R2 and R6, and R3 and R5 are adjacent along the Y-axis.

[0051] That is, the path from resonator R1 through resonator R2, resonator R3, resonator R4, resonator R5 and resonator R6 to resonator R7 is a symmetrical reversal with resonator R4 as the reversal point.

[0052] Resonators R1-R7 and RT1 are resonators based on the TE101 mode. Figure 3 The Z-axis direction is used as the electric field direction, and the signal is transmitted in a resonant mode in which the magnetic field rotates along the plane direction of the XY plane.

[0053] like Figure 3 As shown, internal conductors 120A to 120G are respectively arranged in the resonant space of the dielectric waveguides of resonators R1 to R7. Figure 5 As shown, the internal conductors of each resonator consist of flat, opposing wiring conductors and vias extending along the stacking direction of the dielectric substrate 110 and connecting the wiring conductors to each other. More specifically, for the internal conductors 120A-120C and 120E-120G of resonators R1-R3 and R5-R7, they have a structure where wiring conductors 121 and 122, which are positioned differently in the stacking direction, are connected through vias V120. Figure 5 (A)).

[0054] Furthermore, the internal conductor 120D of the resonator R4 (central resonator), which serves as the turning point of the signal transmission path, has a structure in which wiring conductors 125 and 126, which are positioned differently in the stacking direction, are connected through two through-holes V125 and V126. Figure 5 (B) In other words, the internal conductor 120D has an annular shape with through-holes V125 and V126 connected in parallel between the wiring conductors 125 and 126. In such an annular internal conductor, since the hollow diameter of the inductor formed by the internal conductor is increased, the Q value can be improved while keeping the size of the dielectric substrate 110 the same. Alternatively, the Q value can be maintained while reducing the size of the dielectric substrate 110.

[0055] Furthermore, the “wiring conductors 125 and 126” in the internal conductor 120D correspond to the “first wiring conductor” and “second wiring conductor” in this disclosure, respectively, and the “through holes V125 and V126” correspond to the “first columnar conductor” and “second columnar conductor” in this disclosure, respectively.

[0056] The internal conductors 120A to 120G described above are not connected to either of the conductor plates P1 or P2. Therefore, localized capacitance components are formed between each internal conductor and conductor plate P1, and between each internal conductor and conductor plate P2. In other words, the internal conductors 120A to 120G partially narrow the spacing of the electric field direction (i.e., the Z-axis direction) of the resonant space of the dielectric waveguide in resonators R1 to R7.

[0057] The resonant frequencies of resonators R1 to R7 can be adjusted by utilizing the local capacitance formed by the internal conductor and conductor plates P1 and P2. Furthermore, since the capacitance of the dielectric waveguide resonant space increases due to this local capacitance, miniaturization of the resonator size is possible to achieve a specified resonant frequency.

[0058] The notch resonator RT1 comprises an internal conductor 130 and a via V10. The internal conductor 130, like the internal conductors of other resonators, consists of flat, plate-shaped wiring conductors arranged opposite each other and a via connecting them. The via V10 is connected to conductor plates P1 and P2. The resonant frequency of the notch resonator RT1 can be adjusted through the internal conductor 130 and the via V10. Furthermore, in... Figures 2-4 The example shown illustrates that the via V10 contains five vias V11 to V15, but the via V10 may contain at least one via.

[0059] Adjacent waveguide resonators are coupled through inductive or capacitive coupling. Generally, it is known that if the spacing of the electric field direction in the coupling window between adjacent resonators (i.e., the spacing in the Z-axis direction) becomes narrower, it is called capacitive coupling; if the spacing in the coupling window in the direction orthogonal to the electric field direction becomes narrower, it is called inductive coupling.

[0060] In the bandpass filter 100, since the spacing of the electric field direction (Z-axis direction) of the coupling window does not narrow between resonators R1 and R2, R2 and R3, R3 and R4, R4 and R5, R5 and R6, and R6 and R7, all of these relationships are inductively coupled. The coupling path from the input terminal T1 through resonators R1, R2, R3, R4, R5, R6, and R7 to the output terminal T2 is called the "main coupling path." In this case, resonators R1 to R7 are coupled in series along the main coupling path, and adjacent resonators along the main coupling path are inductively coupled to each other.

[0061] In the bandpass filter 100 of Embodiment 1, as described above, resonators R1 to R7 are arranged symmetrically with resonator R4 as the turning point, and resonators R1 and R7, R2 and R6, and R3 and R5 are adjacent to each other. Therefore, "skip coupling" that skips a part of the coupling of the main coupling path may occur between resonators R1 and R7, between resonators R2 and R6, and between resonators R3 and R5. The coupling path that produces such "skip coupling" is also called a "secondary coupling path". For example, for the secondary coupling path between resonators R1 and R7, since the width direction of the coupling window is narrowed by the via V20, it becomes inductive coupling.

[0062] A notch resonator RT1 is disposed between resonators R2 and R6, and between resonators R3 and R5. Therefore, skip coupling occurs between resonators R2 and R6, and between resonators R3 and R5, via the notch resonator RT1. In the case of the bandpass filter 100 of Embodiment 1, the internal conductor 130 of the notch resonator RT1 is disposed between resonators R3 and R5, and the via V10 is disposed between resonators R2 and R6.

[0063] For the secondary coupling path between resonators R3 and R5, since the spacing of the coupling window in the height direction (i.e., the electric field direction) is narrowed by the internal conductor 130, it becomes capacitive coupling. Figure 4 (Arrow AR1). For the secondary coupling path between resonators R2 and R6, since the spacing in the width direction of the coupling window is narrowed by the via V10, it is essentially likely to be inductive coupling. However, in the case of the bandpass filter 100, the via V10 contains five vias V11 to V15. Since the via V10 contains a large number of vias, it functions as a shielding wall, and almost no skip coupling occurs between resonators R2 and R6.

[0064] In the bandpass filter 100, skip coupling may also occur in the secondary coupling paths between resonators R2 and R5, and between resonators R3 and R6, via the notch resonator RT1. That is, skip coupling occurs between two or more sets of waveguide resonators in the notch resonator RT1. In the secondary coupling paths between resonators R2 and R5, and between resonators R3 and R6, since the coupling is via the internal conductor 130 of the notch resonator RT1, it is essentially capacitive coupling. Figure 4 (Arrows AR2 and AR3). However, the degree of coupling is weaker than the capacitive coupling between resonators R3 and R5 due to the influence of the via V10.

[0065] Furthermore, the coupling degree between resonators can be analyzed through simulation, as follows. First, determine the resonant frequencies of the two resonators in the analysis. Generally, the resonant frequency corresponds to the orientation of the generated magnetic field, producing two modes (even mode and odd mode).

[0066] If the resonant frequency in the even mode is set to F even Set the resonant frequency in odd mode to F. odd In general, F odd >F even The coupling coefficient K between the resonators is calculated using the following equation (1). Furthermore, in the case of inductive coupling, the coupling coefficient is positive, and in the case of capacitive coupling, the coupling coefficient is negative.

[0067] K = (F odd -F even ) / {(F odd +F even ) / 2}…(1)

[0068] The larger the absolute value of the calculated coupling coefficient, the stronger the coupling between the resonators.

[0069] Figure 6 This is a diagram showing the coupling structure between the resonators in the bandpass filter 100. Figure 6 In diagrams (A) and (B), solid arrows indicate the main coupling path from resonator R1 through resonator R4 to resonator R7, while dashed arrows indicate the secondary coupling path caused by skip coupling. In the diagrams, "L" represents inductive coupling, and "C" represents capacitive coupling. Figure 6 As shown in (A) and (B), in resonators R5 and R6, there is a combination of signals transmitted by inductive coupling in the main coupling path and signals transmitted by capacitive coupling in the secondary coupling path.

[0070] Generally, the transmission phase of a resonator has the characteristic of being 90° phase-delayed at lower frequencies than the resonant frequency and 90° phase-leading at higher frequencies than the resonant frequency. Furthermore, since inductive and capacitive coupling are phase-reversed, as in resonators R5 and R6, if a signal based on inductive coupling and a signal based on capacitive coupling are combined, there will be frequencies where the signals are opposite in phase and have the same amplitude. Therefore, attenuation occurs at such frequencies.

[0071] Furthermore, when capacitive coupling is strong, attenuation electrodes are more likely to be generated on the higher frequency side of the passband, while when capacitive coupling is weak, attenuation electrodes are more likely to be generated on the lower frequency side of the passband. In the example of the bandpass filter 100 of Embodiment 1, the capacitive coupling between resonators R3 and R5 is strong, while the capacitive coupling between resonators R2 and R5, and between resonators R3 and R6, is weak. Therefore, one attenuation electrode is generated on the higher frequency side of the passband, and two attenuation electrodes are generated on the lower frequency side.

[0072] Figure 7 This is a graph showing the pass-through characteristics of the bandpass filter 100 according to Embodiment 1. Additionally, in Figure 8 In the example, as a comparison, the pass characteristics of a bandpass filter that does not produce skip coupling are shown. Figure 7 and Figure 8 In the diagram, the horizontal axis represents frequency, and the vertical axis represents insertion loss (solid lines LN10, LN15) and reflection loss (dashed lines LN11, LN16).

[0073] Reference Figure 7 and Figure 8 In the comparative example bandpass filter, no attenuation electrode is generated on either the higher frequency side or the lower frequency side of the passband. However, in the bandpass filter 100 of Embodiment 1, an attenuation electrode AP1 is generated on the higher frequency side of the passband, and two attenuation electrodes AP2 and AP3 are generated on the lower frequency side of the passband. As described above, attenuation electrode AP1 is generated by the jump coupling between resonator R3 and resonator R5, and attenuation electrodes AP2 and AP3 are generated by the jump coupling between resonator R2 and resonator R5, and between resonator R3 and resonator R6.

[0074] In the bandpass filter 100 of Embodiment 1, it is known that through these attenuation poles, a steeper and higher attenuation characteristic is obtained on both the higher frequency side and the lower frequency side of the passband compared to the comparative example. In particular, in the case of the bandpass filter 100, since two attenuation poles are generated on the lower frequency side of the passband, a steeper attenuation characteristic is obtained on the lower frequency side.

[0075] As described above, in a bandpass filter using the dielectric waveguide resonator of this disclosure, by using a notch resonator, at least two sets of waveguide resonators generate skip coupling due to capacitive coupling, producing multiple attenuation poles in the non-passband. Therefore, since the number of waveguide resonators along the main coupling path is not increased, it is possible to suppress the increase in device size and improve the attenuation characteristics in the non-passband.

[0076] In addition, Figures 2-4 In the bandpass filter 100 shown, an example with a seven-stage waveguide resonator is described. However, the resonator R1 connected to the input terminal T1 and the resonator R7 connected to the output terminal T2 do not contribute to the generation of the attenuation stage described above. Therefore, in a five-stage bandpass filter with the input terminal T1 connected to the resonator R2 and the output terminal T2 connected to the resonator R6, omitting the resonators R1 and R7, the attenuation characteristics can be improved in the same way as described above.

[0077] In Embodiment 1, "conductor plate P1" and "conductor plate P2" correspond to "first conductor plate" and "second conductor plate" in this disclosure, respectively. In Embodiment 1, "grounding via VG" and "via V20" correspond to "first connecting conductor" in this disclosure. In Embodiment 1, "via V10" corresponds to "second connecting conductor" in this disclosure. In Embodiment 1, "internal conductor 130" corresponds to "first internal conductor" in this disclosure. In Embodiment 1, "internal conductors 120A to 120G" correspond to "second internal conductors" in this disclosure, respectively. In Embodiment 1, "resonators R2 to R6" correspond to "first resonator" to "fifth resonator" in this disclosure, respectively.

[0078] [Implementation Method 2]

[0079] In Embodiment 1, an example of a structure that improves the attenuation characteristics on the lower frequency side of the passband is described.

[0080] As described above, by adjusting the degree of capacitive coupling in the skip coupling, the frequency of the attenuation electrode changes. In Embodiment 2, a structural example is described where the attenuation characteristics are improved at higher frequencies than the passband.

[0081] Figure 9 and Figure 10 This is a perspective view of the bandpass filter 100X according to embodiment 2. Figure 11 This is a top view of the 100X bandpass filter. Furthermore, in Figure 10 In, compared with implementation method 1 Figure 3Similarly, the boundaries between the resonators included in the bandpass filter 100X are shown. In addition, similar to the bandpass filter 100 of Embodiment 1, dielectric waveguide resonators R1 to R7 are formed in the main coupling path from the input terminal T1 to the output terminal T2.

[0082] In the bandpass filter 100X, a waveguide resonator RT2, serving as a notch resonator, is also configured between resonators R2 and R6, and between resonators R3 and R5. The notch resonator RT2 is configured by including an internal conductor 140 and a through-hole V40.

[0083] The internal conductor 140, like the internal conductors of other resonators, is composed of flat, plate-shaped wiring conductors arranged opposite each other and vias connecting them. The internal conductor 140 extends over approximately the entire area between resonators R2 and R6, and approximately half the area between resonators R3 and R5. The vias V40, including vias V41 to V44, are configured to surround the end of the wiring conductor of the internal conductor 140 on the resonator R4 side.

[0084] With this notch resonator RT2 structure, capacitive jump coupling is generated in the secondary coupling paths between resonators R2 and R6, between resonators R2 and R5, between resonators R3 and R5, and between resonators R3 and R6.

[0085] Furthermore, a via V25 is provided between resonators R1 and R7 in the bandpass filter 100X. In the case of the bandpass filter 100X, since the via V25 contains a large number of vias, it functions as a shielding wall, and almost no skip coupling occurs between resonators R1 and R7.

[0086] In the bandpass filter 100X, such as Figure 11 and Figure 12 As shown, relatively strong capacitive skip coupling occurs in the secondary coupling paths between resonators R2 and R6 (arrow AR10), between resonators R2 and R5 (arrow AR11), and between resonators R3 and R6 (arrow AR12). On the other hand, for the secondary coupling path between resonators R3 and R5 (arrow AR13), the capacitive coupling is slightly weaker than the other skip couplings due to the influence of the via V40. Therefore, in the bandpass filter 100X, three attenuation electrodes are generated on the higher frequency side of the passband, and one attenuation electrode is generated on the lower frequency side of the passband.

[0087] Figure 13 This is a graph showing the pass-through characteristics of the bandpass filter 100X according to Embodiment 2. Figure 13 In the diagram, the solid line LN20 represents insertion loss, and the dashed line LN21 represents reflection loss.

[0088] Reference Figure 13 As described above, in the bandpass filter 100X, attenuation electrodes AP21 to AP23 are generated at higher frequencies than the passband through the relatively strong capacitive coupling jump coupling in the secondary coupling paths between resonators R2 and R6, between resonators R2 and R5, and between resonators R3 and R6. Additionally, attenuation electrode AP24 is generated at lower frequencies than the passband through the relatively weak capacitive coupling jump coupling between resonators R3 and R5. These attenuation electrodes, along with... Figure 8 Compared to the comparative example shown, the attenuation characteristics are improved on both the higher and lower frequency sides of the passband. In particular, by generating attenuation poles AP21 to AP23 on the higher frequency side of the passband, a steeper and higher attenuation characteristic is obtained on the higher frequency side of the passband.

[0089] Furthermore, in the bandpass filter 100X, the strength of capacitive coupling can be adjusted according to the position of the via in the internal conductor 140 of the notch resonator RT2. For example, if the via is positioned closer to the negative direction of the X-axis, the capacitive coupling between resonators R2 and R6 becomes stronger; if the via is positioned closer to the positive direction of the X-axis, the capacitive coupling between resonators R2 and R5, and between resonators R3 and R6, becomes stronger. This is because the magnetic coupling between resonators R2 and R5, and between resonators R3 and R6, is weakened by being blocked by the via in the internal conductor 140, thus relatively enhancing the capacitive coupling.

[0090] As described above, in the bandpass filter of embodiment 2, by having a notch resonator RT2 with multiple jump couplings that generate relatively strong capacitive coupling, the attenuation characteristics, especially at higher frequencies than the passband, can be improved.

[0091] [Variation Example]

[0092] As described in Embodiments 1 and 2 above, the attenuation characteristics of the bandpass filter at lower frequencies and / or higher frequencies can be adjusted by changing the structure of the notch resonator.

[0093] The following variations illustrate other structural examples of notch resonators.

[0094] (Variation Example 1)

[0095] Figure 14 This is a top view of the bandpass filter 100A of Modified Example 1. In the bandpass filter 100A, it becomes... Figure 4In the bandpass filter 100 of Embodiment 1 shown, the notch resonator RT1 and the via V20 are replaced with a notch resonator RT3 and a via V20A, respectively. Figure 14 In the middle, without repetition with Figure 4 Explanation of recurring elements.

[0096] Reference Figure 14 The via V20A is positioned between resonators R1 and R7. Therefore, inductive jump coupling may occur between resonators R1 and R7. Furthermore, because the number of vias included in via V20A is greater than... Figure 4 The bandpass filter 100 contains a large number of vias in its via V20, therefore the inductive coupling is weaker than that of the bandpass filter 100.

[0097] The notch resonator RT3 comprises an internal conductor 130A and vias V11A and V12A. The internal conductor 130A is positioned between resonators R2 and R6. The vias V11A and V12A are positioned along the Y-axis between resonators R3 and R5. By configuring the notch resonator RT3 in this way, a jump coupling (arrow AR1A) caused by relatively strong capacitive coupling is generated between resonators R2 and R6. Additionally, jump coupling (arrows AR2A and AR3A) caused by relatively weak capacitive coupling is generated in the secondary coupling paths between resonators R3 and R6, and between resonators R2 and R5. Furthermore, jump coupling caused by inductive coupling is generated in the secondary coupling path between resonators R3 and R5.

[0098] Therefore, in the bandpass filter 100A of Modified Example 1, and Figure 4 Similarly, the bandpass filter 100 generates one attenuation electrode on the higher frequency side of the passband and two attenuation electrodes on the lower frequency side.

[0099] (Variation Example 2)

[0100] Figure 15 This is a top view of the bandpass filter 100B in Modified Example 2. In the bandpass filter 100B, it becomes... Figure 4 In the bandpass filter 100 of Embodiment 1 shown, the notch resonator RT1 and the via V20 are replaced with a notch resonator RT4 and a via V20B, respectively. Figure 15 In the middle, without repetition with Figure 4 Explanation of recurring elements.

[0101] Reference Figure 15 The via V20B has the same characteristics as... Figure 14The via V20A has the same structure and is positioned between resonators R1 and R7. Therefore, inductive jump coupling may occur between resonators R1 and R7.

[0102] The notch resonator RT4 comprises an internal conductor 130B and vias V11B to V14B. The internal conductor 130B is positioned near the boundaries of the four resonators R2, R3, R5, and R6. Furthermore, the vias V11B to V14B are positioned to surround the internal conductor 130B.

[0103] More specifically, via V11B is positioned between the internal conductor 120B of resonator R2 and the internal conductor 120F of resonator R6. Via V12B is positioned between the internal conductor 120C of resonator R3 and the internal conductor 120E of resonator R5. Via V13B is positioned near the negative Y-axis of internal conductor 130B. Via V14B is positioned near the positive Y-axis of internal conductor 130B.

[0104] By configuring the internal conductor 130B and the vias V11B to V14B in this way, jump coupling caused by relatively weak capacitive coupling is generated in the secondary coupling paths between resonators R2 and R6 (arrow AR1B), between resonators R2 and R5 (arrow AR2B), between resonators R3 and R6 (arrow AR3B), and between resonators R3 and R5 (arrow AR4B).

[0105] Therefore, in the bandpass filter 100B of Modified Example 2, four attenuation poles are generated on the lower frequency side of the passband.

[0106] (Variation Example 3)

[0107] Figure 16 This is a top view of the bandpass filter 100C in Modified Example 3. In the bandpass filter 100C, it becomes... Figure 4 In the bandpass filter 100 of Embodiment 1 shown, the notch resonator RT1 and the via V20 are replaced with notch resonator RT5 and via V20C, respectively.

[0108] Reference Figure 16 The via V20C has the same characteristics as... Figure 14 The via V20A has the same structure and is positioned between resonators R1 and R7. Therefore, inductive jump coupling may occur between resonators R1 and R7.

[0109] The notch resonator RT5 is constructed by including an internal conductor 130C and vias V11C and V12C. The notch resonator RT5 corresponds to the removal of... Figure 15The structure of vias V11B and V12B in the notch resonator RT4 of the bandpass filter 100B shown in Modified Example 2.

[0110] In bandpass filter 100C, similarly to bandpass filter 100B in Modified Example 2, skip coupling caused by relatively weak capacitive coupling occurs in the secondary coupling paths between resonators R2 and R6 (arrow AR1C), between resonators R2 and R5 (arrow AR2C), between resonators R3 and R6 (arrow AR3C), and between resonators R3 and R5 (arrow AR4C). Furthermore, since no vias are provided at the positions corresponding to vias V11B and V12B in Modified Example 2, the capacitive couplings of the skip coupling in bandpass filter 100C are slightly stronger compared to the case of Modified Example 2.

[0111] Therefore, in the bandpass filter 100C of Modified Example 3, four attenuation poles are also generated on the lower frequency side of the passband.

[0112] (Variation Example 4)

[0113] Figure 17 This is a top view of the bandpass filter 100D in Modified Example 4. In the bandpass filter 100D, it becomes... Figure 4 In the bandpass filter 100 of Embodiment 1 shown, the notch resonator RT1 and the via V20 are replaced with the notch resonator RT6 and the via V20D, respectively.

[0114] Reference Figure 17 The via V20D has the same characteristics as Figure 14 The via V20A has the same structure and is positioned between resonators R1 and R7. Therefore, inductive jump coupling may occur between resonators R1 and R7.

[0115] The notch resonator RT6 is constructed by including an internal conductor 130D and vias V11D and V12D. The notch resonator RT6 corresponds to the removal of... Figure 15 The structure of vias V13B and V14B in the notch resonator RT4 of the bandpass filter 100B shown in Modified Example 2.

[0116] In the bandpass filter 100D, skip coupling caused by relatively weak capacitive coupling occurs in the secondary coupling paths between resonators R2 and R6 (arrow AR1D) and between resonators R3 and R5 (arrow AR4D). On the other hand, skip coupling caused by relatively strong capacitive coupling occurs in the secondary coupling paths between resonators R2 and R5 (arrow AR2D) and between resonators R3 and R6 (arrow AR3D).

[0117] Therefore, in the bandpass filter 100D of Modified Example 4, two attenuation poles are generated on the side higher than the passband and the side lower than the passband, respectively.

[0118] (Variation Example 5)

[0119] Figure 18 This is a top view of the bandpass filter 100E in Modified Example 5. In the bandpass filter 100E, it becomes... Figure 4 In the bandpass filter 100 of Embodiment 1 shown, the notch resonator RT1 and the via V20 are replaced with the notch resonator RT7 and the via V20E, respectively.

[0120] Reference Figure 18 The via V20E has the same characteristics as... Figure 4 The via V20 of Implementation 1 has the same structure and is disposed between resonators R1 and R7. As a result, inductive jump coupling may occur between resonators R1 and R7.

[0121] The notch resonator RT7 is constructed by including an internal conductor 130E and vias V11E to V13E. The notch resonator RT7 corresponds to a structure with a different shape for the vias in the notch resonator RT1 of Embodiment 1. More specifically, via V11E is a via with a generally elliptical cross-section that integrates vias V11 and V12 in the bandpass filter 100 of Embodiment 1. Similarly, via V12E is a via with a generally elliptical cross-section that integrates vias V14 and V15 in the bandpass filter 100. Thus, the vias included in the notch resonator can also be in shapes other than cylindrical.

[0122] In the bandpass filter 100E, similarly to the bandpass filter 100 of Embodiment 1, a jump coupling caused by relatively strong capacitive coupling (arrow AR1E) is generated in the secondary coupling path between resonators R3 and R5, while a jump coupling caused by relatively weak capacitive coupling is generated in the secondary coupling paths between resonators R2 and R5 (arrow AR2E) and between resonators R3 and R6 (arrow AR3E). Furthermore, since the via V12E has a roughly elliptical cross-section, the degree of capacitive coupling between resonators R2 and R5 and between resonators R3 and R6 is further weakened compared to the case of Embodiment 1.

[0123] Therefore, in the bandpass filter 100E of Modified Example 5, one attenuation electrode is generated on the higher frequency side of the passband, and two attenuation electrodes are generated on the lower frequency side of the passband.

[0124] (Variation Example 6)

[0125] In Embodiments 1, 2, and Variations 1 to 5 described above, examples of structures in which a notch resonator is disposed between resonators R2, R3, R5, and R6 were described. In Variation 6 and Variation 7 described later, a structure in which a notch resonator is disposed between resonators R1, R2, R6, and R7 was described.

[0126] Figure 19 This is a top view of the bandpass filter 100F in Modified Example 6. In the bandpass filter 100F, a notch resonator RT8 is arranged between resonators R1, R2, R6, and R7, and a via V30F is provided between resonators R3 and R5. Inductive coupling skips through the via V30F in the secondary coupling path between resonators R3 and R5.

[0127] The notch resonator RT8 comprises an internal conductor 130F and vias V11F to V13F. The internal conductor 130F is positioned between resonators R1 and R7. The vias V11F to V13F are positioned between resonators R2 and R6. This structure generates jump coupling (arrow AR1F) due to relatively strong capacitive coupling in the secondary coupling path between resonators R1 and R7. Conversely, it generates jump coupling (arrow AR1F) due to relatively weak capacitive coupling in the secondary coupling paths between resonators R1 and R6 (arrow AR2F) and between resonators R2 and R7 (arrow AR3F).

[0128] Therefore, in the bandpass filter 100F of Modified Example 6, one attenuation electrode is generated on the higher frequency side of the passband, and two attenuation electrodes are generated on the lower frequency side of the passband.

[0129] (Variation Example 7)

[0130] Figure 20 This is a top view of the bandpass filter 100G in Modified Example 7. In the bandpass filter 100G, in order to... Figure 19 In Modification 6, the notch resonator RT8 and via V30F in the bandpass filter 100F are replaced with a notch resonator RT9 and via V30G.

[0131] Reference Figure 20 The via V30G has the same characteristics as... Figure 19 The via V30F has the same structure and is positioned between resonators R3 and R5. Therefore, inductive jump coupling may occur in the secondary coupling path between resonators R3 and R5.

[0132] The notch resonator RT9 comprises an internal conductor 130G and vias V11G and V12G. The internal conductor 130G is positioned near the boundaries of the four resonators R1, R2, R6, and R7. Furthermore, the vias V11G and V12G are positioned along the Y-axis between the internal conductor 120A of resonator R1 and the internal conductor 120G of resonator R7.

[0133] With this configuration, jump coupling caused by inductive coupling is generated in the secondary coupling path between resonators R1 and R7. Additionally, jump coupling caused by relatively strong capacitive coupling is generated in the secondary coupling paths between resonators R2 and R6 (arrow AR1G), between resonators R2 and R7 (arrow AR2G), and between resonators R1 and R6 (arrow AR3G).

[0134] Therefore, in the bandpass filter 100G of Modified Example 7, three attenuation poles are generated on the higher frequency side of the passband.

[0135] As described above, in a bandpass filter composed of multiple dielectric waveguide resonators, the two sets of waveguide resonators within these resonators are coupled by a notch resonator, skipping a portion of the main coupling path. This results in more than two attenuation poles in the non-passband, on the lower-frequency side and / or higher-frequency side of the passband, without increasing the number of orders of the dielectric waveguide resonators. Furthermore, by adjusting the configuration of the internal conductors and vias within the notch resonator to control the degree of capacitive coupling, and by adjusting the frequency at which the attenuation poles are generated, the desired attenuation characteristics can be achieved. Therefore, in a bandpass filter, it is possible to suppress the increase in device size and improve the attenuation characteristics in the non-passband.

[0136] The embodiments disclosed herein should be considered illustrative in all respects and are not intended to limit the invention. The scope of this disclosure is not defined by the description of the above embodiments, but by the claims, which are intended to include all modifications equivalent to and within the scope of the claims.

[0137] Explanation of reference numerals in the attached figures

[0138] 10…Communication device; 12…Antenna; 20…High-frequency front-end circuit; 22, 28, 100, 100A~100G, 100X…Bandpass filter; 24…Amplifier; 26…Attenuator; 30…Mixer; 32…Local oscillator; 40…D / C converter; 50…RF circuit; 110…Dielectric substrate; 120A~120G, 130, 130A~130G, 140…Internal conductor; 121, 122, 125, 126…Wiring conductor; AP1~AP3, AP21~AP24… Attenuation electrode; GND… Ground electrode; P1, P2… Conductor plate; P2A, P2B… Planar electrode; R1~R7, RT1~RT9… Resonator; T1… Input terminal; T2… Output terminal; V1, V10~V15, V11A~V11F, V12A~V12G, V13B, V13E, V13F, V14B, V20, V20A~V20E, V25, V30F, V30G, V40~V44, V120, V125, V126… Through hole; VG… Grounding through hole.

Claims

1. A bandpass filter, comprising: A dielectric substrate has a first surface and a second surface that are opposite to each other, and a side surface that connects the outer edge of the first surface and the outer edge of the second surface. Input terminals and output terminals; The first conductor plate and the second conductor plate are disposed inside the dielectric substrate and are arranged opposite to each other. A first connecting conductor is disposed between the first conductor plate and the second conductor plate, connecting the first conductor plate and the second conductor plate; Multiple waveguide resonators are coupled in series within the space held by the first conductor plate and the second conductor plate, along the main coupling path from the input terminal to the output terminal. as well as Notch resonator, In the aforementioned waveguide resonators, adjacent waveguide resonators along the main coupling path are inductively coupled to each other. The two sets of waveguide resonators contained in the aforementioned multiple waveguide resonators are coupled by the aforementioned notch resonator, skipping a portion of the aforementioned main coupling path. The aforementioned notch resonators capacitively couple the waveguide resonators contained in each group to each other. The aforementioned notch resonator includes: A first internal conductor extends in a direction from the first conductor plate toward the second conductor plate and is not electrically connected to either the first conductor plate or the second conductor plate; and At least one second connecting conductor connects the first conductor plate and the second conductor plate.

2. The bandpass filter according to claim 1, wherein, Each of the aforementioned waveguide resonators includes a second inner conductor, wherein the second inner conductor extends in a direction from the first conductor plate toward the second conductor plate and is not electrically connected to either the first conductor plate or the second conductor plate.

3. The bandpass filter according to claim 2, wherein, The number of the aforementioned waveguide resonators is odd. The aforementioned waveguide resonators are arranged symmetrically with the central resonator located at the center along the main coupling path as the turning point. The second internal conductor in the aforementioned central resonator comprises: The first wiring conductor and the second wiring conductor are disposed opposite each other on different layers of the dielectric substrate between the first conductor plate and the second conductor plate. as well as The first columnar conductor and the second columnar conductor are connected in parallel between the first wiring conductor and the second wiring conductor.

4. The bandpass filter according to claim 1, wherein, The aforementioned waveguide resonators include a first resonator, a second resonator, a third resonator, a fourth resonator, and a fifth resonator that are coupled in series along the aforementioned main coupling path. The aforementioned waveguide resonators are arranged symmetrically with respect to the third resonator as the turning point. The first resonator, the fourth resonator, the second resonator, and the fifth resonator are capacitively coupled via the notch resonator.

5. The bandpass filter according to claim 4, wherein, The second and fourth resonators are capacitively coupled via the notch resonator. The capacitive coupling between the second resonator and the fourth resonator is stronger than that between the first resonator and the fourth resonator, and between the second resonator and the fifth resonator.

6. The bandpass filter according to claim 5, wherein, The first resonator and the fifth resonator, as well as the second resonator and the fourth resonator, are capacitively coupled via the notch resonator. The capacitive coupling between the first resonator and the fifth resonator is stronger than that between the second resonator and the fourth resonator.

7. A high-frequency front-end circuit comprising a bandpass filter according to any one of claims 1 to 6.

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