JP2009303065A - Variable passband high frequency filter, method for manufacturing the same, and communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable passband high frequency filter with low loss. <P>SOLUTION: An input electrode 103a, an output electrode 103b, and a plurality of resonator electrodes 104a to 104c are provided on a first dielectric layer 102 on a substrate 101. An input capacitance is formed between the input electrode 103a and the resonator electrode 104a. An output capacitance is formed between the output electrode 103b and the resonator electrode 104b. A coupling capacitance is formed by a plurality of resonator electrodes 104a to 104c. A second dielectric layer 106 is disposed over the plurality of resonator electrodes 104a to 104c with a space. The second dielectric layer 106 is placed close to or distant from the plurality of resonator electrodes 104a to 104c by mechanically moving the second dielectric layer 106. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a passband variable high-frequency filter used in a mobile communication radio circuit such as a mobile phone, a manufacturing method thereof, and a communication device.

  In recent years, communication devices such as mobile phones require a large number of wireless circuits to support multiband and multimode, and parts included in the wireless circuits are required to be further downsized. Such a component requires a filter that allows a desired band signal to pass through with low loss and greatly attenuates an unnecessary band signal, and is required to be small in size and correspond to a plurality of bands. As such a filter corresponding to the pass band, a pass band variable high frequency filter using a dielectric resonator is known.

  FIG. 9 is a diagram showing an equivalent circuit of a conventional passband variable high frequency filter. FIG. 10 is a diagram illustrating an example of pass characteristics of a conventional variable passband high-frequency filter. In FIG. 9, a plurality of interstage capacitors 902 are arranged in series between two input / output terminals 901, and a dielectric resonator 903 is connected between each interstage capacitor 902 and the ground. . A parallel capacitor 904 and a voltage variable capacitor 905 are further connected in series between the connection point where the dielectric resonator 903 between the interstage capacitors 902 is connected and the ground. Each parallel capacitor 904 and each voltage variable capacitor 905 is connected to a control terminal 906, respectively. Thus, a passband variable high frequency filter is configured.

  The dielectric resonator 903 resonates at a resonance frequency corresponding to its length, and the resonance frequency is adjusted by the combined capacitance of the parallel capacitor 904 and the voltage variable capacitor 905 arranged in parallel with the dielectric resonator 903. Between the two input / output terminals 901, an interstage capacitor 902 determined to have a desired passband width is coupled to the dielectric resonator 903 whose resonance frequency is adjusted as described above, and is shown in FIG. A bandpass filter having such a pass characteristic 1001 is configured. Further, by applying a DC voltage to the control terminal 906, the voltage variable capacitor 905 is changed, whereby the combined capacitance of the parallel capacitor 904 and the voltage variable capacitor 905 is changed. As a result, the adjusted resonance frequency is further adjusted, and a band-pass filter having a pass characteristic 1002 as shown in FIG. 10 is formed.

Moreover, the conventional passband variable high frequency filter can also be configured as shown in FIG. 11 (see Patent Document 1 and Patent Document 2). FIG. 11 is a diagram showing an equivalent circuit of a conventional passband variable high frequency filter. The passband variable high frequency filter shown in FIG. 11 is different from the passband variable high frequency filter shown in FIG. 9 in the following two points. The first point is that the resonance frequency is changed by changing the capacitance value by switching the adjustment capacitor 1105 arranged in parallel with the dielectric resonator 1104 with the switch 1106. The second point is that the passband width of the filter is adjusted by adjusting the interstage capacitance 1102 with the switch 1103.
Japanese Utility Model Publication No. 2-8220 JP 2002-208801 A

  However, in the configuration of the conventional passband variable high frequency filter shown in FIGS. 9 and 11, the filter is configured through the voltage variable capacitor 905 having a low Q value representing the performance and the switch 1103 having a large loss. There was a problem that loss in the band increased. Moreover, although the capacitance value of the voltage variable capacitor 905 varies depending on the voltage, there is a problem that the capacitance value varies due to variations in the voltage value and the resonance frequency varies.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a passband variable high-frequency filter that ensures low loss characteristics in the passband and is resistant to variations in voltage values for varying the passband.

  The present invention is directed to a passband variable high frequency filter. The passband variable high-frequency filter according to the present invention includes an input electrode, an output electrode, and a plurality of resonator electrodes on the first dielectric layer on the substrate. The resonator includes at least a resonator electrode and a second resonator electrode, an input capacitance is formed between the input electrode and the first resonator electrode, and an output capacitance is formed between the output electrode and the second resonator electrode. And a coupling capacitor is formed between the plurality of resonator electrodes. A second dielectric layer is disposed on the plurality of resonator electrodes via a space, and the second dielectric layer is mechanically disposed. The second dielectric layer is placed close to and away from the plurality of resonator electrodes.

  Preferably, in the passband variable high-frequency filter, a third dielectric layer fixed on the plurality of resonator electrodes is disposed.

  In the passband variable high-frequency filter, a movable electrode that is movable in conjunction with the second dielectric layer is disposed on the second dielectric layer.

  The present invention is also directed to a communication device provided with an antenna, a transmission circuit, and a reception circuit. The communication device includes a passband variable high-frequency filter in at least one of the transmission circuit and the reception circuit.

  The present invention is also directed to a method for manufacturing a passband variable high frequency filter. The manufacturing method includes a step of forming a first dielectric layer on a substrate, and a step of forming an input electrode, an output electrode, a plurality of resonator electrodes, and a lower electrode on one main surface of the first dielectric layer. An oxide film forming step to be a post, an oxide film flattening step, a step of forming a second dielectric layer on the flattened oxide film, and one main surface of the second dielectric layer And a step of forming the upper electrode in a portion facing the lower electrode in projection and a step of removing the oxide film corresponding to the lower portion of the movable portion of the second dielectric layer.

  The lower electrode is a common electrode with the grounded resonator electrode.

  As described above, according to the present invention, it is possible to realize a passband variable high-frequency filter that is small in size and has low loss characteristics in the passband and that is resistant to variations in voltage values for varying the passband.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating an example of the configuration of a passband variable high-frequency filter according to the first embodiment of the present invention. Specifically, FIG. 1A shows a perspective view of the high-pass filter operating state of the passband variable high-frequency filter, and FIG. 1B shows the low-pass filter operating state of the passband variable high-frequency filter. A perspective view is shown. FIG. 2 is a diagram illustrating an example of an equivalent circuit of the passband variable high-frequency filter according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating pass characteristics of the passband variable high-frequency filter according to the first embodiment of the present invention.

Next, the present embodiment will be described in detail with reference to FIGS. In FIG. 1, a substrate 101 is made of a material such as silicon, glass, gallium arsenide or the like. A first dielectric layer 102 is formed on the substrate 101. The first dielectric layer 102 is made of a ferroelectric material such as barium strontium titanate (Ba _x Sr _1-x TiO ₃ ) or strontium titanate (SrTiO ₃ ).

  On the first dielectric layer 102, an input electrode 103a, an output electrode 103b, a resonator electrode 104, a first lower electrode 105a, and a second lower electrode 105b are formed. The input electrode 103a and the output electrode 103b are made of a metal material such as aluminum, copper, tungsten, or titanium. The resonator electrode 104 includes a first resonator electrode 104a, a second resonator electrode 104b, and a ground electrode 104c that are connected together.

  A movable second dielectric layer 106 is formed on the first lower electrode 105a and the second lower electrode 105b via a space. Further, on the second dielectric layer 106, a first upper electrode 107a, a second upper electrode 107b, an additional input coupling electrode 108a, an additional inter-resonator coupling electrode 108b, and an additional output coupling electrode 108c are configured. The

  Next, the operation of the passband variable high-frequency filter according to the first embodiment of the present invention configured as described above will be described. The signal input from the input electrode 103a is capacitively coupled by the first resonator electrode 104a and the input coupling capacitor 201, and the interstage coupling capacitance 202 between the first resonator electrode 104a and the second resonator electrode 104b. Are coupled by the second resonator electrode 104b, the output electrode 103b, and the output coupling capacitor 203, and output from the output electrode 103b.

  The first resonator electrode 104a and the second resonator electrode 104b are microstrip line resonators having the lower surface of the first dielectric layer 102 and the upper surface of air or vacuum, and the end surfaces thereof are connected to the ground electrode 104c. Thus, the first dielectric layer 102 on the lower surface operates as a quarter wavelength dielectric resonator whose wavelength is shortened. As a result, the passband variable high-frequency filter enters a high-pass filter operation state (the state shown in FIG. 1A), and has a band characteristic 301 having a passband near the resonance frequency of the quarter-wave dielectric resonator. A path filter is realized.

  The first upper electrode 107 a is disposed at a position facing the first lower electrode 105 a through the space and the second dielectric layer 106. By applying a DC voltage difference between the first upper electrode 107a and the first lower electrode 105a, the electrostatic force is excited, the two electrodes are attracted, and move together with the movable second dielectric layer 106. As a result, the passband variable high-frequency filter enters the low-pass filter operation state (the state shown in FIG. 1B).

  Note that it is preferable to provide a DC voltage difference between the second upper electrode 107b and the second lower electrode 105b. The second upper electrode 107b is disposed at a position facing the second lower electrode 105b with the space and the second dielectric layer 106 therebetween. This is because by applying a DC voltage difference between the second upper electrode 107b and the second lower electrode 105b, the electrostatic force is further excited, and the second dielectric layer 106 is easily moved downward.

  When the low-pass filter operation state (the state shown in FIG. 1B) is reached, the first resonator electrode 104a and the second resonator electrode 104b have the lower surface of the first dielectric layer 102 and the upper surface of the second resonator electrode 104b. A stripline resonator having the dielectric layer 106 is formed. Thereby, the effect of shortening the wavelength is strengthened, and the resonance frequency of each quarter-wave dielectric resonator is lowered.

  Further, the capacitance between the input electrode 103a and the first resonator electrode 104a increases when the second dielectric layer 106 is close to the upper portion. Further, due to the proximity of the input electrode 103a and the additional input coupling electrode 108a, the capacitance between the input electrode 103a and the additional input coupling electrode 108a and the capacitance between the additional input coupling electrode 108a and the first resonator electrode 104a are connected in series. The combined capacity is added in parallel, and the input coupling capacity 201 is increased.

  Similarly, the interstage coupling capacitance 202 between the first resonator electrode 104a and the second resonator electrode 104b also increases due to the proximity of the second dielectric layer 106 and the additional inter-resonator coupling electrode 108b. Similarly, the output coupling capacitance 203 between the second resonator electrode 104b and the output electrode 103b also increases due to the proximity of the second dielectric layer 106 and the additional output coupling electrode 108c. An equivalent circuit of the thus configured passband variable high frequency filter is represented as shown in FIG. In the low-pass filter operating state (the state shown in FIG. 1B), the resonance frequency of the quarter-wave dielectric resonator is lowered, and accordingly, the input coupling capacitance 201, the interstage coupling capacitance 202, and the output coupling capacitance. 203 increases. As a result, a bandpass filter having a pass characteristic 302 (see FIG. 3) shifted to a lower frequency than the pass characteristic 301 in the high-pass filter operating state (the state shown in FIG. 1A) is realized.

  FIG. 4 is a diagram showing an A-A ′ cross section of the passband variable high-frequency filter shown in FIG. 1. 4A shows a cross section in the high-pass filter operating state, and FIG. 4B shows a cross-section in the low-pass filter operating state. 4A and 4B, the first dielectric layer 102 and the second dielectric layer 106 are held by the first post 401a and the second post 401b. In the movable region 402 in which the second dielectric layer 106 is movable, no post exists between the first dielectric layer 102 and the second dielectric layer 106. Note that the heights of the first post 401a and the second post 401b are appropriately adjusted according to the filter pass band to be switched and the drive electrode.

  5 and 6 are diagrams showing a method of manufacturing the passband variable high-frequency filter according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating a manufacturing process of the high-pass filter and the low-pass filter common part. FIG. 6 is a diagram illustrating a manufacturing process of the low-pass filter section. The manufacturing process of the high-pass filter and the low-pass filter common part will be described with reference to FIG. 5. A strontium titanate film is formed on the silicon substrate 101 (see FIG. 5A). Next, the lower electrode 501 is formed (see FIG. 5B), and the lower electrode 501 is patterned into a predetermined shape by a normal photolithography technique (see FIG. 5C). Next, tetraethoxysilane (TEOS: Tetra Ethyl Ortho Silicate) to be a post is formed (see FIG. 5D), and convexity by the resonator electrode 104 and the lower electrode 105 is performed by chemical mechanical polishing (CMP). Is removed and flattened (see FIG. 5E).

  The manufacturing process of the low-pass filter portion will be described with reference to FIG. 6. A strontium titanate film is formed on the planarized TEOS by CMP (see FIG. 6A). Next, the upper electrode 601 is formed (see FIG. 6B), and the upper electrode 601 is patterned into a predetermined shape by a normal photolithography technique (see FIG. 6C). Later, a plurality of through holes are formed in the second dielectric layer 106 in the region to be the movable region 402, TEOS is dry-etched with Vapor-HF through the through holes, a space is formed, and Vapor-HF is used. First post 401a and second post 401b are formed as non-etched regions (see FIG. 6D). As a result, the above-described passband variable high frequency filter is realized.

  As described above, according to the passband variable high frequency filter according to the first embodiment of the present invention, the voltage variable capacitor 905 having a low Q value representing the performance and the switch 1103 having a large loss are not provided. The low loss characteristics can be ensured. In addition, the movement of the dielectric layer due to electrostatic force changes the proximity and separation of the dielectric layer depending on a certain voltage value (pull-in voltage) at which the dielectric layer moves. The variation at a lower voltage value has the effect that the resonance frequency does not change and is resistant to voltage variations. As a result, it is possible to realize a passband variable high-frequency filter that is small in size and has low loss characteristics in the passband and that is resistant to variations in voltage values for varying the passband.

(Second Embodiment)
FIG. 7 is a diagram illustrating an example of a configuration of a passband variable high-frequency filter according to the second embodiment of the present invention. Specifically, FIG. 7A shows a perspective view of the high-pass filter operating state of the passband variable high-frequency filter, and FIG. 7B shows the low-pass filter operating state of the passband variable high-frequency filter. A perspective view is shown.

In FIG. 7, a substrate 701 is made of a material such as silicon, glass, gallium arsenide or the like. A first dielectric layer 702 is formed on the substrate 701. The first dielectric layer 702 is made of a ferroelectric material such as barium strontium titanate (Ba _x Sr _1-x TiO ₃ ) or strontium titanate (SrTiO ₃ ).

  On the first dielectric layer 702, an input electrode 703a, an output power 703b, and a resonator electrode 704 are configured. The input electrode 703a and the output power 703b are made of a metal material such as aluminum, copper, tungsten, or titanium. The resonator electrode 704 includes a first resonator electrode 704a, a second resonator electrode 704b, a ground electrode 704c, a first lower electrode 704d, and a second lower electrode 704e that are connected together.

  On the ground electrode 704c, the first lower electrode 704d, and the second lower electrode 704e, a movable second dielectric layer 706 is formed through a space. An upper electrode 707, an additional input coupling electrode 708a, an additional inter-resonator coupling electrode 708b, and an additional output coupling electrode 708c are formed on the second dielectric layer 706. The upper electrode 707 includes a first upper electrode 707a, a second upper electrode 707b, and a grounding counter electrode 707c connected together.

  The first resonator electrode 704a and the second resonator electrode 704b are SIR: Stepped Impedance Resonator type, and the resonator length can be shortened at the same resonance frequency as compared with the straight type. Further downsizing can be realized. In addition, a dielectric layer made of an oxide film or the like is provided over all the electrodes arranged on the first dielectric layer 702, the input electrode 703a, the output electrode 703b, and the resonator electrode 704.

  Next, the operation of the passband variable high frequency filter according to the second embodiment of the present invention configured as described above will be described. A signal input from the input electrode 703a is capacitively coupled by the first resonator electrode 704a and the input coupling capacitor 201, and the interstage coupling capacitor 202 between the first resonator electrode 704a and the second resonator electrode 704b. Are coupled by the second resonator electrode 704b, the output electrode 703b, and the output coupling capacitor 203, and output from the output electrode 703b.

  The first resonator electrode 704a and the second resonator electrode 704b are microstripline resonators whose lower surface is the first dielectric layer 702 and whose upper surface is air or vacuum, and whose end surfaces are connected to the ground electrode 704c. Accordingly, the first dielectric layer 702 on the lower surface operates as a dielectric resonator whose wavelength is shortened. As a result, the passband variable high-frequency filter enters a high-pass filter operation state (the state shown in FIG. 7A), and a bandpass filter having a pass characteristic 301 having a passband near the resonance frequency of the dielectric resonator is realized. The

  The first upper electrode 707a is disposed at a position facing the first lower electrode 704d through the space and the second dielectric layer 706. By applying a DC voltage difference between the first upper electrode 707a and the first lower electrode 704d, the electrostatic force is excited, the two electrodes are attracted, and move together with the movable second dielectric layer 706. As a result, the passband variable high-frequency filter enters the low-pass filter operation state (the state shown in FIG. 7B).

  In addition, since the first lower electrode 704d and the second lower electrode 704e are grounded at the same potential as the ground electrode 704c in a direct current (DC) direction, by applying a direct current voltage to the upper electrode 707, The electrostatic force is excited, and the second dielectric layer 706 moves downward.

  When the low-pass filter operation state (the state shown in FIG. 7B) is reached, the first resonator electrode 704a and the second resonator electrode 704b have the lower surface as the first dielectric layer 702 and the upper surface as the second dielectric layer 702. A stripline resonator having the dielectric layer 706 is formed. Thereby, the effect of shortening the wavelength is strengthened, and the resonance frequency of each dielectric resonator is reduced as compared with the case where the second dielectric layer 706 is positioned upward.

  Further, the capacitance between the input electrode 703a and the first resonator electrode 704a is increased by the proximity of the second dielectric layer 706 on the top. Further, when the input electrode 703a and the additional input coupling electrode 708a are close to each other, a capacitance between the input electrode 703a and the additional input coupling electrode 708a and a capacitance between the additional input coupling electrode 708a and the first resonator electrode 704a are connected in series. The combined capacitance is added in parallel, and the input coupling capacitance 201 is also increased.

  Similarly, the interstage coupling capacitance 202 between the first resonator electrode 704a and the second resonator electrode 704b also increases due to the proximity of the second dielectric layer 706 and the additional inter-resonator coupling electrode 708b. Similarly, the output coupling capacitance 203 between the second resonator electrode 704b and the output electrode 703b also increases due to the proximity of the second dielectric layer 706 and the additional output coupling electrode 708c. An equivalent circuit of the thus configured passband variable high frequency filter is represented as shown in FIG. In the low-pass filter operation state (the state shown in FIG. 7B), the resonant frequency of the dielectric resonator is lowered, and the input coupling capacitance 201, the interstage coupling capacitance 202, and the output coupling capacitance 203 are increased accordingly. . As a result, a bandpass filter having a pass characteristic 302 (see FIG. 3) shifted to a lower frequency than the pass characteristic 301 in the high-pass filter operation state (the state shown in FIG. 7A) is realized.

  As described above, according to the passband variable high-frequency filter according to the second embodiment of the present invention, as in the first embodiment, the small-sized and low-loss characteristic in the passband is ensured, and the passband is reduced. It is possible to realize a passband variable high frequency filter that is resistant to variations in voltage value for varying.

  In addition, it is preferable to have a dielectric layer made of an oxide film or the like on all the electrodes arranged on the first dielectric layer 702, that is, on the input electrode 703a, the output electrode 703b, and the resonator electrode 704. . Accordingly, there is an effect of suppressing a variation in resonance frequency due to a minute gap between the electrode and the dielectric layer 706 due to the flatness of the electrode when the second dielectric layer 706 comes close.

(Third embodiment)
The passband variable high-frequency filter according to the first and second embodiments is small and can support a plurality of frequency bands, and a filter in a communication circuit such as a mobile phone corresponding to a plurality of systems and a plurality of frequency bands. Can be used as Moreover, it can be applied to uses such as a filter for a radio base station according to the specification. Below, the example which applied the pass-band variable high frequency filter to the communication apparatus is demonstrated.

  FIG. 8 is a block diagram showing an example of the configuration of a communication device according to the third embodiment of the present invention. In FIG. 8, the communication device includes a transmission terminal 801, a baseband unit 802, a power amplifier 803, a transmission filter 804, an antenna 805, a reception filter 806, an LNA 807, and a reception terminal 808. A signal input from the transmission terminal 801 is amplified by the power amplifier 803 via the baseband unit 802, filtered by the transmission filter 804, and transmitted by radio waves from the antenna 805. A signal received by the antenna 805 is filtered by the reception filter 806, amplified by the LNA 807, and transmitted to the reception terminal 808 via the baseband unit 802. The passband variable high-frequency filter according to the first or second embodiment is used for at least one of the transmission filter 804 and the reception filter 806 in the above description. Accordingly, the communication device has a small size and low loss characteristics, and can cope with a plurality of bands.

  In the first to third embodiments, the shape of the resonator electrode is not limited to the straight type or the SIR type, and the same effect can be obtained by the configuration of the open-ended half-wavelength dielectric resonator. The shape of each electrode is not limited to this.

  In addition, each material such as the substrate, the electrode, and the dielectric layer is not limited to the above-described example. For example, the material is different between the upper electrode and the lower electrode, or the first dielectric layer and the second dielectric layer. It may be.

The dielectric layer is composed of a ferroelectric material such as barium strontium titanate (Ba _x Sr _1-x TiO ₃ ) or strontium titanate (SrTiO ₃ ). However, it is not limited to this. Further, the materials of the substrate and the electrodes are not limited to the above examples.

  The passband variable high-frequency filter of the present invention is useful as a filter in a radio circuit of a mobile phone or the like.

The figure which shows an example of a structure of the pass-band variable high frequency filter which concerns on the 1st Embodiment of this invention. The figure which shows an example of the equivalent circuit of the pass-band variable high frequency filter which concerns on the 1st Embodiment of this invention The figure which shows the pass characteristic of the pass-band variable high frequency filter which concerns on the 1st Embodiment of this invention The figure showing the A-A 'section of the pass-band variable high frequency filter shown in FIG. The figure which shows the manufacturing method of the pass-band variable high frequency filter which concerns on the 1st Embodiment of this invention (manufacturing process of a high-pass filter and a low-pass filter common part) The figure which shows the manufacturing method of the pass-band variable high frequency filter which concerns on the 1st Embodiment of this invention (manufacturing process of a low-pass filter part) The figure which shows an example of a structure of the pass-band variable high frequency filter which concerns on the 2nd Embodiment of this invention. The block diagram which shows an example of a structure of the communication apparatus which concerns on the 3rd Embodiment of this invention. The figure which shows the equivalent circuit of the conventional pass-band variable filter The figure which shows an example of the pass characteristic of the conventional pass-band variable filter The figure which shows the equivalent circuit of the conventional pass-band variable filter

Explanation of symbols

101 Substrate 102 First dielectric layer 103a Input electrode 103b Output electrode 104 Resonator electrode 104a First resonator electrode 104b Second resonator electrode 104c Ground electrode 105a First lower electrode 105b Second lower electrode 106 Second Second dielectric layer 107a First upper electrode 107b Second upper electrode 108a Additional input coupling electrode 108b Additional inter-resonator coupling electrode 108c Additional output coupling electrode 201 Input coupling capacitance 202 Interstage coupling capacitance 203 Output coupling capacitance 301 High region Filter pass characteristic 302 Low pass filter pass characteristic 401a First post 401b Second post 402 Movable region 501 Lower electrode 601 Upper electrode 701 Substrate 702 First dielectric layer 703a Input electrode 703b Output electrode 704 Resonator electrode 704a First resonator electrode 704b Second resonator electrode 70 c ground electrode 704d first lower electrode 704e second lower electrode 706 second dielectric layer 707 upper electrode 707a first upper electrode 707b second upper electrode 707c ground counter electrode 708a additional input coupling electrode 708b additional resonator Inter-coupling electrode 708c Additional output coupling electrode 801 Transmission terminal 802 Baseband unit 803 Power amplifier 804 Transmission filter 805 Antenna 806 Reception filter 807 LNA
808 Reception terminal 901 Input / output terminal 902 Interstage capacitance 903 Dielectric resonator 904 Parallel capacitance 905 Voltage variable capacity 1001 Low pass filter pass characteristic 1002 High pass filter pass characteristic 1101 Input / output terminal 1102 Interstage capacity 1103 Switch 1104 Dielectric Resonator 1105 Adjustment capacitor 1106 Switch

Claims (6)

On the first dielectric layer on the substrate, an input electrode, an output electrode, and a plurality of resonator electrodes are provided,
The plurality of resonator electrodes include at least a first resonator electrode and a second resonator electrode,
Forming an input capacitance between the input electrode and the first resonator electrode;
Forming an output capacitance between the output electrode and the second resonator electrode;
Forming a coupling capacitance between the plurality of resonator electrodes;
A second dielectric layer is disposed on the plurality of resonator electrodes via a space,
A variable pass-band high-frequency filter, wherein the second dielectric layer is mechanically moved, and the second dielectric layer is disposed close to and away from the plurality of resonator electrodes.   The variable passband high-frequency filter according to claim 1, wherein a third dielectric layer fixed on the plurality of resonator electrodes is disposed.   3. The passband variable high-frequency filter according to claim 1, wherein a movable electrode movable in conjunction with the second dielectric layer is disposed on the second dielectric layer. 4. .   A communication device including an antenna, a transmission circuit, and a reception circuit, wherein the passband variable high-frequency filter according to any one of claims 1 to 3 is provided in at least one of the transmission circuit and the reception circuit. . A method of manufacturing a passband variable high frequency filter,
Forming a first dielectric layer on a substrate;
Forming an input electrode, an output electrode, a plurality of resonator electrodes, and a lower electrode on one main surface of the first dielectric layer;
An oxide film forming step to be a post;
A planarization step of the oxide film;
Forming a second dielectric layer on the planarized oxide film;
Forming an upper electrode on one principal surface of the second dielectric layer on a portion facing the lower electrode in projection;
And a step of removing the oxide film corresponding to the lower part of the movable portion of the second dielectric layer.   The manufacturing method according to claim 5, wherein the lower electrode is a common electrode with the resonator electrode to be grounded.

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