WO2017036673A1 - Filtre à ondes de surface - Google Patents

Filtre à ondes de surface Download PDF

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Publication number
WO2017036673A1
WO2017036673A1 PCT/EP2016/067654 EP2016067654W WO2017036673A1 WO 2017036673 A1 WO2017036673 A1 WO 2017036673A1 EP 2016067654 W EP2016067654 W EP 2016067654W WO 2017036673 A1 WO2017036673 A1 WO 2017036673A1
Authority
WO
WIPO (PCT)
Prior art keywords
parallel
resonators
band
filter
series
Prior art date
Application number
PCT/EP2016/067654
Other languages
German (de)
English (en)
Inventor
Volker Schulz
Original Assignee
Epcos Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Epcos Ag filed Critical Epcos Ag
Publication of WO2017036673A1 publication Critical patent/WO2017036673A1/fr

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H03H9/6423—Means for obtaining a particular transfer characteristic
    • H03H9/6433—Coupled resonator filters
    • H03H9/6483—Ladder SAW filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02818—Means for compensation or elimination of undesirable effects
    • H03H9/02866—Means for compensation or elimination of undesirable effects of bulk wave excitation and reflections
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02818—Means for compensation or elimination of undesirable effects
    • H03H9/02834—Means for compensation or elimination of undesirable effects of temperature influence

Definitions

  • SAW filters to reduce the thermal response of SAW filters are those provided with a normally S1O 2 comprehensive compensation ⁇ layer.
  • Compensating layer can be constructed, for example on lithium niobate crystals with a cutting angle red-128. On this substrate material, the resonance frequency of the acoustic Rayleigh mode is used.
  • the layer structure of such SAW filters has the consequence that in addition to the horizontally propagating Rayleigh wave as a secondary mode still a vertically extending to the layer plane plate mode occurs whose frequency is above the frequency of the Rayleigh wave and at a given layer structure at a fixed distance having.
  • Frequency band which is for example a counter-band for a band combination in the carrier aggregation operation, which is to suppress for this application, so disturbs the disk mode and can lead to that because of the inadmissible
  • a SAW filter having a conventional ladder-type structure. This comprises a series branch connected between the filter inlet and outlet, in which series resonators are arranged. From this series branch n in parallel to a fixed potential comparable switched parallel branches branch off, in each of which one is arranged parallel ⁇ resonator. There are provided at least two parallel branches ⁇ (n> 2). To improve the selection of the filter, the number n of parallel branches can be increased to example ⁇ example five.
  • Parallel resonators span a pass band together.
  • ⁇ contemporary SAW filter is a first parallel resonator, a finger period p, which is less than a design optimization would actually require and when it for the design the passport would be required. Accordingly, the main resonance of the first parallel resonator appears at a higher frequency and is thus closer to the left
  • the invention is advantageously applicable in particular to resonators with a layer structure in which a plate mode, which is also called Z-harmonic mode and occurs at a fixed distance from the main resonance, occurs as a secondary mode. This plate fashion is located above the passband.
  • a SAW filter is obtained, which is a well-matched pass band according to the required exactly as a SAW filter optimized in a conventional way
  • the disturbing secondary mode in particular the disturbing plate mode is now shifted out of the opposite band, so that the filter in the frequency range of
  • the parallel inductance is preferably formed with high quality and implemented, for example, as a copper coil. If the SAW filter is applied in a flip-chip design on a carrier, then the parallel inductance in the form of the copper coil between the carrier and the chip can be arranged on the carrier. However, it is also possible, the SAW filter with a trained as a discrete component
  • Main resonance of a parallel resonator is also such that also the frequency of a dependent secondary mode is to be suppressed counter-band, it is according to a
  • Embodiment of the invention the main resonance of this parallel resonator and associated simultaneously shifted the secondary mode towards higher frequencies, so that the resonance of the secondary mode is outside of the opposing band to be suppressed.
  • parallel inductors are connected in series with the parallel resonator.
  • Side mode has, for example, realized on a lithium niobate substrate, which has a cutting angle between red 125 and red 130.
  • filters can also have an SiO 2 layer over their electrode metallization, which is used to compensate for the temperature coefficient of the frequency (TCF).
  • such a filter can still have a trim layer
  • Resonators is required to compensate for the higher tolerance in the production of said layer structure.
  • a SAW filter with such a TCF compensation layer and optionally a trim layer usually has the pronounced plate mode. For certain applications, this disk mode is just to be suppressed
  • TX filter embodying the invention may be part of a duplexer.
  • Duplexer may be connected in parallel to or together with another duplexer to a common antenna port.
  • two duplexers can then be operated in parallel at the same time in order to use at least in one direction (upstream or downstream) two different bands for a single communication connection or data transmission. This increases the bandwidth during data transmission.
  • the Carrier Aggregation Mode includes a band combination in which two of the bands have exactly the same distance to each other as the distance of the plate mode from the band
  • Main resonance corresponds to a resonator used in a filter
  • the invention can be used advantageously for such applications. According to a further embodiment of the invention and
  • a further improvement is achieved in that the static Capacitance CS RS i of this first series resonator, so the series resonator, which is located closest to the antenna connection is minimally formed.
  • the static capacitance may be reduced by a smaller aperture, by a reduced number of fingers and / or by a cascading of
  • Resonators can be achieved.
  • the cascading of resonators also has the advantage that the resulting resonators are more powerful than resonators, their static capacitance by reducing the aperture or
  • a filter according to the invention has the advantage that it manages with a limited number of resonators, which is not increased compared to known filters. The invention can therefore be realized without much additional effort.
  • a filter according to the invention or a duplexer with a filter according to the invention also requires none
  • FIG. 1 shows the transmission curve of a band 3 duplexer with disturbing secondary modes in the region of the band 1 RX filter.
  • FIG. 2 shows the real part of the admittance for the
  • FIG. 3 shows a schematic block diagram of the ladder-type structure of a SAW filter according to the invention.
  • FIG. 4 shows the real part of the admittance of
  • FIG. 5 shows the associated transmission curve of a
  • FIG. 6 shows the reflection factor at the antenna connection of a band 3 duplexer according to the invention in the Tx range of FIG Volume 1 compared to the course of the reflection factor of a conventional duplexer.
  • FIG. 7 shows the corresponding reflection curves on
  • Parallel resonator RP which is optimized for the pass band in the Tx area of band 3, shows, for example, the transmission curve shown in FIG. The optimization goal
  • the passband is fully compliant with Band 3 specifications.
  • the filter exhibits low insertion loss, and in the overlying RX portion of Band 3, good attenuation.
  • the filter itself has one
  • FIG. 2 shows that this secondary mode is due to the main resonance of parallel resonators, which, precisely in the case of the conventional structure of the ladder-type SAW filter, lie exactly in the mentioned counter-band.
  • f RP the main resonance of the parallel resonators
  • f PM the position of the secondary resonance, that is the resonant frequency of the plate mode is designated. This is between the two
  • FIG. 3 shows a block diagram of a SAW filter according to the invention, which differs from the conventional SAW filter with the transmission curve according to FIG.
  • Resonant frequencies of the parallel resonators is changed.
  • RP1, RP2 and RP3 is the
  • the parallel resonators are each connected via a parallel inductance LP1 to LP3 to a fixed potential, in particular to ground.
  • the corresponding series branch SZ of the filter connects a first terminal Tl to a second terminal T2, which are respectively assigned to the filter inlet or filter outlet.
  • additional reactances such as may be used in a conventional ladder-type design, but which do not relate to the gist of the invention.
  • the value of the parallel inductance becomes, for example
  • FIG. 4 shows the real part of the admittances of the parallel resonators of the inventive filter according to FIG.
  • the main resonances f RP are
  • Parallel resonators RP closer together and appear at about 15 MHz higher frequency. Parallel to this main resonance shifts also the secondary mode, here the Resonant frequency f PM of the plate mode, which appears at a fixed distance to the main resonance of the resonators.
  • Each counterband is therefore essential for such filters / duplexers.
  • Reflection factor RF of a band 3 duplexer according to the invention in the frequency range of the band 1 Rx Martinezbands.
  • the lower graph shows the corresponding reflection factor for a known duplexer in the same range.
  • the minimum of the reflection by shifting the resonance of the secondary mode now lies to the right of the counterpart band BIRX.
  • the RF is improved within the entire counter-band BIRX.
  • the reflection factor RF is also improved in the Tx frequency range B1TX of band 1.
  • the invention can be applied to all constellations in which the disturbing secondary mode comes to rest in the region of an opposing band to be suppressed.
  • the disturbing secondary mode does not have to be a plate mode, but can be a be any other parasitic mode.
  • the invention is not limited to the said embodiment of a B1B3 carrier aggregation mode. It is always usable when the distance between the main frequency and
  • Secondary mode corresponds approximately to the distance of an opposite band from the main band.
  • the substrate material of the SAW filters is not limited to said lithium niobate and may be any other single crystalline substrate
  • parallel resonators RP can deviate from the example shown in FIG. 3 and be chosen to be higher or lower.
  • a SAW filter may have a layer structure above the

Landscapes

  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

L'objet de l'invention est d'éviter une résonance parasite dans la contre-bande d'un filtre à ondes de surface à structure du type à échelle. À cet effet, la période de doigt des résonateurs parallèles est réduite et à l'inverse, les bras parallèles sont connectés à une inductance correspondante pour élargir à nouveau la largeur de bande et la ramener à sa valeur initiale. Le décalage de la résonance principale permet simultanément de décaler la fréquence du mode secondaire hors de la zone de la contre-bande.
PCT/EP2016/067654 2015-09-03 2016-07-25 Filtre à ondes de surface WO2017036673A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102015114751.3A DE102015114751A1 (de) 2015-09-03 2015-09-03 SAW Filter
DE102015114751.3 2015-09-03

Publications (1)

Publication Number Publication Date
WO2017036673A1 true WO2017036673A1 (fr) 2017-03-09

Family

ID=56611235

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2016/067654 WO2017036673A1 (fr) 2015-09-03 2016-07-25 Filtre à ondes de surface

Country Status (2)

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DE (1) DE102015114751A1 (fr)
WO (1) WO2017036673A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016114071B3 (de) * 2016-07-29 2018-01-25 Snaptrack, Inc. Elektroakustisches Filter mit reduzierten Plattenmoden
DE102018104955A1 (de) * 2018-03-05 2019-09-05 RF360 Europe GmbH Schallwellenvorrichtungen mit verbesserter Störmodenunterdrückung

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030058066A1 (en) * 2000-08-21 2003-03-27 Norio Taniguchi Surface acoustic wave filter device
US20030186673A1 (en) * 2002-03-29 2003-10-02 Fujitsu Media Devices Limited Filter chip and filter device
EP2141805A2 (fr) * 2008-06-30 2010-01-06 Murata Manufacturing Co. Ltd. Dispositif de résonateur, filtre l'incluant, et duplexeur
US20130285504A1 (en) * 2010-12-29 2013-10-31 Murata Manufacturing Co., Ltd. Surface acoustic wave device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013080461A1 (fr) * 2011-11-30 2013-06-06 パナソニック株式会社 Filtre d'onde élastique de type échelle et duplexeur d'antenne utilisant celui-ci

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030058066A1 (en) * 2000-08-21 2003-03-27 Norio Taniguchi Surface acoustic wave filter device
US20030186673A1 (en) * 2002-03-29 2003-10-02 Fujitsu Media Devices Limited Filter chip and filter device
EP2141805A2 (fr) * 2008-06-30 2010-01-06 Murata Manufacturing Co. Ltd. Dispositif de résonateur, filtre l'incluant, et duplexeur
US20130285504A1 (en) * 2010-12-29 2013-10-31 Murata Manufacturing Co., Ltd. Surface acoustic wave device

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