WO2011024579A1 - Filtre, duplexeur, module de communication et dispositif de communication - Google Patents

Filtre, duplexeur, module de communication et dispositif de communication Download PDF

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Publication number
WO2011024579A1
WO2011024579A1 PCT/JP2010/062148 JP2010062148W WO2011024579A1 WO 2011024579 A1 WO2011024579 A1 WO 2011024579A1 JP 2010062148 W JP2010062148 W JP 2010062148W WO 2011024579 A1 WO2011024579 A1 WO 2011024579A1
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Prior art keywords
filter
input
output
terminal
capacitance
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PCT/JP2010/062148
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English (en)
Japanese (ja)
Inventor
潤 堤
基揚 原
将吾 井上
政則 上田
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太陽誘電株式会社
岩城 匡郁
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Publication of WO2011024579A1 publication Critical patent/WO2011024579A1/fr

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/0023—Balance-unbalance or balance-balance networks
    • H03H9/0028—Balance-unbalance or balance-balance networks using surface acoustic wave devices
    • H03H9/0033—Balance-unbalance or balance-balance networks using surface acoustic wave devices having one acoustic track only
    • H03H9/0038—Balance-unbalance or balance-balance networks using surface acoustic wave devices having one acoustic track only the balanced terminals being on the same side of the track

Definitions

  • the present disclosure relates to a filter, a duplexer, a communication module, and a communication device.
  • Patent Document 1 discloses a reception filter having a balanced output.
  • bridging capacitance may occur between the input terminal and one output terminal and between the input terminal and the other output terminal.
  • the signal input from the input terminal is bypassed by the bridging capacitance without passing through the filter.
  • the two bridge capacities generally have different values in a balanced filter (such as a double mode elastic wave filter) using an actual elastic wave filter in order to perform balance conversion.
  • a balanced filter such as a double mode elastic wave filter
  • the influence of the bypass between the input and output terminals is not canceled out, so that there is a problem in that suppression degradation occurs in the reception filter.
  • the purpose of the present application is to improve the degree of suppression of the balanced filter by eliminating the unbalance of the bridging capacitance existing between the input terminal and the two output terminals and removing unnecessary common-mode components.
  • the filter disclosed in the present application includes an input terminal, a filter element that filters a signal input to the input terminal, and a first output terminal and a second output terminal that differentially output a signal from the filter element.
  • a balanced filter having a capacitance connected between the input terminal and one of the first output terminal and the second output terminal. is there.
  • Block diagram of the radio unit corresponding to one frequency band of an FDD (Frequency Division Duplex) mobile phone using an antenna duplexer Block diagram of a radio unit in which the reception interstage filter 104 and the transmission interstage filter 108 are deleted from the radio unit illustrated in FIG.
  • Block diagram of balanced antenna duplexer The figure which showed the concept of bridging capacity C1 and C2 which generate
  • the schematic diagram of the receiving filter which is an example of the balance type filter concerning this Embodiment
  • the characteristic diagram which shows the frequency characteristic of a reception filter in the case where the value of the bridge capacitance C1 is 0.03 pF and the value of the bridge capacitance C2 is 0.05 pF with and without the capacitance C3 added.
  • Block diagram of balanced antenna duplexer Schematic diagram showing a specific configuration of the reception filter 32 in FIG.
  • the characteristic diagram which shows the isolation characteristic between transmission / reception of a duplexer provided with the receiving filter with which the electrostatic capacitance was added, and the duplexer provided with the receiving filter without the electrostatic capacitance
  • the schematic diagram which shows the wiring layout of the receiving filter concerning this Embodiment Diagram showing capacitance arrangement pattern Communication module block diagram Block diagram of communication device
  • the filter is a balanced type including an input terminal, a filter element that filters a signal input to the input terminal, and a first output terminal and a second output terminal that differentially output a signal from the filter element.
  • a capacitance is connected between the input terminal and any one of the first output terminal and the second output terminal.
  • the filter element may be a double mode type acoustic wave filter, and the capacitance may be connected between an input terminal and an output terminal of the double mode type acoustic wave filter.
  • the filter may have a configuration in which a filter pass characteristic of a path from the input terminal to the first output terminal and a filter pass characteristic of a path from the input terminal to the second output terminal are different.
  • the filter element includes a first double mode type acoustic wave filter connected between the input terminal and the first output terminal, and between the input terminal and the second output terminal. And a second double mode type elastic wave filter and an input interdigital transducer and an output interdigital transducer, respectively.
  • the electrostatic capacitance includes a potential difference between nearest electrode fingers between the input interdigital transducer and the output interdigital transducer in the first double-mode acoustic wave filter, and the second double-mode acoustic wave.
  • Input interdigital transducer and output in filter Among the potential difference between the nearest electrode fingers each other between-digital transducer may be a configuration that is connected to a path towards a potential difference is small. As a result, capacitance is added to the double mode SAW filter of the path with the smaller bridging capacity, and the imbalance of the bridging capacity that originally exists can be reduced, and the degree of suppression can be improved. It becomes possible.
  • the capacitance may be formed on the filter element. With such a configuration, capacitance can be added without increasing the size of the filter, the degree of suppression can be improved while maintaining a small size, and a more desirable structure can be obtained.
  • FIG. 1 shows a radio unit corresponding to one frequency band of an FDD (Frequency Division Duplex) type mobile phone using an antenna duplexer.
  • the radio unit shown in FIG. 1 includes an antenna 101, a duplexer 102, an LNA (Low) Noise Amplifier) 103, a reception interstage filter 104, an LNA 105, a reception circuit 106, a transmission circuit 107, a transmission interstage filter 108, and a power amplifier 109.
  • the radio unit shown in FIG. 1 is mounted for the frequency band, and there is a problem that the size of the device is increased.
  • FIG. 2 shows a radio unit obtained by deleting the reception interstage filter 104 and the transmission interstage filter 108 from the radio unit shown in FIG.
  • the reception port 102a of the duplexer 102 when the inter-reception stage filter 104 is deleted from the radio unit, the reception port 102a of the duplexer 102 must be a balanced output.
  • the duplexer 102 takes charge of the function of suppressing unnecessary waves in the inter-reception stage filter 104. That is, a high attenuation characteristic (transmission band) between the antenna and the receiving terminal is required.
  • the duplexer 102 considering that the largest unwanted wave to be attenuated is leakage of the transmission signal to the reception side, it is important for the duplexer 102 to improve isolation between the transmission and reception terminals (transmission band). It becomes.
  • the reception port 102a is required to have a balanced output and have high attenuation and high isolation characteristics. .
  • FIG. 3 is a block diagram of a balanced antenna duplexer.
  • the balanced antenna duplexer includes a single-ended transmission filter 1, a single-ended-balance conversion reception filter 2, and a matching circuit 3.
  • the transmission filter 1 is connected to one transmission terminal 1a (single input).
  • Two reception terminals 2a and 2b (balance output) are connected to the reception filter 2.
  • An antenna terminal 4 connected to the antenna is connected to the matching circuit 3.
  • FIG. 4 is a diagram showing the concept of the bridging capacitances C1 and C2 generated between the input and output of the reception filter 2. As shown in FIG.
  • the signal input to the input terminal 2c of the reception filter 2 does not pass through the filter element 5, and the bridging capacitances C1 and C2 To the output terminals 2a and 2b. That is, the signal input to the input terminal 2 c bypasses the reception filter 2. Therefore, the degree of suppression in the reception filter 2 is degraded.
  • Japanese Patent Laid-Open No. 2005-318308 discloses that there is a bridging capacitance in each of the paths between the two input / output terminals in the balanced filter, but both the bridging capacitances between the two input / output terminals are Cc. And are considered identical. That is, the unbalance of the bridging capacity is not disclosed, and only when the same bridging capacity exists ideally is shown. Furthermore, Japanese Patent Laid-Open No. 2005-318308 discloses the common GND inductance Lg3 as another factor that hinders the balance, but the solution is only to reduce the common GND inductance Lg3. There is no mention of other correction methods.
  • FIG. 5 is a diagram showing the concept of the filter according to the present embodiment.
  • the reception filter 2 which is a balanced filter using an acoustic wave filter, has an input terminal 2c and one of the two output terminals 2a and 2b (in the example shown in FIG. 5).
  • a capacitance C3 is connected between the output terminal 2a). In this way, by connecting the capacitance C3, the unbalance of the bridging capacitance existing in the respective paths between the input terminal 2c and the two output terminals 2a and 2b is reduced, and the suppression is improved. be able to.
  • the input / output of the reception filter 2 is connected by connecting an electrostatic capacitance of an arbitrary value to at least one of the path of the input terminal 2c-output terminal 2a and the path of the input terminal 2c-output terminal 2b.
  • a balance between the two bridging capacities in between can be ensured.
  • FIG. 6 is a schematic diagram of a reception filter that is an example of a balanced filter according to the present embodiment.
  • the reception filter shown in FIG. 6 includes a double-mode SAW filter designed with a pass band of 2110 to 2170 MHz and a stop band of 1920 to 1980 MHz.
  • the reception filter shown in FIG. 6 is a filter in which two double-mode SAW filters 21 and 22 having anti-phase and in-phase outputs are connected.
  • the double mode SAW filter 21 includes an input IDT electrode 21a and output IDT electrodes 21b and 21c.
  • the input IDT electrode 21a is connected to the input terminal 2c.
  • the output IDT electrodes 21b and 21c are connected to the output terminal 2a.
  • the input IDT electrode 21a is provided with a grounded IDT electrode 21h that is grounded at an opposing position.
  • the output IDT electrode 21b is provided with a grounded IDT electrode 21i that is grounded at an opposing position.
  • the output IDT electrode 21c is provided with a grounded IDT electrode 21j that is grounded at an opposing position.
  • Reflectors 21k are disposed at both ends of the input IDT electrode 21a and the output IDT electrodes 21b and 21c in the arrangement direction.
  • the double mode SAW filter 22 includes an input IDT electrode 22a and output IDT electrodes 22b and 22c.
  • the input IDT electrode 22a is connected to the input terminal 2c.
  • the output IDT electrodes 22b and 22c are connected to the output terminal 2b.
  • the input IDT electrode 22a is provided with a grounded IDT electrode 22h that is grounded at an opposing position.
  • the output IDT electrode 22b is provided with a grounded IDT electrode 22i that is grounded at an opposing position.
  • the output IDT electrode 22c is provided with a grounded IDT electrode 22j that is grounded at an opposing position.
  • Reflectors 22k are disposed at both ends of the input IDT electrode 22a and the output IDT electrodes 22b and 22c in the arrangement direction.
  • a signal input via the input terminal 2 c is input to the double mode SAW filters 21 and 22.
  • the electrode finger 21d at the end of the input IDT electrode 21a and the electrode finger 21e at the end of the output IDT electrode 21b have the same potential, and the electrode finger 21d at the end of the input IDT electrode 21a
  • the electrode finger 21e at the end of the output IDT electrode 21b has the same potential. Therefore, the surface acoustic wave excited by the input IDT electrode 21a is received in the opposite phase (phase inverted by 180 °) at the output IDT electrodes 21b and 21c. Therefore, the signal output from the output terminal 2a is inverted in phase (phase difference 180 degrees) with respect to the signal input to the input terminal 2c.
  • the double mode SAW filter 22 has a potential difference between the electrode finger 22d at the end of the input IDT electrode 22a and the electrode finger 22e at the end of the output IDT electrode 22b, and the electrode finger 22d at the end of the input IDT electrode 22a.
  • the electrode finger 22e at the end of the output IDT electrode 22b has a potential difference. Therefore, the surface acoustic wave excited by the input IDT electrode 22a is received in the same phase by the output IDT electrodes 22b and 22c. Therefore, the signal output from the output terminal 2b is in phase with the signal input to the input terminal 2c.
  • the reception filter 2 that is a balanced filter can output a signal having a reverse phase from the output terminal 2a and a signal having the same phase from the output terminal 2b based on the signal input to the input terminal 2c. .
  • bridging capacitances C1 and C2 exist between the input terminal 2c and the output terminals 2a and 2b, respectively.
  • the bridging capacitances C1 and C2 in FIG. 6 are equivalently showing the bridging capacitances present in the reception filter 2, and are not actually connected with capacitors or the like.
  • the bridging capacitances C1 and C2 are unbalanced in value due to the structure of the double mode SAW filters 21 and 22.
  • the bridging capacitances C1 and C2 are generated based on a potential difference between adjacent electrode fingers in the double mode SAW filters 21 and 22.
  • the electrode finger 21d at the end of the output IDT electrode 21b and the electrode finger 21e at the end of the input IDT electrode 21a (electrode finger adjacent to the electrode finger 21d) in the double mode SAW filter 21 are both signal potentials. Therefore, the potential is the same, and the bridging capacity between the electrode finger 21d and the electrode finger 21e becomes a small value.
  • the electrode finger 21f at the end of the ground IDT electrode facing the input IDT electrode 21a, and the electrode finger 21g (the electrode finger adjacent to the electrode finger 21f) at the end of the ground IDT electrode facing the output IDT electrode 21c Since both are ground potentials, they are the same potential, and the bridging capacity between the electrode finger 21f and the electrode finger 21g is a small value.
  • the bridging capacitance C1 since the adjacent electrode fingers have the same potential, the bridging capacitance C1 has a small value.
  • the electrode finger 22d at the end of the output IDT electrode 22b in the double mode SAW filter 22 and the electrode finger 22e at the end of the input IDT electrode 22a (electrode finger adjacent to the electrode finger 22d) Since the electrode finger 22e is a ground potential at the signal potential, it is a different potential, and the bridging capacity between the electrode finger 22d and the electrode finger 22e becomes a large value.
  • an electrode finger 22f at the end of the ground IDT electrode facing the input IDT electrode 22a, and an electrode finger 22g (an electrode finger adjacent to the electrode finger 22f) at the end of the ground IDT electrode facing the output IDT electrode 22c are different potentials because the electrode finger 22f is a signal potential and the electrode finger 22g is a ground potential, and the bridging capacity between the electrode finger 22f and the electrode finger 22g is a large value.
  • the bridging capacitance C2 since the potential difference between adjacent electrode fingers is large, the bridging capacitance C2 has a large value.
  • the value of the bridging capacitance C1 is 0.03 pF and the value of the bridging capacitance C2 is 0.05 pF.
  • an electrostatic capacitance C3 having a capacitance of 0.02 pF is added to the bridging capacitance C1 side.
  • FIG. 7 shows the frequency characteristics of the reception filter when the capacitance C3 is added to the filter having the bridge capacitance C1 of 0.03 pF and the value of the bridge capacitance C2 of 0.05 pF. .
  • the characteristic indicated by the solid line is the frequency characteristic of the reception filter 2 to which the capacitance C3 is added as shown in FIG.
  • the characteristic indicated by the broken line is, for example, the frequency characteristic of the reception filter 2 to which the capacitance C3 is not added as shown in FIG.
  • by adding the capacitance C3 to the reception filter 2 it is possible to increase the attenuation in the stop band (about 1920 to 1980 MHz) and improve the degree of suppression.
  • FIG. 8 is a block diagram of a balanced antenna duplexer.
  • the balanced antenna duplexer includes a transmission filter 31, a reception filter 32, an inductor 33, and an antenna terminal 34.
  • the transmission filter 31 includes a ladder type SAW filter in which a plurality of resonators are connected in a ladder type. In this embodiment, a 7-stage single-ended (single input-single output) type ladder-type SAW filter is provided.
  • the transmission filter 31 is connected to a transmission terminal 31a.
  • the reception filter 32 includes a double mode type SAW filter.
  • the reception filter 32 is a single input-balance output type filter, and is connected to reception terminals 32a and 32b.
  • the inductor 33 is an inductor for phase matching between the transmission filter 31 and the reception filter 32.
  • the antenna terminal 34 is connected to an antenna (not shown).
  • the duplexer shown in FIG. 8 can be mounted on a W-CDMA (Wideband Code Division Multiple Access) system Band_I mobile phone.
  • the transmission band is, for example, 1920 to 1980 MHz
  • the reception band is, for example, 2110 to 2170 MHz.
  • FIG. 9 is a schematic diagram showing a specific configuration of the reception filter 32 in FIG.
  • the reception filter 32 shown in FIG. 9 includes double mode SAW filters 41 and 42, SAW filters 43 to 46, an input terminal 47, output terminals 48a and 48b, and a capacitance C40.
  • SAW filters 43 and 44 are connected in series to the input terminal 47.
  • the SAW filter 44 is connected to the input IDT electrode 41 a of the double mode SAW filter 41 and the input IDT electrode 42 a of the double mode SAW filter 42.
  • the output IDT electrodes 41 b and 41 c of the double mode SAW filter 41 are connected to the SAW filter 45.
  • the output IDT electrodes 42 b and 42 c of the double mode SAW filter 42 are connected to the SAW filter 46.
  • An output terminal 48 a is connected to the SAW filter 45.
  • An output terminal 48 b is connected to the SAW filter 46.
  • the electrostatic capacitance C40 is connected to the input side of the SAW filter 43
  • the nearest electrode fingers of the input IDT electrode 41a and the two output IDT electrodes 41b and 41c have the same potential.
  • the surface acoustic wave excited by the input IDT electrode 41a is received in the opposite phase (phase inverted by 180 °) at the output IDT electrodes 41b and 41c.
  • the closest electrode fingers (electrode fingers) of the input IDT electrode 42a and the two output IDT electrodes 42b and 42c. 42d and electrode finger 42e, and electrode finger 42f and electrode finger 42g) have different potentials.
  • the surface acoustic wave excited by the input IDT electrode 42a is received in the same phase by the output IDT electrodes 42b and 42c. Based on such a principle, signals having a phase difference of 180 ° can be output from the output terminal 48a and the output terminal 48b.
  • the bridge capacity existing in the path connecting the input terminal 47 and the output terminal 48a and the path connecting the input terminal 47 and the output terminal 48b will be described.
  • One cause of the bridging capacitance is the capacitance generated between the nearest electrode fingers between the input IDT electrode and the output IDT electrode.
  • the potentials of the closest electrode fingers of the double mode type SAW filter 41 and the double mode type SAW filter 42 are different in order to realize unbalance-balance conversion. Specifically, a pair of nearest electrode fingers in the double mode type SAW filter 41 is grounded, and the generated capacitance is not regarded as a bridging capacitance.
  • the bridging capacity existing between the input terminal 47 and the output terminal 48a is smaller than the bridging capacity existing between the input terminal 47 and the output terminal 48b. Will exist.
  • the value of the capacitance C40 is, for example, 3 fF.
  • FIG. 10 shows isolation characteristics between transmission and reception of a duplexer including a reception filter to which a capacitance having a value of 3 fF is added and a duplexer including a reception filter to which no capacitance is added.
  • a solid line characteristic indicates an isolation characteristic in a duplexer including a reception filter to which a capacitance of 3 fF is added.
  • the broken line characteristic indicates the isolation characteristic in a duplexer including a reception filter to which no capacitance is added.
  • the transmission filter and the reception filter are formed on a 42 ° rotated Y-cut lithium tantalate (LiTaO 3 ) substrate, and are mainly composed of aluminum (Al). It was produced using an electrode material. As shown in FIG. 10, the isolation improvement of 10 dB or more at the maximum was observed by connecting a capacitance C40 of 3 fF between the input and output of the reception filter.
  • FIG. 11 is a schematic diagram illustrating a wiring layout of the reception filter according to the present embodiment.
  • the reception filter was formed on a 42 ° rotated Y-cut LiTaO 3 substrate 50.
  • wiring patterns such as double-mode SAW filters 51 and 52, SAW resonators 53 to 56, and an input terminal 57 are formed.
  • the wiring pattern shown in FIG. 11 shows an example of a specific wiring pattern of the reception filter shown in FIG.
  • a path for adding capacitance is determined by paying attention to the potential difference between the nearest electrode fingers between the input IDT electrode and the output IDT electrode.
  • the wiring layout of the reception filter manufactured in this embodiment is substantially the same between the path of the input terminal 57-output terminal 58a and the path of the input terminal 57-output terminal 58b. This is because it is considered that the location where the imbalance of the bridging capacitance exists is between the nearest electrode fingers between the input IDT electrode and the output IDT electrode in the double mode SAW filters 51 and 52.
  • a capacitance 59 was connected between the input terminal 57 and the output terminal 58a.
  • the electrostatic capacitance 59 is drawn from the input terminal 57 and includes a wiring pattern 59a mainly containing Al, a wiring pattern 59b drawn mainly from the output terminal 58a and mainly containing Al, and between the wiring pattern 59a and the wiring pattern 59b.
  • the gap 59c is formed.
  • the dimensions of the wiring patterns 59a and 59b (the length dimension from the input terminal 57 and the output terminal 58a, the dimension L of the gap 59c, etc.) can be determined by experiments so as to achieve a desired improvement in isolation.
  • the length of the wiring pattern 59a and 59b is adjusted to adjust the width dimension L of the gap 59c.
  • the value can be adjusted arbitrarily.
  • the wiring 59 is drawn out from the input terminal 57 and the output terminal 58a and the capacitance 59 is added.
  • the location where the bridging capacitance imbalance occurs is a double mode. Since it is the type SAW filters 51 and 52, the same effect can be obtained regardless of the arrangement as long as the double mode type SAW filters 51 and 52 are sandwiched.
  • a capacitance may be added to the path on the input terminal 57-output terminal 58b side.
  • the capacitance is added to the path having the larger bridging capacitance, the effect of improving the suppression can be further obtained.
  • a capacitance may be connected as shown in any one of reference numerals C41 to C47 shown in FIG.
  • Capacitances C40 to C43 are examples connected to the path on the input terminal 47-output terminal 48a side, and are connected in parallel between the input and output of the double mode SAW filter 41.
  • Capacitances C44 to C47 are examples connected to the path on the input terminal 47-output terminal 48b side, and are connected in parallel between the input and output of the double-mode SAW filter 42.
  • FIG. 13 shows an example of a communication module including the filter according to the present embodiment.
  • the duplexer 62 includes a reception filter 62a and a transmission filter 62b.
  • the reception filter 62a is connected to reception terminals 63a and 63b corresponding to, for example, balanced output.
  • the transmission filter 62b is connected to the transmission terminal 65 via the power amplifier 64.
  • the reception filter 62a includes the filter according to the present embodiment.
  • the reception filter 62a When performing a reception operation, the reception filter 62a passes only a signal in a predetermined frequency band among reception signals input via the antenna terminal 61, and outputs the signal from the reception terminals 63a and 63b to the outside. Further, when performing a transmission operation, the transmission filter 62b passes only a signal in a predetermined frequency band among transmission signals input from the transmission terminal 65 and amplified by the power amplifier 64, and outputs the signal from the antenna terminal 61 to the outside. To do.
  • the degree of suppression in the reception filter 62a can be improved by providing the communication module with the filter according to the present embodiment. Further, the isolation between the reception filter 62a and the transmission filter 62b can be improved.
  • the bridging capacity between both terminals is obtained. Can be further corrected.
  • the configuration of the communication module shown in FIG. 13 is an example, and the same effect can be obtained even if the filter according to the present embodiment is mounted on a communication module of another form.
  • FIG. 14 shows an RF block of a mobile phone terminal as an example of a communication apparatus including the filter according to the present embodiment or the communication module described above. Further, the communication apparatus shown in FIG. 14 shows a configuration of a mobile phone terminal that supports a GSM (Global System for Mobile Communications) communication system and a W-CDMA (Wideband Code Division Multiple Access) communication system. Further, the GSM communication system in the present embodiment corresponds to the 850 MHz band, 950 MHz band, 1.8 GHz band, and 1.9 GHz band.
  • the mobile phone terminal includes a microphone, a speaker, a liquid crystal display, and the like. However, illustration is omitted because they are unnecessary in the description of the present embodiment.
  • the reception filters 73a and 77 to 80 include the filters according to the present embodiment.
  • the received signal input through the antenna 71 selects an LSI to be operated by the antenna switch circuit 72 depending on whether the communication method is W-CDMA or GSM.
  • the input received signal is compatible with the W-CDMA communication system, switching is performed so that the received signal is output to the duplexer 73.
  • the reception signal input to the duplexer 73 is limited to a predetermined frequency band by the reception filter 73 a, and a balanced reception signal is output to the LNA 74.
  • the LNA 74 amplifies the input received signal and outputs it to the LSI 76.
  • the LSI 76 performs a demodulation process on the audio signal based on the input received signal, and controls the operation of each unit in the mobile phone terminal.
  • the LSI 76 when transmitting a signal, the LSI 76 generates a transmission signal.
  • the generated transmission signal is amplified by the power amplifier 75 and input to the transmission filter 73b.
  • the transmission filter 73b passes only a signal in a predetermined frequency band among input transmission signals.
  • the transmission signal output from the transmission filter 73 b is output from the antenna 71 to the outside via the antenna switch circuit 72.
  • the antenna switch circuit 72 selects any one of the reception filters 77 to 80 according to the frequency band and outputs the received signal. To do. A reception signal whose band is limited by any one of the reception filters 77 to 80 is input to the LSI 83.
  • the LSI 83 performs a demodulation process on the audio signal based on the input received signal, and controls the operation of each unit in the mobile phone terminal. On the other hand, when transmitting a signal, the LSI 83 generates a transmission signal.
  • the generated transmission signal is amplified by the power amplifier 81 or 82 and output from the antenna 71 to the outside via the antenna switch circuit 72.
  • the degree of suppression in the reception filter 62a can be improved by providing the communication device with the filter or communication module according to the present embodiment. Further, the isolation in the reception filters 73a and 77 to 80 can be improved.
  • an electrostatic capacitance having an arbitrary value is connected to at least one of the plurality of double mode SAW filters included in the balanced filter, and thus occurs in the plurality of double mode filters.
  • the imbalance of the bridge capacity can be suppressed. Therefore, the degree of suppression of the filter can be improved. Further, the isolation of the filter can be improved.
  • a capacitance is connected to one of the two double mode SAW filters.
  • an unbalance of bridging capacitance that occurs in the two double mode SAW filters is suppressed.
  • a capacitance may be connected to each of the two double mode SAW filters.
  • a balanced filter comprising an input terminal, a filter element for filtering a signal input to the input terminal, and a first output terminal and a second output terminal for differentially outputting a signal from the filter element. And A filter in which a capacitance is connected between the input terminal and any one of the first output terminal and the second output terminal.
  • Appendix 3 The filter according to appendix 1 or 2, wherein a filter pass characteristic of a path from the input terminal to the first output terminal is different from a filter pass characteristic of a path from the input terminal to the second output terminal.
  • the filter element is connected between a first double mode type acoustic wave filter connected between the input terminal and the first output terminal, and between the input terminal and the second output terminal.
  • the first double-mode acoustic wave filter and the second double-mode acoustic wave filter each include an input interdigital transducer and an output interdigital transducer,
  • the capacitance includes a potential difference between nearest electrode fingers between an input interdigital transducer and an output interdigital transducer in the first double-mode acoustic wave filter, and the second double-mode acoustic wave filter.
  • a duplexer comprising a transmission filter that outputs a transmission signal and a reception filter that filters a signal input from an antenna, The duplexer, wherein the reception filter includes the filter according to any one of appendices 1 to 5.
  • Appendix 7 A communication module comprising the filter according to any one of appendices 1 to 5.
  • Appendix 8 A communication device comprising the filter according to any one of appendices 1 to 5.
  • the present disclosure is useful for filters, duplexers, communication modules, and communication devices.

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

Abstract

L'invention concerne un filtre équilibré dont le niveau de suppression est amélioré par l’élimination des composantes en phase inutiles et en annulation du déséquilibre dans la capacité de pontage existant entre une borne d'entrée et deux bornes de sortie. Le filtre équilibré est doté d'une borne d'entrée, d'un élément filtrant qui filtre un signal injecté sur la borne d'entrée, et d’une première borne de sortie et une seconde borne de sortie délivrant un signal différentiel provenant de l'élément filtrant, et d'un condensateur connecté entre la borne d'entrée et une borne de sortie choisie entre la première borne de sortie et la seconde borne de sortie.
PCT/JP2010/062148 2009-08-26 2010-07-20 Filtre, duplexeur, module de communication et dispositif de communication WO2011024579A1 (fr)

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JP2009195544A JP5235004B2 (ja) 2009-08-26 2009-08-26 フィルタ、デュープレクサ、通信モジュール、通信装置
JP2009-195544 2009-08-26

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JP5823168B2 (ja) * 2011-05-24 2015-11-25 太陽誘電株式会社 通信モジュール
JP6465065B2 (ja) * 2016-04-25 2019-02-06 株式会社村田製作所 弾性波装置

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WO2005101657A1 (fr) * 2004-04-16 2005-10-27 Toyo Communication Equipment Co., Ltd. Filtre d’onde acoustique de surface de type équilibré
JP2005102328A (ja) * 2004-12-16 2005-04-14 Murata Mfg Co Ltd 弾性表面波装置
JP2009010448A (ja) * 2007-06-26 2009-01-15 Panasonic Corp 弾性波フィルタ装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112543012A (zh) * 2020-12-09 2021-03-23 诺思(天津)微系统有限责任公司 滤波器电路和复用双工器以及通信设备

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