• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    An object of the present invention is to provide a longitudinally coupled resonator type surface acoustic wave filter capable of significantly reducing a transversal response than a conventional surface acoustic wave filter. According to the configuration of the present invention, in a surface acoustic wave filter having a piezoelectric substrate and at least two IDTs formed side by side along the propagation direction of the surface acoustic wave on the piezoelectric substrate, at least one of the IDTs includes a metal. The metallization ratio forms an electrode finger different from the metallization recipe of the other electrode fingers of the IDT.
    公开号:KR20020095121A
    申请号:KR1020020032490
    申请日:2002-06-11
    公开日:2002-12-20
    发明作者:나코가츠히로；다카미네유이치
    申请人:가부시키가이샤 무라타 세이사쿠쇼；
    IPC主号:
    专利说明:

    Longitudinally-coupled resonator surface-acoustic-wave filter and communication apparatus using the same
    [19] The present invention relates to a longitudinally coupled resonator type surface acoustic wave filter and a communicator device using the same.
    [20] In recent years, a communication device such as a cellular phone has a transmission frequency band and a reception frequency band close to each other due to an increase in subscribers or diversification of services. In addition, some communication devices require a certain amount or more of attenuation in the very vicinity of the pass band in order to prevent interference with other communication devices. Therefore, the surface acoustic wave filter which is widely used as a band pass filter of the RF stage of a mobile telephone has also a strong demand for increasing the amount of attenuation extremely close to the pass band to a certain level or more.
    [21] On the other hand, there has been a strong demand for surface acoustic wave filters to have a balanced-unbalanced signal conversion function and a so-called balun function for the purpose of reducing the number of parts. A longitudinally coupled resonator type surface acoustic wave filter having such a balanced-unbalanced signal conversion function is disclosed in, for example, Japanese Patent Laid-Open No. 5-267990.
    [22] However, in the conventional longitudinally coupled resonator type surface acoustic wave filter as described above, deterioration of the shoulder characteristic called transversal response on the higher side than the pass band (the steepness of the frequency characteristic) Deterioration) appears. Therefore, there has been a problem that the amount of attenuation at the high frequency side is not sufficiently large than that of the pass band required by the PCS (Personal Communication System) type communication device. In order to solve this problem, a ladder-type surface acoustic wave filter disclosed in Japanese Patent Laid-Open No. Hei 10-126212 can be cited as a filter having a larger attenuation amount on the high side than a pass band. However, this ladder type surface acoustic wave filter has a problem in that a balanced-unbalanced signal conversion function cannot be configured. That is, in the related art, it is difficult to construct a surface acoustic wave filter having a sufficient amount of attenuation on the higher side than the pass band and having a balanced-unbalanced signal conversion function.
    [23] The longitudinally coupled resonator type surface acoustic wave filter of the present invention has been made in view of the above-described problems, and the longitudinally coupled resonator capable of significantly reducing the transversal response than the conventional surface acoustic wave filter and also having a balanced-unbalanced signal conversion function. A surface acoustic wave filter is provided.
    [1] FIG. 1A is a schematic diagram illustrating a longitudinally coupled resonator type surface acoustic wave filter of a first embodiment of the present invention, and FIG. 1B is a diagram for describing metalization ratios.
    [2] Fig. 2 is a graph showing the change in the metallization recipe of each IDT of the longitudinally coupled resonator type surface acoustic wave filter of the first embodiment of the present invention.
    [3] Fig. 3 is a graph showing the frequency-amplitude characteristics of the longitudinally coupled resonator type surface acoustic wave filter of the first embodiment of the present invention.
    [4] 4 is a graph showing the frequency-amplitude characteristics of a longitudinally coupled resonator type surface acoustic wave filter in a conventional configuration.
    [5] Fig. 5 is a graph showing the change in the metallization ratio of each ID T of the longitudinally coupled resonator type surface acoustic wave filter of the second embodiment of the present invention.
    [6] 6 is a graph showing the frequency-amplitude characteristics of the longitudinally coupled resonator type surface acoustic wave filter of the second embodiment of the present invention.
    [7] Fig. 7 is a graph showing changes in the metallization recipe of each IDT of the longitudinally coupled resonator type surface acoustic wave filter of the third embodiment of the present invention.
    [8] Fig. 8 is a graph showing the frequency-amplitude characteristics of the longitudinally coupled resonator type surface acoustic wave filter of the third embodiment of the present invention.
    [9] Fig. 9 is a schematic diagram showing the longitudinally coupled resonator type surface acoustic wave filter of the fourth embodiment of the present invention.
    [10] Fig. 10 is a schematic diagram showing the longitudinally coupled resonator type surface acoustic wave filter of the fifth embodiment of the present invention.
    [11] Fig. 11 is a schematic diagram showing the longitudinally coupled resonator type surface acoustic wave filter of the sixth embodiment of the present invention.
    [12] Fig. 12 is a schematic diagram showing the longitudinally coupled resonator type surface acoustic wave filter of the seventh embodiment of the present invention.
    [13] Fig. 13 is a schematic block diagram of a communication device equipped with the longitudinally coupled resonator type surface acoustic wave filter of the present invention.
    [14] <Brief description of the main parts of the drawing>
    [15] 101, 301, 401, 501, 601: longitudinally coupled resonator type surface acoustic wave filter
    [16] 105, 106: reflector 201: unbalanced terminal
    [17] 202 and 203: balanced terminals
    [18] 102, 103, 104, 302, 303, 304, 305, 306, 307, 402, 403, 404, 502, 503, 504, 602, 603, 604: IDT
    [24] In order to achieve the above object, the surface acoustic wave filter of the present invention is a surface acoustic wave filter having a piezoelectric substrate and at least two IDTs (interdigital transducers) formed side by side along the propagation direction of the surface acoustic waves on the piezoelectric substrate, The at least one IDT is characterized in that a metallization ratio is formed of an electrode finger different from the metallization recipe of another electrode finger of the IDT.
    [25] In a specific aspect of the present invention, in at least one of the IDTs adjacent to each other among the IDTs, an electrode finger having a metallization recipe different from the metallization recipe of another electrode finger of the IDT, It is formed in the area | region up to about 1/4 of said IDT from an adjacent part. It is characterized by the above-mentioned.
    [26] In a specific aspect of the present invention, the metallization recipe of the electrode finger is continuously changed in the propagation direction of the surface acoustic wave in at least one of the IDTs.
    [27] Thereby, the longitudinal response can be reduced, and a longitudinally coupled resonator type surface acoustic wave filter having a large amount of attenuation at the passband high band side can be obtained. At this time, by continuously changing the metallization recipe of the electrode finger in the propagation direction of the surface acoustic wave, the effect of the present invention can be obtained without increasing the insertion loss in the pass band.
    [28] Another invention of the present invention is a communication device comprising the above-described longitudinally coupled resonator type surface acoustic wave filter.
    [29] By using the longitudinally coupled resonator type surface acoustic wave filter of the present invention in a communication device, a communication device having good communication quality and high reliability can be obtained.
    [30] Embodiment of the Invention
    [31] Hereinafter, a longitudinally coupled resonator type surface acoustic wave filter which is an embodiment of the present invention will be described with reference to FIGS.
    [32] Fig. 1A shows the configuration of the first embodiment. This first embodiment is an example of a filter for EGSM-Rx. In addition, in the following second to seventh embodiments, the EGSM-Rx filter will be described as an example. In the longitudinally coupled resonator type surface acoustic wave filter 101 of the first embodiment, an IDT and a reflector formed of an Al electrode are formed on a 40 ± 5 ° Ycut X propagation LiTaO 3 substrate 100 which is a piezoelectric substrate. Specifically, the longitudinally coupled resonator type surface acoustic wave filter 101 has an electrode finger group connected to the ground terminal 204 and an electrode finger group connected to the signal terminal 205 facing each other along the propagation direction of the surface acoustic wave. It consists of three IDTs 102, 103 and 104 arranged, and two reflectors 105 and 106 arranged to sandwich the IDTs 102, 103 and 104. The IDT 102 and IDT 104 are connected in parallel to a common signal terminal 205.
    [33] In addition, as shown in FIG. 1A, a plurality of electrode fingers of a portion where the IDT 103 and the IDT 102 are adjacent to each other, and several electrode fingers of a portion where the IDT 103 and the IDT 104 are adjacent to each other are identified by the IDT. It is a narrow pitch electrode finger having a smaller pitch than the other parts. In FIG. 1A, the number of electrode fingers is shown to be small in order to simplify the drawing.
    [34] In addition, the longitudinally coupled resonator type surface acoustic wave filter 101 of the first embodiment changes the metallization recipe of each IDT.
    [35] Here, the metallization recipe is represented by d = d1 / (d1 + d2) when the width of the IDT electrode finger is d1 and the width of the gap of the electrode finger is d2, as shown in FIG. 1B. Refers to the value d.
    [36] Fig. 2 is a graph showing the change in metallization recipe of each IDT of the longitudinally coupled resonator type surface acoustic wave filter of the first embodiment. In the longitudinally coupled resonator type surface acoustic wave filter 101 of the first embodiment, the metallization recipe of the electrode fingers of the IDTs 102, 103, and 104 is continuously changing in the range of 0.54 to 0.73 as shown in FIG. It is characterized by. Specifically, for the IDT 102, the metallization recipe of the electrode finger is continuously changed from 0.54 to 0.73 from the left end to the right. The IDT 103 is continuously changed from 0.73 to 0.54 from the left end to the center in the right direction of the IDT 103 and continuously changed from 0.54 to 0.73 from the center to the right end of the IDT 103. . In the IDT 104, the metallization recipe of the electrode finger is continuously changed from 0.73 to 0.54 from the left end to the right.
    [37] The other detailed configuration of the longitudinally coupled resonator type surface acoustic wave filter 101 is as follows when the wavelength determined by the pitch of the narrow pitch electrode finger is lambda I2 and the wavelength determined by the pitch of the other electrode finger is lambda I1.
    [38] Cross width W: 47.7λI1
    [39] Number of electrode fingers of IDT 102: 27 (of which four are from the right side are narrow pitch electrode fingers)
    [40] Number of electrode fingers of IDT 103: 35 (of which 4 are from the left and 4 from the right are narrow pitch electrode fingers)
    [41] Number of electrode fingers of IDT 104: 27 (of which four are from the left are narrow pitch electrode fingers) IDT wavelengths λI1: 4.19 μm, λI2: 3.86 μm
    [42] Wavelength (λR) of reflectors 105, 106: all 4.26μm
    [43] Number of reflectors (105, 106): 120 total
    [44] IDT-IDT interval (109, 110 in FIG. 1A): 0.50 lambda I2
    [45] IDT― Reflector Spacing: 0.52λR
    [46] Reflector metallization recipe: 0.55
    [47] Electrode Film Thickness: 0.08λI1
    [48] 3 shows frequency-amplitude characteristics of the first embodiment. As a comparison, in the configuration of Fig. 1A, the frequency-amplitude characteristics of the longitudinally coupled resonator type surface acoustic wave filter using a longitudinally coupled resonator type surface acoustic wave filter having a conventional configuration in which the IDT metallization recipe is set to 0.73 is used. 4 is shown. Further, the detailed configuration of the longitudinally coupled resonator type surface acoustic wave filter of the conventional configuration is the same as that of the first embodiment shown above, but in order to take the impedance adjustment, the cross width is from 47.7λI1 in Example 1 to 35.8λI1. It is different in that it is changed.
    [49] Comparing Fig. 3 with Fig. 4, in the first embodiment, the amount of attenuation at 990 to 1020 MHz (an oblique portion in Figs. 3 and 4) on the passband high band side is improved by about 4 dB over the conventional configuration shown in Fig. 4. It is. This is because the transversal response is reduced by continuously changing the metallization recipe of the electrode fingers in the IDT. In addition, in this embodiment, the effect that the passband width at 4 dB from the through level is about 0.5 MHz wider than the conventional example can also be obtained. As described above, by continuously changing the metallization recipe of the electrode fingers in the IDT in the direction of the surface acoustic wave propagation, the transversal response is reduced, and a longitudinally coupled resonator type surface acoustic wave filter having improved attenuation near the passband high frequency side can be obtained. have.
    [50] In the first embodiment, the metallization recipe of the electrode finger is continuously changed in all the IDTs of the IDTs 102, 103, and 104. However, changing the metallization recipe of the electrode finger is the same effect even if not in all the IDTs. Can be obtained.
    [51] Fig. 5 is a graph showing changes in the metallization recipe of each IDT of the longitudinally coupled resonator type surface acoustic wave filter of the second embodiment.
    [52] As shown in Fig. 5, in the second embodiment, the metallization recipe of the IDT 103 is not changed, but the metallization recipe of the electrode fingers of the IDTs 102 and 104 is continuously changed. Specifically, for the IDT 102, the metallization recipe of the electrode finger is continuously changed from 0.54 to 0.73 from the left end to the right. In the IDT 104, the metallization recipe of the electrode finger is continuously changed from 0.73 to 0.54 from the left end to the right. In addition, the metallization recipe of IDT 103 is constant at 0.73. At this time, the construction of the longitudinally coupled resonator type surface acoustic wave filter was the same as that of the first embodiment, except that the method of changing the metallization recipe and the crossing width of the IDT were 40.5 lambda I1.
    [53] The frequency-amplitude characteristic of the longitudinally coupled resonator type surface acoustic wave filter of the second embodiment is shown in FIG. In this second embodiment, the amount of attenuation at 990 to 1020 MHz (the diagonal portion in Fig. 6) on the passband high band side is improved as compared with the conventional configuration. In addition, the passband width at 4 dB from the through level is wider by about 2 MHz than in the conventional configuration. Thus, changing the metallization recipe of the electrode finger can obtain the same effects as those of the first embodiment even if not all IDTs.
    [54] Further, in the first and second embodiments, the metallization recipe of the electrode finger was continuously changed, but the effect of the present invention can be obtained without changing continuously.
    [55] Fig. 7 is a graph showing changes in metallization recipes of IDTs of the longitudinally coupled resonator type surface acoustic wave filter of the third embodiment. In this third embodiment, the metallization recipe of the electrode finger is changed discontinuously. Specifically, the metallization recipe of the IDTs 102 and 104 is based on 0.73, and substantially every other two is 0.584. In addition, the metallization recipe of IDT 103 is constant at 0.73. At this time, it is the same as a 1st Example and a 2nd Example except the method of changing a metallization recipe, and making the crossing width of IDT into 40.5 (lambda) I1.
    [56] 8 shows frequency-amplitude characteristics of the longitudinally coupled resonator type surface acoustic wave filter of the third embodiment. The longitudinally coupled resonator type surface acoustic wave filter of this third embodiment is not as effective as the longitudinally coupled resonator type surface acoustic wave filter of the first and second embodiments, but is 990 to 1020 MHz in the passband high band side as compared with the conventional configuration. The amount of attenuation in the diagonal line in FIG. 8 is improving.
    [57] That is, also in the third embodiment, by discontinuously changing the metallization recipe of the electrode finger, the transversal response is reduced, and a longitudinally coupled resonator type surface acoustic wave filter having an attenuation near the passband high band side can be obtained. The effect can be obtained. In addition, in the case where the metallization recipe of the electrode finger is changed discontinuously, the insertion loss in the pass band is increased by creating a discontinuous portion in the IDT, ideally, as in the first or second embodiment, It is preferable to change to.
    [58] In each embodiment of the present invention, the metallization recipe is changed throughout the IDT, but by forming a portion for changing the metallization recipe of the electrode finger in a region from the portion where the IDT is adjacent to about 1/4 of the IDT, The effect of reducing the transversal response and increasing the amount of attenuation on the high pass side of the pass band can be obtained.
    [59] In each embodiment of the present invention, a 40 ± 5 ° Ycut X propagation LiTaO 3 substrate was used, but the present invention is not limited to this substrate, for example, a 64 to 72 ° Ycut X propagation LiNbO 3 substrate or 41 ° Ycut X propagation. The same effect can also be obtained with a LiNbO 3 substrate or the like. In addition, although the present invention has been described as an example of a 3IDT type longitudinally coupled resonator type surface acoustic wave filter, the same effect can be obtained in other configurations. For example, even if a 2IDT configuration using two IDTs, a multiple IDT configuration using four, five or more IDTs, and a configuration in which the longitudinally coupled resonator type SAW filter of the present invention is connected in two stages in series, The effect can be obtained. In addition, you may add a 1 terminal pair elastic surface resonator in series or in parallel.
    [60] Further, by applying the longitudinally coupled resonator type surface acoustic wave filter shown in the first to third embodiments of the present invention to a longitudinally coupled resonator type surface acoustic wave filter having a balanced-unbalanced signal conversion function, the balanced-unbalanced signal conversion function is applied. And a longitudinally coupled resonator type surface acoustic wave filter having a large attenuation near the passband high frequency side.
    [61] 9 to 12 show the configuration of the longitudinally coupled resonator type surface acoustic wave filter of the present invention having a balanced-unbalanced signal conversion function, respectively.
    [62] Fig. 9 shows a longitudinally coupled resonator type surface acoustic wave filter having a balanced-unbalanced signal conversion function of the fourth embodiment. The longitudinally coupled resonator type surface acoustic wave filter 301 of the fourth embodiment is connected in parallel with two longitudinally coupled resonator type surface acoustic wave filters substantially the same as the longitudinally coupled resonator type surface acoustic wave filter 101 of the first embodiment shown in Fig. 1A. It is composed. In FIG. 9, the difference from FIG. 1A is that the vertical direction of the IDT 306 is reversed among three IDTs (305, 306, 307 in order from the left) of the longitudinally coupled resonator type surface acoustic wave filter on the right side. . The longitudinally coupled resonator type surface acoustic wave filter 301 is connected to an unbalanced terminal 201 of one of the opposing electrode finger groups of the IDTs 302, 304, 305, and 307, and has the opposite electrode finger group of the IDT 303. One side is connected to the balanced terminal 202, and one side of the electrode finger group of the IDT 306 is connected to the balanced terminal 203.
    [63] Next, Fig. 10 shows a longitudinally coupled resonator type surface acoustic wave filter having a balanced-unbalanced signal conversion function of the fifth embodiment. The longitudinally coupled resonator type surface acoustic wave filter 401 of the fifth embodiment has the same configuration as the longitudinally coupled resonator type surface acoustic wave filter 101 of the first embodiment shown in Fig. 1A, and includes three IDTs (402, 403 in order from the left). , 404 is characterized by the connection between the electrode finger of the IDT 403, the balanced terminal, and the unbalanced terminal. In other words, one of the opposite electrode finger groups of the IDT 403 is connected to the balanced terminal 202, and the other of the opposite electrode finger groups of the IDT 403 is connected to the balanced terminal 203. In addition, one of the electrode finger groups facing the IDTs 402 and 404 is connected to the unbalanced terminal 201.
    [64] Next, Fig. 11 shows a longitudinally coupled resonator type surface acoustic wave filter having a balanced-unbalanced signal conversion function of the sixth embodiment. The longitudinally coupled resonator type surface acoustic wave filter 501 of the sixth embodiment is basically the same as the longitudinally coupled resonator type surface acoustic wave filter 101 of the first embodiment shown in Fig. 1A. The difference is that among the three IDTs (502, 503, 504 in order from the left), the vertical direction of the IDT 504 is reversed, and the directions of the electrode fingers adjacent to each other in the vicinity of the center of the IDT 503 are the same. This is the point where the electrode is inverted. In the longitudinally coupled resonator type surface acoustic wave filter 501, one of the electrode finger groups facing the IDTs 502 and 504 is connected to the unbalanced terminal 201. In addition, one of the electrode finger groups on the left side of the IDT 503 that is inverted by the IDT electrode is connected to the balanced terminal 202. In addition, one of the electrode finger groups on the right side of the IDT 503 that is inverted by the IDT electrode is connected to the balanced terminal 203.
    [65] 12, the longitudinally coupled resonator type surface acoustic wave filter having the balanced-unbalanced signal conversion function of the seventh embodiment is shown. The longitudinally coupled resonator type surface acoustic wave filter 601 of the seventh embodiment is basically the same as the longitudinally coupled resonator type surface acoustic wave filter 101 of the first embodiment shown in Fig. 1A. The difference is that the vertical direction of the IDT 604 is reversed among the three IDTs (602, 603, 604 in order from the left). The longitudinally coupled resonator type surface acoustic wave filter 601 is connected to the balanced terminal 202 on one side of the electrode finger group of the IDT 602. In addition, one of the electrode finger groups of the IDT 604 is connected to the balanced terminal 203. In addition, one of the electrode finger groups facing the IDT 603 is connected to the unbalanced terminal 201.
    [66] As described above, for example, as shown in the fourth to seventh embodiments, the balanced-unbalanced signal conversion function is achieved by setting the longitudinally coupled resonator type surface acoustic wave filter to include the balanced-unbalanced signal conversion function. And a longitudinally coupled resonator type surface acoustic wave filter having a large amount of attenuation at the passband high band side.
    [67] Fig. 13 is a schematic block diagram showing an embodiment of the communicator 160 equipped with the longitudinally coupled resonator type surface acoustic wave filter according to the present invention.
    [68] In FIG. 13, the duplexer 162 is connected to the antenna 161. The longitudinally coupled resonator type surface acoustic wave filter 164 and the amplifier 165 are connected between the duplexer 162 and the receiver side mixer 163. An amplifier 167 and a longitudinally coupled resonator type surface acoustic wave filter 168 are connected between the duplexer 162 and the transmitter-side mixer 166. As described above, when the amplifier 165 corresponds to the balanced signal, by using the longitudinally coupled resonator surface acoustic wave filter having the configuration of the present invention as the longitudinally coupled resonator surface acoustic wave filter 164, communication quality is good and reliability is achieved. This high communicator device can be obtained.
    [69] According to the present invention as described above, it is possible to obtain a longitudinally coupled resonator type surface acoustic wave filter which reduces the transient response and has a large amount of attenuation at the passband high band side. In that case, a sufficient effect can be acquired by forming the site | part which continuously changes the metallization recipe of an electrode finger in the propagation direction of a surface acoustic wave in the area | region of about 1/4 of IDT from the part which IDT adjoins. Further, by continuously changing the metallization recipe of the electrode finger in the propagation direction of the surface acoustic wave, a better effect of the present invention can be obtained without increasing the insertion loss in the pass band.
    [70] Further, by using the longitudinally coupled resonator type surface acoustic wave filter of the present invention in a communication device, a communication device having good communication quality and high reliability can be obtained.
    权利要求:
    Claims (4)
    [1" claim-type="Currently amended] A longitudinally coupled resonator type surface acoustic wave filter having a piezoelectric substrate and at least two IDTs formed on the piezoelectric substrate side by side in a propagation direction of the surface acoustic wave,
    The longitudinally coupled resonator type surface acoustic wave filter as claimed in at least one of the IDTs, wherein the metallization ratio is different from the metallization ratio of the other electrode fingers of the IDT.
    [2" claim-type="Currently amended] The electrode finger according to claim 1, wherein the metallization recipe differs from the metallization recipe of another electrode finger of the IDT in at least one of the IDTs adjacent to each other among the IDTs. A longitudinally coupled resonator type surface acoustic wave filter, which is formed in a region up to about 1/4 of an IDT.
    [3" claim-type="Currently amended] The longitudinally coupled resonator type surface acoustic wave filter according to claim 1 or 2, wherein in at least one of said IDTs, the metallization recipe of the electrode finger is continuously changed in the propagation direction of the surface acoustic wave.
    [4" claim-type="Currently amended] A communicator device comprising the longitudinally coupled resonator type surface acoustic wave filter according to claim 1.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2001-06-12|Priority to JPJP-P-2001-00177423
    2001-06-12|Priority to JP2001177423
    2002-04-15|Priority to JPJP-P-2002-00112263
    2002-04-15|Priority to JP2002112263A
    2002-06-11|Application filed by 가부시키가이샤 무라타 세이사쿠쇼
    2002-12-20|Publication of KR20020095121A
    优先权:
    申请号 | 申请日 | 专利标题
    JPJP-P-2001-00177423|2001-06-12|
    JP2001177423|2001-06-12|
    JPJP-P-2002-00112263|2002-04-15|
    JP2002112263A|JP3780415B2|2001-06-12|2002-04-15|Longitudinal coupled resonator type surface acoustic wave filter and communication device using the same|
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