JP4063273B2 - Surface acoustic wave device - Google Patents

Description

  The present invention relates to a surface acoustic wave device including a surface acoustic wave filter having a balance-unbalance conversion function.

  In recent years, there has been a remarkable technological advancement toward miniaturization and weight reduction of mobile phones (communication devices). As means for realizing this, not only the reduction and miniaturization of each component, but also the development of a component combining a plurality of functions has progressed.

  Against this backdrop, a surface acoustic wave device used in the RF stage of a mobile phone, which has a balanced-unbalanced conversion function, that is, a so-called balun function, has been actively studied in recent years, and GSM (Global System for Mobile communications) and so on.

  Several patents relating to surface acoustic wave devices having such a balance-unbalance conversion function have been filed. FIG. 3 shows a surface acoustic wave having a balanced-unbalanced conversion function disclosed in the following Patent Document 1 in which the impedance on the unbalanced signal terminal side is set to 50Ω and the impedance on the balanced signal terminal side is set to 200Ω. Indicates the device.

  The configuration of FIG. 3 is a longitudinally coupled resonator type surface acoustic wave filter 301 having three interdigital electrodes (hereinafter referred to as IDTs) along the surface acoustic wave propagation direction. The IDT 303 that is positioned is divided into two substantially symmetrically in the propagation direction of the surface acoustic wave, and each is connected to the balanced signal terminals 308 and 309, and the left and right IDTs 302 and 304 that are reversed in polarity are connected to the unbalanced signal terminal 307. ing. Thus, in the above configuration, a balance-unbalance conversion function can be provided by reversing the polarity, and the impedance on the balanced signal terminal side is approximately 4 times the impedance on the unbalanced signal terminal side by dividing the IDT 303 into two. Can be doubled.

  In a filter having a balanced-unbalanced conversion function, the amplitude characteristics are equal and the phase is inverted by 180 degrees in the transmission characteristics within the passband between the unbalanced signal terminal and each terminal of the balanced signal terminal. Are called amplitude balance and phase balance, respectively.

For the amplitude balance and the phase balance, the filter device having the balance-unbalance conversion function is regarded as a three-port device. For example, the unbalanced input terminal is port 1, the balanced output terminal is port 2, and the port 3 is Amplitude balance = | A |, A = | 20log (S21) | − | 20log (S31) |, phase balance = | B−180 |, B = | ∠S21−∠S31 | . Ideally, the degree of balance is 0 dB in amplitude balance and 0 degree in phase balance within the passband of the surface acoustic wave filter.
JP 11-97966 A

  However, the conventional configuration shown in FIG. 3 has a problem of poor balance. The reason is that the polarities of the electrode fingers adjacent to the IDT 303 are different from each other in the IDT 302 and the IDT 304 (310 and 311 in FIG. 3), and thereby, parasitic capacitances and bridges entering the balanced signal terminals 308 and 309, respectively. This is because the capacity and the like are different from each other. Conventionally, a surface acoustic wave device that is a 5IDT type longitudinally coupled resonator type surface acoustic wave filter, has a balance-unbalance conversion function, and has an excellent balance is demanded.

  An object of the present invention is to provide a 5IDT type surface acoustic wave device having a balance-unbalance conversion function with improved balance.

The surface acoustic wave device according to the present invention has a piezoelectric substrate and a longitudinal-vertical conversion function having a balance-unbalance conversion function, which includes a piezoelectric substrate and five comb-shaped electrode portions arranged along the propagation direction of the surface acoustic wave on the piezoelectric substrate. In a surface acoustic wave filter device including a coupled resonator type surface acoustic wave filter, one of the five comb-shaped electrode portions of the comb-shaped electrode portion is positioned in the surface acoustic wave propagation direction. It has first and second divided electrode portions formed by dividing, and the first and second divided electrode portions are connected to the first and second balanced signal terminals and are located in the center. One of the two comb-shaped electrode portions located on both sides of the comb-shaped electrode portion is inverted to the other comb-shaped electrode portion, and on both sides of the central comb-shaped electrode portion. 2 interdigital electrode portion is connected to the unbalanced signal terminal, the central Located in the 3 interdigital electrode portions on both sides of the area being located 2 interdigital electrode portion first, respectively, are connected to the second balanced signal terminal, the five interdigital transducer In FIG. 2, narrow-pitch electrode fingers are respectively provided at the gap-side end of one of the comb-shaped electrode portions adjacent to each other in the surface wave propagation direction across the gap and at the gap-side end of the other comb-shaped electrode portion. It is characterized by that.

  In a specific aspect of the surface acoustic wave device according to the present invention, the narrow-pitch electrode finger portion is an electrode finger pitch of a portion other than the narrow-pitch electrode finger portion of the comb-shaped electrode portion where the narrow-pitch electrode finger portion is provided. Compared to the electrode finger portion, the electrode finger pitch is relatively narrow.

  In the surface acoustic wave device, the piezoelectric substrate may be mounted on a package by flip chip bonding, and the asymmetrical wiring may be formed on the package.

  In the surface acoustic wave device, the piezoelectric elements other than the asymmetrical routing wiring described later with respect to a virtual axis provided in the center of the comb-shaped electrode portion located at the center and perpendicular to the propagation direction of the surface acoustic wave. The routing wiring on the substrate and the package may be formed substantially symmetrically.

  Further, in still another specific aspect of the surface acoustic wave device according to the present invention, the outermost electrode finger of the comb-shaped electrode portion located at the center is a floating electrode or a grounded electrode, and the comb located at the center. Of the two comb electrode parts adjacent to the mold electrode part, the balanced signal terminal located on the side close to the comb electrode part where the outermost electrode finger adjacent to the comb electrode part located in the center is grounded The routing wiring is formed asymmetrically so that the parasitic capacitance becomes relatively larger.

  According to the above configuration, of the two comb-shaped electrode portions adjacent to the comb-shaped electrode portion positioned at the center, the comb-shaped electrode whose outermost electrode finger adjacent to the comb-shaped electrode portion positioned at the center is grounded Improve the balance between each balanced signal terminal, especially the phase balance, by forming the routing wiring asymmetrically so that the balanced signal terminal located closer to the electrode section has a relatively large parasitic capacitance. it can.

  In still another specific aspect of the surface acoustic wave device according to the present invention, the outermost electrode finger of the comb-shaped electrode portion positioned at the center is a signal electrode, and 2 adjacent to the comb-shaped electrode portion positioned at the center. Among the two comb-shaped electrode portions, the balanced signal terminal located on the side closer to the comb-shaped electrode portion where the outermost electrode finger adjacent to the comb-shaped electrode portion located at the center is a signal electrode is relatively parasitic capacitance The lead-out wiring is formed asymmetrically so as to increase.

  According to the above configuration, of the two comb-shaped electrode portions adjacent to the comb-shaped electrode portion positioned at the center, the comb-shaped electrode whose outermost electrode finger adjacent to the comb-shaped electrode portion positioned at the center is a signal electrode Improve the balance between balanced signal terminals, especially the phase balance, by forming asymmetrical wiring so that the balanced signal terminals located on the side closer to the electrode section have a relatively large parasitic capacitance. it can.

  In still another specific aspect of the surface acoustic wave device according to the present invention, the outermost electrode finger of the comb-shaped electrode portion located at the center is a floating electrode or a grounded electrode, and the comb-shaped electrode located at the center Among the two comb electrodes adjacent to the comb portion, the reactance component or the reactance component is located on the balanced signal terminal located on the side close to the comb electrode portion where the outermost electrode finger adjacent to the comb electrode portion located at the center is grounded A delay line is added.

  According to the above configuration, the reactance component or the delay line is added to the balanced signal terminal located on the side close to the comb electrode part where the outermost electrode finger adjacent to the comb electrode part located at the center is grounded. The balance between the balanced signal terminals, particularly the phase balance, can be improved.

  In still another specific aspect of the surface acoustic wave device according to the present invention, the outermost electrode finger of the comb-shaped electrode portion positioned at the center is a signal electrode, and 2 adjacent to the comb-shaped electrode portion positioned at the center. A reactance component or a delay line is added to the balanced signal terminal located on the side close to the comb-shaped electrode portion where the outermost electrode finger adjacent to the comb-shaped electrode portion located at the center of the two comb-shaped electrodes is a signal electrode. ing.

  According to the above configuration, the outermost electrode finger of the comb-shaped electrode portion located at the center is a signal electrode, and the two comb-shaped electrode portions adjacent to the comb-shaped electrode portion located at the center are located at the center. The balance between each balanced signal terminal is obtained by adding a reactance component or delay line to the balanced signal terminal located on the side close to the comb electrode part where the outermost electrode finger adjacent to the comb electrode part is a signal electrode. In particular, the phase balance can be improved.

  In the surface acoustic wave device, the piezoelectric substrate may be mounted on a package by flip chip bonding, and the reactance component or delay line may be formed on the package.

  In the surface acoustic wave device, on the piezoelectric substrate other than the reactance component or the delay line with respect to a virtual axis provided perpendicular to the propagation direction of the surface acoustic wave at the center of the comb-shaped electrode portion located at the center. And the routing wiring on the package may be set substantially symmetrically.

  In the surface acoustic wave device, the reactance component may be a capacitance component, and may be connected in parallel between the balanced signal terminal and a ground potential. In the surface acoustic wave device, the reactance component may be an inductance component and connected in series to the balanced signal terminal.

  In the surface acoustic wave device, surface acoustic wave resonators may be added in series and / or in parallel to the surface acoustic wave filter. In the surface acoustic wave device, a plurality of the surface acoustic wave filters may be cascade-connected to each other. In the surface acoustic wave device, it is preferable that the total number of electrode fingers of the cascade-connected surface acoustic wave filters is an even number.

  In the surface acoustic wave device, the comb-shaped electrode portions positioned at both ends of the surface acoustic wave filters cascaded to each other are connected to each other via a signal line and transmit the signal line. It is desirable that the phases of the signals are set to be different from each other by about 180 degrees.

  In the surface acoustic wave device, electrode fingers in the vicinity of adjacent portions in at least one of the comb electrode portions adjacent to each other in the surface acoustic wave filter may be weighted. In the surface acoustic wave device, the weighting may be serial weighting.

  In the surface acoustic wave device, the piezoelectric substrate is mounted on a package by flip chip bonding, and the package has six external terminals, one unbalanced signal terminal, two balanced signal terminals, and three ground terminals. And the six terminals are arranged substantially symmetrically with respect to a virtual axis provided in a direction perpendicular to the propagation direction of the surface acoustic wave at the center of the comb-shaped electrode portion located at the center of the surface acoustic wave filter. Also good.

  In the surface acoustic wave device, the piezoelectric substrate is mounted on a package by flip chip bonding, and the package has five external terminals: one unbalanced signal terminal, two balanced signal terminals, and two ground terminals. And five terminals are arranged substantially symmetrically with respect to a virtual axis provided in the direction perpendicular to the propagation direction of the surface acoustic wave at the center of the comb-shaped electrode portion located at the center of the surface acoustic wave filter. Also good.

  As described above, the surface acoustic wave device according to the present invention is a 5IDT type surface acoustic wave device configured to have a balance-unbalance conversion function, and the narrow pitch electrode fingers are adjacent to each other. Since it is provided in the mold electrode part, it is possible to provide a 5IDT type surface acoustic wave device having a balance-unbalance conversion function with improved balance.

  Hereinafter, specific embodiments of the surface acoustic wave device of the present invention will be described. Prior to the description of the surface acoustic wave device according to the embodiment of the present invention, a surface acoustic wave device of a reference example, which is a premise of the present invention, will be described with reference to the drawings.

  A surface acoustic wave device of a reference example, which is a premise of the surface acoustic wave device according to the present invention, will be described below with reference to FIG. As shown in FIG. 1, the surface acoustic wave device includes a longitudinally coupled resonator type surface acoustic wave filter 101 having three IDTs formed along a propagation direction of a surface acoustic wave on a piezoelectric substrate 501. Of the three IDTs of the longitudinally coupled resonator-type surface acoustic wave filter 101, the IDT 103 located in the center is divided into two substantially symmetrically in the propagation direction of the surface acoustic wave, and each is connected to the balanced signal terminals 108 and 109, and the polarity is set. In the surface acoustic wave device having the balanced-unbalanced conversion function by connecting the inverted left and right IDTs 102, 104 to the unbalanced signal terminal 107, either of the balanced signal terminals 108, 109 is connected to the piezoelectric substrate. The reactance component 120 formed in the above, or formed in a package or externally attached to the package is connected in parallel.

  In the above structure, the surface acoustic wave device has a balanced-unbalanced conversion function, the impedance of the balanced signal terminal is about four times the impedance of the unbalanced signal terminal, and the balance is improved by the reactance component 120. Is obtained.

The configuration of Reference Example 1 will be described with reference to FIGS. In the following reference examples and examples, description will be made by taking a DCS reception filter as an example. First, the electrode configuration of Reference Example 1 will be described with reference to FIG. In Reference Example 1, a longitudinally coupled resonator type surface acoustic wave filter 401 and an elastic surface connected in series to the longitudinally coupled resonator type surface acoustic wave filter 401 on a piezoelectric substrate 501 made of 40 ± 5 ° YcutX propagation LiTaO _3. The wave resonators 402 are each formed of an aluminum (Al) electrode.

  In the configuration of the longitudinally coupled resonator type surface acoustic wave filter 401, the IDTs 403 and 405 are formed so as to sandwich the IDT 404 from both sides along the propagation direction of the surface acoustic wave, and the reflectors 406 and 407 are provided on both sides thereof. Each is formed.

  The IDT 403 includes two comb-shaped electrodes each having a strip-shaped base end (bus bar) and a plurality of parallel electrode fingers extending in a direction orthogonal from one side of the base end. Each of the comb electrodes has the comb electrodes in a state where the side portions of the electrode fingers of the comb electrodes face each other so as to face each other.

  In such an IDT 403, signal conversion characteristics are set by setting the length and width of each electrode finger, the interval between adjacent electrode fingers, and the crossing width indicating the length of confrontation between the electrode fingers. In addition, the pass band can be set. Further, the basic structure of each other IDT is the same as that of the IDT 403. The reflector has a function of reflecting the propagated surface acoustic wave in the propagated direction.

  Moreover, in the above configuration, as can be seen from FIG. 4, the pitch of several electrode fingers in the vicinity between IDT 403 and IDT 404 and in the vicinity between IDT 404 and IDT 405 is smaller than the other parts of IDT. (Locations 414 and 415 in FIG. 4).

  Further, one of the comb-shaped electrodes in the central IDT 404 is divided into two comb-shaped electrodes 416 and 417 in the propagation direction of the surface acoustic wave, and the comb-shaped electrodes 416 and 417 correspond to the balanced signal terminals 412. 413. Further, in Reference Example 1, the other comb-shaped electrode facing the electrodes different from the comb-shaped electrodes 416 and 417 in the IDT 404 is a floating electrode, but may be a ground electrode grounded to the ground. The IDT 405 has a structure that is phase-inverted with respect to the IDT 403. Thereby, the said structure has a balance-unbalance conversion function.

  In the surface acoustic wave resonator 402, the reflectors 409 and 410 are formed so as to sandwich the IDT 408. One comb electrode of the IDT 408 is connected to the unbalanced signal terminal 411, and the other comb electrode of the IDT 408 is connected to each other. IDTs 403 and 405 are connected.

  FIG. 5 shows a layout on the actual piezoelectric substrate 501 of Reference Example 1. In FIG. 5, portions corresponding to FIG. 4 are indicated using the same numbers. In the above layout, electrode pads 502 to 506 for providing electrical continuity with the package are provided, the electrode pad 502 corresponds to the unbalanced signal terminal 411, and the electrode pads 503 and 504 are respectively connected to the balanced signal terminal 412, The electrode pads 505 and 506 are ground terminals, and each IDT is shown in a simplified manner.

  FIG. 6 shows the electrode terminals 641 to 645 on the back surface (rectangular shape) 640a side of the substantially rectangular parallelepiped package 640 containing the configuration of Reference Example 1 (viewed from the upper surface side of the surface acoustic wave device (device)). Shown in perspective). The electrode terminal 641 is disposed substantially at the center of one end in the longitudinal direction of the back surface 640a. The electrode terminals 642 and 643 are respectively disposed at both corners of the other end in the longitudinal direction of the back surface 640a. Each of the electrode terminals 644 and 645 is disposed at substantially the center of both measuring portions in the longitudinal direction of the back surface 640a.

  The electrode terminal 641 is connected to the electrode pad 502, the unbalanced signal terminal is connected, the electrode terminals 642 and 643 are connected to the electrode pads 503 and 504, and the electrode terminals 644 and 645 are connected to the electrode terminals 505. , 506 are ground terminals.

  As shown in FIG. 7, the surface acoustic wave device of Reference Example 1 is manufactured using a face-down method in which conduction is established between the electrode surface of the piezoelectric substrate 501 and the die attach surface 653 of the package 640 with bumps 656. Yes.

  The package 640 includes a rectangular plate-shaped bottom plate 651, each side wall portion 652 erected adjacent to each other from each side portion of the bottom plate 651, and each upper end portion of each side wall portion 652 in close contact with each other to cover the package 640. And a cap 654 for sealing the inside.

  As shown in FIG. 5, the characteristic of the reference example 1 is that the strip-shaped lead wiring 508 connecting the comb-shaped electrode 417 and the electrode pad 504 connects the comb-shaped electrode 416 and the electrode pad 503. The point is that the ground capacity corresponding to the reactance component 120 shown in FIG.

  In order to increase the ground capacity in this way, in Reference Example 1, the protruding portion 509 is additionally provided so as to protrude outward from the lead wiring 508 on the piezoelectric substrate 501.

  The protruding portion 509 is preferably formed of a routing wire 508 at a position close to the routing wire 511 connecting the electrode pad 506 on the ground side and the IDT 405.

  Further, the protruding portion 509 is provided so as to extend away from the routing wiring 511 substantially perpendicular to the longitudinal direction of the routing wiring 508 and substantially parallel to the longitudinal direction of the routing wiring 511. Is desirable.

  Due to the protruding portion 509, the ground capacity of the balanced signal terminal 413 shown in FIG. 4 is larger than the balanced signal terminal 412, for example, by about 0.16 pF, so that the routing wires 508 and 511 are asymmetric with each other. Will be formed.

  At this time, the electrode fingers adjacent to the IDTs 403 and 405 in the IDT 404 (the comb electrodes 416 and 417) are signal electrodes, respectively. The comb-shaped electrode 417 connected to the electrode pad 504 serving as the lead wiring that increases the ground capacitance and the electrode finger of the adjacent IDT 405 are also signal electrodes. On the other hand, the electrode finger of the IDT 403 adjacent to the comb electrode 416 connected to the electrode pad 503 is a ground electrode.

  Furthermore, in Reference Example 1, the configuration other than the asymmetry of the protruding portion 509 is a virtual configuration in which the IDT 404 divided in two shown in FIGS. With respect to the axis A, the layout on the piezoelectric substrate 501 and the package 640 are all set to be axially symmetric. This prevents an unbalanced component other than the point where the polarities of the electrode fingers adjacent to the IDT 404 are different from each other between the IDT 403 and the IDT 405.

The detailed design of the longitudinally coupled resonator-type surface acoustic wave filter 401 is as follows.
Cross width: 78.9λI
Number of IDTs (in the order of 403, 404, 405): 19 (3) / (3) 26 (3) /
(3) 19 (number of electrode fingers with smaller pitch in parentheses)
Number of reflectors: 200 Duty: 0.67 (both IDT and reflector)
Electrode film thickness: 0.095λI
The detailed design of the surface acoustic wave resonator 402 is as follows.
Cross width: 46.5λI
Number of IDTs: 150 Number of reflectors: 100 Duty: 0.67
Electrode film thickness: 0.097λI
Next, operations and effects relating to the configuration of Reference Example 1 will be described. FIG. 8 shows the phase balance of the configuration of Reference Example 1. In Comparative Example 1 as a comparison, as shown in FIG. 9, the layout on the piezoelectric substrate 501 is not provided with a protruding portion 509 that is a portion where the ground capacitance is increased in the routing wiring 508 with respect to the reference example 1 in FIG. 5. The configuration of the reference example 1, the design of the surface acoustic wave device, the layout on the piezoelectric substrate 501, the mounting method of the package, etc., except that the routing wiring 508 is set symmetrically with respect to the routing wiring 507 and the virtual axis A. The same. FIG. 8 also shows the phase balance of Comparative Example 1 in which the layout on the piezoelectric substrate 501 is changed to no protrusions.

  The pass band of the DCS reception filter is 1805 to 1880 MHz. According to FIG. 8, the deviation of the phase balance within the passband range is about 22 degrees at the maximum in Comparative Example 1, whereas it is about 12 degrees at the maximum in Reference Example 1, and the phase balance is about 10 degrees. It has been improved. This is an effect of correcting the phase shift between the balanced signal terminal 412 and the balanced signal terminal 413 by adjusting the ground signal terminal 413 so as to increase the ground capacity.

  In Reference Example 1, the protruding wiring 508 is provided with a protruding portion 509 that is a portion where the ground capacity increases. Next, on the contrary, as shown in FIG. 10, the lead wire 507 is provided with a protruding portion 515 as a location where the ground capacitance is increased, and the phase when the ground capacitance of the balanced signal terminal 412 is increased by about 0.16 pF. The balance was investigated. FIG. 11 shows the phase balance in the case of FIG. As a comparison, the result in the case of Comparative Example 1 shown in FIG. 9 is also shown in FIG.

  When the ground capacity of the balanced signal terminal 412 is increased, the phase balance is worse than that of the first comparative example. Which of the balanced signal terminals to increase the ground capacity may be determined by the arrangement of the electrode fingers adjacent to each other in the IDTs 402 to 404, that is, the presence or absence of a non-electric field region where the signal electrodes or the ground electrodes are adjacent to each other.

  In the case of the reference example 1, in the IDT 404, the electrode fingers adjacent to the IDTs 403 and 405 are the signal electrodes of the comb electrodes 416 and 417, respectively. On the other hand, the electrode finger adjacent to the IDT 404 in the IDT 405 adjacent to the comb-shaped electrode 417 connected to the electrode pad 504, which is a routing wiring that increases the ground capacitance, is a signal electrode and faces it. A signal electrode which is the outermost electrode finger of the comb-shaped electrode 417 and a no (small) electric field region are formed. On the other hand, in the IDT 403 adjacent to the comb electrode 416 connected to the electrode pad 503, the electrode finger adjacent to the IDT 404 is a ground electrode and is the outermost electrode finger of the facing comb electrode 416. A signal electrode and an electric field region in which an electric field is often larger than the no (small) electric field region are formed.

  In the case of such an electrode finger arrangement, as in Reference Example 1, it is connected to a comb-shaped electrode 417 having a non-electric field region in the vicinity of the outermost electrode finger (or facing the outermost electrode finger). The phase balance can be improved by setting the ground capacity of the balanced signal terminal 413 to be relatively larger than the balanced signal terminal 412 connected to the comb-shaped electrode 416, for example, by the protruding portion 509. it can.

  Next, as shown in FIG. 12, the case where each electrode finger adjacent to each IDT 703 and 705 of the IDT 704 is a neutral point electrode (which may be a floating electrode or a ground electrode) was investigated. FIG. 13 shows the phase balance in the case of the layout on the piezoelectric substrate 501 shown in FIG. 10 in the case of the electrode configuration of FIG. 12 (a modification of Reference Example 1), and FIG. 14 shows the electrode configuration of FIG. FIG. 6 shows the phase balance in the case of the layout shown in FIG. 5 (Comparative Example 3). As Comparative Example 2, the degree of phase balance in the case of the layout shown in FIG. 9 (without protrusions) in the case of the electrode configuration of FIG. 12 is also shown as Comparative Example 2 in accordance with FIGS. FIG. 13 and FIG. 14 show the results when adjustment is made so that the ground capacitance of about 0.02 pF enters the projecting portion 515 and the projecting portion 509, respectively.

  In the case of the arrangement of the electrode fingers shown in FIG. 12, the ground capacitance of the balanced signal terminal 712 connected to the comb-shaped electrode 716 is equal to the balanced signal terminal connected to the comb-shaped electrode 717 as in the layout shown in FIG. It can be seen that the phase balance is improved by making it relatively larger than 713.

  Next, in the electrode configuration of FIG. 12, the phase balance when the delay line and the inductance component were added in series with each balanced signal terminal unbalanced was investigated.

  FIG. 15 shows a configuration in which a delay line 720 as the reactance component 120 shown in FIG. 1 is added to the balanced signal terminal 712 connected to the comb-shaped electrode 716 (another modified example of the reference example 1). FIG. 16 shows a configuration in which an inductance component 722 as the reactance component 120 shown in FIG. 1 is added (another modification of the reference example 1).

  FIG. 17 and FIG. 18 show the phase balance in the case of each configuration of FIG. 15 and FIG. For comparison, the phase balance when the delay line and the inductance component are not added in the layout of FIG. 9 in the configuration of FIG. 12 is also shown in FIGS. 17 and 18 as Comparative Example 2, respectively.

  Although a specific method of forming the delay line 720 and the inductance component 722 is omitted, for example, a delay line having a long lead wiring on the piezoelectric substrate or in the package is provided, or an inductance component by a microstrip line is provided. Can be considered.

  Further, if possible, for example, as shown in FIGS. 31 (a) and 31 (b), they may be externally attached to positions outside the package. In FIG. 31A, a delay line and a circuit 655 serving as an inductance component (reactance component) are provided at a boundary portion between the side wall portion 652 and the bottom plate 651. In FIG. 31B, the circuit is laminated on the bottom plate 651. A plate 657, a via hole 658 in the thickness direction of the laminated plate 657, a delay line formed between the bottom plate 651 and the laminated plate 657, and a circuit 659 serving as an inductance component are provided via the via hole 658. May be.

  As is apparent from FIGS. 17 and 18, it can be seen that the phase balance is improved with respect to the comparative example 2 when either the delay line 720 or the inductance component 722 is inserted. In the electrode configuration of FIG. 4, the delay line 720 or the inductance component 722 may be added to the balanced signal terminal 413.

  As described above, the reference example 1 includes the longitudinally coupled resonator type surface acoustic wave filter having three IDTs formed along the propagation direction of the surface acoustic wave on the piezoelectric substrate. In a surface acoustic wave device that has a balance-unbalance conversion function by dividing the IDT located in the center into two in the propagation direction of the surface acoustic wave and inverting the polarities of the left and right IDTs, the ground capacitance is connected in series By making the inductance component and the reactance component, which is at least one of the delay lines, asymmetric between the two balanced signal terminals, the phase balance of the surface acoustic wave device can be improved.

  As a method of increasing the ground capacity in Reference Example 1, as shown in FIG. 5, a method in which the signal electrode on the piezoelectric substrate 501 is brought close to the ground electrode is shown, but this is a comb-shaped electrode as shown in FIG. May be formed. Further, the routing wiring in the package 640 may be adjusted.

  Further, in Reference Example 1, the layout on the piezoelectric substrate 501, the package 640, etc. are the same except that a ground capacitance, an inductance component, and a delay line are asymmetrically added to the balanced signal terminal in order to eliminate unnecessary unbalanced components. I tried to be the same. Therefore, although the example (refer FIG. 6) in case the number of each electrode terminal 641-645 in the back surface 640a side of the package 640 was five was shown, this invention is not restricted to such a package, The center IDT divided into 2 is shown. Any package may be used as long as the package can be axisymmetric with respect to the virtual axis A drawn in the center perpendicular to the propagation direction of the surface acoustic wave.

  For example, in the case of a package 800 having six electrode terminals 801 to 806 as shown in FIG. 20, the electrode terminal 801 is an unbalanced signal terminal, the electrode terminals 802 and 803 are balanced signal terminals, and the electrode terminals 804 to 806 are ground terminals. By doing so, it can be made axially symmetric with respect to the virtual axis A.

  At that time, as shown in FIG. 21, the pattern layout on the piezoelectric substrate 501 is such that the propagation direction of the surface acoustic wave is along the long side direction of the piezoelectric substrate 501, and the electrode pad 901 on the piezoelectric substrate 501 is connected to the electrode terminal 801. The electrode pad 902 is connected to the electrode terminal 802, the electrode pad 903 is connected to the electrode terminal 803, and the electrode pads 904 to 906 are connected to the electrode terminals 804 to 806 serving as ground terminals, so that the piezoelectric substrate 501 is also connected. It can be easily symmetric with respect to the virtual axis A.

  In Reference Example 1, as shown in FIG. 7, the surface acoustic wave device was manufactured by a method of establishing conduction between the package and the piezoelectric substrate by the face-down method, but there is no problem even if this is the wire bond method.

  Further, the structure manufactured by the face-down method is not limited to the structure shown in FIG. 7. For example, as shown in FIG. 22, a piezoelectric substrate 1002 is bonded to the collective substrate 1001 by the flip chip method, and the resin 1003 is covered and sealed. The structure is cut and cut into one package unit by dicing. Similarly, as shown in FIG. 23, the piezoelectric substrate 1102 is joined on the collective substrate 1101 by the flip chip method, and the sheet-like resin material 1103 is covered and sealed. In addition, the surface acoustic wave device may be manufactured in a configuration in which it is cut into one package unit by dicing.

  In Reference Example 1, a configuration in which surface acoustic wave resonators are connected in series to a longitudinally coupled resonator type surface acoustic wave filter having three IDTs is shown. However, a configuration in which surface acoustic wave resonators are not connected, It is clear that the same effect can be obtained even in a configuration in which these are connected in parallel.

  FIG. 24 is a schematic plan view showing an electrode structure of a surface acoustic wave device as an embodiment of the present invention. In this embodiment, two IDTs are further provided on both sides of the three IDTs. That is, an IDT type longitudinally coupled resonator type surface acoustic wave filter is configured. The present embodiment is configured in the same manner as the reference example 1 except that it is a 5IDT type. It may be a 5IDT longitudinally coupled resonator type configuration.

  In addition, as shown in FIG. 25, the effect of the present invention can be obtained even when the electrode fingers 130 near the IDT are adjacent to each other. In the configuration of FIG. 25, the balance is further improved. As an example of weighting, serial weighting is used in FIG. 25, but this may be thinning weighting, cross width weighting, or duty weighting.

  Further, as shown in FIG. 2, the longitudinally coupled resonator type surface acoustic wave filter 101 may be cascade-connected to another longitudinally coupled resonator type surface acoustic wave filter 201. At that time, the IDT 203 located at the center of the longitudinally coupled resonator type surface acoustic wave filter 201 preferably has an even number of electrode fingers.

  Further, the phase of signals transmitted through the signal lines 205 and 206 connecting the longitudinally coupled resonator type surface acoustic wave filter 101 and the longitudinally coupled resonator type surface acoustic wave filter 201 to each other is different by about 180 degrees. It is desirable to adjust the orientations of the IDTs 102 and 104 and the IDTs 202 and 204 in advance. By adopting the above configuration, a surface acoustic wave device having a further excellent balance can be obtained.

  The example of the layout on the piezoelectric substrate 501 in the case of using the electrode configuration of FIG. 2 is mounted on a package having each of the five electrode terminals shown in FIG. 6 in FIGS. 26, 27, and 6 shown in FIG. FIG. 28 and FIG. 29 show the case of mounting on a package having two electrode terminals.

  At that time, each electrode pad 1201, 1301, 1401, 1501 is connected to an unbalanced signal terminal, each electrode pad 1202, 1203, 1302, 1303, 1402, 1403, 1502, 1503 is connected to a balanced signal terminal, and the rest is connected to a ground terminal. It becomes a composition.

In Reference Example 1, a 40 ± 5 ° YcutX propagation LiTaO ₃ substrate was used as the piezoelectric substrate 501, but as can be seen from the principle that the effect can be obtained, the present invention is not limited to this piezoelectric substrate 501, but 64 ° to 72 ° YcutX. Similar effects can be obtained with piezoelectric substrates such as propagating LiNbO ₃ and 41 ° YcutX propagating LiNbO ₃ .

  Next, a communication device using the surface acoustic wave device according to the present invention, which is one of the above-described Reference Example 1 and each of the variations thereof, or a combination of these features, according to the present invention will be described with reference to FIG. .

  As illustrated in FIG. 30, the communication apparatus 600 includes an antenna 601, an antenna sharing unit / RFTop filter 602, an amplifier 603, an Rx interstage filter 604, a mixer 605, and a 1st IF filter 606 as a receiver side (Rx side) that performs reception. , A mixer 607, a 2nd IF filter 608, a 1st + 2nd local synthesizer 611, a TCXO (temperature compensated crystal oscillator) 612, a divider 613, and a local filter 614. It is preferable to transmit from the Rx interstage filter 604 to the mixer 605 using each balanced signal in order to ensure balance, as indicated by the double line in FIG.

  The communication apparatus 600 shares the antenna 601 and the antenna sharing unit / RFTop filter 602 as a transceiver side (Tx side) that performs transmission, and also includes a TxIF filter 621, a mixer 622, a Tx interstage filter 623, an amplifier 624, a coupler 625, an isolator 626, and an APC (automatic power control) 627.

  The above-described surface acoustic wave device of the present embodiment can be suitably used for the Rx interstage filter 604, the 1st IF filter 606, the TxIF filter 621, the Tx interstage filter 623, and the antenna sharing unit / RFTop filter 602.

  The surface acoustic wave device according to the present invention has an unbalanced-balanced conversion function as well as a filter function, and has excellent characteristics such that amplitude characteristics and phase characteristics between balanced signals are closer to ideals. Therefore, the communication device having the surface acoustic wave device can reduce the number of components and reduce the size and improve the transmission characteristics by using the composite surface acoustic wave device. .

It is a block diagram of the surface acoustic wave apparatus of the reference example used as the premise of the surface acoustic wave apparatus of this invention. It is a block diagram of the modification (cascade connection) of the said surface acoustic wave apparatus. It is a block diagram of the conventional surface acoustic wave apparatus. It is a block diagram which shows the electrode structure of the surface acoustic wave apparatus which concerns on the reference example 1 of this invention. 4 is a plan view showing a layout on a piezoelectric substrate in the surface acoustic wave device of Reference Example 1. FIG. It is a top view which shows arrangement | positioning of each terminal in the back surface side of the package which accommodated the surface acoustic wave apparatus of the said reference example 1 by the perspective view from the upper surface (opposite surface of a back surface) side of a package, respectively. It is sectional drawing of the package which accommodated the surface acoustic wave apparatus of the said reference example 1. FIG. It is a graph which shows the phase balance degree in each structure of the said reference example 1 and the comparative example 1, respectively. It is a top view which shows the layout of the surface acoustic wave apparatus of the said comparative example 1. FIG. 6 is a plan view showing a layout of a surface acoustic wave device as Comparative Example 2. FIG. It is a graph which shows the phase balance degree in each structure of the structure (comparative example 2) shown in FIG. 10, and the said comparative example 1, respectively. It is a block diagram which shows the electrode structure regarding the surface acoustic wave apparatus as a modification of the said reference example 1. FIG. 13 is a graph showing the frequency-phase balance of Comparative Example 2 when the electrode configuration of FIG. 12 is configured with the layout on the piezoelectric substrate of FIG. 13 is a graph showing the frequency-phase balance of Comparative Example 2 when the electrode configuration of FIG. 12 is configured with the layout on the piezoelectric substrate of FIG. It is a block diagram which shows the surface acoustic wave apparatus of the other modification of the said reference example 1. It is a block diagram which shows the surface acoustic wave apparatus of the further another modification of the said reference example 1. FIG. 16 is a graph showing the configuration of FIG. 15 and the frequency-phase balance of Comparative Example 2; 17 is a graph showing the configuration of FIG. 16 and the frequency-phase balance of Comparative Example 2 respectively. It is a block diagram which shows the surface acoustic wave apparatus of the further another modification of the said reference example 1. FIG. FIG. 12 is a plan view showing another example regarding the arrangement of the electrode terminals in the package of the reference example 1. It is a block diagram which shows the further another modification of the surface acoustic wave apparatus of the said reference example 1. FIG. It is sectional drawing which shows one manufacturing process of the surface acoustic wave apparatus of the said reference example 1. FIG. It is sectional drawing which shows the other manufacturing process of the surface acoustic wave apparatus of the said reference example 1. FIG. It is a block diagram which shows the surface acoustic wave apparatus which concerns on the Example of this invention. It is a block diagram which shows the further another modification of the surface acoustic wave apparatus of the said reference example 1. FIG. FIG. 7 is a plan view showing an example of a layout on a piezoelectric substrate when the electrode configuration shown in FIG. 2 is mounted on a package having each electrode terminal on the back surface side shown in FIG. 6. FIG. 7 is a plan view showing another example of the layout on the piezoelectric substrate when the electrode configuration shown in FIG. 2 is mounted on the package having each electrode terminal on the back surface side shown in FIG. 6. FIG. 21 is a plan view showing an example of a layout on a piezoelectric substrate when the electrode configuration shown in FIG. 2 is mounted on a package having each electrode terminal on the back surface side shown in FIG. 20. FIG. 21 is a plan view showing another example of the layout on the piezoelectric substrate when the electrode configuration shown in FIG. 2 is mounted on the package having the electrode terminals on the back surface side shown in FIG. 20. It is a principal part block diagram of the communication apparatus which concerns on this invention. It is sectional drawing of the said package when a reactance component or a delay line is externally attached to the package when the surface acoustic wave device of the reference example 1 is accommodated in the package, and (a) is a bottom plate, a side wall, (B) is an example in which a circuit as a reactance component or a delay line is formed in between, and the reactance component or a delay line is formed as a circuit in a multilayer plate in which a laminated plate is further formed on the bottom plate. It is an example.

Explanation of symbols

101 longitudinally coupled resonator type surface acoustic wave filter 107 unbalanced signal terminals 108 and 109 balanced signal terminals

Claims (7)

A piezoelectric substrate;
Elasticity provided with a longitudinally coupled resonator type surface acoustic wave filter having a balance-unbalance conversion function having five comb-shaped electrode portions arranged along the propagation direction of the surface acoustic wave on the piezoelectric substrate. In the surface wave filter device,
Of the five comb-shaped electrode portions, one of the comb-shaped electrode portions located in the center has first and second divided electrode portions formed by dividing in the surface acoustic wave propagation direction. The first and second divided electrode portions are connected to the first and second balanced signal terminals, and two comb-shaped electrode portions located on both sides of the comb-shaped electrode portion located in the center. one interdigital transducer of which are inverted to the other IDT, and 2 interdigital electrode portions on both sides of the central IDT is connected to the unbalanced signal terminal, the center-side The two comb electrode portions on both sides of the region where the three comb electrode portions located at 1 are arranged are respectively connected to the first and second balanced signal terminals;
In the five comb electrode portions, a narrow pitch is provided at the gap side end portion of one comb electrode portion and the gap side end portion of the other comb electrode portion adjacent to each other in the surface wave propagation direction with a gap therebetween. 2. A surface acoustic wave device comprising an electrode finger portion.   The narrow pitch electrode finger portion has a relatively narrow electrode finger pitch compared to the electrode finger pitch of the portion other than the narrow pitch electrode finger portion of the comb electrode portion where the narrow pitch electrode finger portion is provided. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is an electrode finger.   The surface acoustic wave device according to claim 1, wherein the surface acoustic wave filter further includes a package that is flip-chip bonded.   The outermost electrode finger of the comb-shaped electrode portion located at the center is a floating electrode or a grounded electrode, and is located at the center of two comb-shaped electrode portions adjacent to the comb-shaped electrode portion located at the center. The lead-out wiring is formed asymmetrically so that the balanced signal terminal located on the side closer to the comb-shaped electrode portion where the outermost electrode finger adjacent to the comb-shaped electrode portion is grounded has a relatively large parasitic capacitance. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is provided. The outermost electrode finger of the comb-shaped electrode portion located at the center is a signal electrode,
Of the two comb-shaped electrode portions adjacent to the comb-shaped electrode portion located in the center, the outermost electrode finger adjacent to the comb-shaped electrode portion located in the middle is closer to the comb-shaped electrode portion that is a signal electrode. 3. The surface acoustic wave device according to claim 1, wherein the routing wiring is formed asymmetrically so that the parasitic signal capacity of the balanced signal terminal located is relatively large. The outermost electrode finger of the comb-shaped electrode portion located in the center is a floating electrode or a grounded electrode,
Of the two comb-shaped electrodes adjacent to the comb-shaped electrode portion positioned at the center, the outermost electrode finger adjacent to the comb-shaped electrode portion positioned at the center is positioned on the side close to the comb-shaped electrode portion that is grounded The surface acoustic wave device according to claim 1, wherein a reactance component or a delay line is added to the balanced signal terminal. The outermost electrode finger of the comb-shaped electrode portion located at the center is a signal electrode,
Of the two comb-shaped electrodes adjacent to the comb-shaped electrode portion positioned at the center, the outermost electrode finger adjacent to the comb-shaped electrode portion positioned at the center is positioned on the side close to the comb-shaped electrode portion that is a signal electrode The surface acoustic wave device according to claim 1, wherein a reactance component or a delay line is added to the balanced signal terminal.

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