JP2003318700A - Surface acoustic wave device and communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave device having a balanced-to- unbalanced conversion function which is improved in balance property, and to provide a communication device using the same. <P>SOLUTION: Comb-like electrodes 2, 1, and 3 of a longitudinally-coupled resonator, having the balanced-to-unbalanced conversion function, are respectively provided along the propagating direction of a surface acoustic wave, on a piezoelectric substrate 8. A crossing-weighted electrode finger 22a, which is subjected to weighting such as cross weighting, is disposed, e.g. in an electrode finger 21 in the vicinity of a region facing comb-like electrode 1, among the electrode fingers 21, 22 of comb-like electrode 2 being at least one of the comb- like electrode 2, 1, 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device used for a filter having an unbalanced-balanced conversion function and a communication device using the same.

[0002]

2. Description of the Related Art In recent years, technological progress has been remarkable in reducing the size and weight of communication devices such as mobile phones.
As a filter used in such a communication device, a surface acoustic wave device that can be downsized is used as the used frequency band becomes higher. Furthermore, in order to reduce the number of components and reduce the size of the communication device,
Development of parts that combine multiple functions has also progressed.

Against this background, mobile phone R
A surface acoustic wave filter used in the F stage, which has a balanced-unbalanced conversion function, that is, a so-called balun function, has been actively researched in recent years, and GSM (Global System for Mobile).
communications) etc. have come to be used mainly. Several patents have been filed regarding surface acoustic wave filters having such a balanced-unbalanced conversion function.

As a surface acoustic wave filter having a balanced-unbalanced conversion function in which the input impedance and the output impedance are substantially equal, a structure as shown in FIG. 67 is known.

The surface acoustic wave device shown in FIG. 67 has a comb-shaped electrode portion (also referred to as a comb-shaped electrode portion, hereinafter referred to as IDT) on the piezoelectric substrate 100.
101 is provided, and the IDT 102 and the IDT 103 are provided on the left and right sides of the IDT 101 (along the propagation direction of the surface acoustic wave).
Is a 3IDT type longitudinally coupled resonator type surface acoustic wave device having a balanced-unbalanced conversion function.

In the surface acoustic wave device, a reflector (reflector) 104 and a reflector 105 are arranged so as to sandwich the IDTs 102, 101, 103 from the left and right, respectively, and each terminal serves as a balanced signal terminal. 10
6, 107 and a terminal 108 as an unbalanced signal terminal are provided.

Another surface acoustic wave device having a balanced-unbalanced conversion function by making the input impedance and the output impedance different from each other, for example, by a factor of 4, is disclosed in, for example, Japanese Patent Laid-Open No. 10-117123. Is mentioned.

The surface acoustic wave device described in the above publication is shown in FIG.
As shown in FIG. 8, the first surface acoustic wave filter 111 and the second surface acoustic wave filter 112 having an output signal phase difference of 180 degrees from the first surface acoustic wave filter 111 are provided on the piezoelectric substrate. is doing. 68, the illustration of the piezoelectric substrate is omitted. Accordingly, the surface acoustic wave device can exhibit the balanced-unbalanced conversion function as well as the filter function.

The first surface acoustic wave filter 111 is 3I.
DT type longitudinally coupled resonator type surface acoustic wave filter 118
And a 3IDT type longitudinally coupled resonator type surface acoustic wave filter 124 which is mirror-symmetrical with respect to the longitudinally coupled resonator type surface acoustic wave filter 118 with a line of symmetry along the propagation direction of the surface acoustic wave interposed therebetween. Cascade connection, that is, two-stage cascade connection.

Vertically coupled resonator type surface acoustic wave filter 118
Arranges the IDTs 114, 115 on the left and right sides of the central IDT 113 (along the propagation direction of the surface acoustic wave), and the reflectors 116, 117 so as to further sandwich the IDTs 114, 113, 105 from both the left and right sides. Are arranged respectively. Similarly, in the longitudinally coupled resonator type surface acoustic wave filter 124, the IDTs 120 and 121 are arranged on the left and right sides of the central IDT 119, respectively, and the IDTs 120, 119 and 121 are sandwiched therebetween.
The reflectors 122 and 123 are arranged.

The second surface acoustic wave filter 112 is 3I.
DT type longitudinally coupled resonator type surface acoustic wave filter 124
Same as the longitudinally coupled resonator type surface acoustic wave filter 128 and 3
IDT type longitudinally coupled resonator type surface acoustic wave filter 11
8 is a two-stage cascade connection with a longitudinally coupled resonator type surface acoustic wave filter 127 having an IDT 133 in which the direction of the central IDT 103 is inverted and the phase is inverted (that is, about 180 °). .

The first and second surface acoustic wave filters 111,
The terminals 129 and 130 on one side of 112 are electrically connected in parallel, the terminals 131 and 132 on the other side are electrically connected in series, and the unbalanced terminals 108 are connected in series by the terminals connected in parallel. Balanced terminals 106 and 10
Make up 7.

In a surface acoustic wave device having a balance-unbalance conversion function, an unbalanced terminal 108 and each balanced terminal 106,
The transmission characteristics in the pass band between the respective terminals of 107 are equal in amplitude characteristics and 1 in phase characteristics.
It is required to be inverted by 80 degrees. These characteristics are called the amplitude balance degree and the phase balance degree, respectively.

With regard to the amplitude balance and the phase balance, the surface acoustic wave device having the balance-unbalance conversion function is considered as a 3-port device. For example, the unbalanced input terminal is port 1, and each balanced output terminal is When port 2 and port 3 are set, amplitude balance = | A |, A = | 20 log (S21) | − | 20 log (S31) | Equation (1) Phase balance = | B |, B = | ∠S21−∠S31 | ... Defined by equation (2). Note that S21 is a transfer coefficient from port 1 to port 2, and S31 is a transfer coefficient from port 1 to port 3. Such a balance is ideally set to 0 dB for the amplitude balance and 180 degrees for the phase balance in the pass band in the filter characteristics of the surface acoustic wave device.

[0015]

However, the surface acoustic wave device having the balanced signal terminals as described above has a problem that the degree of balance between the balanced signal terminals is deteriorated. There are several causes of poor balance,
As one of them, the distance between the electrode finger connected to the balanced signal terminal 106 and the signal electrode finger of the IDT 102 (see FIG. 6).
7) and the distance between the electrode finger connected to the balanced signal terminal 107 and the signal electrode finger of the IDT 103 (FIG. 6).
110) of 7 is 0.5 of the wavelength determined by the pitch of the electrode fingers.
It can be said that it is twice different.

As a result, each balanced signal terminal 106, 10
The total capacitance of the electrode fingers connected to each of 7 is different, the conversion efficiency between the electric signal and the surface acoustic wave is different, and as a result, the balance is deteriorated.

Therefore, as shown in FIG. 70, the balanced signal terminal 107 of FIG. 67 is connected to the ground and the amplitude characteristic with respect to the frequency output from the balanced signal terminal 106, and as shown in FIG. 71, the balanced signal terminal of FIG. 106 is connected to the ground, and the amplitude characteristic output from the balanced signal terminal 107 is measured,
FIG. 69 shows the difference in the above amplitude characteristics as a result thereof. The two amplitude characteristics greatly differ from each other, and this difference leads to deterioration of the balance degree.

Further, in the cascade-connected surface acoustic wave device shown in FIG. 68, two adjacent IDTs are arranged.
In the above, there is a problem that the degree of balance deteriorates due to the polarities of the two electrode fingers facing each other in asymmetrical manner.

That is, the IDT 113 has the IDs adjacent to each other.
At T114 and 115 and each position (125 in FIG. 68), the outermost electrode fingers of the IDTs 113, 114, and 115 that are adjacent to each other are both ground electrode fingers.
33 is a signal electrode finger and a ground electrode at each location (126 in FIG. 68) adjacent to each of the adjacent IDTs 134 and 135. Each adjacent IDT in this way
When the combination of polarities in the outermost electrode fingers of No. 2 changes, the frequency and amplitude level of the resonance mode shown in FIG. 72 change due to conversion between the electric signal and the surface acoustic wave.

As shown in FIG. 68, two longitudinally coupled resonator type surface acoustic wave filters having different combinations of the outermost electrode fingers in adjacent IDTs are combined to perform balanced-unbalanced conversion, as shown in FIG. When a surface acoustic wave device having a function is configured, this shift of the resonance mode causes deterioration of the balance degree between the balanced signal terminals.

This phenomenon occurs even when a surface acoustic wave device having a balanced-unbalanced conversion function is constructed by using one longitudinally coupled resonator type surface acoustic wave filter as shown in FIG. Similarly, the shift of the resonance mode occurs, which causes deterioration of the balance between the balanced signal terminals.

The object of the present invention is to correct the above-mentioned difference between the balanced signal terminals, which is one of the causes of the deterioration of the balanced degree between the balanced signal terminals, so that the balanced degree between the balanced signal terminals is good. An object is to provide a surface acoustic wave device having a balance conversion function, and a communication device using the same.

[0023]

In order to solve the above-mentioned problems, another surface acoustic wave device of the present invention has at least two IDTs formed on a piezoelectric substrate along the propagation direction of surface acoustic waves. A surface acoustic wave device comprising at least one surface acoustic wave filter having: and an input signal terminal and an output signal terminal for the surface acoustic wave filter, wherein at least one of the input signal terminal and the output signal terminal is It is characterized in that it is connected to the balanced signal terminal and that at least some electrode fingers of the surface acoustic wave filter are weighted.

According to the above configuration, at least two IDs
By weighting at least a part of the electrode fingers of the surface acoustic wave filter having T, the balance of each characteristic (at least one of amplitude balance, phase balance, and transmission characteristic) between balanced signal terminals can be adjusted. The balance of can be improved.

In the surface acoustic wave device, it is preferable that some of the electrode fingers are weighted so as to improve at least one of amplitude balance and phase balance between the pair of balanced signal terminals. .

In the surface acoustic wave device, the weighting is performed by the IDs of the surface acoustic wave filters adjacent to each other.
The IDTs of at least one of the Ts may be applied to several electrode fingers from the outermost electrode fingers at the positions adjacent to each other.

In the above-mentioned surface acoustic wave device, the weighting is performed for at least one of the IDTs adjacent to each other in the surface acoustic wave filter, and the weighting is performed for several IDTs adjacent to the outermost electrode fingers. It may be applied to the electrode fingers.

In the surface acoustic wave device, the weighting is performed by the IDs of the surface acoustic wave filters adjacent to each other.
The IDTs of at least one of the Ts may be applied to the electrode fingers in the range from the outermost electrode fingers adjacent to each other to within ½ of the propagation direction of the surface acoustic wave of the IDTs.

In the surface acoustic wave device, the weighting is performed by the IDs of the surface acoustic wave filters adjacent to each other.
The IDTs of at least one of the Ts may be applied to the outermost electrode fingers adjacent to each other.

In the above surface acoustic wave device, the electrode fingers of the adjacent IDTs of the surface acoustic wave filter, which are adjacent to each other, are a ground electrode finger and a signal electrode finger, respectively. The weighting may be applied to at least one of them.

In the surface acoustic wave device, the weighted electrode fingers may be signal electrode fingers of the surface acoustic wave filter.

In the surface acoustic wave device, the weighting may be applied to the electrode finger of the IDT connected to the balanced signal terminal of the surface acoustic wave filter.

In the above surface acoustic wave device, the surface acoustic wave filter includes at least one IDT and another IDT.
It may have a phase inversion with respect to T, and the weighting may be applied to the electrode finger of the IDT in which the phase is inverted.

In the surface acoustic wave device, the weighting may be thinning weighting.

In the surface acoustic wave device, it is preferable that a dummy electrode is provided on the opposing bus bar facing the bus bar to which the thinned and weighted electrode fingers are connected.

The surface acoustic wave device may be provided with a ground connecting portion for connecting the electrode fingers connected to the grounds of the IDTs adjacent to each other through the dummy electrodes.

In the surface acoustic wave device, the weighting may be a crossing width weighting that makes the crossing width of an electrode finger different from that of another electrode finger.

In the above-mentioned surface acoustic wave device, it is preferable that the cross width weighting is performed at a substantially central portion in the cross direction.

In the above-mentioned surface acoustic wave device, the electrode fingers adjacent to the cross-width weighted electrode fingers are also cross-width weighted, and face each of the two cross-width weighted electrode fingers. Thus, a bent dummy electrode may be provided.

In the surface acoustic wave device, the cross-width-weighted electrode finger is one outermost electrode finger of adjacent IDTs, and the other IDT is the cross-width-weighted electrode finger. Dummy electrodes may be provided so as to face each other.

In the surface acoustic wave device, the dummy electrode may be connected to the ground.

In the surface acoustic wave device, the weighting makes the duty of an electrode finger different from that of another electrode finger, du.
It may be ty weighting.

In the surface acoustic wave device, the surface acoustic wave filter has at least three IDTs, and at least one of the IDTs adjacent to each other is weighted as described in any of the above. In addition, the weightings may be different from each other.

In the surface acoustic wave device, the two surface acoustic wave filters are provided, and each of the surface acoustic wave filters is given the weighting described in any one of the above. May be different from each other.

In the surface acoustic wave device, the surface acoustic wave filter has at least three IDTs adjacent to each other, and in at least one of the IDTs adjacent to each other, the outermost region of the portion where the IDTs are adjacent to each other. The cross width is weighted for several electrode fingers different from the outermost electrode finger, and different I adjacent to each other.
In at least one of the DTs, the IDTs are thinned and weighted with respect to the outermost electrode fingers adjacent to each other, and the thinned and weighted portions are connected with busbars to which the thinned and weighted electrode fingers are connected. A dummy electrode connected to the opposing bus bar may be provided.

In the surface acoustic wave device, the surface acoustic wave filter has at least three IDTs that are adjacent to each other, and in at least one of the IDTs that are adjacent to each other, the outermost electrode fingers of the locations where the IDTs are adjacent to each other. Of the IDTs that are different from each other and are different from each other in weight.
In at least one of the IDTs, the IDTs are thinned and weighted with respect to the outermost electrode fingers adjacent to each other, and the thinned and weighted portions face a bus bar to which the thinned and weighted electrode fingers are connected. A dummy electrode connected to the opposing bus bar may be provided.

In the surface acoustic wave device, the two surface acoustic wave filters are provided, and at least one of the IDTs of one of the surface acoustic wave filters adjacent to each other is located at the outermost position of the adjacent IDTs. The cross width is weighted with respect to several electrode fingers different from the outermost electrode finger in the region, and the ID is provided in at least one of the adjacent IDTs of the other surface acoustic wave filter.
T is thinned and weighted with respect to the outermost electrode fingers adjacent to each other, and the thinned and weighted portion is connected to an opposing bus bar facing the bus bar to which the thinned and weighted electrode fingers are connected. A dummy electrode may be provided.

In the surface acoustic wave device, the surface acoustic wave filter may be provided so as to have a balanced signal input-balanced signal output filter function.

In the surface acoustic wave device, the surface acoustic wave filter may be provided so as to have a balanced signal input-unbalanced signal output filter function or an unbalanced signal input-balanced signal output filter function. .

In the surface acoustic wave device, the ID
At least one of T may be divided into two in the cross width direction.

In the surface acoustic wave device, the pair of balanced signal terminals may be respectively connected to the bipolar comb-shaped electrodes of one IDT.

In the surface acoustic wave device, the ID
At least one of T may be divided into two in the propagation direction of the surface acoustic wave.

In the surface acoustic wave device, it is not necessary to have a grounded electrical neutral point between the balanced signal terminals forming the pair.

In the surface acoustic wave device, two surface acoustic wave filters may be provided so as to have a balanced signal input-balanced signal output filter function.

In the surface acoustic wave device, the two surface acoustic wave filters are provided so that the phase of the output signal differs from that of the input signal by about 180 degrees, and each of the surface acoustic wave filters described above has a balanced signal input. -It may be provided so as to have an unbalanced signal output filter function or an unbalanced signal input-balanced signal output filter function.

In the surface acoustic wave device, a surface acoustic wave filter may be further connected in cascade on the side of the unbalanced signal terminal.

In the surface acoustic wave device, the surface acoustic wave filter may be a longitudinally coupled resonator type surface acoustic wave filter.

In the surface acoustic wave device, the longitudinally coupled resonator type surface acoustic wave filter may have an odd number of IDTs.

In the surface acoustic wave device, the longitudinally coupled resonator type surface acoustic wave filter may have three IDTs.

In the surface acoustic wave device, the longitudinally coupled resonator type surface acoustic wave filter has at least one I
The total number of electrode fingers of DT may be an even number.

In the surface acoustic wave device, the longitudinally coupled resonator type surface acoustic wave filter is connected to at least a balanced signal terminal among three or more IDTs.
The total number of the electrode fingers may be even.

In the above surface acoustic wave device, the longitudinally coupled resonator type surface acoustic wave filter has three or more IDs.
The total number of electrode fingers of the IDT located at least in the central portion of T may be an even number.

In the surface acoustic wave device, at least one surface acoustic wave resonator may be connected to the surface acoustic wave filter in at least one of series and parallel.

In the surface acoustic wave device, the surface acoustic wave filter may be one in which two or more surface acoustic wave filter parts are cascade-connected.

In order to solve the above problems, another surface acoustic wave device of the present invention has an input IDT having a plurality of electrode fingers and an output IDT having a plurality of electrode fingers on a piezoelectric substrate.
And T are provided along the propagation direction of the surface acoustic wave so as to form a longitudinally coupled resonator type, and an inner electrode different from the outermost electrode finger of each electrode finger of at least one of the input IDT and the output IDT. The finger is characterized by having a weighted weighted electrode finger.

In the surface acoustic wave device, the input ID
One of T and the output IDT is for balance, and it is preferable that at least one of the IDTs on the balance side has a weighting electrode finger. The surface acoustic wave device may have an unbalanced-balanced conversion.

According to the above configuration, by providing a weighting electrode finger on at least one electrode finger of at least one of the input IDT and the output IDT, each characteristic (amplitude) between the output signal, particularly each output signal for balancing is increased. Since the balance (balance, phase balance, transmission characteristics) can be adjusted, the balance of each characteristic can be improved.

In the surface acoustic wave device, it is preferable that the weighting electrode fingers are provided within a range from the position next to the outermost electrode finger in one IDT to within ½ of all electrode fingers. In the surface acoustic wave device, the weighting electrode fingers are preferably set shorter than the other electrode fingers.

In the surface acoustic wave device, the input ID
It is desirable that at least one electrode finger of at least one of the T and the output IDT is formed with two or more continuous ground electrode fingers including the outermost electrode finger at a position facing another IDT.

According to the above construction, by forming two or more continuous ground electrode fingers including the outermost electrode fingers at the positions facing each other on each electrode finger on one side, for example, output signals for balancing are balanced. Thus, setting the phase difference close to 180 ° can be ensured with a simple configuration.

In the surface acoustic wave device, the weighting electrode fingers are formed between adjacent ground electrode fingers which are grounded electrode fingers of at least one of the input IDT and the output IDT. It is desirable that the size is set to control the size of the electric field section.

In the surface acoustic wave device, the input ID is used.
T or the output IDT is for balancing, and there are two I for balancing.
In DT, it is preferable that the size of the non-electric field portion is set to be substantially the same.

According to the above structure, the weighting electrode fingers are controlled so that the size of the electric field-free portion is controlled, and more preferably, the size of the electric field-free portion is set to be substantially the same by two IDTs for balancing. Each IDT, especially the output IDT
Since the balance of the conversion of elastic energy into electric energy can be adjusted, the balance can be improved.

In the surface acoustic wave device, it is preferable that the grounded first balancing electrode finger is formed so as to extend toward the weighting electrode finger in accordance with the length of the weighting electrode finger.

According to the above configuration, the electrodeless finger portion formed by the weighting electrode fingers set to be short can be covered to some extent by the first balancing electrode finger, so that the deterioration of balance due to the electrodeless finger portion can be avoided. it can.

In the above surface acoustic wave device, the grounded second balancing electrode finger is formed to a position different from the weighting electrode finger so as to match the length of the weighting electrode finger, and the second balancing electrode finger is formed. A dummy electrode that is bent and formed so as to face the finger and the weighting electrode finger may be provided.

According to the above structure, by providing the dummy electrode, the transmission characteristics can be further improved while maintaining good balance.

The communication device of the present invention is characterized by using the surface acoustic wave device according to any one of the above in order to solve the above problems. According to the above configuration, since the surface acoustic wave device having excellent balance is used, the performance of the above configuration can be improved.

[0079]

BEST MODE FOR CARRYING OUT THE INVENTION The following will describe each embodiment of the present invention in reference to FIGS. 1 to 65.

(First Embodiment) As shown in FIG. 1, a surface acoustic wave device according to a first embodiment of the present invention has an unbalanced-balanced conversion function and a filter function. , The input IDT 1 and the output IDTs arranged on both sides thereof (along the propagation direction of the surface acoustic wave).
The piezoelectric substrate 8 is provided with the reflectors 2 and 3 and the reflectors 4 respectively arranged outside them. Note that the above input and output can be interchanged with each other.

That is, the output IDTs 2 and 3 are arranged such that the input IDT 1 is sandwiched between them. Furthermore, each reflector 4 has an IDT 2, I between them.
They are arranged so as to sandwich the DT1 and the IDT3, and reflect the propagating surface acoustic wave. The piezoelectric substrate 8 is, for example, 40 ± 5 ° YcutX propagation LiT.
It is composed of aO ₃ .

Each of the IDTs 1, 2, and 3 includes a strip-shaped base end portion (bus bar) and a plurality of parallel electrode strip fingers that are parallel to each other and extend at equal intervals from one side portion of the base end portion. And two electrode finger portions each having the above-mentioned electrode finger portion in a state in which the side portions of the electrode fingers of each of the electrode finger portions are interdigitated between the electrode fingers so as to face each other. is there.

In such IDTs 1, 2, and 3, the length and width of each electrode finger, the distance between adjacent electrode fingers, and the cross width indicating the facing length in a complicated state between the electrode fingers are respectively set. By setting it, the signal conversion characteristics and pass band can be set. In the first embodiment, the IDT
The number of electrode fingers of 1 is set to 39, and the number of electrode fingers of IDTs 2 and 3 is set to 23.

The electrode fingers, bus bars, and reflectors 4 described above are formed on the piezoelectric substrate 8 by the photolithography method or the like.
It is formed of, for example, an aluminum (Al) electrode (foil) formed on top.

In the first embodiment, in order to input an unbalanced type signal and output a balanced type signal, each input IDT 1 is connected to the unbalanced input terminal 5. The signal electrode fingers 11 and the grounded ground electrode fingers 12 are provided in a mutually intricate state as described above.

Further, in the IDT 1, the ground electrode fingers 12 are set so that the outermost electrode fingers at both ends in the propagation direction of the surface acoustic wave are the ground electrode fingers. The outermost electrode finger is located at a position facing one of the outermost electrode fingers of the IDTs 2 and 3, respectively.

On the other hand, in the IDT 2, each ground electrode finger 21 and the signal electrode finger 22 connected to the balancing output terminal 6 are provided in a mutually intricate state as described above. The bus bar 23 connected to each ground electrode finger 21 is arranged so as to be substantially linear with respect to the bus bar 13 connected to each signal electrode finger 11 of the input IDT 1. Further, in the IDT 2, the outermost electrode fingers, which are the electrode fingers at both ends in the propagation direction of the surface acoustic wave, are the ground electrode fingers 21, respectively.

In the IDT 3, each ground electrode finger 31 and the signal electrode finger 32 connected to the output terminal 7 for balancing are provided in a mutually intricate state as described above. The bus bar 33 connected to each ground electrode finger 31 is the bus bar 1 connected to each signal electrode finger 11 of the input IDT 1.
3 is arranged so as to be substantially linear.

The bus bar 14 of each ground electrode finger 12 of the IDT 1 is set so that the bus bar 24 of each signal electrode finger 22 of the IDT 2 and the bus bar 34 of each signal electrode finger 32 of the IDT 3 are linear. ing.

Further, in the first embodiment, the output IDTs 2 and 3 are provided so as to be mutually inverted in terms of structure. That is, in the IDT2, the signal electrode finger and the ground electrode finger are alternately set from the one closer to the IDT1 starting from the ground electrode finger,
At T3, the signal electrode finger starts from the side closer to IDT1, and the ground electrode finger and the signal electrode finger are alternately set.

As a result, in the first embodiment, the amplitude difference between the IDTs 2 and 3 is 0 and the phase difference is 180.
Since it is set to be close to °, the balanced-unbalance conversion function can be exhibited.

In the first embodiment, IDT1
And the IDT3 are adjacent to each other, the outermost electrode fingers of the IDT3 are thinned and weighted. The dummy electrode 31a, which is grounded, is provided at the position of the thinned and weighted electrode finger.
Are formed. Thereby, IDT1 and IDT3
In the IDT 3 that is in the vicinity of the ground electrode fingers, the ground electrode fingers are the dummy electrode 31a and the ground electrode finger 31b.
The books are arranged in a row.

Further, in the first embodiment, the input I of the signal electrode fingers 22 in the output IDT 2 is input.
The cross-weighting electrode finger 22a was set at the position of the signal electrode finger 22 next to the ground electrode finger 21 on the side close to DT1 (outermost electrode finger). In the above-mentioned cross-weighting electrode finger 22a, the length of the cross-weighting electrode finger 22a is set to, for example, about half of the lengths of the other signal electrode fingers 22, that is, the cross-weighting is performed by adjusting the crossing width. Has been done.

Moreover, the weighting electrode fingers 2 set to be short are used.
Strip-shaped dummy electrodes (first balancing electrode fingers) 21a, which are offset electrode fingers, are formed so as to fill the space created by 2a and extend from the grounded bus bar 23. The dummy electrodes 21a extend toward the tips of the cross-weighting electrode fingers 22a at substantially equal intervals with respect to the adjacent ground electrode fingers 21.

Next, the operation and effect of the first embodiment will be described. First, as a comparison, in FIG. 2, the balance-unbalance of the first comparative example in which neither the thinning weighting nor the cross weighting is performed is performed. The schematic block diagram of each IDT of the surface acoustic wave device which has a balance conversion function is shown. In the configuration of the first comparative example,
While the ground electrodes are arranged side by side at the positions where the IDT 1 and the IDT 40 are adjacent to each other, the signal electrode and the ground electrode are arranged between the IDT 1 and the IDT 41. Therefore, between the IDT 1 and the IDT 40, there is the non-electric field portion 9 in which electricity and surface acoustic wave are not converted.
Conversion between the electric signal (signal) and the surface acoustic wave is performed between the IDT 1 and the IDT 41. Therefore, the frequencies and amplitude levels of the signals output from the balanced signal terminals 6 and 7 are different, and the phase is not completely inverted by 180 degrees, resulting in poor balance between the balanced signal terminals.

In the first embodiment of the present invention, first, the IDT in which the signal electrode and the ground electrode shown in the first comparative example are arranged side by side.
1. The electrode fingers of the IDT 41 adjacent to each other are shown in FIG.
As shown in, the dummy electrodes 31a were formed at the positions of the electrode fingers that were thinned and weighted. That is, the IDT in the vicinity between IDT1 and IDT3
Two ground electrode fingers are arranged in line 3 in FIG. Thereby, between IDT1 and IDT3, IDT1 and IDT4
A surface acoustic wave device is obtained in which the difference in conversion efficiency between the electric signal and the surface acoustic wave between 0 and 0 is corrected, and the degree of balance between the balanced signal terminals 6 and 7 is improved.

Further, by forming the dummy electrode 31a, it is possible to prevent an increase in loss due to conversion of the surface acoustic wave into a bulk wave and to obtain a surface acoustic wave device having a good insertion loss in the pass band. Further, the dummy electrode 31a may be a floating electrode without being grounded, but the floating electrode causes deterioration of the balance between the balanced signal terminals 6 and 7, so it is preferable to ground it.

However, in the configuration shown in FIG. 3, the non-electric field portion 9 performs the IDT1 and IDT40 by performing thinning weighting.
The side where the IDT1 and the IDT3 are arranged becomes larger than the side where the and are arranged. With this, a sufficient degree of balance between the balanced signal terminals 6 and 7 cannot be obtained yet. Therefore, as shown in FIG. 4, the cross-weighting electrode finger 2 in which the cross-width weighting is applied to the signal electrode finger 22 on the side where the IDT 1 and the IDT 2 are arranged side by side.
2a was set, and a dummy electrode 21a was further provided. As a result, the boundary portion X ₁ between the IDT 1 and the IDT ₂ , and
It is possible to obtain a surface acoustic wave device in which the sizes of the electroless fields 9 and 9 at the boundary X ₂ between the IDT 1 and the IDT 3 are substantially the same, and the balance between the balanced signal terminals is further improved.

Further, by forming the dummy electrode 21a, it is possible to prevent an increase in loss due to conversion of a surface acoustic wave into a bulk wave and to obtain a surface acoustic wave device having a good insertion loss in the pass band.

Such grounded dummy electrode 21a,
Reference numeral 31a denotes each of the ground electrode fingers 21 and 31b adjacent to each other.
And the electric fieldless portions 9 are formed between the respective electric fieldless portions and the electric fieldless portions 9, and the formation areas of the respective electric fieldless portions 9 (capacity formation areas) will be described later.
You can control the size of.

The cross-weighting described above is more efficient when applied to the signal electrode because the non-electric field portion can be adjusted with less weight, but of course the earth electrode may be weighted.

In addition, in the first embodiment, the weighting is performed by the electrode finger at a position where the input IDT 1 and the output IDT 2, 3 are adjacent to each other, and the second electrode finger from the electrode finger. , This may be done at any part of the IDT. However, the resonance mode (resonance mode of C in FIG. 72) on the highest frequency side of the pass band, which is greatly affected by the difference in the polarity of the electrode fingers adjacent to the IDT, is adjacent to the IDT as shown in FIG. Since the distribution of the current is large at the matching points, as shown in FIG. 4, it is performed from a position where the IDTs 1 and 2 are adjacent to each other to within a range of half the length a of the surface acoustic wave in the IDT 2 in the propagation direction. However, it is effective.

Further, in the first embodiment, the cross width weighting is carried out by setting the cross weighting electrode finger 22a in which the signal electrode finger 22 is shortened to substantially the central portion. , It may be adjusted if necessary. For example, a similar effect can be obtained by weighting the signal electrode finger 22 on the IDT 1 side with a cross width of about 1/4 and further weighting the next signal electrode finger 22 with a cross width of about 1/4. To be

FIG. 5 shows the amplitude balance between the balanced signal terminals 6 and 7 with respect to the frequency in the configuration of the first embodiment, and FIG. 6 shows the phase balance. As a comparison, FIG. 7 shows the amplitude balance between the balanced signal terminals with respect to the frequency in the configuration of the first comparative example shown in FIG. 2, and FIG. 8 shows the phase balance. EGS
The frequency range of the pass band of the M transmission filter is 880 MH
z to 915 MHz.

The amplitude balance between the balanced signal terminals 6 and 7 with respect to the frequency in this range is -1.6 dB in the first comparative example.
~ +1.5 dB (deviation 3.1 dB, if the deviation is small,
While the amplitude balance is good), in the first embodiment of the present invention, -0.7 dB to +1.2 dB (deviation 1.9 dB).
Is improved by about 1.2 dB. Balanced signal terminals 6, 7
The degree of phase balance between them is 172 degrees to 189 degrees in the first comparative example (deviation 17 degrees, phase deviation is good if deviation is small)
On the other hand, in the first embodiment, 178 degrees to 18 degrees
It is improved by 4 degrees (6 degrees deviation), which is about 11 degrees.

As described above, in the first embodiment, one longitudinally coupled resonator type surface acoustic wave filter is used to weight the structure of the surface acoustic wave device having the balanced-unbalanced conversion function. A surface acoustic wave device in which the degree of balance between the balanced signal terminals 6 and 7 is improved as compared with the conventional surface acoustic wave device is obtained.

In the first embodiment of the present invention, the configuration in which one longitudinally coupled resonator type surface acoustic wave filter having three IDTs is used has been described, but the present invention is not limited to this configuration and the balanced signal terminals 6 and 7 are used. The same effect can be obtained in any structure as long as it is a surface acoustic wave device using the surface acoustic wave filter having.

For example, FIG. 9 shows a surface acoustic wave device having a balanced-unbalanced conversion function using a longitudinally coupled resonator type surface acoustic wave filter having five IDTs (balanced signal terminals 401, 402, unbalanced signal terminals). The signal terminal 403) also has a configuration using the longitudinally coupled resonator type surface acoustic wave filter having three or more IDTs and a configuration using a longitudinally coupled resonator type surface acoustic wave filter having two IDTs. The effects of the present invention can be obtained. Of course, not only the longitudinally coupled resonator type surface acoustic wave filter but also a surface acoustic wave device using a transversal type surface acoustic wave filter or a laterally coupled resonator type surface acoustic wave filter can be similarly effective. To be

In the first embodiment, the surface acoustic wave device having the balanced-unbalanced conversion function has been described. However, for example, in FIG. 10 (balanced signal terminal 501 and balanced signal terminal 502 are paired, balanced signal terminal 503). And the balanced signal terminal 504 are paired) and FIG. 11 (the balanced signal terminal 601 and the balanced signal terminal 602 are paired, and the balanced signal terminal 603 and the balanced signal terminal 604 are paired). , Balanced signal input −
The effect of the present invention can be obtained even in a surface acoustic wave device that outputs a balanced signal.

In the first embodiment, an example in which a surface acoustic wave device having a balanced-unbalanced conversion function is constructed by using one longitudinally coupled resonator type surface acoustic wave filter has been described. Is effective not only in this structure but also in a surface acoustic wave device having any balance-unbalance conversion function.

For example, as shown in FIG. 12, balanced signal terminals 701 and 702 are connected to the comb-teeth electrodes of both poles of one IDT in one longitudinally coupled resonator type surface acoustic wave filter (703 is an unbalanced signal terminal). ), A configuration having no electrical neutral point grounded to the ground, and a configuration in which one of the IDTs is divided in the cross width direction and the impedance is changed as shown in FIG. 13 (801 and 802 are balanced signals). Terminal, 803 is an unbalanced signal terminal), and further, as shown in FIG. 14, it is divided in the propagation direction of the surface acoustic wave, and the balanced signal terminals 901 and 902 are connected to each of the divided comb-shaped electrodes (903 is unbalanced). The effect of the present invention can be obtained also in a balanced signal terminal).

At this time, as shown in FIG. 15, by connecting the unbalanced signal terminals 1003 to the comb-teeth electrodes in different directions in the left and right IDTs, the attenuation outside the pass band is further improved, and the elasticity is improved. Surface wave device is obtained (100
1, 1002 is a balanced signal terminal).

Further, the effects of the present invention can be obtained even in the structure of a surface acoustic wave device having a balanced-unbalanced conversion function by combining a plurality of longitudinally coupled resonator type surface acoustic wave filters.

For example, as shown in FIG. 16, the phase of the output signal with respect to the input signal of the longitudinally coupled resonator type surface acoustic wave filter 1105 is different from that of the longitudinally coupled resonator type surface acoustic wave filter 1105 by about 180 degrees, and Balanced signal terminal 110
1, 1102 connected in series with the IDT connected in parallel, and IDT connected with the unbalanced signal terminal 1103 connected in parallel,
A configuration of a surface acoustic wave device having an unbalance conversion function, further, as shown in FIG. 17, a configuration in which one longitudinally coupled resonator type surface acoustic wave filter 1201 is cascade-connected to the configuration of FIG.
Further, as shown in FIG. 18, even if the configuration of FIG. 68 is weighted, the effect of the present invention can be obtained.

As described above, in the structure in which the longitudinally coupled resonator type surface acoustic wave filters are cascade-connected, not only the balance degree between the balanced signal terminals is improved but also the surface acoustic wave having a large attenuation outside the pass band is obtained. The device is obtained. that time,
As shown in FIG. 19, the phases of the electric signals transmitted through the respective signal lines 1301 and 1302 connecting the two cascaded longitudinally coupled resonator type surface acoustic wave filters are different from each other by about 180 degrees. Each IDT13
03, 1304 are inverted with respect to each other, and similarly, the IDTs 1307, 1 are arranged so that the phases of the electric signals transmitted through the signal lines 1305, 1306 are different from each other by about 180 degrees.
By reversing 308 with each other, a surface acoustic wave device with further improved balance between balanced signal terminals can be obtained.

Further, as shown in FIG. 20, the effect of the present invention can be obtained even in the structure in which one longitudinally coupled resonator type surface acoustic wave filter 1401 is cascade-connected to the surface acoustic wave device of FIG. With this configuration, not only the balance between the balanced signal terminals is improved, but also a surface acoustic wave device having a large attenuation outside the pass band can be obtained. At this time, as shown in FIG. 21, each signal line 1501,
By inverting each of the IDTs 1503 and 1504 so that the phases of the electric signals transmitted through 1502 are different from each other by about 180 degrees, a surface acoustic wave device in which the balance between the balanced signal terminals is further improved can be obtained.

When two or more longitudinally coupled resonator type surface acoustic wave filters are cascade-connected, it is not necessary to use the longitudinally coupled resonator type surface acoustic wave filters having the same configuration, and impedances at input and output can be used. If you want to adjust, you can adjust the cross width, or if you want to increase the attenuation outside the passband, you can change the logarithm of the IDT, the center distance between adjacent IDTs, the center distance between the IDT and the reflector. The surface acoustic wave filters may have different designs.

Further, in the first embodiment, each IDT is applicable to any longitudinally coupled resonator type surface acoustic wave filter.
Although the total number of electrode fingers of the IDT is set to an odd number, it may be an even number, and in particular, as shown in FIG. 22, the IDTs located in the central portion of the three IDTs and further connected to the balanced signal terminals. The effect of the present invention can also be obtained by setting the total number of electrode fingers to be an even number.

In this case, the left-right symmetry with respect to the center of the longitudinally coupled resonator type surface acoustic wave filter is improved, and the number of electrode fingers connected to the balanced signal terminals is equalized. A surface acoustic wave device having an improved balance between them is obtained.

Also, as shown in FIG. 23, in a configuration in which surface acoustic wave resonators 1601 and 1602 are connected in series, a configuration in which surface acoustic wave resonators (not shown) are connected in parallel, or a configuration in which both are connected, The effect of the present invention can be obtained. With this configuration, not only the degree of balance between the balanced signal terminals is improved, but also a surface acoustic wave device having a large amount of attenuation particularly near the pass band can be obtained.

(Second Embodiment) The second embodiment of the present invention will be described below with reference to FIGS. 24 to 28. In the second embodiment, the members having the same functions as those of the surface acoustic wave device shown in FIG. 1 are given the same member numbers and the description thereof is omitted.

In the surface acoustic wave device according to the second embodiment, as a weighting method, as shown in FIG. 24, instead of the thinning weighting and the crossing weighting in the crossing width in the above first embodiment, , Serial weighting is used.
That is, the IDT 25 is provided in place of the IDT 2 described in the first embodiment.

In the IDT 25, the (next) ground electrode finger 21 inside the cross-weighting electrode finger 22a is replaced with the dummy electrode 21a of the IDT 2 described above, and the cross-weighting electrode finger 22 is replaced with the ground electrode finger 21.
A cross-weighting electrode finger (second balancing electrode finger) 21b that is shortened as in the case of a is provided, and a dummy electrode 25a that is separated (that is, in a floating state) from the above is provided.

The dummy electrode 25a has the same width as the cross-weighting electrode finger 22a, extends between the cross-weighting electrode finger 22a and the next signal electrode finger 22 substantially in parallel with them, and then the cross-weighting electrode finger 22a. It passes between the tip of the finger 22a and the tip of the cross-weighting electrode finger 21b, and
It is an electrode finger formed by bending between the cross-weighting electrode finger 21b and the outermost ground electrode finger 21 so as to extend substantially parallel to them.

With respect to the surface acoustic wave device having such an IDT 25, the amplitude balance degree and the phase balance degree near the pass band were measured. The results are shown in FIGS. 25 and 26, respectively. As is clear from these results, the amplitude balance between the frequency and balanced signal terminals in the pass band range of the EGSM transmission filter is -0.7 dB or more.
+1.2 dB (deviation 1.9 dB), which is the same as that of the first embodiment, but the degree of phase balance between balanced signal terminals is 177 degrees or more.
This is 182 degrees (deviation of 5 degrees), which is an improvement of 1 degree over the first embodiment.

Further, FIG. 27 shows the transmission characteristic in the pass band with respect to the frequency in the first embodiment, and FIG. 28 shows the transmission characteristic in the pass band with respect to the frequency in the second embodiment. Comparing the two, the ripple A (see FIG. 27) is generated in the pass band in the first embodiment, but the ripple A is generated in the second embodiment.
28 is not generated (see FIG. 28), and a surface acoustic wave device having a smaller deviation in the pass band than the first embodiment is obtained.

As described above, by performing the series weighting in which the cross width weighting is further expanded, the surface acoustic wave device in which the balance between the balanced signal terminals and the deviation in the pass band are further improved can be obtained. To be

Moreover, in the second embodiment, the generation of ripples in the transmission characteristics is suppressed, and it is understood that the second embodiment has more excellent transmission characteristics as compared with the first embodiment. .

(Third Embodiment) The third embodiment of the present invention will be described below with reference to FIGS. 29 to 32. FIG. 29 shows a configuration according to the first embodiment of the present invention. In the third embodiment of the present invention, PCS
The reception filter will be described as an example.

In the surface acoustic wave device of the third embodiment,
A longitudinally coupled resonator type surface acoustic wave filter 201 of 3IDT and surface acoustic wave resonators 202 and 203 connected in series to the surface acoustic wave filter 201 are formed on the piezoelectric substrate 200 by a photolithography method or the like. It is formed of an aluminum (Al) electrode (foil). Examples of the material of the piezoelectric substrate 200 include 40 ± 5 ° YcutX propagation LiTaO ₃ . Such a surface acoustic wave filter 201 is almost the same as that shown in FIG.

In the surface acoustic wave filter 201, the IDTs 204 and 206 are formed so as to sandwich the IDT 205, which is the center and is the balanced signal terminal side, from the left and right (along the propagation direction of the surface acoustic wave). Further, reflectors 207 and 208 for reflecting the surface acoustic waves from the IDTs 204 to 206 are formed on both outer sides of the IDTs 204 and 206 (along the propagation direction of the surface acoustic waves). That is, in each IDT and the reflector, the width direction of each electrode finger is along the propagation direction of the surface acoustic wave,
Moreover, it is set on the propagation path of the surface acoustic wave.

Further, in the surface acoustic wave filter 201,
As is clear from FIG. 29, IDT 204 and IDT 20
Several electrode fingers (narrow-pitch electrode fingers) where 5 is adjacent to each other and their vicinity, and where IDT 205 and IDT 206 are adjacent to each other and their vicinity.
The pitch is set to be smaller than the other portions of each IDT (locations 213 and 214 in FIG. 29), as described above.

In the surface acoustic wave device, each terminal 2
10, 211 are balanced signal terminals, and terminal 209 is an unbalanced signal terminal. Therefore, IDT204 and IDT206 are
It becomes the unbalanced signal side, and the signal electrode fingers 204 respectively
a and ground electrode finger 204b, signal electrode finger 206
a and a ground electrode finger 206b. On the other hand, I
The DT 205 is on the side of the balanced signal terminal and has the signal electrode fingers 205a and 205b. Therefore, the third embodiment is an example in which the configuration grounded to the ground and having no electrical neutral point is weighted.

The surface acoustic wave resonators 202 and 203 are connected in series between the unbalanced signal terminal 209 and the IDTs 204 and 206 via the signal line 212. The surface acoustic wave resonator 202 includes an IDT 202a and each of the reflectors 202 along the propagation direction of the surface acoustic wave so as to sandwich the IDT 202a.
b and 202c. Surface acoustic wave resonator 203
Has an IDT 203a and reflectors 203b and 203c sandwiching the IDT 203a along the propagation direction of the surface acoustic wave.

The feature of the third embodiment is that the IDT 205
And IDT 206 are adjacent to each other and are thinned and weighted at a position of electrode finger 219 of IDT 206 at a position facing each other in the propagation direction of the surface acoustic wave.

In the third embodiment, as the thinning weight, the electrode finger of the signal electrode finger 206a of the IDT 206 adjacent to the IDT 205 (the closest one) is thinned and weighted.

Further, in the third embodiment of the present invention, the pitch of each electrode finger is secured, and the IDTs adjacent to each other, that is,
To maintain the spacing between each IDT 205, 206,
The electrode fingers 219 on the ground electrode fingers 206b have the same crossing width, the same pitch, and the same du as the ground electrode fingers 206b on the narrow pitch side.
ty and the same line width. Accordingly, in the IDT 206, a plurality of ground electrode fingers 206b, for example, two ground electrode fingers 206b are present adjacent to each other at a position adjacent to the IDT 205.

The detailed design of the surface acoustic wave filter 201 is such that the wavelength determined by the pitch of the narrow pitch electrode fingers is λI ₂ (locations 213 and 214 in FIG. 29) and the wavelength determined by the pitch of the other electrode fingers is λI ₁ . Then, the cross width W: 60.6 λI ₁ Number of IDTs (in the order of 204, 205, 206): 29
(4) / (4) 44 (4) / (4) 29 (number of electrode fingers with a small pitch in parentheses) IDT wavelength λI ₁ : 2.06 μm, λI ₂ : 1.88 μm Reflector wavelength λR: 2.07 μm Number of reflectors: 100 IDT-IDT Interval: 0.50 λI ₂ Interval between the wavelength λI ₁ and the wavelength λI ₂ between the electrode fingers (215, 216, 217, 218 in FIG. 29) :
0.25λI ₁ + 0.25λI ₂ IDT-reflector spacing: 0.47λR duty: 0.60 (both IDT and reflector) Electrode film thickness: 0.080λI ₁ The detailed design of the surface acoustic wave resonator 202 is described below. Shown in. Crossing width W: 40.6λ Number of IDTs: 241 wavelengths λ (both IDT and reflector): 1.97 μm Number of reflectors: 30 IDT-reflector interval: 0.50λ duty: 0.60 (IDT, reflector Both) Electrode film thickness: 0.084λ The detailed design of the surface acoustic wave resonator 203 is shown below. Crossover width W: 49.1λ Number of IDTs: 401 wavelengths λ (both IDT and reflector): 2.04 μm Number of reflectors: 30 IDT-reflector interval: 0.50λ duty: 0.60 (IDT, reflector Together) Electrode film thickness: 0.080λ The above-mentioned “spacing” is the distance between the centers (centers in the width direction) of two electrode fingers adjacent to each other.

Next, the characteristics of the third embodiment of the present invention were measured, and the results are shown in FIGS. 30 and 31. FIG. 30 is a graph showing the measurement result of the amplitude balance degree between the balanced signal terminals with respect to the frequency in the configuration of the third embodiment.
A graph of the degree of phase balance is shown in FIG.

For comparison, two IDTs shown in FIG.
Also shown in FIGS. 30 and 31 are the amplitude balance degree and phase balance degree in the configuration of the second comparative example which has the IDT 206c in which the thinning weighting is not applied in the adjacent positions in place of the IDT 206.

The configuration of the second comparative example shown in FIG. 32 is different from that of the third embodiment in that the IDT2 is not weighted.
The configuration is exactly the same except that the IDT 206 is replaced with 06c. The frequency range of the pass band in the PCS reception filter is 1930 MHz to 1990 MHz.

The maximum amplitude balance in this range is -1.6 dB to +0.7 dB (deviation 2.3 d in the second comparative example).
B), the third embodiment is -1.5 dB.
The amplitude balance is improved to about +0.7 dB (deviation of 2.2 dB), which is about 0.1 dB. Next, the degree of phase balance is 162 degrees to 182 degrees (deviation 20 degrees) in the second comparative example, whereas it is 162 degrees to 181 degrees (deviation 1 in the third embodiment).
9 degrees), the phase balance is improved by about 1 degree.

This is done by applying thinning weighting to the ID
In the second comparative example, the polarities of the electrode fingers at the portions where T205 and IDT206 are adjacent to each other are + and +, which are both signal electrode fingers.
This is an effect that the asymmetry on the left and right is improved because the polarities of 204 and the IDT 205 are − and +, which are the same as the polarities of adjacent portions.

As described above, in the third embodiment of the present invention, in the surface acoustic wave filter having the balanced-unbalanced conversion function, by thinning and weighting the electrode fingers at the positions where the two IDTs are adjacent to each other, A surface acoustic wave filter having an improved degree of balance between balanced signal terminals can be obtained as compared with the surface acoustic wave filter of FIG.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIGS. 33 to 41. In the fourth embodiment, an EGSM reception filter will be described as an example.

The surface acoustic wave device according to the fourth embodiment is
The two longitudinally coupled resonator type surface acoustic wave filters 1918 and 1920 shown in FIG. 18 in which the phase of the output signal differs from that of the input signal by 180 degrees are connected to balanced signal terminals 1906 and 1.
The 907 side is connected in series, and the unbalanced signal terminal 1905 side is connected in parallel to provide a balanced-unbalanced conversion function. Furthermore, two longitudinally coupled resonator type surface acoustic wave filters 1918 and 192 are provided.
A new longitudinally coupled resonator type surface acoustic wave filter 1918, 1918 is cascade-connected to each 0, and the longitudinally coupled resonator type surface acoustic wave filter 192 is provided.
In this example, 0 is subjected to thinning weighting and has a dummy electrode 1901b.

In the fourth embodiment, four longitudinally coupled resonator type surface acoustic wave filters 1918 and 192 are provided on the piezoelectric substrate 8.
0 is formed by an Al electrode. The four longitudinally coupled resonator type surface acoustic wave filters 1918 and 1920 all have the same design except that the phase of the output signal differs from the input signal by about 180 degrees and that they are weighted.
Further, in the fourth embodiment, as in the third embodiment, 2
Several narrow pitch electrode fingers are provided between two adjacent IDTs. The configuration of the fourth embodiment is basically the same as the configuration of the second conventional example shown in FIG. 68 except for weighting.

Vertically coupled resonator type surface acoustic wave filter 191
In the detailed design of No. ₈ , the wavelength determined by the pitch of the narrow pitch electrode fingers is λI ₂ , and the wavelength determined by the pitches of the other electrode fingers is λI ₂ .
Assuming I ₁ , the cross width: 25.2λ I ₁ Number of IDTs (in the order of 1902, 1901, 1903): 2
3 (4) / (4) 26 (4) / 23 (4) (number of electrode fingers with narrow pitch in parentheses) IDT wavelength λI ₁ : 4.204 μm, λI ₂ : 3.85
4 μm Reflector wavelength λR: 4.279 μm Number of reflectors: 90 IDT-IDT interval: Place between electrode fingers of wavelength λI ₁ and wavelength λI ₂ : 0.
25λI ₁ + 0.25λI ₂ Location between electrode fingers of wavelength λI ₂ : 0.50λI ₂ IDT-reflector interval: 0.470λR IDTduty: 0.720 Reflector duty: 0.55 Electrode film thickness: 0.08λI _{Is 1} .

The feature of the fourth embodiment is that the phase of the output signal with respect to the input signal of the longitudinally coupled resonator type surface acoustic wave filter 1918 differs from that of the longitudinally coupled resonator type surface acoustic wave filter 1918 by about 180 degrees. IDT inverted to
One of the points is that one of the electrode fingers located at both ends of 1901a and connected to the unbalanced signal terminal 1905 is thinned out, and a dummy electrode 1901b connected to the ground is provided at that portion.

Next, the operation and effect of the fourth embodiment will be described. FIG. 34 shows the amplitude balance between the balanced signal terminals with respect to the frequency in the configuration of the fourth embodiment. For comparison, FIG. 34 also shows the amplitude balance degree between the balanced signal terminals with respect to the frequency in the second conventional example of FIG. The configuration of the second conventional example of FIG. 68 is exactly the same as the configuration of the fourth embodiment except that no thinning weighting is applied. EGSM
The frequency range of the pass band in the reception filter is 925.
MHz to 960 MHz.

The amplitude balance between the balanced signal terminals in this range is -0.2 dB to +1.3 dB (deviation of 1.5 dB) in the second conventional example, while in the fourth embodiment it is-.
With 0.7 dB to +0.2 dB (deviation of 0.9 dB), the amplitude balance is improved by about 0.6 dB.

The reason why the effect of the fourth embodiment is obtained will be described below. Excitation of the surface acoustic wave is performed at the electrode fingers when the electrode fingers having different polarities are adjacent to each other. Figure 3
5, surface acoustic wave filters 118 and 1 shown in FIG.
Around 27, where IDTs are adjacent to each other in FIG.
The state of excitation of the surface acoustic wave in the portion surrounded by () is illustrated.

In FIG. 35, only the three electrode fingers from the end of the portion where the IDTs are adjacent to each other are shown, and the others are omitted. The longitudinally coupled resonator type surface acoustic wave filters 118 and 127 shown in FIG. 68 are the same as the longitudinally coupled resonator type surface acoustic wave filters 2007 and 2008 shown in FIG.
In FIG. 35, 113, 114, and 115 are IDT2.
001, 2002, 2003, the IDT 13 of FIG.
3, 134 and 135 are IDTs 2004 and 20 of FIG.
05 and 2006, respectively. In the figure, the part marked with a circle indicates that the surface acoustic wave is excited, and the part marked with a x indicates that the surface acoustic wave is not excited.

In the case of the second conventional example, in the longitudinally coupled resonator type surface acoustic wave filter 2007, IDTs 2001 and 20 are used.
Since the outermost electrode fingers of 02 and 2003 are ground electrodes, surface acoustic waves are not excited between the adjacent electrode fingers.

On the other hand, in the longitudinally coupled resonator type surface acoustic wave filter 2008, the IDT 2001 of the longitudinally coupled resonator type surface acoustic wave filter 2007 is reversed in direction from the IDT 2001.
According to 2004, the phase of the output signal with respect to the input signal of the longitudinally coupled resonator type surface acoustic wave filter 2007 is about 18
Since they are different from each other by 0 degrees, the outermost electrode fingers of the IDT 2004 are signal electrodes, and the outermost electrode fingers of the IDTs 2005 and 2006 are ground electrodes.

Therefore, in the longitudinally coupled resonator type surface acoustic wave filter 2008, unlike the case of the longitudinally coupled resonator type surface acoustic wave filter 2007, the surface acoustic wave is excited between the adjacent electrode fingers. When compared as a whole, the longitudinally coupled resonator type surface acoustic wave filter 200 is compared.
7, a longitudinally coupled resonator type surface acoustic wave filter 200 is provided.
In No. 8, the number of places where surface acoustic waves are excited increases by two.

As a result, in the second conventional example, the effective current of the surface acoustic wave in the adjacent electrode finger spacing is made by the longitudinally coupled resonator type surface acoustic wave filter 2007 and the longitudinally coupled resonator type surface acoustic wave filter 2008. 72 have different intensity distributions, and as a result, among the three resonance modes shown in FIG.
The distance between the resonance mode located at the center and the resonance mode located at the highest frequency side was different, and the degree of balance between the balanced signal terminals was deteriorated.

Next, FIG. 36 shows the longitudinally coupled resonator type surface acoustic wave filters 1918 and 1920 shown in FIG.
The excitation state of the surface acoustic wave is shown in the vicinity (the portion circled in the figure) where the IDTs are adjacent to each other. Similarly to FIG. 35, also in FIG. 36, only the three electrode fingers from the end of the portion where the IDTs are adjacent to each other are shown, and the others are omitted.

The longitudinally coupled resonator type surface acoustic wave filters 1918 and 1920 shown in FIG. 33 correspond to the longitudinally coupled resonator type surface acoustic wave filters 2107 and 2108 shown in FIG. 36, and the longitudinally coupled resonator type surface acoustic wave shown in FIG. Filter 191
The IDTs 1902, 1901 and 1903 of FIG. 8 are the same as the IDTs 2102, 2101, 2103 of FIG. 36 and the IDT of the longitudinally coupled resonator type surface acoustic wave filter 1920 of FIG.
1901a, 1902, and 1903 are IDT2s in FIG.
104, 2105, and 2106, respectively.

In the case of the fourth embodiment, by inverting the direction of the IDT connected to the input side, the phase of the output signal with respect to the longitudinally coupled resonator type surface acoustic wave filter 2107 and the input signal is about 180 degrees. In the different longitudinally coupled resonator type surface acoustic wave filters 2108, the outermost electrode fingers of the IDT 2104 are thinned and weighted, and the dummy electrode 2 is attached to that portion.
109 (dummy electrode 1901b in FIG. 33) is provided and connected to the ground.

Therefore, in the longitudinally coupled resonator type surface acoustic wave filter 2108, the signal electrode finger and the ground electrode finger are alternately arranged in the portion 2110 where the two IDTs on one side are adjacent to each other, so that the surface acoustic wave is excited. On the other hand, in the portion 2111 where the other two IDTs are adjacent to each other, there are two portions where surface acoustic waves are not excited because three ground electrode fingers are lined up.

As a result, the longitudinally coupled resonator type surface acoustic wave filter 2107 and the longitudinally coupled resonator type surface acoustic wave filter 21 are provided.
In 08, since the total number of places where surface acoustic waves are not excited between the electrode fingers, that is, the total number of places where surface acoustic waves are excited between the electrode fingers are equal, the spacing of the resonance mode is smaller than that of the second conventional example. The difference is reduced, and the amplitude balance between the balanced signal terminals is improved.

For example, a first longitudinally coupled resonator type surface acoustic wave filter 2202 in which two longitudinally coupled resonator type surface acoustic wave filters 2201 as shown in FIG. 37 are connected in cascade, and a first longitudinally coupled resonator. Of the first longitudinally coupled resonator type surface acoustic wave by reversing the direction of the IDT 2203 of the longitudinally coupled resonator type surface acoustic wave filter 2201a connected to the output side of the second stage with respect to the surface acoustic wave filter 2202. Filter 2
202 is the phase of the output signal with respect to the input signal is about 180
An unbalanced signal terminal having the second longitudinally coupled resonator type surface acoustic wave filter 2204 and the central IDTs of the first staged longitudinally coupled resonator type surface acoustic wave filters 2201 connected in parallel. 2205 is the center I of each of the longitudinally coupled resonator type surface acoustic wave filters 2201 and 2201a in the second stage.
The balanced signal terminal 2206 may be formed by connecting DTs in series.

Even in the above case, the outermost electrode finger of the IDT 2203 is thinned and weighted, and the dummy electrode 220 is attached to that portion.
By providing 7 and connecting to the ground, the excited state of the surface acoustic wave in the vicinity (the part circled in FIG. 37) where two IDTs in the output side longitudinally coupled resonator type surface acoustic wave filter are adjacent to each other is As shown in FIG. 38, in the first longitudinally coupled resonator type surface acoustic wave filter 2202 and the second longitudinally coupled resonator type surface acoustic wave filter 2204, the total number of locations where surface acoustic waves are not excited between the electrode fingers, That is, since the total number of locations where surface acoustic waves are excited between the electrode fingers are equal to each other, the amplitude balance between the balanced signal terminals is improved.

Further, as shown in FIG. 39, instead of the central IDT of the second-stage longitudinally coupled resonator type surface acoustic wave filter,
By inverting the direction of the outer IDT, the phase of the output signal may differ from the input signal by about 180 degrees.

Also in the above case, the direction I is reversed.
The outermost electrode fingers of one of the IDTs of the DT 2301 are thinned and weighted, and dummy electrode fingers 2302 are provided at that portion to be connected to the ground, whereby two IDTs in the output side longitudinally coupled resonator type surface acoustic wave filter are provided. As shown in FIG. 40, the excited state of the surface acoustic wave in the vicinity (the part surrounded by circle in FIG. 39) adjacent to is as shown in FIG. 40, the first longitudinally coupled resonator type surface acoustic wave filter 2303 and the second longitudinally coupled resonator. In the resonator type surface acoustic wave filter 2304, since the total number of places where surface acoustic waves are not excited between the electrode fingers, that is, the total number of places where surface acoustic waves are excited between the electrode fingers are equal to each other,
The degree of amplitude balance between the balanced signal terminals is improved.

Also, as shown in FIG. 41, in the case where a 5IDT type longitudinally coupled resonator type surface acoustic wave filter is used instead of the 3IDT type longitudinally coupled resonator type surface acoustic wave filter shown in FIG. , The outermost electrode finger on one side of the IDT 2401 whose direction is reversed is thinned and weighted, and a dummy electrode finger 2402 is attached to that portion.
Is provided and is connected to the ground, so that in the first longitudinally coupled resonator surface acoustic wave filter 2403 and the second longitudinally coupled resonator surface acoustic wave filter 2404, the surface acoustic wave is not excited between the electrode fingers. , That is, the total number of locations where surface acoustic waves are excited between the electrode fingers are equal to each other, so that the degree of amplitude balance between the balanced signal terminals is improved.

As described above, in the fourth embodiment, two surface acoustic wave filters in which the phase of the output signal differs from the input signal by about 180 degrees are connected in series on the balanced signal terminal side and in parallel on the unbalanced signal terminal side. By connecting and providing a balanced-unbalanced conversion function, and by further thinning and weighting a configuration in which one surface acoustic wave filter is cascade-connected to each of the two surface acoustic wave filters, a conventional surface acoustic wave device is provided. Also, a surface acoustic wave device having an improved balance between balanced signal terminals can be obtained.

(Fifth Embodiment) A fifth embodiment of the present invention will be described with reference to FIGS. 42 to 46. In the fifth embodiment of the present invention, a DCS reception filter will be described as an example.

In the fifth embodiment, two longitudinally coupled resonator type surface acoustic wave filters shown in FIG. 16 in which the phase of the output signal differs from that of the input signal by about 180 degrees are connected in series on the balanced signal terminal side, and the unbalanced signal is connected. The terminal side is an example in which weighting is applied to a configuration in which the terminals are connected in parallel and have a balanced-unbalanced conversion function.

In the fifth embodiment, a longitudinally coupled resonator type surface acoustic wave filter 2501 on the piezoelectric substrate 8 and a surface acoustic wave resonator 2502 connected in series to the longitudinally coupled resonator type surface acoustic wave filter 2501. And 2503 are formed by Al electrodes. The two longitudinally coupled resonator type surface acoustic wave filters have an output signal whose phase is about 18 times that of the input signal.
All have the same design except 0 degrees apart. In addition, in the fifth embodiment, as in the third embodiment, two IDTs are used.
Several narrow pitch electrode fingers are provided between adjacent to each other.

The detailed design of the longitudinally coupled resonator type surface acoustic wave filter has a wavelength λI determined by the pitch of the narrow pitch electrode fingers.
₂ , and the wavelength determined by the pitch of the other electrode fingers is λI ₁ , the crossing width is 37.12λI _{1 The} number of IDTs (2504, 2505, 2506 in this order):
(4) 19 / (4) 31 (4) / 19 (4) (number of electrode fingers with narrow pitch in parentheses) IDT wavelength λI ₁ : 2.156 μm, λI ₂ : 1.92
6 μm Reflector wavelength λR: 2.177 μm Number of reflectors: 150 IDT-IDT interval: Place between electrode fingers of wavelengths λI ₁ and λI ₂ : 0.25λI ₁ + 0.25λI ₂ , wavelength λ
Place between I ₂ electrode fingers: 0.50 λ I ₂ IDT-reflector spacing: 0.50 λR IDT duty: 0.63 Reflector duty: 0.60 Electrode film thickness: 0.09 λ I ₁ surface acoustic wave resonator 2502 The detailed design of is shown below. Crossover width: 14.3λI Number of IDTs: 241 IDT wavelength and reflector wavelength: 2.102 μm Number of reflectors: 30 IDT-reflector spacing: 0.50λR The detailed design of the surface acoustic wave resonator 2503 is described below. Show. Crossover width: 37.1λI Number of IDTs: 241 IDT wavelength and reflector wavelength: 2.023 μm Number of reflectors: 30 IDT-reflector interval: 0.50λR.

The feature of the fifth embodiment is that it is located at the end of the IDT 2509, which is inverted in order to make the phase of the output signal with respect to the input signal of the surface acoustic wave filter 2508 different from the surface acoustic wave filter 2507 by about 180 degrees. One of the signal electrode fingers is thinned out, a dummy electrode 2510 connected to the ground is provided at that portion, and the ground electrode of each of the three IDTs is shared via the dummy electrode 2510. .

Next, the operation and effect of the fifth embodiment will be described. First, FIG. 43 shows the amplitude balance between the balanced signal terminals with respect to the frequency in the configuration of the fifth embodiment.
For comparison, the amplitude balance between the balanced signal terminals with respect to the frequency in the third comparative example shown in FIG. 44 is also shown in FIG. 43. The configuration of the third comparative example in FIG. 44 is exactly the same as the configuration of the fifth embodiment except that no thinning weighting is applied.

The frequency range of the pass band in the DCS reception filter is 1805 MHz to 1880 MHz.
In the third comparative example, the degree of amplitude balance between the balanced signal terminals in this range is -1.0 dB to +3.2 dB (deviation of 4.2 dB).
B), the fifth embodiment is -0.5 dB.
The amplitude balance is improved to about +1.5 dB (deviation of 2.0 dB), which is about 2.2 dB.

The reason why the effect of the fifth embodiment is obtained will be described. In the third comparative example shown in FIG. 44, as shown in FIG. 45, the IDTs are adjacent to each other (a part surrounded by a circle in FIG. 44). 46), the number of locations where surface acoustic waves are excited differs between the first surface acoustic wave filter 2601 and the second surface acoustic wave filter 2602, while in the case of the fifth embodiment, FIG. As shown in FIG. 24, the number of places where surface acoustic waves are excited around the IDTs adjacent to each other (the portion surrounded by a circle in FIG. 42) is the same as that of the first longitudinally coupled resonator surface acoustic wave filter 2511 and the second surface acoustic wave filter 2511. The same applies to the surface acoustic wave filter 2512. For this reason, among the three resonance modes shown in FIG. 72, the interval between the resonance mode seen at the center of the band and the resonance mode seen at the high band side is between the signals output from the two balanced signal terminals. This is because they are more consistent than in the third comparative example.

As described above, in the fifth embodiment, two longitudinally coupled resonator type surface acoustic wave filters in which the phase of the output signal differs from the input signal by about 180 degrees are connected in series on the balanced signal terminal side, and the unbalanced signal terminal is connected. The side is connected in parallel and thinned and weighted in the configuration with the balanced-unbalanced conversion function.
It is possible to obtain a surface acoustic wave device in which the degree of balance between balanced signal terminals is improved as compared with the conventional surface acoustic wave device.

The grounding of the surface acoustic wave device is strengthened by sharing the grounding of each of the three IDTs, including the dummy electrode 2510 provided at the thinned-out position. Out-of-band attenuation is improved.
Further, it is possible to omit the ground terminal of the IDT in the central portion.

(Sixth Embodiment) A sixth embodiment of the present invention will be described with reference to FIGS. 47 to 54. In the sixth embodiment, a DCS reception filter will be described as an example.

Like the third embodiment, the sixth embodiment has one longitudinally coupled resonator type surface acoustic wave filter 2701.
The balanced signal terminals 2711 and 2712 are connected to the comb-teeth electrodes serving as the two poles of one IDT 2704 in FIG. 1, respectively, and the balanced signal terminals 2711 and 2712 have a configuration in which there is no electrical neutral point grounded to the ground. This is an example of weighting.

In the sixth embodiment, the piezoelectric substrate 8 described above is used.
A longitudinally coupled resonator type surface acoustic wave filter 2701 and surface acoustic wave resonators 2702 and 2703 connected in series to the longitudinally coupled resonator type surface acoustic wave filter 2701 are formed by an Al electrode.

Vertically coupled resonator type surface acoustic wave filter 270
The configuration of 1 is IDT2705 on the left and right of IDT2704,
2706 is placed and these IDTs are sandwiched between them.
Reflectors 2707 and 2708 are formed.

In the sixth embodiment, similar to the third embodiment, several narrow pitch electrode fingers are provided between two IDTs adjacent to each other (at 2709 and 2710 in FIG. 47). Terminals 2711 and 2712 are balanced signal terminals, 271
Reference numeral 3 is an unbalanced signal terminal. FIG. 48 shows the IDT of FIG.
An enlarged view between 2704 and 2705 is shown.

IDT connected to balanced signal terminal 2711
The outermost electrode finger 2704a of 2704 is weighted with a cross width and further weighted, and a dummy electrode 2705a is provided at the deleted portion and is connected to the ground.

Vertically coupled resonator type surface acoustic wave filter 270.
In the detailed design of No. 1, the wavelength determined by the pitch of the narrow pitch electrode fingers is λ I ₂ , and the wavelength determined by the pitch of the other electrode fingers is λ ₂ .
Let I ₁ be: crossing width: crossing width is not weighted (280 in FIG. 48)
5): 71.2λI ₁ cross width weighted portion (2806 in FIG. 48): 35.
Number of 6λI ₁ IDTs (in the order of 2705, 2704, 2706): 2
1 (4) / (4) 35 (4) / (4) 21 (number of electrode fingers with a smaller pitch in parentheses) IDT wavelength λI ₁ : 2.18 μm, λI ₂ : 1.96 μm Reflector wavelength λR : 2.18 μm Number of reflectors: 150 IDT-IDT interval: Location sandwiched between electrode fingers of wavelengths λI ₁ and λI ₂ (2714 in FIG. 47): 0.25λI ₁ +0.
25λI ₂ A part sandwiched between electrode fingers of wavelength λI ₂ (271 in FIG. 47).
5): 0.50 λI ₂ IDT-reflector interval: 0.460 λR IDT duty: part where pitch is not narrowed: 0.6
3. Part where pitch is narrowed: 0.60 Reflector duty: 0.57 Electrode film thickness: 0.09 λI ₁ The detailed design of the surface acoustic wave resonator 2702 is shown below. Crossover width: 23.6λI Number of IDTs: 241 IDT wavelength and reflector wavelength: 2.12 μm Number of reflectors: 30 IDT-reflector spacing: 0.50λR The detailed design of the surface acoustic wave resonator 2703 is as follows. Show. Crossover width: 58.5λI Number of IDTs: 241 IDT wavelength and reflector wavelength: 2.04 μm Number of reflectors: 30 IDT-reflector interval: 0.50λR.

The feature of the sixth embodiment is that the central IDT 270 adjacent to the ground electrode finger and connected to the balanced signal terminal.
4 are formed by forming cross-weighted electrode fingers 2704a in which the cross-weighted electrode fingers located at both ends of the No. 4 are formed, and dummy electrodes 2705a, 270 are formed at the cross-weighted portions.
6a is provided and connected to the ground.

Next, the operation and effect of the sixth embodiment will be described. FIG. 49 shows the amplitude balance between the balanced signal terminals with respect to the frequency in the configuration of the sixth embodiment. As a comparison, the amplitude balance between the balanced signal terminals with respect to the frequency in the fourth comparative example shown in FIG. 50 is also shown in FIG. 49. The configuration of the fourth comparative example of FIG. 50 is different from that of the sixth embodiment except that the longitudinally coupled resonator type surface acoustic wave filter 2701a in which the electrode fingers at both ends of the central IDT are not cross-weighted is used. The structure is exactly the same. The frequency range of the pass band in the DCS reception filter is 1805 MHz to 1
It is 880 MHz.

The amplitude balance between the balanced signal terminals in this range is -1.3 dB to +3.3 dB (deviation 4.6 dB) in the fourth comparative example, whereas in the sixth embodiment it is-.
The amplitude balance is improved from 2.0 dB to +1.9 dB (deviation 3.9 dB), which is about 0.7 dB.

Further, in the fourth comparative example, the amplitude balance between the balanced signal terminals is largely deviated to the + side, but in the sixth embodiment, the deviations in the + direction and the-direction are substantially equal.
When the deviations in the + direction and the-direction are substantially equal as in the sixth embodiment, the noise level of the in-phase signal becomes smaller than when the deviations are largely deviated to either the + side or the-side. Therefore, the sixth embodiment is also superior in this respect.

The reason why the effect of the sixth embodiment is obtained is as follows.
The electrode fingers on both ends of the central IDT 2704 adjacent to the ground electrode finger are cross-weighted, and dummy electrodes are provided at the positions where the cross-width is weighted to connect to the ground to balance with the IDT connected to the balanced signal terminal 2711. This is because the electrode fingers on both ends of the IDT connected to the terminal 2712 come to be adjacent to the ground electrode fingers, and therefore the polar relationship with the adjacent electrode fingers is the same.

Next, the result of investigation of the optimum value of the cross width weighting will be described. The survey method is shown in FIGS.
In the configuration of FIG.
The ratio of the cross width 2806 of the weighted portion (hereinafter, cross width weighting ratio) was changed and the change in the amplitude balance between the balanced signal terminals within the pass band was investigated.

The cross width weighting ratio is 1 in the case of FIG. 50 not weighted and 1/2 in the case of FIG. 47, and when the cross width weighting ratios are 1/4, 1/2, and 3/4, The amplitude balance between the balanced signal terminals was investigated. FIG. 51
Fig. 7 shows the result value of the amplitude balance degree between the balanced signal terminals when the crossing width weighting ratio is changed. In FIG. 51,
As for the degree of amplitude balance between the balanced signal terminals, the deviation on the + side is plotted.

From FIG. 51, the cross width weighting ratio is set to approximately 0.
In the case of 5, that is, when the weighting is performed at the position substantially in the center of the electrode finger, the amplitude balance between the balanced signal terminals in the pass band becomes the minimum. This is because the electrode fingers on both ends of the central IDT are weighted at positions substantially in the center and the weighted electrode fingers are connected to the ground, so that the IDT connected to the balanced signal terminal 2711 and the balanced signal terminal 2712 are connected. I
Since the ground electrode fingers are adjacent to the electrode fingers at both ends of the DT at about half of the overall crossing width, the effect is that the polarity relationship with the adjacent electrode fingers is the same.

As described above, in the sixth embodiment, one comb-shaped electrode of each IDT (preferably the center IDT) in one longitudinally coupled resonator type surface acoustic wave filter is balanced. In a configuration where the signal terminals are connected and there is no electrical neutral point grounded to earth,
By weighting the electrode fingers at both ends of the central IDT at a substantially central position and connecting a dummy electrode provided at a position removed by weighting to the ground, the balance between the balanced signal terminals can be improved as compared with the conventional surface acoustic wave device. A surface acoustic wave device having an improved amplitude balance is obtained.

In the sixth embodiment, the electrode fingers on both ends of the IDT connected to the balanced signal terminal are described as being adjacent to the ground electrode fingers on both sides. For example, as shown in FIG. Even in the configuration in which the ground electrode finger and the signal electrode finger on the other side are adjacent to each other, only the signal electrode finger on the side adjacent to the ground electrode finger is cross-weighted,
By connecting the dummy electrode provided at the position removed by weighting to the ground through the IDT, the surface acoustic wave device with improved amplitude balance between the balanced signal terminals can be obtained.

Further, as shown in FIG. 53, there are two or more IDTs.
Even in the configuration in which the balanced signal is extracted from both electrodes of the two electrodes, the outermost electrode fingers of each of the two IDTs are cross-width weighted and the weighted electrode fingers are connected to the ground via the IDT and the reflector so that the balanced signal terminals are The amplitude balance of can be improved.

In the sixth embodiment, the longitudinally coupled resonator type surface acoustic wave filter has a 3IDT type structure.
For example, also in the case of a longitudinally coupled resonator type surface acoustic wave filter having four or more IDTs, the electrode fingers at both ends of the IDT for extracting a balanced signal are cross-width weighted as shown in FIG. By connecting the provided dummy electrode to the ground via the IDT, the degree of amplitude balance between the balanced signal terminals can be improved.

(Seventh Embodiment) A seventh embodiment of the present invention will be described with reference to FIGS. 55 to 61.
In the seventh embodiment, a PCS reception filter will be described as an example.

In the seventh embodiment, like the third embodiment, the balanced signal terminals are respectively connected to the comb-teeth electrodes of both poles of one IDT of one longitudinally coupled resonator type surface acoustic wave filter, and are connected to the ground. It is an example in which a configuration having no grounded electrical neutral point is weighted.

In the seventh embodiment, the longitudinally coupled resonator type surface acoustic wave filter 2901 and the surface acoustic wave resonances connected in series to the longitudinally coupled resonator type surface acoustic wave filter 2901 are mounted on the piezoelectric substrate 8. The children 2902 and 2903 are formed of Al electrodes. The configuration of the seventh embodiment is basically the same as that of FIG. 29 of the third embodiment.

The feature of the seventh embodiment is that the electrode fingers 291 are
The duty of 9 and 2920 is 0.40. In the seventh embodiment, the signal line 291 is used.
A shield line 2921 connected to the ground is inserted between 2 and the balanced signal terminal 2910. By inserting a shield line that is connected to the ground at the location where the signal electrodes are adjacent to each other in this way, the bridging capacitance between the signal electrodes is reduced, and the balance between the balanced signal terminals is improved. A surface wave device is obtained.

The operation and effect of the seventh embodiment will be described below. In the configuration of the seventh embodiment shown in FIG. 56,
FIG. 57 shows the amplitude balance between the balanced signal terminals with respect to the frequency, and FIG. 57 shows the phase balance. For comparison, the amplitude balance and phase balance between the balanced signal terminals in the configuration of the second comparative example shown in FIG. 32 are also shown in FIGS. 56 and 57. The configuration of the second comparative example of FIG. 32 is different from that of the seventh embodiment in that d of electrode fingers adjacent to IDTs 2904 and 2906 of IDT 2905.
The configuration is exactly the same, except that the uty is not changed. P
The frequency range of the pass band in the CS receiving filter is 1
It is 930 MHz to 1990 MHz.

The deviation of the phase balance degree between the balanced signal terminals in this range is almost unchanged between the seventh embodiment and the second comparative example, but the amplitude balance degree between the balanced signal terminals is not changed in the second comparative example. -0.5 dB to +2.3 dB (deviation 2.8 dB)
On the other hand, in the seventh embodiment, −0.6 dB to +
With 2.0 dB (deviation of 2.6 dB), the amplitude balance is improved by about 0.2 dB.

Further, in the second comparative example, the amplitude balance degree and the phase balance degree between the balanced signal terminals are largely deviated to either the + side or the − side, but in the seventh embodiment, the + direction and the − direction are different. The difference in deviation is small. As in the seventh embodiment, the smaller the difference between the + direction and the-direction deviation, the more +
The seventh embodiment has the advantage that the noise level of the in-phase signal becomes smaller than the one greatly deviating to either the side or the minus side, and the seventh embodiment is also excellent in this respect.

The reason why the effect of the seventh embodiment is obtained is as follows.
By making the duty of the electrode fingers adjacent to the IDTs 2904 and 2906 of the IDT 2905 smaller than the duty of the other electrode fingers, the balanced signal terminals 2910 and 291 can be obtained.
This is an effect obtained by correcting the total capacitance of the electrode fingers connected to 1 and the conversion efficiency between the electric signal and the surface acoustic wave.

The difference in the total capacitance of the electrode fingers is particularly 2
Since the two IDTs are large at the positions adjacent to each other, the greatest effect can be obtained by adjusting the duty of the electrode fingers in this portion as in the seventh embodiment. In order to obtain a further effect, the duty of several electrode fingers near the location where two IDTs are adjacent to each other may be adjusted as shown in FIG.

Next, as another configuration of the seventh embodiment, as shown in FIG. 59, an IDT 2904a and an IDT 290 are provided.
6a shows the amplitude balance between the balanced signal terminals with respect to the frequency when the duty of the electrode fingers (3001 and 3002 in FIG. 59) adjacent to the IDT 2905b is smaller than the duty of the other electrode fingers. FIG. 61 shows the degree of phase balance. At this time, the electrode fingers 3001 and 30
The duty of 02 is 0.40.

For comparison, the amplitude balance and phase balance between the balanced signal terminals in the configuration of the second comparative example of FIG. 32 are also shown in FIGS. 60 and 61. The deviation of the phase balance between the balanced signal terminals in this range is almost the same between the modified example of the seventh embodiment and the second comparative example. In the example, -0.5 dB to +2.
3 dB (deviation 2.8 dB), in the modified example of the seventh embodiment, -0.5 dB to +2.0 dB (deviation 2.5 dB), the amplitude balance is improved by about 0.3 dB. .

As described above, the effect of the present invention can also be obtained by adjusting the duty of the electrode finger of the IDT connected to the unbalanced signal terminal as shown in FIG. Of course, in addition to this, the effect of the present invention can be obtained by adjusting the duty of the IDT 2905b.

As described above, in the seventh embodiment, the balanced signal terminals are respectively connected to the comb-teeth electrodes which are the both poles of one IDT in one longitudinally coupled resonator type surface acoustic wave filter, and are connected to the ground. In a configuration that does not have an electrical neutral point that is grounded to, a weighting is applied to a part of the IDT, particularly a portion where two IDTs are adjacent to each other, so that the signal between the balanced signal terminals is greater than that in the conventional surface acoustic wave device. A surface acoustic wave device having an improved amplitude balance is obtained.

(Eighth Embodiment) An eighth embodiment according to the present invention will be described with reference to FIGS. 62 to 64. The configuration of the eighth embodiment does not only set the duty of only the electrode fingers adjacent to the IDT 2904 and IDT 2906 of the IDT 2905 to 0.40 as in the seventh embodiment, but in the eighth embodiment, Signal terminal 291
The duty of the electrode finger of IDT2905 connected to 0
For all other electrode fingers, for example smaller,
It is set to 0.40. All other configurations are the same as the configurations of the seventh embodiment.

The operation and effect of the eighth embodiment will be described below. FIG. 63 shows the amplitude balance between the balanced signal terminals with respect to the frequency in the configuration of the eighth embodiment.
4 shows the degree of phase balance. For comparison, the amplitude balance and phase balance between the balanced signal terminals in the configuration of the second comparative example shown in FIG. 32 are also shown in FIGS. 63 and 64. In the frequency range of the pass band of the PCS reception filter, the phase balance between the balanced signal terminals is slightly worse than that in the second comparative example, but the amplitude balance between the balanced signal terminals is about the same as that in the second comparative example. It is improved by 0.5 dB.

Further, in the second comparative example, the amplitude balance degree and the phase balance degree between the balanced signal terminals are largely deviated to either the + side or the − side, but in the eighth embodiment, the + direction and the − direction are different. The difference in deviation is small. As in the eighth embodiment, the smaller the difference between the + direction and the-direction deviation, the more
The eighth embodiment has the advantage that the noise level of the in-phase signal becomes smaller than the one that is greatly deviated to either the side or the negative side, and the eighth embodiment is also excellent in this respect.

As described above, in the eighth embodiment, the balanced signal terminals are respectively connected to the comb-shaped electrodes of both poles of one IDT of one longitudinally coupled resonator type surface acoustic wave filter, and they are grounded. In the configuration having no electrical neutral point, the duty balance is applied to all electrode fingers connected to one of the balanced signal terminals, so that the amplitude balance degree between the balanced signal terminals is higher than that of the conventional surface acoustic wave device. A surface acoustic wave device having improved characteristics is obtained.

As shown in FIG. 62, by adjusting all the duty of the electrode fingers of the IDT 2905c connected to the balanced signal terminal 2910, the amplitude balanced degree between the balanced signal terminals can be further improved, but the phase balanced degree is On the contrary, it gets worse. However, as shown in FIG. 55 and FIG. 58, by adjusting the required number without adjusting all the electrode fingers, or by varying the adjustment amount of the duty for each electrode finger, the phase between the balanced signal terminals can be changed. It is possible to improve the amplitude balance without degrading the balance.

(Ninth Embodiment) A ninth embodiment of the present invention will be described with reference to FIG. The ninth embodiment basically has the same configuration as the seventh embodiment, but the duty of the electrode fingers 3003 of the IDT 2905d is reduced at the position where the IDT 2904 and the IDT 2905d are adjacent to each other, and the IDT 2905d and the IDT 2905d are further reduced.
IDT 2906b at a position adjacent to 2906b
The outermost signal electrode fingers are thinned out, and the dummy electrode 3004 connected to the ground is placed at the thinned out position, and the thinning weighting is performed.

Next, the operation and effect of the ninth embodiment will be described. In this way, by mixing two kinds of weighting methods or mixing several kinds of weighting methods in one longitudinally coupled resonator type surface acoustic wave filter,
The degree of freedom in adjusting the degree of balance between the balanced signal terminals is improved, and a surface acoustic wave device having a balanced signal terminal having a desired degree of balance between the balanced signal terminals can be obtained.

In each of the above embodiments, the 40 ± 5 ° YcutX propagation LiTaO ₃ substrate was used as the piezoelectric substrate, but the present invention is not limited to this substrate, as shown by the principle that the effect can be obtained. 72 ° YcutX propagation LiN
Similar effects can be obtained with a substrate such as bO ₃ or 41 ° YcutX propagation LiNbO ₃ .

In a surface acoustic wave device having a balanced-to-unbalanced conversion function by using two surface acoustic wave filters having three or more IDTs, the surface acoustic wave is applied to the electrode fingers of the surface acoustic wave filter. Is preferably weighted in the direction in which As a result, it is possible to improve the degree of amplitude balance in the pass band while suppressing the narrowing of the pass band width.

As an example of such weighting in the direction in which the excitation of the surface acoustic wave becomes strong, one surface acoustic wave device (first surface acoustic wave device) is not weighted and the other surface acoustic wave device ( For both the outermost electrode fingers (more preferably the signal electrode fingers) of the center IDT of the second surface acoustic wave device), thinning weighting, cross weighting (including formation of dummy electrodes), or serial weighting (most preferable) is performed. Preferred).

Further, although various weightings have been described in the above-mentioned respective embodiments, they have independent actions and effects, and even if they are used in any combination of two or more, the present application The effect of the invention can be obtained.

FIG. 6 shows a communication device equipped with the surface acoustic wave device according to each of the above embodiments according to the present invention.
The description based on 6 is as follows. As shown in FIG. 66, the communication device 3100 equipped with the surface acoustic wave device according to any one of the first to ninth embodiments has an antenna 3101, an antenna common unit / as a receiver side (Rx side) for receiving. RFTop filter 3102, amplifier 310
3, Rx interstage filter 3104, mixer 3105, 1s
tIF filter 3106, mixer 3107, 2ndIF
Filter 3108, 1st + 2nd local synthesizer 3111, TCXO (Temperature Compensated crys)
tal Oscillator 3112,
It comprises a divider 3113 and a local filter 3114. It is preferable to transmit each balanced signal from the Rx interstage filter 3104 to the mixer 3105 in order to secure the balance between the balanced signal terminals, as indicated by the double line in FIG. 66.

Also, the communication device 3100 has the antenna 31 as the transceiver side (Tx side) for transmission.
01 and the antenna common part / RFTop filter 3
102 is shared, and TxIF filter 312
1, mixer 3122, Tx interstage filter 3123, amplifier 3124, coupler 3125, isolator 3126,
APC (Automatic Power Control)
3127 is provided.

Then, the above Rx interstage filter 3104
For the above, the surface acoustic wave device according to any of the first to ninth embodiments described above can be preferably used.

Therefore, in the communication device 3100, since the surface acoustic wave device used has a small size and is excellent in the transmission characteristic, the communication device 3100 has a small transmission characteristic (especially in the GHz band or higher) and a transmission characteristic (communication characteristic). It has excellent characteristics).

[0226]

As described above, the surface acoustic wave device of the present invention has at least one surface acoustic wave filter having at least two IDTs formed along the propagation direction of the surface acoustic wave on the piezoelectric substrate. A surface acoustic wave device configured as described above, wherein at least one of an input signal terminal and an output signal terminal of the surface acoustic wave device is connected to a balanced signal terminal, and at least a part of electrode fingers of the surface acoustic wave filter. Are weighted.

Therefore, in the above-mentioned structure, weighting is performed, so that the degree of balance between the balanced signal terminals can be improved.

As described above, the surface acoustic wave device of the present invention has the input IDT having a plurality of electrode fingers on the piezoelectric substrate.
And an output IDT having a plurality of electrode fingers are formed along the propagation direction of the surface acoustic wave, and each inner electrode different from the outermost electrode finger of at least one of the input IDT and the output IDT. The finger has a weighted electrode finger.

Therefore, the above-described structure has an effect that, by providing the weighted electrode fingers, for example, the degree of balance (balance) between the balanced terminals can be improved.

The communication device of the present invention is characterized by using the surface acoustic wave device as described above.

Therefore, the above-mentioned configuration is miniaturized, especially GH.
In the z band or higher, the effect of excellent transmission characteristics (communication characteristics) is achieved while achieving miniaturization.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram of a surface acoustic wave device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a main configuration of a surface acoustic wave device of a first comparative example.

FIG. 3 is a main part configuration diagram of a surface acoustic wave device according to a modification of the first embodiment.

FIG. 4 is a main part configuration diagram for explaining a weighting region in the surface acoustic wave device of the first embodiment.

FIG. 5 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave device.

FIG. 6 is a graph showing the degree of phase balance (phase balance) of the surface acoustic wave device.

FIG. 7 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave device of the first comparative example.

FIG. 8 is a graph showing the degree of phase balance (phase balance) of the surface acoustic wave device of the first comparative example.

FIG. 9 is a main part configuration diagram of a surface acoustic wave device according to another modification of the first embodiment.

FIG. 10 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 11 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 12 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 13 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 14 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 15 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 16 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 17 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 18 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 19 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 20 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 21 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 22 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 23 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the first embodiment.

FIG. 24 is a configuration diagram of essential parts of a surface acoustic wave device according to a second embodiment of the present invention.

FIG. 25 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave device.

FIG. 26 is a graph showing the phase balance of the surface acoustic wave device.

FIG. 27 is a graph showing transmission characteristics of the surface acoustic wave device according to the first embodiment.

FIG. 28 is a graph showing transmission characteristics of the surface acoustic wave device according to the second embodiment.

FIG. 29 is a main part configuration diagram of a surface acoustic wave device according to a third embodiment of the present invention.

FIG. 30 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave devices according to the third embodiment and the second comparative example.

FIG. 31 is a graph showing the phase balance of the surface acoustic wave devices according to the third embodiment and the second comparative example.

FIG. 32 is a main part configuration diagram of a surface acoustic wave device according to a second comparative example.

FIG. 33 is a main part configuration diagram of a surface acoustic wave device according to a fourth embodiment of the present invention.

FIG. 34 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave devices according to the fourth embodiment and the second conventional example.

FIG. 35 is a main part configuration diagram for showing balance deterioration in the second conventional example.

FIG. 36 is a main part configuration diagram for showing balance improvement in the fourth embodiment.

FIG. 37 is a main-portion configuration diagram of a surface acoustic wave device according to a modification example of the fourth embodiment.

FIG. 38 is a main-part configuration diagram for showing balance improvement in a modification of the fourth embodiment.

FIG. 39 is a main part configuration diagram of a surface acoustic wave device which is another modification of the fourth embodiment.

FIG. 40 is a main-part configuration diagram for showing balance improvement in another modification of the fourth embodiment.

FIG. 41 is a configuration diagram of a main part of a surface acoustic wave device which is still another modification example of the fourth embodiment.

FIG. 42 is a configuration diagram of main parts of a surface acoustic wave device according to a fifth embodiment of the present invention.

FIG. 43 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave devices according to the fifth embodiment and the third comparative example.

FIG. 44 is a main-portion configuration diagram of a surface acoustic wave device according to the third comparative example.

FIG. 45 is a main-part configuration diagram for showing balance deterioration in the third comparative example.

FIG. 46 is a main part configuration diagram for showing balance improvement in the fifth embodiment.

FIG. 47 is a main-portion configuration diagram of a surface acoustic wave device according to a sixth embodiment of the present invention.

FIG. 48 is an enlarged configuration diagram of main parts of the surface acoustic wave device according to the sixth embodiment.

FIG. 49 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave devices according to the sixth embodiment and the fourth comparative example.

FIG. 50 is a main part configuration diagram of a surface acoustic wave device according to a fourth comparative example.

FIG. 51 is a graph showing a change in amplitude balance (amplitude balance) with a change in cross width in the surface acoustic wave device according to the sixth embodiment.

FIG. 52 is a main part configuration diagram of a surface acoustic wave device according to a modification of the sixth embodiment.

FIG. 53 is a main part configuration diagram of a surface acoustic wave device according to another modification of the sixth embodiment.

FIG. 54 is a main part configuration diagram of a surface acoustic wave device according to still another modification of the sixth embodiment.

FIG. 55 is a main-part configuration diagram of a surface acoustic wave device according to a seventh embodiment of the present invention.

FIG. 56 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave devices according to the seventh embodiment and the second comparative example.

FIG. 57 is a graph showing the phase balance of the surface acoustic wave devices according to the seventh embodiment and the second comparative example.

FIG. 58 is a main-portion configuration diagram of a surface acoustic wave device according to a variation of the seventh embodiment.

FIG. 59 is a main-portion configuration diagram of a surface acoustic wave device according to another modification of the seventh embodiment.

FIG. 60 is another modification of the seventh embodiment,
It is a graph which shows the degree of amplitude balance (amplitude balance) of the surface acoustic wave device concerning the second comparative example.

FIG. 61 is another modification of the seventh embodiment,
It is a graph which shows the phase balance of the surface acoustic wave device concerning the second comparative example.

FIG. 62 is a main-part configuration diagram of a surface acoustic wave device according to an eighth embodiment of the present invention.

FIG. 63 is a graph showing the degree of amplitude balance (amplitude balance) of the surface acoustic wave devices according to the eighth embodiment and the second comparative example.

FIG. 64 is a graph showing a phase balance of the surface acoustic wave device according to the eighth embodiment and the second comparative example.

FIG. 65 is a main part configuration diagram of a surface acoustic wave device according to a ninth embodiment of the present invention.

FIG. 66 is a block diagram of main parts of the communication device of the present invention.

FIG. 67 is a main part configuration diagram of a surface acoustic wave device of a first conventional example.

FIG. 68 is a main part configuration diagram of a surface acoustic wave device according to a second conventional example.

FIG. 69 is a graph showing a difference in insertion loss between balanced signal terminals in the related art.

FIG. 70 is a main part configuration diagram of one surface acoustic wave device for showing a difference in insertion loss between the balanced signal terminals in the conventional art.

71 is a main part configuration diagram of the other surface acoustic wave device for showing a difference in insertion loss between the balanced signal terminals in the related art.

FIG. 72 is a schematic configuration diagram for explaining the resonance mode in the surface acoustic wave device, in which (a) is a graph showing the frequency relationship of the resonance mode and (b) shows the effective current distribution of the resonance mode. And a graph of current distribution corresponding thereto.

FIG. 73 is a main part configuration diagram of a surface acoustic wave device according to a third conventional example.

[Explanation of symbols] 1 IDT (comb type electrode part) 2 IDT (comb type electrode part) 3 IDT (comb type electrode part) 22 Signal electrode finger (inner electrode finger) 21a dummy electrode 22a Cross-weighting electrode fingers 31a Dummy electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroki Watanabe             2-10-10 Tenjin, Nagaokakyo, Kyoto Stock             Murata Manufacturing Co., Ltd. (72) Inventor Yu Yada             2-10-10 Tenjin, Nagaokakyo, Kyoto Stock             Murata Manufacturing Co., Ltd. (72) Inventor Youichi Sawada             2-10-10 Tenjin, Nagaokakyo, Kyoto Stock             Murata Manufacturing Co., Ltd. F term (reference) 5J097 AA11 BB03 BB11 BB14 CC03                       CC09 CC14 DD04 DD07 DD10                       DD13 GG03 KK04

Claims (54)

[Claims] 1. A surface acoustic wave filter having at least two comb-shaped electrode portions formed on a piezoelectric substrate along a surface acoustic wave propagation direction, and an input signal terminal for the surface acoustic wave filter. And a surface acoustic wave device comprising an output signal terminal, wherein at least one of the input signal terminal and the output signal terminal is connected to a balanced signal terminal, and at least a part of the electrodes of the surface acoustic wave filter. A surface acoustic wave device in which a finger is weighted. 2. The part of the electrode fingers is weighted so as to improve at least one of amplitude balance and phase balance between the pair of balanced signal terminals. The surface acoustic wave device described. 3. The weighting is performed from at least one of the adjacent comb-shaped electrode portions of the surface acoustic wave filter to the several electrode fingers from the outermost electrode finger at the portion where the comb-shaped electrode portions are adjacent to each other. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is applied to the surface acoustic wave device. 4. The weighting is performed on at least one of the comb-shaped electrode portions adjacent to each other of the surface acoustic wave filter, and the weighted weights are located in the vicinity of the outermost electrode fingers where the comb-shaped electrode portions are adjacent to each other. The surface acoustic wave device according to claim 1 or 2, wherein the surface acoustic wave device is applied to the electrode finger. 5. The weighting is performed from the outermost electrode finger at a location where the comb-shaped electrode portions are adjacent to each other in at least one of the comb-shaped electrode portions adjacent to each other of the surface acoustic wave filter to the comb-shaped electrode portion. The surface acoustic wave device according to any one of claims 1 to 4, wherein the surface acoustic wave device is applied to the electrode fingers within a range within 1/2 of the surface acoustic wave propagation direction. 6. The weighting is applied to outermost electrode fingers at positions where the comb-shaped electrode portions of at least one of the adjacent comb-shaped electrode portions of the surface acoustic wave filter are adjacent to each other. The surface acoustic wave device according to claim 1 or 2. 7. The electrode fingers at the mutually adjacent portions of the adjacent comb-shaped electrode portions of the surface acoustic wave filter are a ground electrode finger and a signal electrode finger, respectively, and at least one of the ground electrode finger and the signal electrode finger. The surface acoustic wave device according to any one of claims 1 to 6, wherein the weighting is applied to. 8. The surface acoustic wave device according to claim 1, wherein the weighted electrode fingers are signal electrode fingers of the surface acoustic wave filter. 9. The weighting is applied to an electrode finger of a comb-shaped electrode portion connected to a balanced signal terminal of the surface acoustic wave filter. The surface acoustic wave device according to. 10. The surface acoustic wave filter has at least one comb-shaped electrode portion that is phase-inverted with respect to another comb-shaped electrode portion, and the weighting is an electrode of the phase-inverted comb-shaped electrode portion. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is applied to a finger. 11. The surface acoustic wave device according to claim 1, wherein the weighting is thinning weighting. 12. The surface acoustic wave device according to claim 11, wherein a dummy electrode is provided on an opposing bus bar facing the bus bar to which the thinned and weighted electrode fingers are connected. 13. Two or more electrodes, each electrode finger of at least one of the input comb-shaped electrode portion and the output comb-shaped electrode portion including an outermost electrode finger at a position facing another comb-shaped electrode portion, 13. The surface acoustic wave device according to claim 1, wherein the continuous ground electrode fingers are formed as weights. 14. The elasticity according to claim 12, further comprising: a grounding connection portion that connects electrode fingers connected to the grounding of the comb-shaped electrode portions adjacent to each other through the dummy electrode. Surface wave device. 15. The surface acoustic wave device according to claim 1, wherein the weighting is a crossing width weighting for making a crossing width of an electrode finger different from that of another electrode finger. 16. The surface acoustic wave device according to claim 1, wherein the weighting is performed such that the electrode fingers are set shorter than the other electrode fingers. 17. The surface acoustic wave device according to claim 15, wherein the cross width weighting is performed at a substantially central portion in the cross direction. 18. The cross-width weighted electrode fingers and adjacent electrode fingers are also cross-width weighted, and the above-mentioned 2
18. The surface acoustic wave device according to claim 15, further comprising a dummy electrode formed by bending so as to face each of the cross-width-weighted electrode fingers of the book. 19. The cross-width-weighted electrode finger is one outermost electrode finger of adjacent comb-shaped electrode portions, and the other comb-shaped electrode portion is the cross-width-weighted electrode finger. 18. The surface acoustic wave device according to claim 15, wherein dummy electrodes are provided so as to face each other. 20. The surface acoustic wave device according to claim 19, wherein the dummy electrode is connected to ground. 21. The surface acoustic wave device according to claim 1, wherein the weighting is a duty weighting that makes a duty of an electrode finger different from that of another electrode finger. 22. The surface acoustic wave filter has at least 3 filters.
At least one of the comb-shaped electrode portions adjacent to each other is provided with the weight according to any one of claims 11 to 21, and the weights are different from each other. A surface acoustic wave device characterized in that 23. The two surface acoustic wave filters are provided, and each of the surface acoustic wave filters has a surface acoustic wave filter according to claim 11.
22. The surface acoustic wave device according to any one of claims 21 to 21, wherein the weighting is different from each other. 24. The surface acoustic wave filter has at least three comb-shaped electrode portions that are adjacent to each other, and in at least one of the comb-shaped electrode portions that are adjacent to each other, the comb-shaped electrode portions are adjacent to each other. A cross width is weighted for several electrode fingers different from the outermost electrode finger in the outermost region, and at least one of the different comb-shaped electrode portions adjacent to each other is a portion where the comb-shaped electrode portions are adjacent to each other. The outermost electrode fingers are thinned and weighted, and the thinned and weighted portions are provided with dummy electrodes connected to the opposing bus bars facing the bus bars to which the thinned and weighted electrode fingers are connected. The surface acoustic wave device according to claim 1 or 2, wherein 25. The surface acoustic wave filter has at least three comb-shaped electrode portions adjacent to each other, and in at least one of the comb-shaped electrode portions adjacent to each other, a portion of the comb-shaped electrode portions adjacent to each other is provided. Duty weighting is performed to make the duty of the outermost electrode fingers different from other electrode fingers, and at least one of the different comb-shaped electrode portions adjacent to each other is the outermost portion of the portion where the comb-shaped electrode portions are adjacent to each other. In addition to being thinned and weighted with respect to the electrode fingers, a dummy electrode connected to an opposing bus bar facing the bus bar to which the thinned and weighted electrode fingers are connected is provided at the thinned and weighted portion. The surface acoustic wave device according to claim 1 or 2. 26. Two surface acoustic wave filters are provided, and at least one of the adjacent comb-shaped electrode portions of one surface acoustic wave filter is the outermost portion of the adjacent comb-shaped electrode portions. The cross width is weighted for several electrode fingers different from the outermost electrode finger in the region, and in at least one of the adjacent comb-shaped electrode portions of the other surface acoustic wave filter, the comb-shaped electrode portion is The outermost electrode fingers adjacent to each other are thinned and weighted, and the thinned and weighted portion is a dummy connected to the opposite bus bar facing the bus bar to which the thinned and weighted electrode fingers are connected. The surface acoustic wave device according to claim 1, wherein an electrode is provided. 27. The surface acoustic wave according to claim 1, wherein the surface acoustic wave filter is provided so as to have a balanced signal input-balanced signal output filter function. apparatus. 28. The surface acoustic wave filter is provided so as to have a balanced signal input-unbalanced signal output filter function or an unbalanced signal input-balanced signal output filter function. 27. The surface acoustic wave device according to claim 26. 29. At least one of the comb-shaped electrode portions,
29. The surface acoustic wave device according to claim 27, wherein the surface acoustic wave device is divided into two in the cross width direction. 30. The balanced signal terminal forming the pair is connected to the comb-shaped electrodes of both poles in one comb-shaped electrode portion, respectively. The surface acoustic wave device described. 31. At least one of the comb-shaped electrode portions,
29. The surface acoustic wave device according to claim 27, wherein the surface acoustic wave device is divided into two in the propagation direction of the surface acoustic wave. 32. The surface acoustic wave device according to claim 27, wherein there is no grounded electrical neutral point between the pair of balanced signal terminals. . 33. Two surface acoustic wave filters,
27. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device has a balanced signal input-balanced signal output filter function. 34. Two said surface acoustic wave filters are provided so that the phase of the output signal differs from the input signal by about 180 degrees, and each said surface acoustic wave filter is a balanced signal input-unbalanced signal output. 27. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device has a filter function or an unbalanced signal input-balanced signal output filter function. 35. The surface acoustic wave device according to claim 34, further comprising a surface acoustic wave filter cascade-connected to the unbalanced signal terminal side. 36. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave filter is a longitudinally coupled resonator type surface acoustic wave filter. 37. The surface acoustic wave device according to claim 36, wherein the longitudinally coupled resonator type surface acoustic wave filter has an odd number of comb-shaped electrode portions. 38. The surface acoustic wave device according to claim 37, wherein the longitudinally coupled resonator type surface acoustic wave filter has three comb-shaped electrode portions. 39. The longitudinally coupled resonator type surface acoustic wave filter according to claim 36, wherein at least one comb-shaped electrode portion has an even number of electrode fingers. The surface acoustic wave device described. 40. A longitudinally coupled resonator type surface acoustic wave filter,
40. The elasticity according to claim 39, wherein the total number of electrode fingers of the comb-shaped electrode portion, which is connected to at least the balanced signal terminal among the three or three or more comb-shaped electrode portions, is an even number. Surface wave device. 41. A longitudinally coupled resonator type surface acoustic wave filter,
The elastic surface according to claim 39 or 40, wherein among the three or three or more comb-shaped electrode portions, the total number of electrode fingers of the comb-shaped electrode portion, which is located at least in the central portion, is an even number. Wave device. 42. At least one surface acoustic wave resonator is connected to the surface acoustic wave filter in at least one of series and parallel.
The surface acoustic wave device according to any one of 1. 43. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave filter comprises two or more surface acoustic wave filter parts connected in cascade. . 44. On a piezoelectric substrate, an input comb-shaped electrode portion having a plurality of electrode fingers and an output comb-shaped electrode portion having a plurality of electrode fingers are elastic so as to form a longitudinally coupled resonator type. Weighted weighted electrode fingers, which are provided along the propagation direction of the surface wave, are attached to inner electrode fingers different from the outermost electrode fingers of at least one electrode fingers of the input comb-shaped electrode portion and the output comb-shaped electrode portion. A surface acoustic wave device having: 45. One of the input comb-shaped electrode portion and the output comb-shaped electrode portion is for balance, and at least one of the comb-shaped electrode portions on the balance side has a weighting electrode finger. The surface acoustic wave device according to claim 44, which is characterized in that. 46. The weighting electrode finger is provided within a range from the position next to the outermost electrode finger in one comb-shaped electrode portion to within ½ of all electrode fingers. Or the surface acoustic wave device according to item 45. 47. Two or more electrodes, each electrode finger of at least one of the input comb-shaped electrode portion and the output comb-shaped electrode portion including an outermost electrode finger at a position facing another comb-shaped electrode portion, The surface acoustic wave device according to any one of claims 44 to 46, wherein continuous ground electrode fingers are formed. 48. The weighting electrode finger is formed between adjacent ground electrode fingers, which are grounded electrode fingers of at least one of the input comb-shaped electrode portion and the output comb-shaped electrode portion. 48. The device according to claim 44, wherein the size of the electric field portion is set to be controlled.
The surface acoustic wave device according to item. 49. The input comb-shaped electrode portion or the output comb-shaped electrode portion is for balancing, and the two comb-shaped electrode portions for balancing are such that the size of the non-electric field portion is substantially the same. 49. The surface acoustic wave device according to claim 48, wherein 50. The weighting electrode finger is set to be shorter than the other electrode fingers.
9. The surface acoustic wave device according to any one of 9 above. 51. The grounded first balancing electrode finger is formed so as to extend toward the weighting electrode finger in accordance with the length of the weighting electrode finger. The surface acoustic wave device according to claim 1. 52. A second balancing electrode finger, which is grounded, is formed to a position different from the weighting electrode finger so as to match the length of the weighting electrode finger. The surface acoustic wave device according to any one of claims 44 to 51, further comprising a dummy electrode formed by bending so as to face a finger. 53. The surface acoustic wave device according to claim 44, which has an unbalanced-balanced conversion function. 54. A communication device comprising the surface acoustic wave device according to any one of claims 1 to 53.