JPH1065490A - Saw frequency band blocking filter and electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the SAW frequency band block filter with a small size at a low loss by forming a ladder circuit with a small number of SAW resonators and not needing a matching circuit. SOLUTION: The SAW frequency band block filter is provided with a 1st SAW resonator in series connection between an input terminal and an output terminal and a parallel connection circuit consisting of a 1st inductor element 5 and a 2nd SAW resonator 2 connected between the input terminal of the 1st SAW resonator or the output terminal and an earth electrode. Through the constitution above, since the resonance frequency of the parallel connection circuit is set optionally by the 1st inductor element 5, the frequency band block filter is configured by ladder circuits with a small size at a low loss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a SAW band rejection filter and an electronic device using the same.

[0002]

2. Description of the Related Art In a conventional electronic device such as a cellular phone, a band rejection filter interposed in a communication path of the electronic device is formed using a SAW resonator in order to reduce the size of the electronic device. A conventional SAW band rejection filter is disclosed in Japanese Patent Application Laid-Open No. 61-220511. As shown in FIG. 7, the circuit configuration was such that a plurality of SAW resonators 26 were connected in series, and a matching circuit 27 was provided at the input / output terminals.

[0003]

However, the conventional SAW band rejection filter is a circuit in which a dozen or more SAW resonators 26 are connected in series, and a matching circuit 27 must be provided in each of the input and output sections. Was
There is a problem that the shape is large and the insertion loss in the pass band is also large.

An object of the present invention is to provide a low-loss and small SAW band rejection filter by using a ladder-type circuit having a small number of SAW resonators and not requiring a matching circuit, and to provide an electronic device using the same. It is intended for.

[0005]

According to the present invention, there is provided a first SAW resonator connected in series between an input terminal and an output terminal, and an input terminal of the first SAW resonator. This is a SAW band rejection filter including a parallel connection of a second SAW resonator and a first inductance element connected between a terminal side or an output terminal side and a ground electrode. According to this configuration, the resonance frequency of the parallel-connected body can be arbitrarily set by the first inductance element, so that the SAW band rejection filter can be configured by a small ladder-type circuit with low loss.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The first aspect of the present invention is directed to a first SAW resonator connected in series between an input terminal and an output terminal, and an input terminal of the first SAW resonator. The SAW band rejection filter includes a parallel connection of the second SAW resonator and the first inductance element, which is connected between the side or the output terminal and the ground electrode. According to the above configuration, the resonance frequency of the parallel-connected body can be arbitrarily set by the first inductance element, so that the band rejection filter can be configured by a small ladder-type circuit with low loss.

Further, according to a second aspect of the present invention, the first S
The series resonance frequency (hereinafter, referred to as Fs1) of the AW resonator and the parallel resonance frequency (hereinafter, referred to as Fp2) of the parallel connection of the second SAW resonator and the first inductance element are set to pass bands as filters. And the first SA
The parallel resonance frequency of the W resonator (hereinafter referred to as Fp1) and the series resonance frequency of the parallel connection of the second SAW resonator and the first inductance element (hereinafter referred to as Fs2) are set as stop bands as filters. The SAW band rejection filter according to claim 1 is provided. With the above configuration, the pass characteristic can be set to an optimum condition as a band rejection filter.

Further, according to a third aspect of the present invention, there is provided the SAW band rejection filter according to the first or second aspect, wherein Fp2 and Fs1 have substantially the same value. With the above configuration, impedance matching can be performed in the pass band of the filter, and a small band rejection filter can be configured without providing a matching circuit at the input / output terminals.

Further, according to the invention of claim 4, Fs2 is
The SAW band rejection filter according to any one of claims 1 to 3, wherein the filter has a value larger than p1. With the above configuration, a band-stop filter having a wide stop band can be configured.

[0010] The invention according to claim 5 is characterized in that the second SA
The SAW band rejection filter according to any one of claims 1 to 4, wherein a parallel connection of the W resonator and the first inductance element is connected between the first SAW resonator and an output terminal. Things. With the above configuration, even when a large power is applied from the input terminal, the second SAW resonator connected to the ground is not easily broken.

[0011] The invention according to claim 6 is the first and second inventions.
Between the connection point of the SAW resonator and the output terminal.
W resonator is connected, and the fourth SAW resonator and the second SAW resonator are connected between the connection point between the third SAW resonator and the output terminal and the ground electrode.
The SAW band rejection filter according to any one of claims 1 to 5, wherein a parallel connection body with the inductance element is connected. According to the above configuration, the attenuation characteristic of the stop band can be improved by increasing the number of elements of the ladder band rejection filter.

Further, according to a seventh aspect of the present invention, the third S
The series resonance frequency (hereinafter, referred to as Fs3) of the AW resonator and the parallel resonance frequency (hereinafter, referred to as Fp4) of a parallel connection of the fourth SAW resonator and the second inductance element are set to pass bands as filters. And the third SA
The parallel resonance frequency of the W resonator (hereinafter referred to as Fp3) and the series resonance frequency of the parallel connection of the fourth SAW resonator and the second inductance element (hereinafter referred to as Fs4) are set as stop bands as filters. A SAW band rejection filter according to claim 5 or claim 6. According to the above configuration, the pass characteristic can be set to an optimum condition as a band rejection filter in a configuration in which the number of elements is increased.

The invention according to claim 8 is the SAW band rejection filter according to any one of claims 5 to 7, wherein Fp4 and Fp3 have substantially the same value. The above configuration enables impedance matching in a configuration in which the number of elements is increased.

According to a ninth aspect of the present invention, there is provided the SAW band rejection filter according to any one of the fifth to eighth aspects, wherein Fs4 is set to a value larger than Fp3. The above configuration makes it possible to widen the stop band in a configuration in which the number of elements is increased.

According to a tenth aspect of the present invention, a first SAW resonator and a third SAW are provided between an input terminal and an output terminal.
Resonators are connected in series, a parallel connection of the second SAW resonator and the first inductance element is connected between the connection point of the first and third SAW resonators and the ground electrode, and the third SAW
Fourth S between the connection point between the resonator and the output terminal and the ground electrode.
The parallel connection of the AW resonator and the second inductance element is connected, and the parallel resonance frequency (Fp
1), the series resonance frequency (Fs1) of the parallel connection of the second SAW resonator and the first inductance element, and the third S
Parallel resonance frequency (Fp3) of AW resonator and fourth SAW
The series resonance frequency (Fs4) of the parallel connection of the resonator and the second inductance element is set to a stop band as a filter, and Fs4>Fs2>Fp3>.
The SAW band rejection filter is Fp1. According to the above configuration, in the four-element band rejection filter, the attenuation in the stop band can be optimally set while securing a wide stop band.

Further, according to the present invention, the first S
The series resonance frequency (Fs1) of the AW resonator and the second SAW
The parallel resonance frequency (Fp1) of the parallel connection of the resonator and the first inductance element, the series resonance frequency (Fs3) of the third SAW resonator, and the parallel connection of the fourth SAW resonator and the second inductance element The parallel resonance frequency (Fp
(4) is set as a pass band as a filter, and Fs1, Fp2, Fs3, and Fp4 are set to substantially the same value as the SAW band rejection filter according to claim 10. With the above-described configuration, impedance matching of the four-element band rejection filter can be performed, and a small band rejection filter can be configured without providing a matching circuit at the input / output terminals.

According to a twelfth aspect of the present invention, the element value of the second inductance element is larger than the element value of the first inductance element.
In the SAW band rejection filter. According to the above configuration, Fs4> Fs2 and Fp4 and Fp
2 can be made substantially the same value.

According to a thirteenth aspect of the present invention, there is provided the SAW band rejection filter according to the twelfth aspect, wherein the first and second inductances are formed by bonding wires. According to the above configuration, the size of the piezoelectric substrate forming the SAW resonator can be reduced.

According to a fourteenth aspect of the present invention, the first to fourth comb-shaped electrode patterns for the SAW resonator are formed on the piezoelectric substrate, and the first and second inductance elements for the first and second inductance elements are formed on the piezoelectric substrate. The SAW band rejection filter according to any one of claims 10 to 12, wherein a line pattern is provided and a bonding wire is connected to the line pattern. With the above configuration, by forming a part of the first and second inductance elements with the line pattern, the element values can be stabilized.

According to a fifteenth aspect of the present invention, the first and third SAW resonators and the second and fourth SAW resonators are provided on the left and right sides of the piezoelectric substrate.
According to a tenth aspect of the present invention, there is provided the SAW band rejection filter according to any one of the tenth to fourteenth aspects, wherein the WW resonator is arranged separately. According to the above configuration, the SAW resonator can be efficiently arranged on the piezoelectric substrate, and the size of the piezoelectric substrate can be reduced.

According to a sixteenth aspect of the present invention, an input terminal and an output terminal are provided on one side of a piezoelectric substrate on which the first and third SAW resonators are distributed, and the second and fourth SAW resonators are distributed. The S according to claim 15, wherein connection electrodes for the first and second inductance elements are provided on the other side of the piezoelectric substrate.
This is an AW band rejection filter. According to the above configuration, the electrodes for wire bonding can be efficiently arranged, and the size of the piezoelectric substrate can be reduced.

The invention according to claim 17 is the SAW band rejection filter according to claim 16, wherein at least one of the first and second inductance elements is formed by a bonding wire. With the above configuration,
The size of the piezoelectric substrate can be reduced.

In the invention according to claim 18, the first and second inductance elements are formed by bonding wires, and the bonding wires for the second inductance elements are made smaller than the bonding wires for the first inductance elements. 17. The SAW according to claim 16, which is lengthened.
This is a band rejection filter. According to the above configuration, the element value of the second inductance element can be made larger than that of the first inductance element by using bonding wires having the same wire diameter.

The invention according to claim 19 is the first invention.
According to another aspect of the present invention, there is provided an electronic apparatus in which any one of the SAW band rejection filters is interposed in a transmission path of a communication device. With the above configuration, a small electronic device with low power consumption can be realized by using a small SAW band rejection filter with small insertion loss.

According to a twentieth aspect of the present invention, the SAW band rejection filter of any one of the first to eighteenth aspects is interposed between the amplifier at the last stage of the transmission path and the anthena. The electronic device described above. With the above configuration, a small SA having a small insertion loss
By using the W band rejection filter, a small electronic device with low power consumption can be realized.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is a simplified block diagram showing a mobile phone as an example of the electronic apparatus. That is, the audio signal input from the microphone 15 is modulated by the modulator 16, and then transmitted from the antenna 20 via the transmission frequency converter 17, the transmission amplifier 18, and the transmission filter 19. On the other hand, the signal received by the antenna 20 passes through a receiving filter 21, a receiving amplifier 22, and a
The signal is demodulated and output from the speaker 25. In the above mobile phone, the transmission filter 1 interposed in the transmission path
Reference numeral 9 denotes a SAW band rejection filter having a circuit as shown in FIG.

FIG. 1 is a circuit diagram showing a SAW band rejection filter according to the present invention. In FIG. 1, reference numeral 1 denotes a first SAW resonator, 2 denotes a second SAW resonator, 3 denotes a third SAW resonator, 4 denotes a fourth SAW resonator, 5 denotes a first inductance element, and 6 denotes a first inductance element. This is a second inductance element. The first SAW resonator 1 and the third SAW resonator 3 are connected in series to a path from an input terminal to an output terminal (hereinafter referred to as a series branch). On the other hand, the second SAW resonator 2 and the first inductance element 5 are connected in parallel to form a parallel connection body,
Is connected between the connection point between the SAW resonator 1 and the third SAW resonator 3 and the ground (hereinafter, a first parallel branch), and furthermore, the fourth SAW resonator 4 and the second inductance element 6 are connected to each other. Are connected in parallel to form a parallel connection body, and are connected between the connection point between the third SAW resonator 3 and the output terminal and ground (hereinafter referred to as a second connection).
Parallel branches). With the above configuration, a four-element ladder-type circuit is configured. In this band rejection filter, the terminal on the first SAW resonator 1 side is an input terminal, and the terminal on the opposite side is an output terminal. The reason for this is that it was experimentally confirmed that the SAW resonator is less likely to break when the first stage is a serial branch than when it is a parallel branch when a large power is input from the input terminal.

The electric characteristics of each circuit will be described below. FIG. 2A is a characteristic diagram showing an input impedance characteristic of a single SAW resonator when a tip is short-circuited. As can be seen from FIG. 2A, the SAW resonator has a series resonance point Fs and a parallel resonance point Fp, and Fs has a characteristic that it exists on the lower side of Fp. FIG. 2B is a characteristic diagram showing an input impedance characteristic of a parallel connection of the SAW resonator and the inductance element. In this case, the parallel resonance frequency Fp occurs on the lower side of the series resonance frequency Fs, and Fp can be arbitrarily moved while Fs is fixed by the element value of the inductance element. If the two are connected alternately to form the ladder circuit of FIG. 1, it is possible to set the parallel branch Fp almost equal to the series branch Fs and the parallel branch Fs almost equal to the series branch Fp. Therefore, a band rejection filter can be formed. Hereinafter, the series resonance frequency of the first series branch or the parallel branch is referred to as FsI, and the parallel resonance frequency is referred to as FpI.

FIG. 3 is a characteristic diagram showing the pass characteristics of the SAW band rejection filter of FIG. FsI, Fp2, Fs
3 and Fp4, and Fp1 <Fp
3 <Fs2 <Fs4. This gives Fs
, Fp2, Fs3, and Fp4, passbands are formed near the frequencies, and Fp1, Fp3, Fs2, and Fs4
It can be seen that an attenuation pole is formed at the frequency and a stop band is formed to form a band stop filter. This is because, in the passband, the series branch is series-resonated and short-circuited, and the parallel branch is parallel-resonated and open, so that the impedance of the output terminal is directly visible from the input terminal (that is, impedance matching is performed), and the input signal is Pass to the output terminal. Further, in the stop band, the series branch is parallel-resonated to be open or the parallel branch is series-resonated to be short-circuited, so that the input signal is reflected and does not reach the output terminal. The pass band and the stop band are determined by the resonance sharpness (Q value) of each resonator. As described above, Fp1 <Fp3 <Fs2 <
By making the stop frequencies slightly different from each other as Fs4, the stop band can be further widened, and desired attenuation characteristics can be easily secured. Note that Fs2 and Fs2
Since s4 can be set arbitrarily as described above,
It is moved to a higher frequency side than Fp1 and Fp3. Further, in order to set Fs4 higher than Fs2, the second
The element value of the inductance element 6 is larger than the element value of the first inductance element 5.

Next, the structure of the SAW band rejection filter will be described. FIG. 4 is a plan view showing a mounted state of the SAW band rejection filter. In FIG.
6 corresponds to the SAW resonator and the inductance element in the circuit diagram of FIG. 1, 7 is a piezoelectric substrate, 8 is an input electrode, 9 is an output electrode, and 10 and 11 are for the first and second inductance elements 5 and 6, respectively. Reference numeral 12 denotes a package.

The first to fourth SAW resonators 1 to 4 are:
Each is constituted by a comb-shaped electrode on the surface of the piezoelectric substrate 7, and the arrangement is such that the first SAW resonator 1 and the third SAW resonator 3 entering the series branch are arranged on the left side in FIG.
The second SAW resonator 2 entering the parallel branch and the fourth SAW resonator 4 entering the second parallel branch are distributed to the right. By providing the input electrode 8 and the output electrode 9 on the left side where the series branches are arranged, and providing the inductance element electrodes 10 and 11 on the right side where the first and second parallel branches are arranged, efficient arrangement is achieved. The size of the piezoelectric substrate 7 and the package 12 is reduced. The first inductance element 5 and the second inductance element 6 are electrodes 10 and 11 for inductance elements, respectively.
And a bonding wire for connecting the ground terminal of the package 12 to the ground terminal. In the case of a band rejection filter in the 800 MHz band, the required inductance value is several nanohenries, so that a bonding wire having a wire diameter of 35 microns has a length of about 2 mm. As mentioned above, the first
Since the second inductance element 6 requires a slightly larger element value than the inductance element 5 described above, the length is slightly longer. The SAW band rejection filter configured as described above has the pass characteristics shown in FIG.
In the z band, values of insertion loss in the pass band of about 1.5 dB and attenuation in the stop band of 45 dB or more were obtained.

In this embodiment, four elements of S
Although the AW band rejection filter is used, any other number of elements may be used. In other words, a circuit of two elements consisting of one series branch and one parallel branch is used as a minimum unit, and the number of elements may be determined according to required characteristics. If the number of elements is increased, the attenuation of the stop band can be increased, but on the other hand, the insertion loss in the pass band also increases. Therefore, it is desirable to use a minimum number of elements capable of securing a desired stop band. . Also, regardless of the number of elements, impedance matching in the pass band can be achieved by setting the series resonance frequency (Fs1, Fs3,...) Of the series branch and the parallel resonance frequency (Fp2, Fp4,. And the series resonance frequency (Fs2, Fs2) of the parallel branch.
4,...) To the parallel resonance frequencies (Fp1, Fp3,
As described above, a wider stop band can be obtained by setting the band higher than...

In the present embodiment, the first inductance element 5 and the second inductance element 6 are each formed by a bonding wire. Alternatively, a method of forming the first inductance element 5 and the second inductance element 6 by a line pattern formed on the piezoelectric substrate 7 may be used. is there. For example, as shown in FIG.
Are formed on the piezoelectric substrate 7, and the zigzag line patterns 13 and 14
By providing 0 and 11, the first and second inductance elements 5 and 6 can be formed by the zigzag line patterns 13 and 14 and the bonding wires, so that a large inductance element value can be obtained and the element values can be stabilized. That can be done.

The values and configurations described in the above embodiment are merely examples, and the present invention is not limited to the details of these values and configurations.

[0035]

As described above, according to the present invention, the first SAW resonator connected in series between the input terminal and the output terminal, and the input terminal side or the output terminal side of the first SAW resonator. A second SAW resonator connected between the second SAW resonator and a grounded electrode and a parallel connection of the first inductance element;
This is an AW band rejection filter. According to the above configuration, the resonance frequency of the parallel-connected body can be arbitrarily set by the first inductance element, so that the SAW band rejection filter can be configured by a small ladder type circuit with low loss.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a SAW band rejection filter according to the present invention.

FIG. 2A is a characteristic diagram showing an input impedance characteristic of a single SAW resonator when a tip is short-circuited, and FIG. 2B is a characteristic diagram showing an input impedance characteristic of a parallel connection of the SAW resonator and an inductance element.

FIG. 3 is a characteristic diagram showing a pass characteristic of the SAW band rejection filter of FIG. 1;

FIG. 4 is a plan view showing a mounting state of a SAW band rejection filter.

FIG. 5 is a plan view showing another example of the mounting state of the SAW band rejection filter.

FIG. 6 is a simplified block diagram showing a mobile phone;

FIG. 7 is a circuit diagram showing a conventional SAW band rejection filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st SAW resonator 2 2nd SAW resonator 3 3rd SAW resonator 4 4th SAW resonator 5 1st inductance element 6 2nd inductance element 7 Piezoelectric substrate 8 Input electrode 9 Output electrode 10 First inductance element electrode 11 Second inductance element electrode 12 Package 13 First zigzag line pattern 14 Second zigzag line pattern 15 Microphone 16 Modulator 17 Transmission frequency converter 18 Transmission amplifier 19 Transmission filter 20 Antenna 21 Receive filter 22 Receive amplifier 23 Receive frequency converter 24 Demodulator 25 Speaker

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasumichi Murase 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (20)

[Claims] 1. A first SAW resonator connected in series between an input terminal and an output terminal, and connected between an input terminal side or an output terminal side of the first SAW resonator and a ground electrode. A SAW band rejection filter comprising a second SAW resonator and a parallel connection of a first inductance element. 2. A series resonance frequency (hereinafter referred to as Fs1) of a first SAW resonator and a second SAW resonator and a first resonance frequency
The parallel resonance frequency (hereinafter referred to as Fp2) of the parallel connection body with the inductance element is set to a pass band as a filter, and the parallel resonance frequency (hereinafter referred to as Fp1) of the first SAW resonator and the second SAW Resonator and first
2. The SAW band rejection filter according to claim 1, wherein a series resonance frequency (hereinafter referred to as Fs2) of a parallel connection with the inductance element is set as a stop band as a filter. 3. The SAW band rejection filter according to claim 1, wherein Fp2 and Fs1 have substantially the same value. 4. The SAW band rejection filter according to claim 1, wherein Fs2 is set to a value larger than Fp1. 5. The method according to claim 1, wherein a parallel connection of the second SAW resonator and the first inductance element is connected between the first SAW resonator and an output terminal. A SAW band rejection filter as described. 6. A third SAW resonator is connected between a connection point of the first and second SAW resonators and an output terminal, and a third SW resonator is connected.
The parallel connection body of the fourth SAW resonator and the second inductance element is connected between the connection point between the AW resonator and the output terminal and the ground electrode, according to any one of claims 1 to 5, wherein A SAW band rejection filter as described. 7. The series resonance frequency (hereinafter referred to as Fs3) of the third SAW resonator and the fourth SAW resonator and the second resonance frequency
The parallel resonance frequency (hereinafter referred to as Fp4) of the parallel connection body with the inductance element is set to the pass band as a filter, and the parallel resonance frequency (hereinafter referred to as Fp3) of the third SAW resonator and the fourth SAW Resonator and second
7. The SAW according to claim 5, wherein a series resonance frequency (hereinafter referred to as Fs4) of a parallel connection body with the inductance element is set to a stop band as a filter.
Band stop filter. 8. The SAW band rejection filter according to claim 5, wherein Fp4 and Fs3 have substantially the same value. 9. The SAW band rejection filter according to claim 5, wherein Fs4 is set to a value larger than Fp3. 10. A first S between an input terminal and an output terminal.
An AW resonator and a third SAW resonator are connected in series, and a second SAW resonator is connected between a connection point of the first and third SAW resonators and a ground electrode.
A parallel connection of the SAW resonator and the first inductance element is connected, and the fourth SAW resonator and the second inductance element are connected between the connection point between the third SAW resonator and the output terminal and the ground electrode. Are connected, the parallel resonance frequency (Fp1) of the first SAW resonator, the series resonance frequency (Fs1) of the parallel connection of the second SAW resonator and the first inductance element, and the third The parallel resonance frequency (Fp3) of the SAW resonator and the series resonance frequency (Fs4) of the parallel connection of the fourth SAW resonator and the second inductance element are each set to a stop band as a filter, and Fs4> Fs2. >Fp3> SAW band rejection filter with Fp1. 11. The series resonance frequency (Fs1) of the first SAW resonator, the parallel resonance frequency (Fp1) of a parallel connection of the second SAW resonator and the first inductance element, and the third SAW resonator And the parallel resonance frequency (Fp4) of the parallel connection of the fourth SAW resonator and the second inductance element are set in the pass band as a filter, and Fs1, Fp2, and Fs3 are set. The SAW band rejection filter according to claim 10, wherein Fp4 and Fp4 have substantially the same value. 12. The SAW band rejection filter according to claim 10, wherein an element value of the second inductance element is larger than an element value of the first inductance element. 13. The SA according to claim 12, wherein the first and second inductances are formed by bonding wires.
W band rejection filter. 14. A first to a fourth comb-shaped electrode patterns for SAW resonators are formed on a piezoelectric substrate, and a line pattern for first and second inductance elements is provided on the piezoelectric substrate. The SAW band rejection filter according to any one of claims 10 to 12, wherein a bonding wire is connected to the pattern. 15. A first and a third SAW on the left and right sides of a piezoelectric substrate.
The SAW band rejection filter according to any one of claims 10 to 14, wherein the resonator and the second and fourth SAW resonators are arranged separately. 16. An input terminal and an output terminal are provided on one side of a piezoelectric substrate on which the first and third SAW resonators are distributed,
16. The SAW band rejection filter according to claim 15, wherein connection electrodes for the first and second inductance elements are provided on the other side of the piezoelectric substrate on which the second and fourth SAW resonators are distributed. 17. The SAW band rejection filter according to claim 16, wherein at least one of the first and second inductance elements is formed by a bonding wire. 18. The method according to claim 16, wherein the first and second inductance elements are formed by bonding wires, and the bonding wire for the second inductance element is longer than the bonding wire for the first inductance element. SAW band rejection filter. 19. An electronic device in which the SAW band rejection filter according to claim 1 is interposed in a transmission path of a communication device. 20. The electronic device according to claim 19, wherein the SAW band rejection filter according to any one of claims 1 to 18 is interposed between an amplifier and an antenna at a last stage of a transmission path.