JP2007202136A - SAW filter and portable terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a SAW filter which has a wide passband that is adjusted to digital ground wave TV electric wave to be low loss and becomes steep outside of the TV electric wave band to acquire a large amount of attenuation. <P>SOLUTION: A constant K-type filter is composed of serial arm SAW resonators 11 and 15, and parallel arm SAW resonators 12 and 16. In addition, a resonance point/anti-resonance point moving inductor is serially connected to the serial arm SAW resonators or parallel connected to the parallel arm SAW resonators to structure circuit elements. A plurality of the circuit elements are mutually tandem-connected at a plurality of steps through the resonance point/anti-resonance point moving inductor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a SAW (surface acoustic wave) filter, and more particularly to a SAW filter for a portable terminal with a digital terrestrial TV receiver.

  In 2003, digital terrestrial broadcasting in Japan began. In 2000, digital terrestrial broadcasting services started in Europe. On the other hand, with the widespread use of mobile terminals, various high value-added services such as mail functions have been provided for the telephone functions of conventional mobile terminals. Under such circumstances, manufacturers of portable terminals around the world use a portable terminal with a digital terrestrial TV receiver having a function of receiving a digital terrestrial TV broadcast in addition to the conventional cellular phone function. Therefore, it is considered to incorporate a service for receiving digital terrestrial broadcasting.

  This type of digital terrestrial TV tuner module for mobile terminals is required for low power consumption, downsizing, and low profile in addition to the characteristics of the tuner, such as reception sensitivity, due to the fact that it is intended for mobile terminals. Furthermore, it is required to prevent the transmission radio wave from interfering with the reception radio wave.

  FIG. 1 shows a configuration diagram of a transmission / reception unit of a portable terminal with a digital terrestrial TV receiver. A portable terminal capable of receiving digital TV broadcasts transmits and receives audio (and data) communication signals to and from the antenna 1 for receiving digital TV broadcasts due to differences in frequency bands between voice (and data) communication and TV broadcasts. Two antennas of the antenna 2 are arranged close to each other. Here, since the digital TV broadcast wave is usually a weak radio wave (−90 dBm), the reception sensitivity of the TV tuner module 3 is designed to be very high. On the other hand, the transmission wave of the voice transmitter 4 that transmits voice (and data) as a portable terminal emits a very strong radio wave (about +30 dBm) from the antenna 2. For this reason, a transmission wave of voice (and data) communication reaches the TV broadcast tuner module 3 via the antenna 1 and interferes with reception of the TV broadcast. For this reason, in a portable terminal with a digital terrestrial TV receiver, it is said that a D / U ratio (Desired / Undesired: power ratio between a desired wave and a ghost wave) is 120 dB as shown in FIG.

  Furthermore, the reception band of digital TV broadcasting in Japan is 470 MHz to 710 MHz, while the transmission band of voice communication is 830 MHz to 840 MHz, which are very close. In addition, digital terrestrial broadcasting in Europe has a digital TV broadcast reception band of 470 MHz to 870 MHz, and an audio wave transmission band of 880 MHz to 915 MHz, which is also very close.

  As described above, when the antennas are arranged close to each other and the transmission / reception radio wave bands are close to each other as described above, the transmission radio waves for voice and data communication wrap around the digital TV broadcast reception antenna via the antenna, There is a problem of disturbing weak received waves. In order to avoid this interference, it is required to provide a filter having a steep attenuation at the base of the receiving antenna for digital TV broadcasting.

  FIG. 3 shows a configuration example of a receiving system of a digital terrestrial TV tuner module that satisfies the above requirements. The BEF circuit (band elimination filter circuit) 3A has a steep suppression (-50 to -60 dB) characteristic in a transmission radio frequency band emitted from a transmission / reception antenna (not shown) of a mobile phone, and is received by the antenna 1. Capture digital terrestrial TV radio waves with low loss. The LC filter 3B includes a chip coil and a chip inductor, and suppresses the transmission radio frequency band (-20 to -40 dB). The balun circuit 3C performs balanced-unbalanced conversion of the TV broadcast wave while suppressing the transmission radio frequency band (−10 to −20 dB). The IC circuit 3D converts a TV signal that becomes a modulated wave into a baseband.

  FIG. 4 shows an example of characteristics required for the BEF circuit. The required characteristics are low loss in the reception band of digital TV broadcasting (small attenuation), steep attenuation in the transmission band of voice and data broadcasting, and a large attenuation. In the conventional technology, a passive circuit using a coil or a capacitor, a dielectric filter using a high Q value of a dielectric, or a multilayer chip such as LTCC or HTCC in which the passive circuit is placed on a pattern and further sintered. There are parts.

  However, since the module is mounted in a portable terminal, its mounting area and space are limited, and there is a limit to downsizing and height reduction in the conventional technology. In addition, since the reception band of digital TV broadcasting and the transmission band of voice and data broadcasting are very close to each other, a steep attenuation characteristic is necessary. In the conventional filter design theory, a filter is used to increase the steepness. Since the resonance circuit which is a component of (2) is connected in two or more stages, the loss of the pass band becomes very large.

  There is a SAW (surface acoustic wave) filter as a filter that enables the low power consumption, downsizing, and low profile. However, it is difficult to obtain a wide passband and a large amount of attenuation if a SAW filter is constituted by a single SAW resonator. For this reason, a ladder-type filter configuration using a plurality of SAW resonators is used, and an inductor is inserted in series with the parallel arm or / and series arm of these SAW resonators to move the resonance point and antiresonance point of each SAW resonator. By doing so, what has been proposed to obtain a large degree of suppression outside a wide passband and out of the band (see, for example, Patent Document 1 and Patent Document 2).

JP-A-5-183380 JP 2004-135322 A

  It can be considered that a SAW filter using the SAW resonator is employed in a digital terrestrial TV tuner module. However, since the transmission band for voice communication and the reception band for digital TV broadcasting are very close, it is difficult to obtain a wide passband and a large degree of suppression outside the band with the conventional SAW filter, and 120 dB. It is difficult to obtain the D / U ratio (see FIG. 2).

  An object of the present invention is to provide a SAW filter that has a wide low-loss passband matched to a digital terrestrial TV radio wave, and can obtain a steep and large attenuation outside the TV radio wave band. .

The SAW filter of the present invention comprises a filter unit by a first SAW resonator inserted in a signal path and a second SAW resonator provided between the signal path and the ground,
A resonance point / anti-resonance point moving inductor provided in series with the first SAW resonator and / or a resonance point / anti-resonance point moving inductor provided in parallel with the second SAW resonator; Configuring a circuit element with a filter unit;
The circuit elements are connected in cascade in two or more stages between the input port and the output port by interposing a resonance point / anti-resonance point moving inductor between the circuit elements.
The inductor included in the circuit element on the input port side is provided between the filter portion of the circuit element and the input port;
The inductor included in the circuit element on the output port side is provided between the filter section of the circuit element and the output port;
It is provided with.
The inductor interposed between the circuit elements adjacent to each other is inserted in the signal path, for example, or provided between the signal path and the ground.
As described above, this SAW filter is a TV broadcast in which two antennas, an antenna 1 for receiving a digital TV broadcast and an antenna 2 for transmitting and receiving a voice (and data) communication signal, are arranged close to each other. It can use suitably for the receiving part of the portable terminal which can receive.
More specifically, the SAW filter of the present invention includes an antenna and a receiving unit for receiving radio waves in the 470 MHz to 710 MHz band, and an antenna for transmitting and receiving radio waves in the 830 MHz to 840 MHz band. Used in the receiver. Alternatively, the SAW filter of the present invention is used in the receiving unit of a portable terminal provided with an antenna and a receiving unit for receiving radio waves in the band of 470 MHz to 870 MHz and an antenna for transmitting and receiving radio waves of 880 MHz to 915 MHz. .
The portable terminal of the present invention includes an antenna and a receiving unit for receiving radio waves for digital terrestrial television broadcasting, and an antenna for transmitting and receiving voice and / or data as the portable terminal,
The receiving unit is provided with the SAW filter of the present invention.

  As described above, according to the present invention, attention is focused on a configuration in which a constant K type (reverse L type) filter having a parallel arm and a series arm using a pair of SAW resonators is connected in cascade, and in this configuration, the passband is increased. Since a point that cannot be widely removed is eliminated by combining an inductor, a BEF circuit having a large attenuation, a wide pass bandwidth, and a low loss can be realized. In particular, it is suitable for preventing a transmission radio wave in a TV tuner of a portable terminal with a digital terrestrial TV receiver from interfering with a reception wave of a digital TV broadcast.

  Prior to the description of the embodiment of the present invention, the configuration of a conventional SAW filter and the filter characteristics exhibited by the SAW filter will be described below.

  FIG. 5A shows an equivalent circuit of the SAW resonator. FIG. 5B shows a series arm configuration in which SAW resonators are connected in series to an input end and an output end each having a termination impedance of 50Ω. FIG. 5C shows the 2-port transmission characteristics in the circuit shown in FIG. In the figure, 51 is a series arm SAW resonator, and 61 and 62 are an input port and an output port, respectively. As shown in FIG. 5C, a SAW resonator generally has one resonance point and one antiresonance point, and a reflection characteristic S11 having a resonance point and a pass characteristic S21 having an antiresonance point are combined. This is the transmission characteristic of the SAW resonator. In the case of FIG. 5C, the resonance point is located between the digital terrestrial broadcasting TV radio wave band (pass band) and the transmission radio wave band (stop band), and the anti-resonance point is close to the transmission radio wave band. Interference can be reduced.

  FIG. 6A shows two-port transmission characteristics in the case of a parallel arm configuration in which SAW resonators are connected in parallel to the input end and the output end each having a termination impedance of 50Ω. In the figure, reference numeral 52 denotes a parallel arm SAW resonator. This case also has one resonance point and one anti-resonance point.

  From the above, the SAW resonator can be used in the BEF circuit of the digital terrestrial TV tuner. However, the position of the resonance point and antiresonance point of the SAW resonator is restricted by the electromechanical coupling coefficient, capacitance, and various design parameters of the piezoelectric substrate to be used. This restriction makes it very difficult to reduce the loss in a wide band as the design freedom is reduced.

  For example, the amount of attenuation in one SAW resonator is about 10 to 30 dB, and in order to obtain a large amount of attenuation in the attenuation band, the parallel arm SAW resonator 52 and the series arm as shown in FIG. The SAW resonators 51 are alternately connected, that is, connected in a ladder shape. According to this configuration, a large attenuation can be expected as shown in the characteristic example in FIG. 7B, but the passband at this time becomes very narrow. This is due to the electromechanical coupling coefficient of the SAW resonator. By connecting the respective resonators, the attenuation bandwidth and the amount of attenuation can be increased, but the passband with less loss is conversely narrowed.

  In order to eliminate such inconvenience, an inductor 71 is provided in series with the series arm SAW resonator 51 shown in FIG. 5 as a solution to obtain a large attenuation in a wide passband with a small loss and a stopband. Insert a SAW filter. FIG. 8A shows a SAW filter having such a configuration, and FIG. 8B shows a characteristic example in this configuration. In this case, the resonance point is shifted toward a lower frequency, matching is achieved in a wide band, and the loss of the pass band is very small.

  FIG. 9A shows an analysis example of impedance characteristics in a single configuration of a SAW resonator, and FIG. 9B shows an analysis example of impedance characteristics in a configuration in which an inductor is inserted in series with the SAW resonator. A1 and A2 are impedance characteristics of the inductor and the SAW resonator, respectively. By inserting an inductor in series with the SAW resonator, the anti-resonance point does not move, but the resonance point that was below the anti-resonance point has moved further downward and degenerated to ∞ Hz. A resonance point appears above the antiresonance point. The frequency of this resonance point can be freely moved by the inductance value of the inductor.

  FIG. 10A shows a configuration in which an inductor 72 is inserted in parallel to the parallel arm SAW resonator 52 of FIG. The characteristics in this configuration are shown in FIG. At this time as well, matching is achieved in a wide band, and the loss of the pass band is very small.

  FIG. 11A shows an analysis example of admittance characteristics in a single configuration of a SAW resonator, and FIG. 11B shows an analysis example of admittance characteristics in a configuration in which an inductor is inserted in parallel with the SAW resonator. B1 and B2 are admittance characteristics of the inductor and the SAW resonator, respectively. By inserting an inductor in parallel with the SAW resonator, the resonance point does not move, but the antiresonance point that is above the resonance point moves further upward, and the antiresonance point that has degenerated to 0 Hz. Appears below the resonance point. The frequency of this antiresonance point can be freely moved by the inductance value of the inductor.

  The present invention has been made based on the above analysis and experimental results. First, a constant-K (reverse L-type) filter is constituted by the series-arm SAW resonator shown in FIG. 8A and the parallel-arm SAW resonator shown in FIG. In this filter, an inductor is provided in series with the SAW resonator of the serial arm, or an inductor is provided in parallel with the SAW resonator of the parallel arm, and the circuit elements thus configured are cascade-connected through a plurality of stages. By adopting such a configuration, a low-loss BEF circuit is realized with a large attenuation, a wide passband width, and the like.

  As an embodiment of the present invention, FIG. 12A shows a case of a two-stage configuration. In this example, an input signal application portion between the input terminal 61a and the common ground is connected to the input port 61 in series with the input port 61 (in a signal path connected to the input terminal 61a). The SAW resonator 11 and the SAW resonator 12 connected in parallel to the input port 61 (connected between the signal path and the common ground) form a constant K-type filter. Such SAW resonator 11 and SAW resonator 12 are referred to as series arm SAW resonator 11 and parallel arm SAW resonator 12, respectively. The series arm SAW resonator 11 is inserted with an inductor 13 in series on the side opposite to the connection point with the parallel arm SAW resonator 12, and the parallel arm SAW resonator 12 is provided with an inductor 14 in parallel. Similarly, on the output port 62 side which is an output signal extraction portion between the output terminal 62 a and the common ground, the SAW resonator 15 inserted in series with the output port 62 and the output port 62 are connected. A constant-K filter is formed by the SAW resonators 16 connected in parallel. The SAW resonator 15 is inserted with an inductor 17 in series on the opposite side of the connection point with the parallel arm SAW resonator 16, and the SAW resonator 16 is provided with an inductor 18 in parallel. These inductors 13 and 17 are connected to each other.

  In this example, one circuit element is constituted by the SAW resonators 11 and 12 and the inductors 13 and 14, and the other circuit element is constituted by the SAW resonators 15 and 16 and the inductors 17 and 18. In each figure, a portion surrounded by a dotted line corresponds to a circuit element. When these circuit elements are connected in cascade, the inductor 13 and the inductor 17 are connected in series. Therefore, in FIG. 12B, the circuit configuration is equivalent to a single inductor 19 having a combined inductance value.

  The design constants of the SAW resonator and the inductor in the configuration of FIG. 12C are as follows. For the SAW resonators 12 and 16, the number of taps is 200 and the aperture length is 23λ (λ is the wavelength at the center frequency). For the SAW resonators 11 and 15, the number of taps is 132 and the aperture length is 28λ. The inductances of the inductors 14 and 18 are 10 nH, the inductance of the inductor 19 is 20 nH, and each of the inductances uses a coil having a frequency of 1 GHz and a Q value of 50.

  FIG. 13A shows the transmission characteristics in this circuit, and FIG. 13B shows an enlarged scale of the vertical axis (attenuation amount). As is apparent from this characteristic diagram, transmission characteristics with a large attenuation in the transmission radio wave band (stop band) and a low loss and a wide pass band in the reception band of the TV radio wave can be obtained. It is suitable as a BEF circuit.

  The reason why such a suitable transmission characteristic can be obtained is based on the following. That is, the resonance point and the anti-resonance point are adjusted by the inductor, and the resonance point is positioned in or near the digital terrestrial band to pass the digital terrestrial wave, while the anti-resonance point is in the transmission radio wave band or its The transmission radio wave that is located in the vicinity and enters the terrestrial TV tuner module is reflected.

  Although FIG. 12 shows a case of a two-stage configuration, the multi-stage configuration can further increase the stopband attenuation. FIGS. 14A and 14B each show an example of a three-stage configuration. FIG. 15A shows transmission characteristics in the circuit configuration of FIG. 14A, and FIG. 15B shows an enlarged scale of the vertical axis (attenuation amount). Further, FIG. 16A shows the transmission characteristics in the circuit configuration of FIG. 14B, and FIG. 16B shows an enlarged scale of the vertical axis (attenuation amount). As can be seen from these results, the transmission characteristics in the circuit configuration of FIG. 14A and the transmission characteristics in the circuit configuration of FIG. 14B are equivalent to each other. That is, the SAW filter shown in FIG. 12, FIG. 14A and FIG. 14B constitutes a constant K type filter by the serial arm SAW resonator 11 (15) and the parallel arm SAW resonator 12 (16). Further, a resonance point / antiresonance point moving inductor 14 (18) is provided in parallel to the parallel arm SAW resonator 12 (16) to constitute a circuit element, and this circuit element is resonated between the circuit elements. It can be said that the point / anti-resonance point moving inductor is interposed and cascaded in two or more stages.

  FIG. 17 shows another embodiment of the present invention. 12 is different from FIG. 12 in that the inductor 19 inserted in series between the SAW resonator 11 and the SAW resonator 15 is omitted, and an inductor 20 is provided in parallel with this portion. That is, an inductor is provided in parallel to the input port 61 on the opposite side of the series arm SAW resonator 11 from the connection point with the parallel arm SAW resonator 12 and the parallel arm SAW resonator 16 in the series arm SAW resonator 15 The circuit element is provided with an inductor in parallel to the output port 62 on the opposite side to the connection point of the two, and one inductor 20 has a parallel inductance value of both inductors.

The design constants of the SAW resonator and the inductor in the configuration of FIG. 17 are as follows. The SAW resonators 12 and 16 have a tap number of 176 and an opening length of 24λ, and the SAW resonators 11 and 15 have a tap number of 121 and an opening length of 25λ. The inductances of the inductors 14 and 18 are 8.2 nH, the inductance of the inductor 20 is 10 nH, and each of the inductances uses a coil having a frequency of 1 GHz and a Q value of 50.
FIG. 18A shows the transmission characteristics in this circuit, and FIG. 18B shows an enlarged scale of the vertical axis (attenuation amount). The same characteristics as in FIG. 12 can be obtained. In the present embodiment, not only two-stage cascade connection but also a three-stage or more multi-stage cascade connection configuration can be adopted.
FIG. 19 shows another embodiment of the present invention. This example is almost the same as the circuit of FIG. 17, and the series arm SAW resonator 11 is inserted between the parallel arm SAW resonator 12 and the inductor 14. The difference is that the series arm SAW resonator 15 is interposed between the parallel arm SAW resonator 16 and the inductor 18.
The design constants of the SAW resonator and inductor in the configuration of FIG. 19 are as follows. The SAW resonators 12 and 16 have 200 taps and an opening length of 23λ, and the SAW resonators 11 and 15 have 132 taps and an opening length of 28λ. The inductances of the inductors 14 and 18 are 14 nH, and the inductance of the inductor 20 is 4 nH. Each of the inductances uses a coil having a frequency of 1 GHz and a Q value of 50. FIG. 20A shows the transmission characteristics in this circuit, and FIG. 20B shows an enlarged scale of the vertical axis (attenuation amount). The same characteristics as in FIG. 12 can be obtained.

21 and 22 show still another embodiment of the present invention. The SAW filter shown in FIG. 21 has inductors 21 and 22 inserted in series with an input port 61 and an output port 62, respectively, instead of the inductors 14 and 18 in the circuit of FIG. The SAW filter shown in FIG. 22 has a configuration in which inductors 21 and 22 are inserted in series in the input / output port 61 and the output port 62, respectively, instead of the inductors 14 and 18 in the circuit of FIG. By adopting such a configuration, characteristics equivalent to those of FIG. 12 or FIG. 17 can be obtained. The transmission characteristics in FIG. 21 are shown in FIG. 23A, and an enlarged scale of the vertical axis (attenuation amount) is shown in FIG. 23 (b). Also, in the circuits shown in FIGS. 21 and 22, the circuit elements surrounded by the dotted lines are not limited to the two-stage cascade connection configuration, but may be a three-stage or more cascade connection configuration.
FIG. 24 shows still another embodiment of the present invention. The SAW filter of this example has a configuration in which the circuit elements shown in FIG. 14A are interposed between the two stages of circuit elements shown in FIG. The circuit constants are not significantly different from the circuit constants already described, but circuit constants for obtaining optimum characteristics are selected. The transmission characteristics in the circuit configuration of FIG. 24 are shown in FIG. 25A, and an enlarged scale of the vertical axis (attenuation amount) is shown in FIG. With this circuit, the same characteristics as in FIG. 12 can be obtained.
In the example described above, the series arm SAW resonator 11 (the first SAW resonator inserted in the signal path) and the parallel arm SAW resonator 12 (the second arm provided between the signal path and the ground). Circuit elements are configured by an inductor (for example, 21) provided in series with the series arm SAW resonator 11 or an inductor (for example, 14) provided in parallel with the parallel arm SAW resonator 12. However, the inductors included in the circuit element are both an inductor (for example, 21) provided in series with the series arm SAW resonator 11 and an inductor (for example, 14) provided in parallel with the parallel arm SAW resonator 12. Also good.

  As described above, the above SAW filter can be suitably used as a SAWBEF circuit (band elimination filter circuit) in the receiving unit of the mobile terminal capable of receiving the TV broadcast shown in FIG. More specifically, a domestic portable terminal that receives radio waves of 470 MHz to 710 MHz, which are digital TV broadcast waves, and transmits and receives radio waves of 830 MHz to 840 MHz for voice or data communication, or radio waves of the 470 MHz to 870 MHz band. It is suitable as a portable terminal for domestic use for Europe that receives and transmits and receives radio waves of 890 MHz to 920 MHz.

The block diagram of the transmission / reception part of a portable terminal with a digital terrestrial TV receiver. The power ratio between the desired wave and the ghost wave of a portable terminal with a digital terrestrial TV receiver. The structural example of the receiving system of TV tuner module for digital terrestrial waves. Example of characteristics required for BEF circuit of digital terrestrial TV tuner. The example of the equivalent circuit of a SAW resonator, a series circuit structure, and a transmission characteristic. The example of the parallel circuit structure and transmission characteristic of a SAW resonator. An example of a ladder configuration and transmission characteristics of a SAW resonator. Example of SAW resonator and series inductor configuration and transmission characteristics. An example of resonance point movement of a SAW resonator and a series inductor configuration. Example of SAW resonator and parallel inductor configuration and transmission characteristics. An example of resonance point movement of a SAW resonator and a parallel inductor configuration. The circuit block diagram of SAW filter and the example of a design constant which show embodiment of this invention. Transmission characteristics in the embodiment. The circuit block diagram of the SAW filter which shows other embodiment of this invention. Transmission characteristics in other embodiments. Transmission characteristics in other embodiments. The circuit structural example of the SAW filter which shows other embodiment of this invention. Transmission characteristics in other embodiments. The circuit structural example of the SAW filter which shows other embodiment of this invention. Transmission characteristics in other embodiments. The circuit block diagram which shows the modification of the SAW filter in this invention. The circuit block diagram which shows the modification of the SAW filter in this invention. Transmission characteristics in the modified example The circuit block diagram which shows the modification of the SAW filter in this invention. Transmission characteristics in other embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital terrestrial TV broadcast antenna 2 Mobile phone antenna 3 TV tuner module 4 Audio transmitter 11, 15 Series arm SAW resonator 12, 16 Parallel arm SAW resonator
13, 14, 17, 18, 19, 20, 21, 22 inductor

Claims (7)

Forming a filter unit by the first SAW resonator inserted in the signal path and the second SAW resonator provided between the signal path and the ground;
A resonance point / anti-resonance point moving inductor provided in series with the first SAW resonator and / or a resonance point / anti-resonance point moving inductor provided in parallel with the second SAW resonator; Configuring a circuit element with a filter unit;
The circuit elements are connected in cascade in two or more stages between the input port and the output port by interposing a resonance point / anti-resonance point moving inductor between the circuit elements.
The inductor included in the circuit element on the input port side is provided between the filter portion of the circuit element and the input port;
The inductor included in the circuit element on the output port side is provided between the filter section of the circuit element and the output port;
A SAW filter comprising:   2. The SAW filter according to claim 1, wherein the inductor interposed between circuit elements adjacent to each other is inserted in a signal path.   2. The SAW filter according to claim 1, wherein the inductor interposed between circuit elements adjacent to each other is provided between a signal path and ground.   2. The SAW filter according to claim 1, wherein a reception band for digital terrestrial television broadcasting is used as a pass band, and a voice and / or data transmission band as a portable terminal is used as a stop band.   The antenna and receiving unit for receiving radio waves in a band of 470 MHz to 710 MHz and the antenna for transmitting and receiving radio waves in the range of 830 MHz to 840 MHz are used for the receiving unit of a portable terminal provided with the antenna. The SAW filter described.   The antenna and receiving unit for receiving radio waves in a band of 470 MHz to 870 MHz and the antenna for transmitting and receiving radio waves of 880 MHz to 915 MHz are used in the receiving unit of a portable terminal equipped with the antenna. The SAW filter described. An antenna and a receiving unit for receiving radio waves for digital terrestrial television broadcasting, and an antenna for transmitting and receiving voice and / or data as a portable terminal,
A portable terminal, wherein the SAW filter according to claim 1 is provided in the receiving unit.

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