JP2009182368A - Duplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact duplexer employing a thin film bulk acoustic wave resonator (FBAR) which reduced the thickness and mounting area of a package. <P>SOLUTION: A duplexer includes a reception filter having first and second terminals, a transmission filter having third and fourth terminals, and an antenna terminal connected with the first and third terminals, wherein the reception filter and the transmission filter are ladder filters equipped with a thin film bulk acoustic wave resonator, a phase matching inductor having one grounded end is connected with a transmission line which connects the first and third terminals with the antenna terminal, and the transmission filter and the reception filter have specific characteristics. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a duplexer as an electronic device, and more particularly to a duplexer using a thin film bulk acoustic wave resonator (FBAR) filter constituted by a thin film bulk acoustic wave resonator (FBAR).

  In recent years, development of small communication devices represented by mobile phones has been actively promoted. These small communication devices use a transmission / reception switch for branching transmission / reception signals, and in order to reduce the size and performance of the device, the transmission / reception switch is also required to be small and high in performance. In recent wireless communication, the high frequency band is often used, and the use of a thin film bulk acoustic wave resonator (FBAR) filter capable of controlling the use frequency by changing the thickness of the piezoelectric region is being studied. .

  Usually, the reception filter and the transmission filter of the duplexer need to control the phase at a predetermined frequency. Therefore, in a duplexer using a thin film bulk acoustic wave resonator (FBAR) filter, a 90 ° phase shifter is conventionally connected in series between the reception filter and the antenna terminal as shown in FIG. reference).

JP 2001-24476 A

  The use of a 90 ° phase shifter as a phase matching circuit is a problem in miniaturization such as an increase in package thickness and an increase in mounting area.

  The present invention has been made in view of the above circumstances, and is a small-sized transmission / reception switching using a thin film bulk acoustic wave resonator (FBAR) filter in which the thickness and mounting area of the package are reduced by changing the phase matching circuit. The purpose is to provide a vessel.

  The present invention is connected to a reception filter including a first terminal and a second terminal, a transmission filter including a third terminal and a fourth terminal, and the first terminal and the third terminal. A transmission / reception switch having a plurality of antenna terminals, wherein the reception filter and the transmission filter are ladder filters each having a thin film bulk acoustic wave resonator, the first terminal, the third terminal, and the antenna terminal Is connected to a transmission line connecting one end of the phase matching inductor, one end of which is connected to the ground, and the reception filter and the transmission filter have a real part value of 1 in their passbands. The imaginary part of the admittance value has the same value in four bands of the pass band and stop band of the reception filter and the pass band and stop band of the transmission filter. About duplexer, characterized in that in the four bands is a filter that has a capacitive.

  According to the present invention, the package can be downsized by reducing the thickness of the package and the length of the phase matching circuit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a duplexer according to the present invention. The duplexer of the present invention comprises a receiving thin film bulk acoustic wave resonator filter 7 having a first terminal 2 and a second terminal 4, and a transmitting thin film bulk acoustic wave resonance having a third terminal 3 and a fourth terminal 5. And an antenna terminal 1 connected to a first terminal 2 of the receiving thin film bulk acoustic wave resonator filter 7 and a third terminal 3 of the transmitting thin film bulk acoustic wave resonator filter 8. The reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 are ladder type filters including a thin film bulk acoustic wave resonator 11. A feature of the present invention is that one end of the transmission line 10 connects the antenna terminal 1, the first terminal 2 of the reception thin film bulk acoustic resonator filter 7, and the third terminal 3 of the transmission thin film bulk acoustic resonator filter 8. Has a phase matching inductor 9 connected to the ground. By using the inductance instead of the conventional 90 ° phase shifter, it is possible to provide a small duplexer that further promotes the merit of miniaturization that is a feature of the thin film bulk acoustic wave resonator (FBAR). .

  FIG. 3 is a schematic cross-sectional view for explaining the structure of the thin film bulk acoustic wave resonator 11. As shown in FIG. 3, the thin film bulk acoustic wave resonator 11 includes a resonance part 19 including an upper electrode 13, a piezoelectric layer 14, and a lower electrode 15, a substrate 16 provided with the resonance part 19, and the lower electrode 15 and a cavity portion 17 formed in the substrate 16. The thin film bulk acoustic wave resonator 11 may have a configuration in which a passivation layer, a support layer, or the like is provided on the upper electrode 13 or the lower electrode 15.

  As the upper electrode 13, a suitable material such as molybdenum (Mo), gold (Au), aluminum (Al), ruthenium (Ru), platinum (Pt), tungsten (W), titanium (Ti) can be used. .

  For the piezoelectric layer 14, an appropriate material such as aluminum nitride (AlN) or zinc oxide (ZnO) can be used.

  For the lower electrode 15, an appropriate material such as molybdenum (Mo), gold (Au), aluminum (Al), ruthenium (Ru), platinum (Pt), tungsten (W), titanium (Ti), or the like can be used. .

As the substrate 16, an appropriate material such as silicon (Si), silicon oxide (SiO ₂ ), gallium arsenide (GaAs), or glass can be used.

  The thin film bulk acoustic wave resonator 11 includes an acoustic mirror layer in which a layer having a high acoustic impedance and a layer having a low acoustic impedance are alternately stacked between the lower electrode 15 and the substrate 16 as shown in FIG. 18 may be provided. Thereby, the energy generated by the resonance part 19 can be confined in the same manner as the structure in which the cavity part 17 is provided.

The acoustic mirror layer 18 includes gold (Au), molybdenum (Mo), tungsten (W) as high acoustic impedance layers, and silicon (Si), silicon oxide (SiO ₂ ), aluminum (Al) as low acoustic impedance layers. Can be used.

  Next, a method for manufacturing the thin film bulk acoustic wave resonator 11 according to the present invention will be described. The thin film bulk acoustic wave resonator FBAR 11 having the cavity portion 17 is formed by depositing the lower electrode 15 on the substrate 16 by a vapor deposition method such as sputtering, and patterning the piezoelectric layer 14 into a desired shape. A step of depositing by a vapor deposition method and patterning in a desired shape; a step of depositing the upper electrode 13 by a vapor deposition method such as sputtering and patterning in a desired shape; and the cavity portion 17 by etching or the like. It is manufactured by a process of providing between the electrode 15 and the substrate 16. Further, a step of providing a passivation layer, a support layer, or the like on the upper electrode 13 or the lower electrode 15 may be included.

  The thin film bulk acoustic wave resonator FBAR11 having the acoustic mirror layer 18 is a process of alternately laminating a layer having a high acoustic impedance and a layer having a low acoustic impedance as the acoustic mirror layer 18 on the substrate 16 by a deposition method such as sputtering. Depositing the lower electrode 15 by a vapor deposition method such as sputtering and patterning it in a desired shape; depositing the piezoelectric layer 14 by a vapor deposition method such as sputtering and patterning it in a desired shape; The upper electrode 13 is manufactured by a process of depositing it by a vapor deposition method such as sputtering and patterning it into a desired shape. Further, a step of providing a passivation layer, a support layer, or the like on the upper electrode 13 or the lower electrode 15 may be included.

  The ladder filter 12 according to the present invention has the thin film bulk acoustic wave resonators 11 connected in series and in parallel as shown in FIG. These thin film bulk acoustic wave resonators 11 connected in series may have the same frequency characteristic, or may have different frequency characteristics. Further, the thin film bulk acoustic wave resonators 11 connected in parallel may have the same frequency characteristic, or may have different frequency characteristics.

  The ladder filter 12 according to the present invention may have a configuration in which the thin film bulk acoustic wave resonators 11 in series or the thin film bulk acoustic wave resonators 11 in series are connected as shown in FIG. .

  In the duplexer according to the present invention, as shown in FIG. 1, the antenna terminal 1, the first terminal 2 of the receiving thin film bulk acoustic resonator filter 7, and the third terminal of the transmitting thin film bulk acoustic resonator filter 8 are provided. 3 is connected by a transmission line 10, and a phase matching inductor 9 is provided between the transmission line 10 and the ground in order to obtain a desired filter characteristic.

  The transmission line 10 connects the first terminal, the third terminal, and the antenna terminal, is provided in a package, and transmits a reception signal and a transmission signal.

  The phase matching inductor 9 may be provided in a package in a line pattern or may be a concentrated inductor. By providing the phase matching inductor 9, phase matching is achieved. For example, FIG. 7 is an admittance diagram of the reception thin film bulk acoustic resonator filter 7 or the transmission thin film bulk acoustic resonator filter 8 before the phase matching inductor 9 is provided, and FIG. 8 is the phase matching inductor. 9 is an admittance diagram of the reception thin film bulk acoustic resonator filter 7 or the transmission thin film bulk acoustic resonator filter 8 when 9 is provided. As can be seen from FIGS. 7 and 8, phase matching is achieved by providing the phase matching inductor 9. Normally, the characteristics shown in FIG. 8 are required as the characteristics of the reception and transmission filters. That is, the pass band 20 has a value close to the impedance of the entire circuit, and the cutoff band 21 needs to have a value much larger than the impedance of the entire circuit. By performing phase matching in this way, the characteristics of the duplexer are not affected.

  The reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 used in the transmission / reception switch have a frequency at which the real part of the admittance value is 1 in each pass band 20. In addition, it is preferable to use a filter in which the imaginary part of the admittance value has the same value in the passband 20 and the stopband band 21 and has a capacity in each band.

  Furthermore, the reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 used in the transmission / reception switch of the present invention have a real part value of 1 in each pass band 20. The admittance is in four bands: a pass band 20 and a stop band 21 of the receiving thin film bulk acoustic resonator filter 7 and a pass band 20 and a stop band 21 of the receiving thin film bulk acoustic resonator filter 8. The filter is characterized in that the imaginary part of the value has a frequency indicating the same value and is capacitive in the four bands.

  The reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 used in the transmission / reception switch of the present invention are values of the real part of the admittance value at any frequency in the passband 20 as shown in FIG. Is 1. That is, the characteristic of the pass band 20 means that the real part of the admittance is on a circle line indicating 1. Further, the imaginary part of the admittance at any frequency in the pass band 20 and any frequency in the stop band 21 has the same value. That is, in the admittance diagram illustrated in FIG. 7, it means that a line having the same imaginary part of the admittance passes through the passband 20 and the stopband 21 of the filter. Further, the imagination of admittance at any frequency within the pass band 20 and the stop band 21 of each of the reception thin film bulk acoustic resonator filter 7 and the transmission thin film bulk acoustic resonator filter 8 used in the duplexer of the present invention. The parts are preferably the same. In the receiving thin film bulk acoustic wave resonator filter 7 and the transmitting thin film bulk acoustic wave resonator filter 8 used in the duplexer according to the present invention, the pass band 20 and the cutoff band 21 are preferably capacitive.

  By using the reception thin film bulk acoustic resonator filter 7 and the transmission thin film bulk acoustic resonator filter 8 as described above, the phase matching amount of the reception thin film bulk acoustic resonator 7 and the transmission thin film bulk acoustic resonator filter 8 can be increased. Therefore, the transmission line 10 connecting the antenna terminal 1 and the first terminal 2 of the reception thin film bulk acoustic resonator filter 7, or the first of the antenna terminal 1 and the transmission thin film bulk acoustic resonator filter 8 is the same. The phase of the receiving thin film bulk acoustic wave resonator filter 7 and the transmitting thin film bulk acoustic wave resonator filter 8 is provided by providing a phase matching inductor 9 having one end connected to the ground on the transmission line 10 connected to the terminal 3 of the transmitting thin film. Can be set to a desired value.

  9A is an LTCC board interior view of a conventional duplexer using the 90 ° phase shifter 6 shown in FIG. 2, and FIG. 9B is the present invention shown in FIG. It is the LTCC board | substrate interior drawing of a transmission / reception switching device. Table 1 shows the line length necessary for forming the inner layer pattern of λ / 4 lines on the LTCC substrate in the duplexer using the conventional 90 ° phase shifter 6. Hereinafter, the configuration of the transmission / reception switching device of the present embodiment will be described with reference to these.

  In the conventional transmission / reception switching device shown in FIG. 2, the 90 ° phase shifter 6 is used in the phase matching circuit, and the LTCC substrate constituting the transmission / reception switching device is as shown in FIG. 9 (a). Table 1 shows the line length when the 90 ° phase shifter 6 constituted by the inner layer pattern of λ / 4 line is formed on the LTCC substrate. When the 90 ° phase shifter 6 of λ / 4 line is installed on the LTCC substrate, the line length is required to be 13.8 mm as shown in Table 1, and the ground pattern is required on the upper and lower surfaces of the inner layer pattern. A space of 0.2 mm is required between them. For this reason, the required number of substrates increases, and the LTCC substrate becomes as thick as 0.6 mm and cannot be reduced in size.

  On the other hand, as shown in FIG. 1, a duplexer according to the present invention using a phase matching inductor 9 having one end grounded to the ground was prepared. The LTCC board which comprises one Embodiment of the duplexer of this invention is as shown in FIG.9 (b). As shown in FIG. 9B, when installed as the phase matching inductor 9 formed of the inner layer pattern on the LTCC substrate, the line length can be configured with 6.0 mm, and no ground pattern is required on the upper and lower surfaces, so the LTCC substrate. Thus, a thin and small duplexer with a thickness of 0.3 mm could be provided.

  Further, the reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 used in the transmission / reception switch have a frequency at which the value of the real part of the admittance value is 1 in each pass band 20. It is preferable to use a filter that has a frequency in which the imaginary part of the admittance value indicates the same value in the passband 20 and the stopband band 21 and that has capacitance in each band. .

  FIG. 10 is an admittance chart characteristic diagram of the receiving thin film bulk acoustic wave resonator filter 8 according to the present invention. The filter having the characteristics shown in FIG. 10 has a frequency in which the real part of the admittance value is 1 in the passband 20 and a frequency in which the imaginary part of the admittance value has the same value in the stopband 21. In addition, a filter having capacitance in the passband 20 and the stopband 21 is shown. That is, the real part of the admittance value is 1 at any frequency in the pass band 20, and the value of the imaginary part of the admittance value at any frequency in the pass band 20 and any frequency in the stop band 21 is the same. A value is taken, and the pass band 20 and the stop band 21 are capacitive. When the phase matching inductor 9 is provided in such a filter, as shown in FIG. 11, the pass band 20 has a value close to the impedance of the entire circuit, and the cutoff band 21 has a value much larger than the impedance of the entire circuit. A filter characteristic that does not affect the characteristics of the duplexer was obtained.

  12 and 13 are admittance chart characteristics diagrams of the transmission thin film bulk acoustic wave resonator filter 8 according to the present invention.

  In FIG. 12, the real part of the admittance value is 1 at a certain frequency in the pass band 20, but the value of the imaginary part of the admittance value at any frequency in the pass band 20 and any frequency in the stop band 21 is the same. It is not. When the phase matching inductor 9 is provided in such a filter, the characteristics shown in FIG. 14 are shown.

  In FIG. 13, the real part of the admittance value of the pass band 20 is 1, and the imaginary part of the admittance value at any frequency of the pass band 20 and any frequency of the stop band 21 takes the same value. The pass band 20 and the stop band 21 are capacitive. When the phase matching inductor 9 is provided using a filter having such characteristics, the pass band 20 has a value close to the impedance of the entire circuit as shown in FIG. 15, and the cutoff band 21 is larger than the impedance of the entire circuit. A much larger value was obtained, and a filter characteristic that does not affect the characteristics of the duplexer was obtained.

  Further, as the reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 used in the transmission / reception switcher, the values of the real part of the admittance value in each pass band 20 as shown in FIGS. In the four bands of the pass band 20 and the stop band 21 of the reception thin film bulk acoustic resonator filter 7 and the pass band 20 and the stop band 21 of the transmission thin film bulk acoustic resonator filter 8. In addition, a filter having a frequency in which the imaginary part of the admittance value has the same value and having capacitance in the four bands is used. That is, the value of the imaginary part of the admittance value at any frequency of the reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 is the reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave. The transmission / reception switching device is configured by using the reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 that have the same value in the resonator filter 8. Thus, the phase matching amount becomes the same, and the phase matching inductor 9 is provided, so that both the reception thin film bulk acoustic wave resonator filter 7 and the transmission thin film bulk acoustic wave resonator filter 8 have the same transmission / reception switch configuration. The important pass band has a value close to the impedance of the entire circuit, and the cutoff band can be set to a value much larger than the impedance of the entire circuit, so that an optimum duplexer can be obtained.

It is a circuit diagram which shows the transmission / reception switching device concerning embodiment. It is a circuit diagram which shows the conventional transmission / reception switching device. It is sectional drawing of the thin film bulk acoustic wave resonator which has a cavity part. It is sectional drawing of the thin film bulk acoustic wave resonator which has an acoustic reflection film. It is a circuit diagram which shows a ladder type filter. It is a circuit diagram which shows a ladder type filter. It is an admittance diagram showing filter characteristics before phase matching. It is an admittance diagram showing the filter characteristics after phase matching. It is an inner layer pattern figure which shows the package of the transmission / reception switching device concerning embodiment. It is an admittance diagram which shows the filter characteristic before the phase matching of the reception thin film bulk acoustic wave resonator filter concerning embodiment. It is an admittance diagram which shows the filter characteristic after the phase matching of the receiving thin film bulk acoustic wave resonator filter concerning embodiment. It is an admittance diagram which shows the filter characteristic before the phase matching of the transmission thin film bulk acoustic wave resonator filter concerning embodiment. It is an admittance diagram which shows the filter characteristic before the phase matching of the transmission thin film bulk acoustic wave resonator filter concerning embodiment. It is an admittance diagram which shows the filter characteristic after the phase matching of the transmission thin film bulk acoustic wave resonator filter concerning embodiment. It is an admittance diagram which shows the filter characteristic after the phase matching of the transmission thin film bulk acoustic wave resonator filter concerning embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna terminal 2 Reception thin film bulk acoustic resonator filter first terminal 3 Transmission thin film bulk acoustic resonator filter third terminal 4 Reception thin film bulk acoustic resonator filter second terminal 5 Transmission thin film bulk acoustic resonator filter 4th terminal 6 90 ° phase shifter 7 receiving thin film bulk acoustic wave resonator filter 8 transmitting thin film bulk acoustic wave resonator filter 9 phase matching inductor 10 transmission line 11 thin film bulk acoustic wave resonator 12 ladder filter 13 upper electrode 14 piezoelectric Layer 15 Lower electrode 16 Substrate 17 Cavity part 18 Acoustic mirror layer 19 Resonant part 20 Pass band 21 Stop band

Claims (1)

A reception filter having a first terminal and a second terminal, a transmission filter having a third terminal and a fourth terminal, and an antenna terminal connected to the first terminal and the third terminal The reception filter and the transmission filter are ladder filters each having a thin film bulk acoustic wave resonator, and connect the first terminal, the third terminal, and the antenna terminal. A phase matching inductor having one end connected to the ground is connected to the transmission line, and the transmission filter and the reception filter used in the transmission / reception switch have a real part of the admittance value in each pass band. The imaginary part of the admittance value has the same value within the four bands of the reception filter pass band and stop band, and the transmission filter pass band and stop band. It has to frequency, the duplexer, wherein in said four bands is a filter which has a capacitive.

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