JP5230270B2 - Duplexer and wireless communication equipment - Google Patents

Description

  The present invention relates to a duplexer incorporating a matching circuit.

  In a communication terminal that employs a CDMA communication system, a duplexer using a surface acoustic wave filter is used. In the CDMA system, a transmission signal in the transmission frequency band and a reception signal in the reception frequency band are simultaneously transmitted and received. Therefore, a demultiplexer is an element that demultiplexes the transmission signal from the transmission circuit to the antenna and the reception signal from the antenna to the reception circuit.

  The duplexer is composed of a transmission filter that transmits the transmission frequency band and a reception filter that transmits the reception frequency band. These filters are connected to an antenna (hereinafter also referred to as an antenna terminal). Connected. In order to prevent the transmission signal from flowing into the reception circuit at the antenna terminal, the reception circuit needs to have a sufficiently large impedance when the antenna side is viewed from the transmission circuit. Similarly, in order to prevent the reception signal from flowing into the transmission circuit, the transmission circuit needs to have a sufficiently large impedance when the transmission circuit side is viewed from the antenna. A matching circuit between transmission and reception fulfills such a function.

  The matching circuit is configured by an inductor, a capacitor, and the like, and is often disposed between the antenna terminal and the transmission / reception filter.

  In order to improve the design efficiency of the communication terminal, it is desirable that the matching circuit between transmission and reception, which is one of the design elements, is built in the duplexer, and its needs are increasing in recent years.

  A duplexer with a built-in matching circuit is disclosed in, for example, Patent Document 1.

However, in recent years, there has been a demand for communication terminals that can handle international roaming and multiple frequency band assignments. In addition, functions other than telephone calls such as TV and radio reception and camera functions are also required. Therefore, the number of components mounted on one communication terminal is increasing, and there is a continuous demand for miniaturization of components. However, in Patent Document 1 described above, the matching circuit is arranged so as not to spatially intersect the wiring connecting the transmission terminal group or the reception terminal group and the external circuit. As a result, there is a problem that the duplexer causes an increase in size.
JP 2000-349586 A

  In order to reduce the size of the duplexer incorporating the matching circuit, the matching circuit may be arranged so as to spatially intersect the wiring connecting the transmission terminal group or the reception terminal group and the external circuit. As a result, the area of the duplexer in the plane direction is reduced, and the duplexer can be miniaturized.

  However, when the matching circuit is disposed so as to spatially intersect the wiring connecting the transmission terminal group or the reception terminal group and the external circuit, there arises a problem that the isolation characteristic between transmission and reception is deteriorated.

  The present invention has been devised in order to improve the above-described problems, and an object of the present invention is to provide a demultiplexer that has a small size and a low profile while improving isolation characteristics between transmission and reception while incorporating a matching circuit. Is to provide a vessel.

  The duplexer according to the present invention includes a piezoelectric substrate, a surface acoustic wave filter for transmission that constitutes a ladder type filter circuit, and an elastic for reception that constitutes a longitudinal multimode filter circuit, which are provided on one main surface of the piezoelectric substrate. A surface wave filter; a circuit board on which the piezoelectric substrate is mounted; and a matching circuit that impedance-matches the surface acoustic wave filter for transmission and the surface acoustic wave filter for reception; and the thickness direction of the circuit board An inductor pattern formed inside the circuit board so as to have a first portion overlapping the surface acoustic wave filter for reception, and the first portion of the inductor pattern and the elasticity for reception in the thickness direction of the circuit board. A receiving-side shielding conductor disposed between the surface wave filter and the surface wave filter.

  In the duplexer of the present invention, the inductor pattern includes a second portion that overlaps the surface acoustic wave filter for transmission in the thickness direction of the circuit board, and the second portion of the inductor pattern and the elastic surface for transmission It is preferable that a transmission-side shielding conductor having a smaller area than the shielding conductor is formed between the wave filter.

  In the duplexer of the present invention, it is preferable that the surface acoustic wave filter for reception includes a longitudinal multimode filter circuit having an unbalanced input and a balanced output.

  In the duplexer of the present invention, it is preferable that the reception-side shielding conductor is electrically connected to a reference potential terminal formed on the lower surface of the circuit board.

  In the duplexer of the present invention, it is preferable that the transmission-side shielding conductor has a double-toothed comb-like shape in which comb-like conductors are formed on both sides of a strip-like conductor, or a net-like shape.

  In the duplexer of the present invention, the transmission-side shielding conductor may be formed inside the circuit board.

  In the duplexer of the present invention, the transmission-side shielding conductor may be formed on the upper surface of the circuit board.

  In the duplexer of the present invention, a reception-side signal terminal connected to the reception surface acoustic wave filter via the reception line is provided on the lower surface of the circuit board, and the matching is performed with the reception line. A reference potential through conductor connected to the reference potential terminal is preferably formed between the circuit and the circuit.

  In the duplexer of the present invention, a transmission-side signal terminal connected to the surface acoustic wave filter for transmission via the transmission line is provided on the lower surface of the circuit board, and the matching is performed with the transmission line. A reference potential through conductor connected to the reference potential terminal is preferably formed between the circuit and the circuit.

  In the duplexer of the present invention, it is preferable that the reception-side shielding conductor is not formed at a position overlapping the surface acoustic wave filter for transmission in the thickness direction of the circuit board.

  The wireless communication device of the present invention is one in which any of the duplexers described above is connected to an antenna.

  According to the duplexer of the present invention, a matching circuit for impedance matching between the surface acoustic wave filter for transmission and the surface acoustic wave filter for reception is configured, and the surface acoustic wave filter for reception is arranged in the thickness direction of the circuit board. An inductor pattern formed inside the circuit board so as to have an overlapping first part, and disposed between the first part of the inductor pattern and the surface acoustic wave filter for reception in the thickness direction of the circuit board Since the receiving side shielding conductor includes the receiving side shielding conductor, the electromagnetic coupling between the matching circuit and the surface acoustic wave filter for receiving can be shielded by the receiving side shielding conductor. However, a duplexer with improved isolation characteristics can be realized.

  Further, by using the duplexer of the present invention, it is possible to improve the design efficiency of the wireless communication device, and it is possible to realize a wireless communication device that realizes multiple functions by mounting a large number of components.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a duplexer according to the present invention will be described in detail with reference to the drawings. In the drawings described below, the same portions are denoted by the same reference numerals. Further, the size of each pattern, the distance between the patterns, the number of vias, the diameter, the shape, and the like are schematically illustrated for explanation, and are not limited thereto.

<First Embodiment>
FIG. 11 shows a perspective view of the duplexer according to the first embodiment of the present invention. The duplexer shown in FIG. 11 is mainly composed of a circuit board 100 in which dielectrics are laminated in multiple layers, and a piezoelectric substrate 101 having a surface acoustic wave filter 5 for transmission and a surface acoustic wave filter 6 for reception. ing. The transmitting surface acoustic wave filter 5 and the receiving surface acoustic wave filter 6 are provided on the main surface of the piezoelectric substrate 101. The piezoelectric substrate 101 has a surface on which the surface acoustic wave filter for transmission 5 and the surface acoustic wave filter for reception 6 are provided (hereinafter also referred to as a first main surface 101A) as an upper surface (hereinafter referred to as a second main surface) of the circuit board 100. The circuit board 100 is flip-chip mounted in a state of being opposed to each other. The piezoelectric substrate 101 is set to a size slightly smaller than the circuit substrate 100, and is entirely covered and protected by a sealing resin 103 (indicated by a dotted line in the figure). The thickness of the circuit board 100 is, for example, 350 μm to 400 μm, and the thickness of the piezoelectric substrate 101 is, for example, 230 μm to 280 μm.

  FIG. 7A is a plan view of the first main surface side of the piezoelectric substrate 101 used in the duplexer according to the first embodiment. The transmitting surface acoustic wave filter 5 in this embodiment constitutes a ladder type filter circuit, and is formed by connecting a plurality of surface acoustic wave elements 22 in series or in parallel as shown in FIG. Yes. On the other hand, the surface acoustic wave filter for reception 6 constitutes a longitudinal multimode filter circuit, and is formed by connecting a plurality of surface acoustic wave elements 22 in series or in parallel as shown in FIG. Yes. 7A, 1 ′ is a terminal electrically connected to the transmission side signal terminal 1 of the circuit board 100, and 2 ′ and 3 ′ are electrically connected to the reception side signal terminals 2 and 3 of the circuit board 100. The terminal 4 ′ to be connected is a terminal electrically connected to the common terminal 4 of the circuit board 100.

  With the configuration as shown in FIG. 7A, the filter portion of the duplexer shown in FIG. 7B is formed. Hereinafter, when the surface acoustic wave filter for transmission 5 and the surface acoustic wave filter for reception 6 are collectively referred to, they are simply referred to as surface acoustic wave filters.

  FIG. 1 is a top view of each dielectric layer constituting the circuit board 100, and FIG. 2 is a block diagram of a circuit incorporated in the duplexer according to the present embodiment.

  As shown in FIG. 2, the duplexer according to the first embodiment includes a common terminal 4, a matching line 7 having one end connected to the common terminal 4 and the other end grounded, the common terminal 4, and the transmission-side signal terminal. 1 and a surface acoustic wave filter for transmission 6 disposed between the common terminal 4 and the signal terminals 2 and 3 on the receiving side.

  The matching line 7 functions as a matching circuit that impedance-matches the surface acoustic wave filter for transmission 5 and the surface acoustic wave filter for reception 6, and is configured by a line pattern formed over a plurality of dielectric layers. . The matching line 7 includes an inductor pattern in a part thereof. In the present embodiment, the receiving-side shielding conductor 31 is interposed between the inductor pattern constituting the matching line 7 and the surface acoustic wave filter 6 for reception. Is provided.

  The surface acoustic wave filter for transmission 5 and the surface acoustic wave filter for reception 6 are set to have different passband frequencies. The specific configuration is as shown in FIG.

  The transmitting filter 5 and the receiving filter 6 may be manufactured on the same substrate or may be manufactured on separate substrates, but are preferably manufactured on the same substrate. Due to the manufacture of the duplexer, manufacturing variations occur in each of the surface acoustic wave filter for transmission 5 and the surface acoustic wave filter for reception 6, but when each filter is manufactured on a separate substrate, various manufactures are possible. Since the transmission filter and the reception filter having variations are combined, the optimum inductance value of the line pattern of the matching circuit may be different depending on the combination. However, when manufactured on the same substrate, since the filters are manufactured in almost the same place on the wafer, any substrate cut out from the wafer when viewed with the transmitting filter and the receiving filter on the same substrate. This is because the optimum inductance value is almost the same, so there is no need to worry about variation due to the combination.

  As a dielectric material constituting the circuit board 100, for example, ceramics mainly composed of alumina, glass ceramics that can be sintered at a low temperature, glass epoxy resins mainly composed of organic materials, and the like are used. In the case of using ceramics or glass ceramics, a green sheet was produced by forming a slurry in which a metal oxide such as ceramics and an organic binder were homogeneously kneaded with an organic solvent into a sheet, and a desired conductor pattern or via was formed. Thereafter, these green sheets are laminated and pressure-bonded so as to be integrally formed and fired.

  The matching line 7 and the reception-side shielding conductor 31 are made of a conductor on the surface of each dielectric layer, and the dielectric layers are connected by vias filled with the conductor. Here, silver, an alloy obtained by adding palladium to silver, tungsten, copper, gold, or the like can be used as the conductor. These patterns are formed by forming a metal conductor by screen printing or a combination of a film forming method such as vapor deposition or sputtering and etching. If the pattern is directly connected to the filter, or the terminal to be connected when the duplexer is mounted on an external circuit such as PCB, Ni or Au is further provided on the surface if necessary for good bonding with the connection terminal of the filter. Plating may be performed.

  A specific example of the circuit board 100 will be described with reference to FIG.

  The circuit board 100 used in the duplexer according to the present embodiment is formed by laminating three dielectric layers. In FIG. 1, (a) is a pattern formed on the surface (second main surface 100A) on which the piezoelectric substrate 101 is mounted, and (g) is formed on the back surface of the circuit board 100 (mounting surface of the duplexer). (C), (e) are patterns formed in the inner layer of the circuit board 100, (b) is a via connecting the pattern shown in (a) and the pattern shown in (c), (d ) Is a via connecting between the pattern shown in (c) and the pattern shown in (e), and (f) is a via connecting between the pattern shown in (e) and the pattern shown in (g). is there. In this example, the piezoelectric substrate 101 on which the surface acoustic wave filter is formed is flip-chip mounted on the circuit substrate 100 with the first main surface 101A and the second main surface 100A facing each other.

  In FIG. 1A, the annular electrode 16 is a pattern for securing a vibration space of the surface acoustic wave element 22 and hermetically sealing the surface acoustic wave element 22, and the first main surface 101 </ b> A of the piezoelectric substrate 101. It is joined to the annular electrode 16 'provided on the substrate via a joining material such as solder.

  In this embodiment, the piezoelectric substrate 101 is flip-chip mounted on the circuit board 100. However, it is not always necessary to perform flip-chip mounting. After face-up mounting, the connection terminal of the filter and the connection terminal of the circuit board May be connected by a method such as wire bonding. In this embodiment, the surface acoustic wave filter for transmission 5 and the surface acoustic wave filter for reception 6 are manufactured on the same piezoelectric substrate, and are provided with a terminal electrode and an annular electrode that can be connected to the pattern shown in FIG. Shows the case. In this example, the surface acoustic wave filter for transmission 5 is disposed in the left region T including the patterns 8, 9, and 10, and the surface acoustic wave filter for reception 6 is disposed in the right region R including the patterns 13, 14, and 15. The

  As shown in FIG. 1, the transmission signal input from the transmission-side signal terminal 1 is input to the surface acoustic wave filter for transmission 5 via the via 50, the pattern 43, the via 35, the pattern 28, the via 19, and the pattern 10. The transmission signal output from the transmitting surface acoustic wave filter 5 is output to an antenna (not shown) connected via the pattern 11, the via 20, the pattern 29, the via 36, the pattern 44, the via 51, and the common terminal 4. The The reception signal input from the antenna is input to the surface acoustic wave filter 6 for reception via the common terminal 4, via 51, pattern 44, via 36, pattern 29, via 20 and pattern 11, and the patterns 13, 15 and vias are received. 22 and 24, patterns 30 and 32, vias 37 and 38, inductor patterns 45 and 47, and vias 52 and 53, and are output from reception side signal terminals 2 and 3.

  The matching line 7 connected to the common terminal 4 is provided for matching the surface acoustic wave filter 5 for transmission and the surface acoustic wave filter 6 for reception. The common terminal 4 has vias 51, patterns 44, and vias. The pattern 29, the via 39, and the inductor pattern 48 are connected via 36. The inductor pattern 48 constituting the main part of the matching line 7 has a spiral shape so as to have a predetermined inductance. The inductor pattern 48 has a first portion 48 ′ (portion surrounded by a dotted line in the figure) that overlaps the surface acoustic wave filter 6 for reception in the thickness direction of the circuit board 100. The reception-side shielding conductor 31 is disposed in the layer (c) located between the inductor pattern 48 and the layer on which the piezoelectric substrate 101 is mounted (the layer shown in FIG. 1A).

  The reception-side shielding conductor 31 suppresses unnecessary electromagnetic coupling between the matching line 7 and the filter wiring pattern on the piezoelectric substrate, and can improve the isolation between the matching line 7 and the reception-side signal terminals 2 and 3. It becomes. The layer on which the reception-side shielding conductor 31 is disposed may be provided between the matching line 7 and the filter wiring pattern on the piezoelectric substrate, and may be provided on the surface layer (second main surface 100A) of the circuit substrate 100. The receiving-side shielding conductor 31 only needs to have an effect of shielding electromagnetic waves having a frequency used in the filter. For example, the receiving-side shielding conductor 31 may be linear or meshed in addition to the solid pattern shown in FIG.

  The reception-side shielding conductor 31 is connected to the grounded reference potential terminal 55 through the via 40, the pattern 46, and the via 54. By electrically connecting the reception-side shielding conductor 31 to the reference potential terminal 55 in this way, the potential of the reception-side shielding conductor 31 becomes close to the reference potential, and the surface acoustic wave filter for transmission 5 or the surface acoustic wave filter for reception is received. The electromagnetic coupling between 6 and the matching line 7 is reduced. In the present embodiment, the reference potential terminal 55 is a terminal that is held at the ground potential.

Second Embodiment
Next, a duplexer according to a second embodiment of the present invention is described. FIG. 3 is a top view of each dielectric layer of the circuit board 100 used in the duplexer in the second embodiment. The difference from the duplexer of the first embodiment is that a transmission-side shielding conductor 56 is provided in the layer (c) located between the transmission-side surface acoustic wave filter 5 and the matching line 7.

  In the present embodiment, the inductor pattern 48 has a second portion 48 ″ that overlaps the surface acoustic wave filter for transmission 5 in the thickness direction of the circuit board 100, and this second portion 48 ″ and the surface acoustic wave filter for transmission 5 The transmission-side shielding conductor 56 is provided in a layer positioned between (a layer (c) in the figure). The transmission-side shielding conductor 56 is formed in a pattern so as to have a smaller area than the reception-side shielding conductor 31. In this embodiment, both the teeth having comb-like conductors connected to both sides of the strip-like conductor are used instead of the solid pattern. It has a comb-like pattern. Thus, by providing the transmission side shielding conductor 56 having a smaller area than the reception side shielding conductor 31 between the second portion 48 ″ of the inductor pattern 48 and the surface acoustic wave filter for transmission 5, the elastic surface for transmission is provided. The electromagnetic interference between the wave filter 5 and the matching line 7 constituting the matching circuit can be shielded to some extent, and thereby the isolation characteristics of the duplexer can be improved. In addition, since the area of the transmission side shielding conductor 56 is relatively small, the parasitic capacitance between the surface acoustic wave filter for transmission 5 employing a ladder filter and the transmission side shielding conductor 56 having a shielding function is reduced. Since it can be made smaller, the insertion loss can be improved as compared with the case where the reception-side shielding conductor 31 extends to the region between the surface acoustic wave filter 5 for transmission and the matching line 7.

  The transmission-side shielding conductor 56 is connected to the grounded reference potential terminal 55 through the via 40, the pattern 46, and the via 54. The surface acoustic wave filter for transmission 5 is composed of a ladder-type surface acoustic wave filter, and the ladder-type surface acoustic wave filter has a property that insertion loss and attenuation characteristics are likely to deteriorate due to parasitic capacitance. Therefore, if the area of the transmission-side shielding conductor 56 is reduced, the parasitic capacitance generated between the filter wiring pattern on the piezoelectric substrate and the transmission-side shielding conductor 56 can be reduced, which has an effect on insertion loss and attenuation characteristics. Can be small. Also, unnecessary electromagnetic coupling between the wiring pattern on the piezoelectric substrate and the matching line 7 can be suppressed. As a result, the isolation characteristic between the matching line 7 and the transmission surface acoustic wave filter 6 can be improved.

  The layer on which the transmission-side shielding conductor 31 is disposed may be provided between the matching line 7 and the filter wiring pattern on the piezoelectric substrate, and may be disposed on the surface layer (a) of the circuit substrate 100. As shown in FIG. 3, when the transmission shielding conductor 31 is formed inside the circuit board 100, since the distance from the piezoelectric substrate 101 can be increased, the parasitic capacitance can be further reduced. Insertion loss can be improved. On the other hand, when the transmission-side shielding conductor 31 is formed on the upper surface of the circuit board 100, a matching line 7 having a larger scale can be formed inside the circuit board 100.

  In addition, the transmission side shielding conductor 31 should just have an effect which shields with respect to the electromagnetic wave of the frequency used with a filter, and may be a linear form and a mesh shape other than a both-tooth comb-like pattern, for example.

<Third Embodiment>
Next, a duplexer according to a third embodiment of the present invention is described. FIG. 4 is a top view of each dielectric layer of the circuit board 100 used in the duplexer according to the third embodiment. The difference from the duplexer shown in FIG. 1 is that reference potential through conductors 59 and 60 connected to the reference potential terminal 55 are provided between the matching line 7 and the receiving line. The matching line 7 includes a pattern 29, a via 39, a pattern 48, and a via 54, and the receiving line includes a pattern 13, a via 22, a pattern 30, a via 37, a pattern 45, a via 52, a pattern 2, and a pattern 15, a via 24, The pattern 32, the via 38, the pattern 47, the via 53, and the pattern 3 are included. Since the transmission line, the matching line, and the reception line are arranged close to each other in the circuit board, an electromagnetic coupling occurs between them, and the isolation characteristic is likely to deteriorate. By providing a shield composed of the reference potential through conductors 59 and 60 between the matching line 7 and the receiving line, unnecessary electromagnetic coupling between the receiving line and the matching line 7 and the transmitting line is suppressed. It is possible to improve the isolation characteristics. Such a shield may be provided between the transmission line and the matching line 7, in which case unnecessary electromagnetic coupling between the transmission line and the matching line 7 and the reception line is further suppressed. Therefore, the isolation characteristics can be further improved.

<Fourth embodiment>
Next, an embodiment of the wireless communication apparatus of the present invention will be described. FIG. 6 is a block diagram of the wireless communication apparatus according to the present embodiment, and any of the duplexers according to the first to third embodiments described above is used as the duplexer. As shown in the figure, the audio signal input from the microphone is A / D converted by the DSP, modulated by the modulator, and further frequency-converted by the mixer using the oscillation signal of the local oscillator. The output of the mixer passes through the transmission band-pass filter and the power amplifier, and is output to the antenna through the duplexer of the present invention. A received signal from the antenna passes through a duplexer, and is input to a mixer through a low noise amplifier and a reception band pass filter. The mixer converts the frequency of the received signal using the oscillation signal of the local oscillator, and the converted signal is demodulated by the demodulator through the low-pass filter, further D / A converted by the DSP, and the audio signal is output from the speaker. The Since the radio communication apparatus shown in FIG. 6 includes the duplexer of the present invention, a call with less noise is possible.

  An embodiment in which a duplexer is manufactured using each circuit board 100 shown in FIGS. In addition, the form shown below is an example of embodiment of this invention to the last, and this invention is not limited to these.

  First, lithium tantalate (LiTaO3) was used as the piezoelectric substrate 101, a Ti thin film having a thickness of 6 nm was formed on the main surface, and an Al—Cu thin film having a thickness of 157 nm was formed thereon.

  Next, a photoresist was applied to a thickness of about 0.5 μm using a resist coating apparatus. Then, a reduced projection exposure apparatus (stepper) was used to form a photoresist pattern serving as a resonator, a signal line, a pad electrode, and the like, and an annular electrode 16 'surrounding the resonator, the signal line, the pad electrode, and the like. The annular electrode 16 ′ is solder-bonded to the annular electrode 16 formed on the circuit board, and has a function as a ground pattern and a function of hermetically sealing the surface acoustic wave element 22. Further, unnecessary portions of the photoresist were dissolved with an alkaline developer by a developing device.

Next, an electrode pattern shown in FIG. 7 was formed by a RIE (Reactive Ion Etching) apparatus. And the protective film was produced on the predetermined area | region of the electrode pattern. That is, a SiO ₂ film having a thickness of about 15 nm was formed on the electrode pattern and the main surface of the piezoelectric substrate by a CVD (Chemical Vapor Deposition) apparatus. Then, the photoresist was patterned by photolithography, and the SiO ₂ film of the flip chip electrode portion (input / output electrode, ground electrode and pad electrode) was etched by an RIE apparatus or the like. Next, using a sputtering apparatus, a laminated electrode made of Cr, Ni and Au was formed on the portion where the SiO2 film was removed. The electrode film thickness at this time was about 1 μm, respectively 0.01 μm, 1 μm, and 0.2 μm. Further, the photoresist and the unnecessary portion of the laminated electrode were simultaneously removed by a lift-off method, and the portion where the laminated electrode was formed was used as a flip chip electrode portion for connecting the flip chip bump.

  Next, the piezoelectric substrate was diced along dicing lines and divided into filter element chips.

Next, a conductive material was printed on the patterned electrode, the input / output conductor, and the ground conductor made of silver on the upper surface of the circuit board 100 having a laminated structure made of ceramic. Solder was used as the conductive material. Then, each chip was temporarily bonded onto the circuit board by a flip chip mounting apparatus with the electrode formation surface on the bottom surface. Temporary bonding was performed in an N ₂ atmosphere. Furthermore, the chip was bonded to the circuit board by baking in an N ₂ atmosphere and melting the solder. The matching inductor is formed by a line provided inside the circuit board as shown in FIGS. Note that this circuit board is a collective board, and is mounted with a plurality of chips.

Next, resin was applied to the circuit board to which the chip was bonded, and baking was performed in an N ₂ atmosphere to seal the chip with resin.

  Next, the large substrate including each circuit substrate was diced along dicing lines and divided into individual pieces, thereby producing the duplexer of the present invention. The ceramic circuit board divided into individual pieces has a mounting area of 2.5 × 2.0 mm and a height of 0.9 mm.

  Thus, the duplexer A of the present invention was produced.

  Further, as a comparative example, a circuit board shown in FIG. 5 was produced in which the shielding pattern built in the circuit board was formed as a solid pattern as usual. Then, the piezoelectric substrate on which the filter was formed was flip-chip solder mounted on the circuit substrate to produce a CSP duplexer. A CSP duplexer was further mounted on a printed circuit board, and S parameters between each port were measured using a network analyzer via an SMA connector and a coaxial cable. The transmission coefficient, out-of-band attenuation, and isolation data between the transmission terminal and the reception terminal in the 2.1 GHz band are shown in Table 1 and FIGS. Example 1 is a duplexer fabricated using the circuit board 100 shown in FIG. 1, Example 2 is a duplexer fabricated using the circuit board 100 shown in FIG. 3, and Example 3 is shown in FIG. This is a duplexer fabricated using the circuit board 100. In Table 1 and FIGS. 1 to 3, the Rx band is a band of 1.92 to 1.98 GHz, and the Tx band is a band of 2.11 to 2.17 GHz.

  From the results shown in Table 1, it can be seen that in Examples 1 to 3, the insertion loss is low and good isolation characteristics are obtained.

  FIG. 8 shows filter characteristics for the duplexer of the first embodiment and the duplexer of the comparative example. FIG. 8A shows transmission characteristics, and FIG. 8B shows isolation characteristics. In each diagram, the horizontal axis represents frequency (unit: GHz), the vertical axis represents attenuation (unit: dB), the solid characteristic curve represents the result of Example 1, and the dashed characteristic curve represents a comparative example. Shows the results. As can be seen from the results shown in FIGS. 8A and 8B, the duplexer of the first embodiment has a significantly improved insertion loss compared to the duplexer of the comparative example (0.8 dB and Rx with the Tx filter). 0.4 dB with a filter). The duplexer of Example 1 is smaller in isolation (0.6 dB in the Tx band and 6 dB in the Rx band) than the comparative duplexer, but is used for matching with the surface acoustic wave filter. When compared with the one having no shielding conductor between the line 7 and the duplexer of the first embodiment, the isolation characteristic is superior. From this result, when both the isolation characteristic and the insertion loss are taken into consideration, the shield conductor 61 having a full solid pattern is not provided between the surface acoustic wave filter and the matching line 7 as in the comparative example. As in the duplexer shown in FIG. 4, it can be said that it is better not to provide a large shielding conductor at the portion facing the transmission-side surface acoustic wave filter.

  FIG. 9 shows filter characteristics for the duplexer of the second embodiment and the duplexer of the comparative example. FIG. 9A shows transmission characteristics, and FIG. 9B shows isolation characteristics. In each diagram, the horizontal axis represents frequency (unit: GHz), the vertical axis represents attenuation (unit: dB), the solid characteristic curve represents the result of Example 2, and the broken characteristic curve represents a comparative example. Shows the results. As can be seen from the results shown in FIGS. 9A and 9B, the Tx band isolation in the second embodiment is 4 dB larger and the Rx band isolation is 1.4 dB smaller than the comparative example, and the insertion loss is reduced by the Tx filter. With 0.5 dB, the Rx filter improves 0.1 dB.

  FIG. 10 shows filter characteristics for the duplexer of the third embodiment and the duplexer of the comparative example. FIG. 10A shows transmission characteristics, and FIG. 10B shows isolation characteristics. In each diagram, the horizontal axis represents frequency (unit: GHz), the vertical axis represents attenuation (unit: dB), the solid characteristic curve represents the result of Example 2, and the broken characteristic curve represents a comparative example. Shows the results. As can be seen from the results shown in FIGS. 10A and 10B, Example 1 of the present invention has an Rx band isolation of 5.8 dB smaller than that of the comparative example, but a Tx band isolation of 4.1 dB larger. The insertion loss is improved by 0.8 dB with the Tx filter and 0.3 dB with the Rx filter.

  As can be seen from Table 1, when Example 1 and Example 3 are compared, both have substantially the same insertion loss. However, for Tx band isolation, the duplexer of Example 3 is more than the duplexer of Example 1. It can also be seen that there is an improvement of 4.7 dB.

  In addition, this invention is not limited to the example of the above embodiment, A various change may be added in the range which does not deviate from the summary of this invention. A shield pattern may be used for the surface layer, and the number of layers of the shield pattern may be two. In that case, unnecessary electromagnetic coupling between the matching line and the filter wiring pattern on the piezoelectric substrate can be further reduced, and the isolation characteristics can be improved.

It is a figure which shows the pattern arrangement | positioning and via | veer arrangement | positioning of each layer of the circuit board which comprise the branching filter concerning 1st Embodiment of this invention. It is a block diagram of the circuit integrated in the duplexer concerning the embodiment of the present invention. It is a figure which shows the pattern arrangement | positioning and via | veer arrangement | positioning of each layer of the circuit board which comprise the duplexer concerning 2nd Embodiment of this invention. It is a figure which shows the pattern arrangement | positioning and via | veer arrangement | positioning of each layer of the circuit board which comprise the branching filter concerning 3rd Embodiment of this invention. It is a figure which shows the pattern arrangement | positioning and via arrangement | positioning of each layer of the circuit board which comprise the splitter of a comparative example. It is a block diagram of the radio | wireless communication apparatus concerning 4th Embodiment of this invention. It is a schematic diagram of the filter pattern used for the duplexer according to the embodiment of the present invention. FIG. 6 is a diagram showing electrical characteristics when a duplexer is manufactured using the circuit board shown in FIG. 1 and the circuit board shown in FIG. 5, (a) shows a measurement result of transmission characteristics, and (b) shows an isolator. It is a figure which shows the measurement result of an oscillation characteristic. FIG. 6 is a diagram showing electrical characteristics when a duplexer is manufactured using the circuit board shown in FIG. 3 and the circuit board shown in FIG. 5, (a) shows a measurement result of transmission characteristics, and (b) shows an isolator. It is a figure which shows the measurement result of an oscillation characteristic. FIG. FIG. 6 is a diagram showing electrical characteristics when a duplexer is manufactured using the circuit board shown in FIG. 4 and the circuit board shown in FIG. 5, (a) is a diagram showing measurement results of transmission characteristics, and (b) is an isolator. It is a figure which shows the measurement result of an oscillation characteristic. It is a perspective view of the duplexer concerning the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transmission side signal terminal 2, 3 ... Reception side signal terminal 4 ... Common terminal 5 ... Surface acoustic wave filter for transmission 6 ... Surface acoustic wave filter for reception 7 ... Matching circuit

Claims (11)

A piezoelectric substrate; and a surface acoustic wave filter for transmission that constitutes a ladder-type filter circuit and a surface acoustic wave filter for reception that constitutes a longitudinal multimode filter circuit provided on one main surface of the piezoelectric substrate;
A circuit board for mounting the piezoelectric substrate on an upper surface;
Wherein the transmitting SAW filter and the receiving SAW filter constitutes a matching circuit for impedance matching, and the circuit first portion and the overlapping with Oite the reception surface acoustic wave filter in the thickness direction of the substrate An inductor pattern formed inside the circuit board so as to have a second portion overlapping the surface acoustic wave filter for transmission ;
A receiving-side shielding conductor disposed between the first portion of the inductor pattern and the receiving surface acoustic wave filter in the thickness direction of the circuit board;
A transmission-side shielding conductor that is disposed between the second portion of the inductor pattern and the transmission surface acoustic wave filter in the thickness direction of the circuit board and has a smaller area than the reception-side shielding conductor. Waver. The duplexer according to claim 1 , further comprising a sealing resin that covers the piezoelectric substrate .   3. The duplexer according to claim 1, wherein the surface acoustic wave filter for reception includes a longitudinal multimode filter circuit having an unbalanced input and a balanced output.   4. The duplexer according to claim 1, wherein the reception-side shielding conductor is electrically connected to a reference potential terminal formed on a lower surface of the circuit board. The sender shielding conductor duplexer according to claim 1 having both toothed comb-shaped or net shape interdigital conductors on both sides are formed of the strip conductor. The sender shielding conductor duplexer according to claim 1, characterized in that formed inside the circuit board. The sender shielding conductor duplexer as claimed in claim 1, wherein formed on the upper surface of the circuit board. The lower surface of the circuit board is provided with a reception-side signal terminal connected to the reception surface acoustic wave filter via a reception line,
5. The duplexer according to claim 4, wherein a reference potential through conductor connected to the reference potential terminal is formed between the reception line and the matching circuit. A transmission side signal terminal connected to the surface acoustic wave filter for transmission and a transmission line is provided on the lower surface of the circuit board,
5. The duplexer according to claim 4, wherein a reference potential through conductor connected to the reference potential terminal is formed between the transmission line and the matching circuit.   The duplexer according to claim 1, wherein the reception-side shielding conductor is not formed at a position overlapping the surface acoustic wave filter for transmission in the thickness direction of the circuit board.   A wireless communication device comprising the duplexer according to claim 1 and an antenna connected to the duplexer.