JP2004214898A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a branching filter capable of reducing a parasitic capacitance between filters without incurring extension of the mount area and a complicated structure. <P>SOLUTION: The electronic apparatus includes: a mount board 11; a transmitter side filter BF1 mounted on the mount board 11; and a receiver side filter BF2 mounted on the same plane as the transmitter side filter BF1 on the mount board 11, wherein the transmitter side filter BF1 and the receiver side filter BF2 are located so that a perpendicular line L1 passing through the center of a side of the transmitter side filter BF1 opposed to the receiver side filter BF2 and in parallel with the mount face and a perpendicular line L2 passing through the center of a side of the receiver side filter BF2 opposed to the transmitter side filter BF1 and in parallel with the mount face are not on the same straight line. The transmitter side filter BF1 and the receiver side filter BF2 are provided with a surface acoustic wave resonator formed on a piezoelectric substrate and have mutually different pass bands to configure the branching filter. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic device in which a plurality of electronic components are mounted on a mounting board, and more particularly to a technique that is effective when applied to reduce parasitic capacitance between electronic components.
[0002]
[Prior art]
2. Description of the Related Art In recent years, mobile communication terminals such as mobile phones are rapidly developing. It is desired that the terminal be particularly small and lightweight because of its easy portability. In order to reduce the size and weight of the terminal, it is essential that the electronic device used therein is also small and lightweight.
[0003]
As a high-frequency band filter which is an electronic device in a mobile communication terminal or the like, a surface acoustic wave device in which a plurality of surface acoustic wave resonators (SAW resonators) are formed on a piezoelectric substrate, that is, a surface acoustic wave filter is known. ing. It is also known to form a duplexer using a plurality of surface acoustic wave filters having different center frequencies.
[0004]
Here, a conventional duplexer using a plurality of surface acoustic wave filters will be described.
[0005]
12 is a plan view showing an example of a conventional duplexer, FIG. 13 is a sectional view of FIG. 12, FIG. 14 is a plan view showing another example of the conventional duplexer, and FIG. 15 is a sectional view of FIG. is there.
[0006]
In these drawings, the duplexer 110 has a transmission filter BF1 and a reception filter BF2, which are two surface acoustic wave filters having different passbands, mounted on a mounting board 111. The mounting substrate 111 includes a signal terminal 112 and a signal terminal 113 electrically connected to the transmission-side filter BF1, a signal terminal 114 and a signal terminal 115 electrically connected to the reception-side filter BF2, and these filters BF1, A ground terminal 116 electrically connected to BF2 is formed.
[0007]
A package side wall 117 is formed on the outer peripheral edge of the mounting substrate 111, and the filters BF1 and BF2 are sealed by bonding the cap 118 to the package side wall 117.
[0008]
In the case shown in FIGS. 12 and 13, the filters BF1 and BF2 are flip-chip mounted.
[0009]
14 and 15, the filters BF1 and BF2 are mounted by wire bonding, and a package partition wall 121 is provided between the transmission-side filter BF1 and the reception-side filter BF2.
[0010]
Since the filters BF1 and BF2 used for these are formed on a ferroelectric material such as LiNbO ₃ or LiTaO ₃ as a piezoelectric substrate, it is necessary to consider parasitic coupling between filters through the piezoelectric substrate.
[0011]
Therefore, conventionally, the distance between the transmission-side filter BF1 and the reception-side filter BF2 is set to be, for example, 0.5 mm or more so that the filters BF1 and BF2 do not interfere with each other, or shown in detail in FIG. In this manner, the grounded conductors 122 are arranged above and below the piezoelectric substrate to provide electromagnetic shielding.
[0012]
[Problems to be solved by the invention]
However, according to such a conventional technique, although the parasitic coupling between the two filters can be avoided, the former technique requires a sufficient distance between the filters, so that the mounting area is increased, and the size of the device is reduced. It is a factor that hinders development.
[0013]
In addition, the latter technique not only requires man-hours and cost for conductor arrangement, but also imposes restrictions on the mounting structure such as management of the gap between the filter and the conductor.
[0014]
Such a problem is widely applied not only to a duplexer using a surface acoustic wave filter but also to an electronic device in which a plurality of electronic components are mounted on a mounting board.
[0015]
Therefore, an object of the present invention is to provide an electronic device that can reduce the parasitic capacitance between electronic components without increasing the mounting area or complicating the structure.
[0016]
[Means for Solving the Problems]
In order to solve the above problems, an electronic device according to the present invention includes a mounting board, a predetermined circuit element formed thereon, mounted on the same plane on the mounting board, and passing through the center of each side facing each other. And a plurality of electronic components arranged such that perpendiculars parallel to the mounting surface are on different straight lines.
[0017]
In order to solve the above problems, an electronic device according to the present invention includes a mounting board and a plurality of electronic components on which predetermined circuit elements are formed and mounted on mutually different planes of the mounting board. It is characterized by.
[0018]
Further, in order to solve the above problems, an electronic device according to the present invention includes a mounting board, a predetermined circuit element formed thereon, a first electronic component mounted on the mounting board, and a predetermined circuit element formed. And a second electronic component mounted on the same plane as the first electronic component on the mounting board, and is mounted on the mounting surface through the center of the side of the first electronic component facing the second electronic component. The first electronic component and the second electronic component such that a parallel perpendicular line and a perpendicular line parallel to the mounting surface passing through the center of a side of the second electronic component facing the first electronic component are on different straight lines. Are arranged.
[0019]
In order to solve the above problems, an electronic device according to the present invention includes a mounting board, a predetermined circuit element formed thereon, a first electronic component mounted on the mounting board, and a predetermined circuit element formed. And a second electronic component mounted on a different plane from the first electronic component on the mounting board.
[0020]
According to such an invention, since the plurality of electronic components are offset from each other, the parasitic capacitance between the electronic components can be reduced without increasing the mounting area and complicating the structure, and Can be improved.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings. Here, in the attached drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted. The embodiment of the present invention is a particularly useful embodiment in which the present invention is implemented, and the present invention is not limited to the embodiment.
[0022]
1 is a plan view showing a duplexer according to an embodiment of the present invention, FIG. 2 is a perspective view of FIG. 1, FIG. 3 is a block diagram showing the duplexer of FIG. 1, and FIG. FIG. 5 is an explanatory view conceptually showing a configuration of a surface acoustic wave resonator provided in a wave resonator, FIG. 5 is an explanatory view showing a distribution of an electric field in a duplexer of FIG. 1 from a plane direction, and FIG. FIG. 7 is a graph showing the relationship between the inter-filter distance and the coupling capacity in the duplexer, and FIG. 8 is a graph showing the offset between the filters and the coupling capacity in the duplexer. , FIG. 9 is a graph showing the relationship between the frequency and the isolation characteristic in the presence or absence of offset in the duplexer, and FIG. 10 is a graph showing the relationship between the offset amount and the isolation characteristic at different frequencies in the duplexer. FIG. 11 is a graph showing another embodiment of the present invention. Is a sectional view showing a duplexer is.
[0023]
As shown in FIGS. 1 and 2, the duplexer (electronic device) 10 of the present embodiment includes two surface acoustic wave filters having different passbands, that is, a transmission-side filter (first electronic component) BF1. The receiving-side filter (second electronic component) BF2 is flip-chip mounted on the mounting board 11 at a predetermined interval. However, the transmission-side filter BF1 and the reception-side filter BF2 may be wire-bonded to the mounting substrate 11 (see FIGS. 14 and 15).
[0024]
In the case of the present embodiment, the receiving filter BF2 has a higher pass band than the transmitting filter BF1. However, the transmission filter BF1 may have a higher pass band than the reception filter BF2.
[0025]
The mounting substrate 11 includes a signal terminal 12 and a signal terminal 13 electrically connected to the transmission-side filter BF1, a signal terminal 14 and a signal terminal 15 electrically connected to the reception-side filter BF2, and these filters BF1, A ground terminal 16 electrically connected to BF2 is formed.
[0026]
A package side wall 17 is formed on the outer peripheral edge of the mounting substrate 11, and the filters BF1 and BF2 are sealed by bonding a cap 18 to the package side wall 17.
[0027]
As shown in FIG. 3, the duplexer 10 includes a common signal terminal C through which signals are input and output, and the signal terminal 12 of the transmission-side filter BF1 is connected to the common signal terminal C via a branch point J. The signal terminal 14 of the receiving filter BF2 is connected to the common signal terminal C via the branch point J. The signal input from the common signal terminal C passes only through the receiving filter BF2 and is output from the signal terminal 15, and the signal input from the signal terminal 13 passes through the transmitting filter BF1 and passes through the common signal terminal BF1. Output to C.
[0028]
Here, the signals passing through the filters BF1 and BF2 need to pass without affecting each other. Therefore, in the pass band of one filter, the characteristic impedance Z _{0 of the} entire circuit is matched, and in the stop band corresponding to the other pass band, the value becomes much larger than the characteristic impedance Z _{0 of the} entire circuit, and the matching is performed. An impedance matching circuit 19 is inserted between the branch point J and the signal terminal 14 of the receiving filter BF2. In the present embodiment, the impedance matching circuit 19 is constituted by a strip line provided inside a package.
[0029]
The transmitting filter BF1 and the receiving filter BF2 are formed on a piezoelectric substrate (dielectric) made of, for example, LiTaO ₃ , as shown in FIG. The surface acoustic wave resonator 20 has a shape electrode and a reflector 20c.
[0030]
In the present embodiment, the transmission-side filter BF1 and the reception-side filter BF2 have a multi-stage structure in which the surface acoustic wave resonator 20 connected in series to the input / output electrodes and the surface acoustic wave resonator 20 connected in parallel are provided. It is a connected, so-called ladder-type filter.
[0031]
Note that the number of interdigital electrodes, the electrode period, the aperture length, the arrangement pattern of the surface acoustic wave resonators 20 in the transmission-side filter BF1 and the reception-side filter BF2, and the like, as long as they can have predetermined passbands and stopbands Various forms can be adopted as appropriate.
[0032]
Further, the piezoelectric substrate is not limited to the above-described one, and various other piezoelectric substrates such as a piezoelectric substrate made of LiNbO ₃ can be used.
[0033]
As shown in FIG. 1, the transmitting side filter BF1 and the receiving side filter BF2 have the same size and are mounted in the same direction. The vertical line L1 parallel to the mounting surface passes through the center of the side of the transmitting filter BF1 facing the receiving filter BF2, and the vertical line L1 passes through the center of the side of the receiving filter BF2 facing the transmitting filter BF1. The transmission line filter BF1 and the reception side filter BF2 are offset from each other so that the vertical line L2 is on a different straight line.
[0034]
Note that the transmitting filter BF1 and the receiving filter BF2 may have mutually different sizes. Also, in the present specification, the same size does not need to be exactly the same in both dimensions, but may be substantially the same.
[0035]
According to the duplexer 10 in which the transmission-side filter BF1 and the reception-side filter BF2 are arranged in an offset manner, as shown in FIGS. 5 and 6, the transmission-side filter BF1 and the reception-side filter BF2 face each other. That is, in the transmission-side filter BF1 and the reception-side filter BF2 provided with the piezoelectric substrate, which is a dielectric, the number of portions where the lines of electric force are high and the electric field is strong is reduced. Then, the electric field lines in the air are not opposed to each other, so that the electric field is weakened. As a result, the strength of the electric field acting between the transmitting filter BF1 and the receiving filter BF2 is reduced as a whole.
[0036]
Here, the relationship between the inter-filter distance and the coupling capacitance in the duplexer 10 is shown in FIG. From this figure, it can be seen that the coupling capacity decreases as the inter-filter distance increases, and that when the transmission filter BF1 and the reception filter BF2 are offset, the coupling capacitance decreases as the inter-filter distance decreases, as compared to the case where the filters are not offset. It can be seen that the effect of reducing the amount has increased.
[0037]
In particular, when the distance between the filters is 500 μm or less, the coupling capacitance increases rapidly when there is no offset, whereas the coupling capacitance increases relatively slowly when it is offset. It is advantageous to offset at a distance of
[0038]
Next, FIG. 8 shows the relationship between the offset amount between the filters (length of the portion where the transmission-side filter BF1 and the reception-side filter BF2 are not opposed) in the duplexer 10 and the coupling capacitance. As shown in FIG. 8, it can be seen that the coupling capacitance decreases in proportion to the increase in the offset amount.
[0039]
Characteristics of frequency and isolation (the amount of input signal leaking to the other filter. In the present embodiment, this is represented by the degree of attenuation of leakage power from signal terminal 13 to signal terminal 15) depending on the presence or absence of offset in duplexer 10. Is shown in FIG. As shown in FIG. 9, when the offset amount is set to 50%, large attenuation is obtained in all frequency bands as compared with the case where no offset is performed, that is, the isolation characteristics are improved. You can see that
[0040]
FIG. 10 shows the relationship between the offset amount and the isolation characteristics at different frequencies in the duplexer 10. From FIG. 10, it can be seen that the degree of attenuation increases in proportion to the increase in the offset amount, and that the higher the frequency band, the greater the effect of improving the isolation characteristics due to the offset.
[0041]
As described above, since the transmitting filter BF1 and the receiving filter BF2 are offset, the number of opposing parts is reduced, and the transmitting filter BF1 and the receiving filter BF2 are not expanded without increasing the mounting area or complicating the structure. The parasitic capacitance between the filter BF2 and the filter BF2 is reduced, and the isolation characteristics can be improved.
[0042]
Here, as shown in FIG. 11, even if the transmitting filter BF1 and the receiving filter BF2 are offset-mounted by being mounted on mutually different planes of the mounting substrate 11, the mounting area and the structure are similarly increased. Without increasing the complexity, the parasitic capacitance between the transmission-side filter BF1 and the reception-side filter BF2 is reduced, and the isolation characteristics are improved. In this case, the perpendiculars L1 and L2 may be on different straight lines or may be on the same straight line.
[0043]
In the above description, the case where the present invention is applied to a duplexer using a surface acoustic wave filter having a surface acoustic wave resonator formed on a piezoelectric substrate as an electronic component has been described. The invention is not limited to this. That is, the surface acoustic wave device is not a resonance type electrode structure as described above, but may be, for example, a delay type electrode structure called a transversal type, that is, a surface acoustic wave device provided with an element using a surface acoustic wave phenomenon. Should be fine. The electronic component may be an electronic device other than a filter such as a duplexer, for example, a resonator, an oscillator, a delay line, a signal processing device, or the like.
[0044]
Further, since the present invention is to alleviate the parasitic coupling between electronic components having a dielectric, the electronic component only needs to have a dielectric.
[0045]
The electronic component may be an integrated circuit element on which a transistor, a resistor, a capacitor, and the like are formed.
[0046]
Further, in the present embodiment, the number of electronic components mounted on the mounting board 11 is two, but may be three or more, that is, a plurality of electronic components.
[0047]
【The invention's effect】
As is clear from the above description, according to the present invention, the following effects can be obtained.
[0048]
That is, since a plurality of electronic components are offset from each other, the parasitic capacitance between the electronic components is reduced without increasing the mounting area or complicating the structure, and the isolation characteristics of the electronic components are improved. Becomes possible.
[Brief description of the drawings]
FIG. 1 is a plan view showing a duplexer according to an embodiment of the present invention.
FIG. 2 is a perspective view of FIG.
FIG. 3 is a block diagram illustrating the duplexer of FIG. 1;
FIG. 4 is an explanatory view conceptually showing a configuration of a surface acoustic wave resonator provided in the duplexer of FIG.
FIG. 5 is an explanatory diagram showing a distribution of an electric field in the duplexer of FIG. 1 from a plane direction.
6 is an explanatory diagram showing a distribution of an electric field in the duplexer of FIG. 1 from a cross-sectional direction.
FIG. 7 is a graph showing a relationship between a distance between filters and a coupling capacitance in a duplexer.
FIG. 8 is a graph showing a relationship between an offset amount between filters in a duplexer and a coupling capacitance.
FIG. 9 is a graph showing a relationship between a frequency and an isolation characteristic depending on the presence or absence of an offset in a duplexer.
FIG. 10 is a graph showing a relationship between an offset amount and an isolation characteristic at different frequencies in a duplexer.
FIG. 11 is a sectional view showing a duplexer according to another embodiment of the present invention.
FIG. 12 is a plan view showing an example of a conventional duplexer.
FIG. 13 is a sectional view of FIG.
FIG. 14 is a plan view showing another example of the conventional duplexer.
FIG. 15 is a sectional view of FIG. 14;
[Explanation of symbols]
10 Demultiplexer (electronic device)
DESCRIPTION OF SYMBOLS 11 Mounting board 12, 13, 14, 15 Signal terminal 16 Grounding terminal 17 Package side wall 18 Cap 19 Impedance matching circuit 20 Surface acoustic wave resonator 20a, 20b Finger electrode 20c Reflector 110 Duplexer 111 Mounting board 112, 113, 114, 115 Signal terminal 116 Ground terminal 117 Package side wall 118 Cap 121 Package side wall 122 Conductor BF1 Transmission filter (first electronic component)
BF2 Receiver filter (second electronic component)
C Common signal terminal J Branch point L1 Vertical line L2 Vertical line

Claims (11)

A mounting board,
A predetermined circuit element is formed and mounted on the same plane on the mounting substrate, and is arranged such that perpendiculars parallel to the mounting surface pass through the centers of the sides facing each other and are on different straight lines. Multiple electronic components,
An electronic device comprising: A mounting board,
A predetermined circuit element is formed, a plurality of electronic components mounted on mutually different planes on the mounting board,
An electronic device comprising: The electronic device according to claim 1, wherein the plurality of electronic components have the same size, and are mounted on the mounting board in the same direction. A mounting board,
A first electronic component on which a predetermined circuit element is formed and mounted on the mounting board;
A predetermined circuit element is formed, and the second electronic component mounted on the same plane as the first electronic component on the mounting board;
A perpendicular line parallel to the mounting surface passes through the center of the side of the first electronic component facing the second electronic component, and passes through a center of the side facing the first electronic component of the second electronic component. An electronic device, wherein the first electronic component and the second electronic component are arranged such that a perpendicular line parallel to a mounting surface is on a different straight line. A mounting board,
A first electronic component on which a predetermined circuit element is formed and mounted on the mounting board;
An electronic device, comprising: a predetermined circuit element formed thereon; and a second electronic component mounted on a different plane from the first electronic component on the mounting board. 6. The electronic device according to claim 4, wherein the first electronic component and the second electronic component have the same size, and are mounted on the mounting board in the same direction. Electronic device. The electronic device according to claim 1, wherein the electronic component includes a dielectric. The electronic device according to any one of claims 1 to 7, wherein a distance between adjacent electronic components is 500 µm or less. The electronic device according to claim 1, wherein the electronic component is a surface acoustic wave device including an element using a surface acoustic wave phenomenon. 10. The device according to claim 4, wherein the first electronic component and the second electronic component are surface acoustic wave filters provided with a surface acoustic wave resonator formed on a piezoelectric substrate. An electronic device according to claim 1. The first electronic component and the second electronic component each include a surface acoustic wave resonator formed on a piezoelectric substrate, and have a pass band different from each other and constitute a duplexer. The electronic device according to claim 4, wherein:

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