JP3525408B2 - Demultiplexer package - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demultiplexer package using a surface acoustic wave bandpass filter, and more particularly to a multi-layer demultiplexer package provided with a phase matching circuit.

In recent years, mobile communication devices typified by portable telephones have been rapidly miniaturized, and there has been a demand for miniaturization and high performance of components used therein. A branching filter is used so that a transmission signal and a reception signal do not interfere with each other in order to branch and generate a signal in these wireless communication devices. Many of the duplexers are composed of a band pass filter using a dielectric, a band stop filter, or a combination thereof, but a filter using an elastic surface filter is being researched and developed today.

[0003]

2. Description of the Related Art When a duplexer is constructed by using two band pass surface acoustic wave filter chips F ₁ and F ₂ , it is necessary to design each filter so as not to interfere with each other's filter characteristics. On the other hand, a phase matching circuit is added.

This is generally a filter chip F as described above.
₁ and F ₂ are designed to have a value close to the characteristic impedance of the entire duplexer circuit (usually 50Ω) near the center frequency of each passband, and a much larger characteristic impedance in other frequency bands. However, it is difficult to prevent interference with the filter characteristic of the partner in the pass band of the filter chip of the partner due to the influence of the resistance component existing in the circuit pattern. The constants of this phase matching circuit are determined by the values of the center frequencies (f ₁ and f ₂ ) of the _two filter chips and their difference.

Heretofore, as the phase matching circuit, there have been proposed one using an L (inductance) element or a C (capacitor) element, one using a line serving as an L or C component, or the like.

[0006] For example, Japanese Patent Laid-Open No. 5-167388
Also, Japanese Patent Laid-Open No. 5-167389 describes a duplexer in which a phase matching circuit is formed on a glass epoxy substrate or a ceramic substrate by a metal strip line. Further, there is also one in which two filter chips and a phase matching circuit are housed in a multilayer ceramic package.

An example of a duplexer using this conventional multilayer ceramic package is shown in FIGS. 10 (a) and 10 (b). This is, as shown in the figure, a multilayer ceramic package 6 provided with a plurality of ground layers GND, phase matching circuits 1 and 2, a grounding terminal 3, a filter side signal terminal 4 and a common signal terminal 5. , Filter chips 7 and 8 are mounted,
Wire 9 between filter chip 7, 8 and each terminal 3, 4, 5
Are connected with.

Phase matching circuit 1 housed in a package
As shown in the figure, 2 and 2 are located below the filter chip layer and sandwiched between the GND layers, and are normally formed by strip lines, and their characteristic impedance is connected to the common signal terminal 5 by an external circuit. It is created to match the characteristic impedance of. As a result, circuit loss can be reduced.

[0009]

However, the characteristic impedance of the filter chip having two different center frequencies forming the duplexer changes depending on the frequency of the signal used. For example, the characteristic impedance of the filter chip has a value substantially equal to the characteristic impedance of the external circuit in the pass band, and is much smaller or larger than the characteristic impedance of the external circuit in the stop band. Then, in order to reduce the circuit loss, it is necessary to prevent the characteristics of the filter chip and the external circuit from deteriorating when the duplexer is configured using them. For that purpose, in the pass band of each other, the characteristic impedances of the other parties are infinite and the reflection coefficient is also approximately 1.
Is ideal.

A circuit for matching the phase is required to bring the characteristics close to such ideal characteristics, and it has been proposed to form the above-described strip line. In this case, the resistance is proportional to the line length. Also increases. An increase in resistance may cause a propagation loss of a signal and an increase in stray capacitance in the distributed constant. This increase in stray capacitance affects the phase circuit constant and the like, and the higher the frequency of the signal used, the greater the degree of the effect. That is, the characteristics of the branch of the transmission / reception signal are deteriorated, and further the transmission of the transmission / reception signal is lost.

Further, when a material having a high dielectric constant is used for the package, each layer must be coupled at a high temperature, and therefore a strip line having a high melting point must also be used, so that the above filter characteristics are deteriorated. Is increased.

Therefore, the present invention has been made in consideration of the above circumstances, and sets the characteristic impedance of the strip line which is a phase matching circuit built in the duplexer package and the duplexer package. An object of the present invention is to provide a duplexer package that can improve the characteristic deterioration of two filters having different band center frequencies by adjusting the number of grounding terminals.

By setting the value of the characteristic impedance of the strip line higher than the value of the characteristic impedance of the external circuit connected to the duplexer,
The purpose is to reduce the signal loss in the normal band and improve the characteristic deterioration compared to when the two characteristic impedances are matched.

Further, the number of grounding terminals of the demultiplexing package is made larger than the number of surface acoustic wave resonators of the parallel arms forming the filter chip, thereby increasing the signal attenuation amount in the stop band and improving the characteristics. The purpose is to improve deterioration.

[0015]

SUMMARY OF THE INVENTION The present invention is a multilayer duplexer package in which two surface acoustic wave filter chips each having a different band center frequency and a phase matching circuit between the two filters are contained in one. And the phase matching circuit is provided between layers in the multilayer duplexer package.
Which are vertically stacked with respect to each other and formed by at least two strip lines,
A parallel arm surface acoustic wave resonator connected in parallel to a common signal terminal for connecting an external circuit and a signal line connecting the strip line, and a series arm surface acoustic wave resonator connected in series. And surface acoustic waves
To increase the signal attenuation in the stop band of the filter chip
In addition, a grounding terminal for grounding the filter chip is packaged so as to surround the filter chip.
With Keru more set than the number of surface acoustic wave resonator in the parallel arm housed inner peripheral surface, the terminal and the filter chip for each ground
The present invention provides a duplexer package characterized in that it is connected to a terminal on a chip by a wire .

Here, the characteristic impedance value of the strip line may be larger than the characteristic impedance value of the external circuit connected to the demultiplexing package, and particularly 1.11.
It is preferably within ± 7%. Also, the width of the strip line may be different at both ends of the strip line.

Further, the filter chip and the strip line may be formed in layers.

Here, the duplexer package is generally formed of alumina or glass ceramic, but any material having a high dielectric constant may be used. The strip line is made of a metal such as gold, tungsten, or copper, but a material having a small resistance and a high conductivity is preferable. Further, the two strip lines are formed by being sandwiched between the layers of the package made of the material having the high dielectric constant as described above, and the two strip lines are formed by laminating the layers of the package. It is preferable.

[0019]

According to the present invention, the number of grounding terminals for grounding the filter chip is larger than the number of surface acoustic wave resonators of the parallel arms forming the filter chip. It is possible to increase the signal attenuation amount and improve the characteristic deterioration.

Further, since the value of the characteristic impedance of the strip line is set to be larger than the value of the characteristic impedance of the external circuit connected to the duplexer package, the signal loss in the pass band of the filter chip is reduced and the characteristic deterioration is prevented. Can be improved.

Further, since the filter chip and the strip line are formed in layers, the duplexer package can be downsized.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. The present invention is not limited to this.

First Embodiment FIG. 1 shows a schematic block diagram of a duplexer according to the present invention. As shown in the figure, two surface acoustic wave bandpass filter chips F1 and F2 are connected to a common terminal TT ′, and two phase matching circuits 1 are provided between these filter chips and TT ′. And 2 are provided.

Here, the common terminals T and T'are terminals for connecting an external circuit for transmitting and receiving radio waves through the antenna. Further, the filter chips F1 and F2 shown in the figure are provided with, for example, an F ₁ terminal to which an external transmitting circuit is connected and an F ₂ terminal to which an external receiving circuit is connected.

FIG. 2 shows an explanatory diagram of frequency characteristics of the filter chip of the duplexer. As shown in the figure, the surface acoustic wave bandpass filter chips F1, F2 has a different band center frequencies from each other, for example, the center frequency f ₁ of the filter tip F1 is 932MH _Z, the center frequency of the filter chip F2
f ₂ is set to 878MH _z. At this time, in order to prevent the band pass characteristics of the respective filter chips from interfering with each other, that is, to prevent the peaks of the passing intensities of the respective filter chips in FIG. A circuit is added.

3 (a) and 3 (b) are a plan view and a sectional view of a duplexer using the multilayer ceramic package according to the present invention. In the figure, reference numerals 1 and 2 denote phase matching circuits, which are formed by strip lines made of a material such as tungsten. GND is a ground layer, and is laminated with two strip lines sandwiched therebetween. 3 is a grounding terminal for grounding the duplexer, 4 is a filter side signal terminal connected to the filter chip after branching the signal, and 5 is a common side signal terminal connected to an external circuit. is there.

Reference numerals 7 and 8 are filter chips, which are GND.
Mounted above the layer. Also, the filter chips 7 and 8
The grounding terminal 3, the filter-side signal terminal 4, and the common-side signal terminal 5 are connected by a wire 9. Further, since the strip lines 1 and 2 and each signal terminal and the filter chip have a hierarchical structure, they are coupled through through holes and vias which are formed over the layers and are electrically connected.

The multilayer ceramic package 6 having the above structure is made of a glass ceramic material (dielectric constant = 5) and can be formed with a height of 7.5 mm, a width of 8.5 mm and a height of 2.1 mm.

Further, the two strip lines 1 and 2 embedded between the GND layers are not simple straight lines but are straight lines that are appropriately bent on the same plane. FIG. 4 shows an example of a plan view of the shape of the strip line 1. The length of the strip line 1 is 35 mm and the line width is
It is about 0.2 mm. The other strip line 2 has a different shape from the strip line 1 and has a short length of 25 mm but the same line width of 0.2 mm.

The two strip lines are shown in FIG.
As shown in (b), it is formed between the GND layers made of a glass ceramic material, but since the characteristic impedance value of the two strip line patterns is 55Ω,
The thickness of each GND layer was set to a value as shown in FIG.
Here, the characteristic impedance value of the strip line (= 55
Ω) is set to be larger than the characteristic impedance value (= 50 Ω) of the external circuit.

FIG. 3 shows an example of a duplexer package having a plurality of grounding terminals on the surface. First, the number of grounding terminals, that is, the number of grounding bonding pads, constitutes a filter chip, and parallel arms inside the same. The characteristics when the number of surface acoustic wave resonators is larger than the number of surface acoustic wave resonators will be described.

Generally, inside the filter chip, a surface acoustic wave resonator of a parallel arm connected in parallel to a signal line connecting the above-mentioned common terminal and the strip line and a series connected in series to this signal. It is composed of a surface acoustic wave resonator for the arm.

Further, as shown in FIG. 3A, the grounding terminal 3, the filter side terminal 4, and the common signal terminal 5 existing on one end of these resonators of the filter chip and on the surface.
Are connected by wires 9. However, since this demultiplexer is laminated, through holes and vias are used for the strip line in the lower layer and for grounding.

FIG. 8 shows an electrical equivalent model of the duplexer package of FIG. Here, the filter chips 7 and 8
However, both are composed of one series arm surface acoustic wave resonator and two parallel arm surface acoustic wave resonators. Further, the filter chip is connected to each terminal by the wire 9,
The wire 9 has an inductance component, and further, the lower layer strip line and the through hole for connecting to the ground terminal also have the inductance component as shown in the figure.

It is known that changing the number of wires connected to this parallel arm surface acoustic wave resonator changes the signal attenuation in the stop band of the filter. This is because the inductance component due to the via changes. In general, this inductance component adversely affects the amount of attenuation as high frequency signal leakage, so it is better to reduce the inductance component.

Therefore, as shown in FIG. 3A, the grounding terminals 3 are provided on the surface of the duplexer in a number larger than that of the parallel arm surface acoustic wave resonators. As a result, the number of wires 9 connecting the filter and the grounding terminal 3 and the number of through holes and vias are increased in parallel, so that the inductance component contributed by them can be reduced.

FIG. 9 shows band characteristics when the number of grounding terminals is increased as described above (A) and when the number of grounding terminals is equal to the number of parallel arm surface acoustic wave resonators (B). The following is a comparative example. Here, when increasing the number of terminals for grounding,
At least two parallel arm surface acoustic wave resonators are provided. In the figure, it can be seen that the amount of attenuation can be improved in the stop band of the filter chip by about 5 dB when the number of grounding terminals is increased. At this time, as shown in FIG. 9, the characteristics of the pass band of the filter chip are hardly deteriorated.

In addition to increasing the number of ground terminals as described above, the amount of attenuation is also improved by increasing the number of wires connecting the same ground terminal and the filter without increasing the number of ground terminals. be able to. It is considered that these are all due to the reduction of the inductance component existing in the through hole and the wire as described above.

From the above, the filter characteristics can be improved by providing as many grounding terminals 3 as the space of the duplexer package allows. Therefore, by providing more grounding terminals than the number of parallel arm surface acoustic wave resonators, the characteristics of the pass band of the filter chip are not deteriorated, and the signal attenuation amount is only for the stop band. Can be increased. This means that the characteristics of the filter chips of each other with respect to the pass band can be improved.

FIG. 5 shows a measurement diagram of a change in the filter characteristic with respect to the characteristic impedance value of the strip line. As the filter characteristic value, the vertical axis indicates the VSWR (Voltage Standing Wave) within the pass band after phase rotation by the strip line.
Ratio: voltage standing wave ratio), the amount of reflection coefficient change in the other pass band before and after phase rotation by the strip line, after phase rotation by the strip line, in the pass band of the other filter chip when combined with the other filter It shows the loss increase.

Here, the in-passband VSWR is normally used at 2 or less, and shows 1 in an ideal filter. Therefore, it is preferable that the VSWR be 2 or less and be as close to 1 as possible.

Further, the reflection coefficient in the pass band on the partner side is ideally desired to be 1. However, in a commonly used filter, a value of 0.85 to 0.90 is shown, in order to avoid deterioration of characteristics of the filter. Is the reflection coefficient change,
It is an essential condition that the reflection coefficient is as close to 1 as possible, that is, 0 or more.

Further, when the characteristic impedance of the strip line is changed, the loss is also increased / decreased in accordance therewith, but here, the range of 0 to 0.5 is allowed as the loss increase that does not cause any problem in the actual signal transmission. And

In the figure, for example, when the characteristic impedance is 50Ω, VSWR shows a better numerical value than when it is 55Ω, but the reflection coefficient change and loss increase show a bad numerical value. ing.

Therefore, in FIG. 5, it can be said that when the characteristic impedance of the strip line is 55Ω rather than 50Ω, the characteristic deterioration of the filter is less. That is,
The characteristic impedance of the strip line means that the characteristic deterioration is smaller when the characteristic impedance of the strip line is set to be slightly larger than the characteristic impedance of the external circuit. Further, when the characteristic impedance is in the vicinity of 60Ω, the VSWR value becomes 2 or more, and the increment of the mismatch loss exceeds 0.5, which is in the state of ignorable deterioration of the filter characteristic.

Therefore, VSWR of 2 or less, reflection coefficient change of 0 or more, and loss increase of 0.5 or less are adopted as criteria for selecting the characteristic impedance of the strip line that causes no practical problem. At this time, since the deterioration of the filter characteristic is suppressed and there is no problem in the actual signal transmission, the characteristic impedance of the strip line is 1.11 times ± 7% (51.
615 to 59.385 Ω: the range shown by the diagonal lines in FIG. 5) can be used.

Here, the upper limit value of the characteristic impedance of the strip line is such that VSWR is 2, and the lower limit value thereof is that in which the variation of the reflection coefficient is 0. The range of the upper limit value and the lower limit value of this characteristic impedance is the characteristic impedance value 50Ω of the external circuit.
The value standardized in 1.11 times is ± 7%.

As described above, by setting the characteristic impedance value of the strip line which is the phase matching circuit to be larger than the characteristic impedance value of the external circuit, the signal loss in the filter chip pass band is reduced and the characteristic deterioration of the filter chip is reduced. Can be improved.

In addition, two strip lines are laminated,
Further, since the filter chip is mounted above the strip line, the size of the entire duplexer package can be reduced. Further, since the characteristic deterioration of the filter chip can be improved as described above, the manufacturing yield of the duplexer package can also be improved.

Second Embodiment Next, an embodiment of the duplexer in which the width of the strip line is made different at both ends thereof will be described. In the duplexer having the layer structure as shown in FIG. 3, the width of the strip line pattern embedded between the ground layers as shown in FIG. 4 is changed, and the strip line 1 is taken as an example. The width connected to the filter chip is set to 240 μm, the pattern width is gradually narrowed in the line length direction, the side connected to the common terminal of the strip line is set to 180 μm, and the line middle is set to 200 μm.

FIG. 6 is a diagram showing changes in characteristic impedance when the line widths of the strip lines are different. However, this includes a component due to the resistance of the line. In the figure, the horizontal axis corresponds to the line length, and the vertical axis represents the characteristic impedance of the strip line. The upper graph of FIG. 6 shows a line length of 35 mm corresponding to the strip line 1, and the lower graph shows a line length of 25 mm corresponding to the strip line 2.

The left side of the graph is the filter chip side with a wide line width, and the right side of the graph is the common terminal side with a narrow line width. From the graph in the figure, when standardizing with the characteristic impedance value of 50Ω of the external circuit, the characteristic impedance of the strip line is 0.95 times on the filter chip side with a wide line width, 1.3 times on the common terminal side with a narrow line width, overall It turns out that the average is 1.11 times.

FIG. 7 shows a comparative measurement diagram when the line width is constant as in the first embodiment and when the line width is changed in the second embodiment. The width is the frequency and the vertical axis is the passing intensity.

According to this, when the line width is changed, the passing intensity is improved and the mismatch loss is about 0.20 dB, which is smaller than that in the case of the constant line width of the first embodiment. It can be seen that it is reduced to about 80%. This is because the characteristic impedance value of the strip line and the characteristic impedance value of the external circuit differ greatly, but the characteristic impedance value of the filter chip becomes the same value as that of the external circuit as a result of the phase rotation caused by the strip line. It is considered that the actual mismatch loss became smaller.

As described above, by making the line width of the strip line different at both ends thereof, it is possible to reduce the signal loss in the pass band of the filter chip and improve the characteristic deterioration of the filter chip. In addition, the improvement in the characteristic deterioration can improve the yield in the manufacture of the duplexer package.

The package material is not limited to glass ceramic, but alumina (dielectric constant: 10) may be used.
Although there are some differences in the absolute value of the attenuation amount, the filter characteristics can be improved in substantially the same manner. Therefore, it goes without saying that the same result can be obtained by using a material such as mullite as the package material.

In the above embodiment, the duplexer package having a structure in which two strip lines are laminated and the filter chip and the strip line are hierarchized is used. The two strip lines and the filter chip may be arranged side by side on the ceramic substrate. In this case, the bottom area increases, but it is possible to reduce the height, and depending on the application, a duplexer with a laminated structure or a duplexer with a filter chip etc. arranged in parallel Should be adopted.

Further, the duplexer may be formed to have a structure in which the strip line and the filter chip are arranged on different substrates, or a structure in which two strip lines are embedded in parallel in a glass ceramic substrate. .

[0059]

According to the present invention, the characteristic impedance value of the strip line is set to be larger than the characteristic impedance value of the external circuit connected to the duplexer package, and the line width is made different at both ends of the strip line. Or, by providing the number of grounding terminals more than the number of parallel arm surface acoustic wave resonators forming the filter chip, characteristic deterioration of the filter chip , especially in the stop band
It is possible to improve the characteristic deterioration due to the increase of the signal attenuation amount .

[Brief description of drawings]

FIG. 1 is a configuration diagram of a duplexer that is an embodiment of the present invention.

FIG. 2 is an explanatory diagram of frequency characteristics of a filter chip of the duplexer.

FIG. 3 is a plan view and a sectional view of a duplexer using a multilayer ceramic package according to an embodiment of the present invention.

FIG. 4 is a plan view showing an example of the shape of a strip line according to the present invention.

FIG. 5 is a measurement diagram showing a change in filter characteristic with respect to a characteristic impedance value of a strip line in the present invention.

FIG. 6 is a measurement diagram showing changes in the characteristic impedance of the strip line according to the second embodiment of the present invention.

FIG. 7 is a comparison diagram of band characteristics between the first embodiment and the second embodiment.

FIG. 8 is an electrically equivalent model of the duplexer package according to the present invention.

FIG. 9 is a measurement diagram of band characteristics in the embodiment of the present invention.

FIG. 10 is a plan view and a sectional view of a conventional duplexer package.

[Explanation of symbols]

1 Phase matching circuit (strip line) 2 Phase matching circuit (strip line) 3 Grounding terminal 4 Filter side signal terminal 5 Common side signal terminal 6 Multilayer ceramic package 7 filter tip 8 filter tips 9 wires

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuhiro Hirasawa               1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture                 Within Fujitsu Limited (72) Inventor Hideki Omori               1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture                 Within Fujitsu Limited                (56) References JP-A-6-112762 (JP, A)

Claims (4)

(57) [Claims] 1. A multi-layer demultiplexer package in which two surface acoustic wave filter chips each having a different band center frequency and a phase matching circuit between the two filters are housed in one, wherein The circuit is based on the multilayer demultiplexer
Between layers in the package, perpendicular to the layers
And a filter arm formed by at least two strip lines, wherein the filter chip is connected in parallel with a common signal terminal for connecting an external circuit and a signal line connecting the strip lines. It is composed of a resonator and a surface acoustic wave resonator of a series arm connected in series .
In order to increase the amount of signal attenuation, a grounding terminal for grounding the filter chip is further provided in the filter chip.
With Keru more set than the number of surface acoustic wave resonator in the parallel arm in a package housing the inner peripheral surface so as to surround, each of the
Use a wire to connect the grounding terminal to the terminal on the filter chip.
A duplexer package characterized by being connected together . 2. The duplexer package according to claim 1, wherein a characteristic impedance value of the strip line is set larger than a characteristic impedance value of an external circuit connected to the duplexer package. 3. The characteristic impedance value of the strip line with respect to the characteristic impedance value of the external circuit is 1.
The duplexer package according to claim 2, wherein the content is within 11 ± 7%. 4. The filter chip and the strip line are formed in a hierarchical structure.
Alternatively, the duplexer package described in 3.