JP2000022495A - Filter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize a characteristic change from a state of before connection in the case that a plurality of surface acoustic wave filter elements are formed in one chip and they are connected in common at their input terminals or output terminals. SOLUTION: First and second filters F1, F2 whose center frequencies f1, f2 of pass bands different from each other are formed in one chip 1 that acts as a band pass filter. Input terminals Tin1, Tin3 of the chip 1 are connected in common at a connecting point A. A 1-port type surface acoustic wave resonator Rs1 is connected in series between the connecting point A and a surface acoustic wave resonator filter 10. A 1-port type surface acoustic wave resonator Rs2 is connected in series between the connecting point A and a surface acoustic wave resonator filter 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a filter device in which a plurality of surface acoustic wave resonator filters are formed on one chip.

[0002]

2. Description of the Related Art In recent years, competition in the development of mobile communication devices such as automobile telephones and portable telephones has intensified. The wireless transmission / reception unit, which is the heart of the device, is small (for example, about 3 mm square). There is a demand for a high-performance filter device. Also, with the recent expansion of the mobile communication market, some users have a plurality of mobile communication devices, and a mobile communication device that can use a plurality of communication systems with one terminal is required.

[0003] As a conventional filter device, there is no filter device in which a plurality of filter elements having different center frequencies having a common input terminal or output terminal are formed on one chip. For example, as shown in FIG. , For example, those provided with input terminals T1 and T3 and output terminals T2 and T4 respectively on the surface acoustic wave filters F1 and F2.

When the surface acoustic wave filters F1 and F2 having different center frequencies are commonly connected and used,
As shown in FIG. 26, a changeover switch 300 for switching between the outside of the surface acoustic wave filters F1 and F2.
is necessary.

When these devices are simply connected to each other without using the changeover switch 300, as shown in FIGS.
The transfer-frequency characteristics near the respective center frequencies are greatly distorted compared to before connection.

Therefore, each of the surface acoustic wave filters F1, F2
In order to prevent the deterioration of the characteristics of the surface acoustic wave filters, a peripheral circuit for adjusting the phase outside each surface acoustic wave filter, for example, as shown in FIG.
It is necessary to provide an LC circuit 301 between 1 and F2 to adjust the phase. In this case, if the LC circuit 301 is configured on a mounting board, the number of components increases, which hinders miniaturization and cost reduction of the entire device.

As shown in FIG. 30, connection points A, A
It is conceivable to adjust the phase by the transmission line 302 composed of a microstrip or the like between the surface acoustic wave filters F1 and F2 to the surface acoustic wave filters F1 and F2. For this purpose, the transmission line 30
It is necessary to make the pattern length of No. 2 redundant. For example, assuming a mobile phone frequency of about 800 MHz to 900 MHz, a pattern width of about 2 mm requires a length of about 40 mm, which does not provide a filter device that can be called a chip.

When the surface acoustic wave filters F1 and F2 having different center frequencies are commonly used as described above, a switch 300 outside the filters or an L for phase adjustment is used.
It is necessary to provide a C circuit 301 or a redundant transmission line 302 or the like.

[0009]

However, it is not desirable to provide a switch, an LC circuit, a redundant transmission line, and the like outside the filter because of signal loss and space.

As described above, in each case, there is a problem that the entire filter including the peripheral circuit becomes large and the filter device cannot be made compact.

The present invention has been made to solve such a problem, and a first object of the present invention is to connect a plurality of filter elements having different center frequencies to a common signal line as compared with before connection. It is to maintain good characteristics without significant distortion of the characteristics.

A second object of the present invention is to integrate a plurality of filter elements having different center frequencies connected to a common signal line into one chip.

Further, a third object of the present invention is to realize a compact mobile communication device which can use a plurality of communication systems.

[0014]

According to a first aspect of the present invention, there is provided a filter device comprising a first chip and a second surface acoustic wave having different center frequencies on one chip. A filter device in which at least one of an input terminal and an output terminal is connected to a common terminal outside or inside the chip, wherein a series connection is made between the common terminal and the first surface acoustic wave resonator filter. And a first surface acoustic wave resonator that operates as at least a part of the first surface acoustic wave resonator filter and performs phase adjustment with the second surface acoustic wave resonator filter side; Connected in series between the common terminal and the second surface acoustic wave resonator filter and operating as at least a part of the second surface acoustic wave resonator filter;
A second surface acoustic wave resonator that performs phase adjustment with the first surface acoustic wave resonator filter.

In the first aspect, a first surface acoustic wave resonator is connected in series between a common terminal and the first surface acoustic wave resonator filter, and the common terminal and the second surface acoustic wave resonator are connected. By connecting the second surface acoustic wave resonator between the filters in series, it is possible to maintain a high impedance on each filter side with respect to the common terminal. Further, by using the first and second surface acoustic wave resonators as capacitive elements, the use area can be made much smaller than when using a capacitor or a transmission line.

Further, by constituting the filter only with the surface acoustic wave resonator, a plurality of filters can be formed on the same piezoelectric substrate, and can be made into one chip.

Further, by storing a plurality of filters having different center frequencies in one chip and using them in the transmitting / receiving section of the mobile communication device, the mobile communication device can be made compact.

According to a second aspect of the present invention, there is provided a filter device comprising:
First and second surface acoustic wave resonator filters having mutually different center frequencies are formed on one chip, and at least one of the input terminal or the output terminal of each is connected to a common terminal outside or inside the chip. In the filter device, any one of the first and second surface acoustic wave resonator filters according to a magnitude relationship of a center frequency between the first surface acoustic wave resonator filter and the second surface acoustic wave resonator filter. A phase adjustment circuit connected between one of the common terminals and the other, and a phase adjustment circuit for adjusting the phase of the other, and the first surface acoustic wave connected in series between the common terminal and the first surface acoustic wave resonator filter; A first surface acoustic wave resonator operating as at least a part of a resonator filter and operating as at least a part of the phase adjustment circuit; the common terminal and the second surface acoustic wave They are connected in series between the pendulum filter,
And a second surface acoustic wave resonator that operates as at least a part of the second surface acoustic wave resonator filter and that operates as at least a part of the phase adjustment circuit.

According to the second aspect of the present invention, the first or second surface acoustic wave depends on the magnitude relationship of the center frequencies of the first surface acoustic wave resonator filter and the second surface acoustic wave resonator filter. By connecting a circuit that adjusts the phase between one of the resonator filters and the common terminal, it is desirable to provide a surface acoustic wave resonator in the chip and to obtain the desired impedance characteristics. Characteristic can be reliably obtained.

In the above-mentioned filter device, the first and second surface acoustic wave resonators may be one-port type surface acoustic wave resonators, and the first and second surface acoustic wave filters may be vertical. A mode-coupled surface acoustic wave resonator filter may be used. Further, these may be used in combination. When a one-port surface acoustic wave resonator is used,
One in which a plurality are connected in series may be used.

Further, the phase adjusting circuit is constituted by a circuit including at least an inductor. In particular, by disposing the inductor outside the chip, the phase adjusting circuit can be constituted with low loss.

As a result, when a plurality of filter elements having different center frequencies are connected to a common signal line, excellent characteristics can be maintained without greatly distorting the characteristics as compared to before connection. In addition, a plurality of filter elements having different center frequencies connected to a common signal line can be integrated into one chip. Further, a mobile communication device that can use a plurality of communication systems can be realized in a small size.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a composite surface acoustic wave filter device according to a first embodiment of the present invention. As shown in FIG. 1, the composite surface acoustic wave filter device according to the first embodiment is formed by forming a plurality of filters F1 and F2 having different center frequencies on one chip 1.

As the filter F1, a first surface acoustic wave resonator filter 10 and a one-port type surface acoustic wave resonator Rs1, which is one of the capacitive elements, are formed. Constitutes a band-pass filter that passes a predetermined frequency band.

As the filter 2, a second surface acoustic wave resonator filter 20 and a one-port type surface acoustic wave resonator Rs2, which is one of the capacitive elements, are formed. Surface acoustic wave resonator filter 10
A bandpass filter that passes a predetermined frequency band at a center frequency f2 different from that of the bandpass filter is configured. That is, the filters F1 and F2 have different center frequencies f
This is a band faction filter having l and f2.

The chip 1 has a signal terminal To1, a ground terminal To2, input terminals Τin1, Tin2 of the filter F1 and input terminals Tin3, Tin4 of the filter F2 and connection points A, A '.
And output terminals Tout1 to Tout4. The signal terminal To1 and the ground terminal To2 are connected to a common signal terminal To.
It is. The signal terminal To1 is commonly connected to the input terminals Tin1 and Tin3 of the filters F1 and F2 at a connection point A. The ground terminal To2 is commonly connected to the input terminals Tin2, Tin4 of the filters F1, F2 at a connection point A '. Therefore, from the common signal terminal To on the chip 1, a signal branches at the connection points A and A 'and the filters F1 and F'
2 are commonly input.

The input terminal Tin1 and the first surface acoustic wave resonator filter 10 are connected via a one-port type surface acoustic wave resonator Rs1. That is, the one-port surface acoustic wave resonator Rs1 is connected in series between the input terminal Tin1 and the first surface acoustic wave resonator filter 10. The input terminal Tin2 is directly connected to the first surface acoustic wave resonator filter 10. First surface acoustic wave resonator filter 10
Are directly connected to the output terminals Tout1 and Tout2.

The input terminal Tin3 and the second surface acoustic wave resonator filter 20 are connected via a one-port type surface acoustic wave resonator Rs2. That is, the one-port surface acoustic wave resonator Rs2 is connected in series between the input terminal Tin3 and the second surface acoustic wave resonator filter 20. The input terminal Tin4 is directly connected to the second surface acoustic wave resonator filter 20. Second surface acoustic wave resonator filter 20
Are directly connected to the output terminals Tout3 and Tout4.

The chip 1 is mounted on a package (not shown). Note that the output terminals Tout 1 to Tou of the chip 1
The t4 side may be used as an input, and the signal terminal To1 and the ground terminal To2 may be used as an output.

Normally, a filter F1 having a certain center frequency
When the filter F1 and the filter F2 having a center frequency different from that of the filter F1 are commonly connected at the connection points A and A ', the pass band characteristics of the filters F1 and F2 greatly change before and after the connection.

In order to minimize this characteristic change, the impedance near the center frequency f2 of the filter F1 and the impedance near the center frequency f1 of the filter F2 when viewed from the connection points A and A 'are taken as the impedance of the entire circuit. It is necessary to make it sufficiently large in comparison.

Therefore, in the first embodiment, a one-port type surface acoustic wave resonator Rs1 which functions as a filter in the filter F1 is connected between the input terminal Tin1 and the first surface acoustic wave resonator filter 10. By connecting in series, a high impedance can be maintained for the connection point A. By using this one-port type surface acoustic wave resonator Rs1 as a capacitive element, the use area can be made much smaller than when a capacitor is used. That is, by setting the capacitance of the one-port type surface acoustic wave resonator Rs1 to a desired value, the impedance near the frequency f2 of the filter F1 can be made sufficiently larger than the impedance of the entire circuit.

The one-port type surface acoustic wave resonator Rs2 which functions as a filter in the filter F2 is connected to the input terminal Tin3 and the second surface acoustic wave resonator filter 20.
And a high impedance with respect to the connection point A can be maintained. By using the surface acoustic wave resonator Rs2 as a capacitive element, the use area can be made much smaller than when a capacitor is used.
That is, by setting the capacitance of the one-port type surface acoustic wave resonator Rs2 to a desired value, the impedance near the frequency f1 of the filter F2 can be made sufficiently large as compared with the impedance of the entire circuit. As described above, according to the composite type surface acoustic wave filter device of the first embodiment, the filters F1 and F2 are formed on one chip 1 and the one-port type surface acoustic wave filter which performs a part of the functions of the filters F1 and F2. Wave resonator Rs1,
By using Rs2 as a capacitive element, the connection points A,
A 'can maintain high impedance with respect to A'
Even if F1 and F2 are commonly connected at the connection points A and A ', the pass band characteristics of the filters F1 and F2 before connection are not largely changed, and a two-wave filter device having a small size and excellent frequency characteristics is realized. be able to.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a view showing a configuration of a composite type surface acoustic wave filter device according to a second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 2, the composite type surface acoustic wave filter device according to the second embodiment includes a longitudinal mode coupling type surface acoustic wave resonator filter 11 as one of the filters F1 and F2 formed on the chip 1. 21 is used.

In this case, the use of the longitudinal mode-coupling type surface acoustic wave resonator filters 11 and 21 makes the filter F1 and the filter F1, compared to the ladder type filter of the first embodiment.
F2 can be made compact.

As described above, according to the composite type surface acoustic wave filter device of the second embodiment, the same effects as those of the first embodiment can be obtained, and the longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21 can be used. By using this, the composite type surface acoustic wave filter device can be further miniaturized as compared with the ladder type.

The longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21 and the one-port type surface acoustic wave resonator Rs
By configuring the filters F1 and F2 with Rs1 and Rs2, so-called one-chip formation on the same piezoelectric substrate can be realized, and the filter device can be miniaturized.

Next, a third embodiment of the present invention will be described. FIG. 3 is a view showing a configuration of a composite type surface acoustic wave filter device according to a third embodiment of the filter device of the present invention. As shown in FIG. 3, inside the chip 1, a filter F1 including a longitudinal mode coupling type surface acoustic wave resonator filter 11 and a one-port type surface acoustic wave resonator Rs1, and a longitudinal mode coupling type surface acoustic wave resonator filter 21 and a filter F2 including one-port surface acoustic wave resonators Rs2a and Rs2b. The longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21 are formed such that, for example, three inter digital transducers (hereinafter, referred to as 3IDTs) are sandwiched between two reflectors.
In addition, a longitudinal mode coupling type surface acoustic wave resonator filter 1
For example, there is a type referred to as 5IDT, IIDT type or the like.

The one-port type surface acoustic wave resonator Rs1 formed in the chip 1 is connected in series between the input terminal Tin1 and the longitudinal mode coupling type surface acoustic wave resonator filter 11. The input terminal Tin1 and the input terminal Tin3 are commonly connected at a connection point A. The input terminal Tin2 and the input terminal Tin4 are commonly connected at a connection point A '.

Similarly, the one-port type surface acoustic wave resonators Rs2a and Rs2b formed in the chip 1 are connected in series between the input terminal Tin3 and the longitudinal mode coupling type surface acoustic wave resonator filter 21. ing.

The longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21 and the one-port type surface acoustic wave resonator Rs
1, Rs2a and Rs2b are formed on a piezoelectric substrate, for example, a lithium niobate substrate, with Al-0.5 wt /% Cu-0.5
It is formed using wt /% Si electrode material.

The center frequency f1 of the filter F1 is, for example, 82
The center frequency f2 of the filter F2 is, for example, 877.5 MHz. That is, the relationship between the frequencies is f
1 <f2.

In this case, the one-port type surface acoustic wave resonator R
By setting the characteristic of s1 to a desired characteristic, the impedance of the filter F1 in the vicinity of the frequency f2 can be made sufficiently large as compared with the impedance of the entire circuit. In the same way, 1
By setting the characteristics of the port-type surface acoustic wave resonators Rs2a and Rs2b to desired characteristics, the impedance near the frequency f1 of the filter F2 can be made sufficiently large as compared with the impedance of the entire circuit. Here, characteristics of the composite surface acoustic wave filter device according to the third embodiment will be described.

FIG. 4 is a Smith chart of the longitudinal mode coupling type surface acoustic wave resonator filter 11 viewed from the connection points B and B '. FIG. 5 shows a Smith chart viewed from the connection points A and A ′ of the filter F1. The hatched portion in the figure indicates the frequency near f2. Comparing the characteristics of FIG. 5 with the characteristics of FIG. 4, it can be seen in FIG. 5 that the phase is rotated near the center frequency f2 and the impedance is high.

FIG. 6 is a Smith chart of the longitudinal mode coupling type surface acoustic wave resonator filter 21 viewed from the connection points C and C ′. FIG. 7 shows a filter F2 viewed from connection points A and A '.
3 shows a Smith chart. The hatched portion in the figure indicates the frequency near f1. Comparing the characteristic of FIG. 7 with the characteristic of FIG. 6, it can be seen from FIG. 7 that the phase is rotated near the center frequency f1 and the impedance is high.

FIG. 8 shows a filter F before compounding (before connection).
1 shows the characteristics of F2. FIG. 9 shows the characteristics after compounding (after connection). Comparing these characteristic diagrams, it can be seen that there is no significant change in the passband characteristics before and after the compounding.

As described above, according to the composite type surface acoustic wave filter device of the third embodiment, the filters F1 and F2 are formed on one chip 1 and one of the filters F1 and F2 has a filter function. Port type surface acoustic wave resonator R
By operating s1 and Rs2 also as capacitive elements,
High impedance can be maintained for connection points A and A ',
Even if the filters F1 and F2 are commonly connected at the connection points A and A ', a large change in the pass band characteristics of the filters F1 and F2 before connection is eliminated, realizing a small-sized two-wave filter device having good frequency characteristics. can do.

The longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21 and the one-port type surface acoustic wave resonator Rs
By forming the filters F1 and F2 with Rs2a and Rs2b, a so-called one chip formed on the same piezoelectric substrate can be realized, and the filter device can be made compact.

In this embodiment, two one-port surface acoustic wave resonators Rs2a and Rs2a are used as the filter F2.
s2b is the longitudinal mode coupling type surface acoustic wave resonator filter 21
In addition to the above, the filter F2 is configured such that the number of electrodes and the opening length of the one-port type surface acoustic wave resonator are adjusted so that the filter F2 and the one-port type surface acoustic wave resonator are connected to the longitudinal mode coupling type. You may comprise a surface acoustic wave resonator filter.

Next, a fourth embodiment of the present invention will be described. FIG. 10 is a diagram showing a configuration of a composite surface acoustic wave filter device according to a fourth embodiment of the filter device of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As in the first embodiment shown in FIG. 1, one chip 1 is provided with filters F having different center frequencies.
1 and F2, the relationship between the center frequency f1 of the filter F1 and the center frequency f2 of the filter F2 is f1 <
In the case of f2, the filter F1 can make the impedance near the center frequency f2 sufficiently higher than the impedance of the entire circuit by setting the capacitance of the one-port surface acoustic wave resonator Rs1 to a desired value, but depending on the frequency, In some cases, simply providing the filter F2 with the one-port surface acoustic wave resonator Rs2 does not make the impedance near the center frequency f1 in the filter F2 sufficiently large in practice compared to the impedance of the entire circuit.

Therefore, in the composite type surface acoustic wave filter device of the fourth embodiment, as shown in FIG. 10, the connection between the filter F2 and the connection points A and A ', that is, the connection with the input terminals Tin3 and Tin4 of the filter F2. Phase shift circuit 10 between points A and A '
0 is provided.

In this case, by rotating the phase of the signal input by the phase shift circuit 100, the impedance near the center frequency f1 in the filter F2 can be made sufficiently larger than the impedance of the entire circuit.

As described above, according to the composite type surface acoustic wave filter device of the fourth embodiment, one chip 1 has a center formed by the surface acoustic wave resonator filter 10 and the one-port type surface acoustic wave resonator Rs1. The center frequency of the bandpass filter F1 having a frequency f1 and the center frequency f2 composed of the surface acoustic wave resonator filter 20 and the one-port surface acoustic wave resonator Rs2 is f2.
And the input terminal Tin
1 and Tin3 (or the output terminal) are connected to the signal terminal To1 of the common signal terminal To at the connection point A, and the input terminals Tin2 and Tin4 (or the output terminal) are connected to the ground terminal To2 of the common signal terminal To at the connection point A '. And the one-port type surface acoustic wave resonators Rs1 and Rs2 are connected in series between each of the surface acoustic wave resonator filters 10 and 20 and the connection point A, and the centers of the filters F1 and F2 are mutually connected. When the frequency relationship is f1 <f2, by providing the phase shift circuit 100 between the filter F2 and the connection points A and A ′, the filter F1 has a desired capacitance of the one-port surface acoustic wave resonator Rs1. , The impedance in the vicinity of the center frequency f2 can be made sufficiently large as compared with the impedance of the entire circuit, and the filter F2 is also connected to the phase shift circuit 100 and the one-port surface acoustic wave resonator. Frequency f in the provision and s2
The impedance near 1 can be made sufficiently large as compared with the impedance of the entire circuit.

As a result, when the filters F1 and F2 are connected to the common connection terminal at the connection points A and A ',
A large change does not occur in the characteristics of the passbands 1 and F2 before and after the connection, and a small-sized composite surface acoustic wave filter device having good characteristics can be realized. Also, some or all of the components of the phase shift circuit 100
1, F2 may be provided outside the same chip.

Next, a fifth embodiment of the present invention will be described. FIG. 11 is a view showing a configuration of a composite surface acoustic wave filter device according to a fifth embodiment of the filter device of the present invention. The same components as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 11, the composite type surface acoustic wave filter device according to the fifth embodiment includes a longitudinal mode coupling type surface acoustic wave resonator filter as one of the filters F1 and F2 formed on one chip 1. 11 and 21 are used.

In this case, by using the longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21, the filter F1 and the filter F1, compared to the ladder type filter of the first embodiment, are used.
F2 can be made compact.

As described above, according to the composite surface acoustic wave filter device of the fifth embodiment, similar to the fourth embodiment,
Even when the relationship between the center frequencies of the filters F1 and F2 is f1 <f2, the center frequencies f1 and f
The impedance near 2 can be made sufficiently large as compared with the impedance of the entire circuit.

As a result, even when the filters F1 and F2 are connected to the common connection terminal To at the connection points A and A ', there is no large change in the pass band characteristics of the filters F1 and F2 before and after the connection. And a composite surface acoustic wave filter device having good characteristics.

Further, by using the longitudinal mode coupled type surface acoustic wave resonator filters 11 and 21, the composite type surface acoustic wave filter device can be further miniaturized as compared with the ladder type.

Further, the longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21 and the one-port type surface acoustic wave resonator Rs
By configuring the filters F1 and F2 with Rs1 and Rs2, so-called one-chip formation on the same piezoelectric substrate can be realized, and the filter device can be miniaturized.
Further, some or all of the components of the phase shift circuit 100 may be provided outside the same chip as the filters F1 and F2.

Next, a sixth embodiment of the present invention will be described. FIG. 12 is a diagram showing a configuration of a composite surface acoustic wave filter device according to a sixth embodiment of the filter device of the present invention. The same components as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 12, in the composite type surface acoustic wave filter device according to the sixth embodiment, the phase shift circuit 100 according to the fourth embodiment is connected to a capacitance C of a desired value.
1, C2 and an inductance L having a desired value. In this case, the capacitances C1 and C2 are connected in series between the connection point A and the one-port surface acoustic wave resonator Rs2. One end of the inductance L is connected between the capacitance C1 and the capacitance C2, and the other end is connected from the connection point A ′ to the surface acoustic wave resonator filter 2.
Connected to the line to zero. This inductance L
Is preferably mounted as a component outside the chip 1 in consideration of a loss surface.

Inductance L and capacitance C
Examples of the mounting form of C1 and C2 include an example in which the inductance L and the capacitances C1 and C2 are all mounted outside a package mounted on the chip 1, or an example in which all of the inductance L and capacitance C1 and C2 are stacked inside the package by pattern wiring or the like. Two example capacitances C1, C2
Is formed on the chip 1 by a comb pattern or a laminated pattern. As described above, according to the composite surface acoustic wave filter device of the sixth embodiment, the same effect as that of the fourth embodiment can be obtained, and the capacitance C2 is formed on the same substrate as the filters F1 and F2.
The number of components in the peripheral circuit can be reduced, and the two-wave type surface acoustic wave filter device can be realized in a small size.

Next, a seventh embodiment of the present invention will be described.

FIG. 13 shows a seventh embodiment of the filter device according to the present invention.
It is a figure showing composition of a compound type surface acoustic wave filter device of an embodiment. The same components as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 13, the composite type surface acoustic wave filter device according to the seventh embodiment includes the phase shift circuit 100 according to the fourth embodiment described above, which has a capacitance C1 having a desired value.
And an inductance L having a desired value. In this example, the capacitance C2 is reduced by performing the same phase adjustment as the circuit of the capacitances C1 and C2 and the inductance L of the sixth embodiment with the capacitance C1, the inductance L, and the one-port surface acoustic wave resonator Rs2. Things. The capacitance C1 is connected in series between the connection point A and the one-port surface acoustic wave resonator Rs2. One end of the inductance L has a capacitance C1 and a one-port surface acoustic wave resonator Rs2.
And the other end is connected to the line from the connection point A ′ to the surface acoustic wave resonator filter 20. The inductance L is preferably mounted as a component outside the chip 1 in consideration of a loss surface.

Inductance L and capacitance C
Examples of mounting form 1 include an example in which the inductance L and the capacitance C1 and the like are all mounted outside a package mounted on the chip 1, or an example in which all of the inductance L and the capacitance C1 are stacked inside the package by pattern wiring or the like. An example in which the capacitance C1 is formed on the chip 1 in a comb-shaped pattern or a laminated pattern can be considered.

As described above, according to the composite surface acoustic wave filter device of the seventh embodiment, the same effect as that of the fourth embodiment can be obtained, and the external peripheral circuit can be configured in the same manner as the sixth embodiment. The size of the two-wave type surface acoustic wave filter device can be reduced. Next, an eighth embodiment of the present invention will be described.

FIG. 14 shows an eighth embodiment of the filter device according to the present invention.
FIG. 15 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to an embodiment, and FIG. 15 is a diagram showing a practical mounting form. In addition,
The same components as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 14, in the composite type surface acoustic wave filter device according to the eighth embodiment, the phase shift circuit 100 of the fourth embodiment described above is connected to a capacitance C2 having a desired value.
And an inductance L having a desired value. In this example, the capacitance C1 is reduced by performing the same phase adjustment as the circuit of the capacitances C1 and C2 and the inductance L of the sixth embodiment using the capacitance C2, the inductance L, and the one-port surface acoustic wave resonator Rs2. Things. The capacitance C2 is connected in series between the connection point A and the one-port surface acoustic wave resonator Rs2. One end of the inductance L has a capacitance C2 and a one-port type surface acoustic wave resonator Rs2.
And the other end is connected to the line from the connection point A ′ to the surface acoustic wave resonator filter 20. The inductance L is preferably mounted as a component outside the chip 1 in consideration of a loss surface.

The inductance L and the capacitance C
Examples of mounting form 2 include an example in which the inductance L and the capacitance C2 are all mounted outside a package mounted on the chip 1, an example in which all are stacked inside the package by pattern wiring or the like, and a further example in the above two examples. An example in which the capacitance C2 is formed on the chip 1 in a comb-shaped pattern or a laminated pattern can be considered.

As shown in FIG. 15, an inductance L may be connected outside the chip 1 and a capacitance C2 may be mounted on the chip 1.

As described above, according to the composite type surface acoustic wave filter device of the eighth embodiment, the same effect as that of the fourth embodiment can be obtained, and the capacitance C2 is reduced by the filter F.
By forming them on the same substrate as 1 and F2, the number of components of the peripheral circuit can be reduced, and a two-wave type surface acoustic wave filter device can be realized in a small size.

Next, a ninth embodiment of the present invention will be described.

FIG. 16 shows a ninth filter according to the present invention.
FIG. 17 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to an embodiment, and FIG. 17 is a diagram showing a practical mounting form. In addition,
The same components as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 16, the composite type surface acoustic wave filter device according to the ninth embodiment is such that the phase shift circuit 100 according to the fourth embodiment described above is constituted only by an inductance L having a desired value. is there. In this example, the capacitances C1 and C2 are reduced by realizing a phase adjustment function equivalent to that of the capacitance C1 and C2 and the inductance L of the sixth embodiment using the one-port surface acoustic wave resonator Rs2 and the inductance L. Things. One end of the inductance L is connected to the line from the connection point A to the one-port surface acoustic wave resonator Rs2, and the other end is connected to the line from the connection point A 'to the surface acoustic wave resonator filter 20. The inductance L is preferably mounted as a component outside the chip 1 in consideration of a loss surface.

Therefore, as a practical mounting form of the inductance L, a surface mounting type coil is used as the inductance L, and this coil L is mounted on a motherboard outside the package on which the chip 1 is mounted as shown in FIG. Can be implemented. The circuit in FIG. 16 and the circuit in FIG. 17 are electrically equivalent.

As a result, the Q of the inductance L can be increased as compared with the case where the inductance L is built in the package or the case where the inductance L is formed by a pattern or the like on the piezoelectric substrate.
Since the loss caused by the inductance L can be reduced, a low-loss composite surface acoustic wave filter device can be realized.

As described above, according to the composite surface acoustic wave filter device of the ninth embodiment, the same effect as that of the fourth embodiment can be obtained, and the external peripheral circuit can be made only of the inductance L, so that the two-wave type The surface acoustic wave filter device described above can be realized in a small size.

The inductance L constituting the phase shift circuit 100 is formed by, for example, a microstrip line inside the package at the expense of some performance, so that it is not necessary to add the inductance L outside the package. In addition, the number of components of the external circuit (peripheral circuit) can be reduced. In this case, when changing the value of the inductance L, an adjustment pattern for adjusting the value of the inductance L is formed inside the package, and these are selected and connected. When the inductance L is formed inside the package mounted on the chip 1 as described above, the phase can be changed by changing the connection outside the chip 1 and only one kind of package needs to be prepared. Manufacturing costs can be kept low.

Next, a tenth embodiment of the present invention will be described.

FIG. 18 shows a first filter device according to the present invention.
FIG. 19 is a diagram illustrating a configuration of a composite type surface acoustic wave filter device according to a zeroth embodiment, and FIG. 19 is a diagram illustrating a specific mounting mode.

As shown in FIG. 18, the composite type surface acoustic wave filter device according to the tenth embodiment has one chip 1
Then, filters F1 and F2 having different center frequencies are formed. The chip 1 has a common signal terminal To and a filter F
1, input terminals Tin1 and Tin2, input terminals Tin3 and Tin4 of the filter F2, connection points A and A ', and output terminals Tout1 to Tout1.
Tout 4 is provided. The common signal terminal To has a signal terminal To1 and a ground terminal To2. The signal terminal To1 is commonly connected to Tin1 and Tin3 of the filters F1 and F2 at a connection point A. In addition, the ground terminal To2
Are commonly connected to the input terminals Tin2 and Tin4 of the filters F1 and F2 at the connection point A '. Therefore, chip 1
From the upper common signal terminal To, a signal is sent to each connection point A, A '.
, And is input commonly to the filters F1 and F2.

The filters F1 and F2 have center frequencies f1 and f2 of pass bands different from each other, and f1 = 820 MHz.
z, f2 = 877.5 MHz. In this case, the relationship between the center frequency f1 of the filter F1 and the center frequency f2 of the filter F2 is f1 <f2.

The filter F1 is composed of one longitudinal mode coupling type surface acoustic wave resonator filter 11 and one 1-port type surface acoustic wave resonator Rs1. Filter F2 is 1
Two longitudinal mode coupled surface acoustic wave resonator filters 21;
It is composed of two one-port surface acoustic wave resonators RS2. The one-port surface acoustic wave resonator Rs1 has an input terminal T
It is connected in series between in1 and the longitudinal mode coupling type surface acoustic wave resonator filter 11. The longitudinal mode coupling type surface acoustic wave resonator filter 11 is directly connected to the output terminals Tout1 and Tout2. The longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21 have a structure in which three inter digital transducers (hereinafter, referred to as 3IDTs) are sandwiched between two reflectors. The one-port type surface acoustic wave resonator Rs2 is connected in series between the input terminal Tin3 and the longitudinal mode coupling type surface acoustic wave resonator filter 21. The longitudinal mode coupling type surface acoustic wave resonator filter 21 includes:
Output terminals Tout3 and Tout4 are directly connected. The chip 1 is mounted on a package (not shown). The one-port type surface acoustic wave resonator Rs2 is for extending a band that has a part of a function as a filter of the longitudinal mode coupling type surface acoustic wave resonator filter 21. Also, the one-port surface acoustic wave resonator Rs2 operates as a part of the phase shift circuit 100 as a capacitance with respect to the inductance L. One end of the inductance L is connected to the input terminal Tin3, and the other end is connected to the input terminal Tin4. That is, the inductance L is connected in parallel between the connection points A and A 'and the filter F2.

Considering the loss surface, the inductance L is
It is preferable to mount it outside the chip 1. Therefore,
As a practical mounting form of the inductance L, it is considered that a coil of a surface mounting type is used as the inductance L, and the coil L is mounted on a board outside a package on which the chip 1 is mounted as shown in FIG. Can be Note that the circuit in FIG. 18 and the circuit in FIG. 19 are electrically equivalent.

The longitudinal mode coupling type surface acoustic wave resonator filters 11, 21 and the one-port type surface acoustic wave resonators Rs1, Rs
2 is, for example, Al- on a lithium niobate substrate.
It is formed using an electrode material of 0.5 wt /% Cu-0.5 wt /% Si.

In the case of the composite surface acoustic wave filter device according to the tenth embodiment, the phase of the signal branched from the common signal terminal To at the connection point A and input to the filter F2 side is changed by the inductance L and the one-port type surface acoustic wave device. By rotating with the wave resonator Rs2b, the frequency f
The impedance near 1 can be made sufficiently large compared to the impedance of the entire circuit.

Here, the characteristics of the composite type surface acoustic wave filter device will be described with reference to FIGS.
FIG. 20 shows a Smith chart viewed from the connection points A and A ′ of the filter F1. The hatched portions in the figure indicate frequencies near the frequency f2. It can be seen that the filter F1 has a sufficiently high impedance near the frequency f2.

FIG. 21 shows the state before the phase shift circuit, that is, the filter F.
2 shows a Smith chart as viewed from points D and D ′ between 2 and an inductance L. The hatched portions in the figure indicate frequencies near the frequency f1 of the filter F2. Referring to FIG. 21, it can be seen that the impedance is not high in the vicinity of the frequency f1 in the filter F2, and that a phase rotation is necessary to obtain a high impedance.

FIG. 22 shows a Smith chart of the phase shift circuit + filter F2 viewed from the connection points A and A '. From FIG. 22, it can be seen that the impedance is sufficiently high near the frequency f1.

FIG. 23 shows the characteristics of the filters F1 and F2 before compounding. FIG. 24 shows the characteristics of the combined filters F1 and F2. There is no significant change in the passband characteristics before and after the combination.

As described above, according to the composite type surface acoustic wave filter device of the tenth embodiment, one chip 1 has a center composed of the surface acoustic wave resonator filter 11 and the one-port type surface acoustic wave resonator Rs1. The center frequency of the bandpass filter F1 having a frequency f1 and the center frequency of the surface acoustic wave resonator filter 21 and the one-port type surface acoustic wave resonator Rs2 is f
And two input terminals Tin1 and Tin3 are connected in common, and when the relationship between the center frequencies of the filters F1 and F2 is f1 <f2, the inductance L is changed to the filter F2. Connection points A, A '
Are connected in parallel, the filter F1 becomes 1
By setting the capacitance of the port-type surface acoustic wave resonator Rs1 to a desired value, the impedance near the center frequency f2 can be made sufficiently larger than the impedance of the entire circuit, and the filter F2 also rotates the phase of the input signal. The impedance near the frequency f1 can be made sufficiently large as compared with the impedance of the entire circuit.

As a result, the impedance on the side of the filters F1 and F2 as viewed from the connection points A and A 'can be made sufficiently large, and there is no large change in the pass band characteristics before and after the connection of the filters F1 and F2. A two-wave filter device with good characteristics can be realized.

In this embodiment, the description has been made using the characteristics of the 3IDT as the longitudinal mode coupling type surface acoustic wave resonator filters 11 and 21. Of course, if the longitudinal mode coupling type surface acoustic wave resonator filter is used, The same applies to the structure having three or more IDTs, for example, the 5IDT, 9IDT, and IIDT types.

In this embodiment, the filter F2 has been described as a single-port type surface acoustic wave resonator Rs2 connected to the longitudinal mode coupling type surface acoustic wave resonator filter 21. F2 is 1 by adjusting the number of electrodes and the opening length of the one-port surface acoustic wave resonator.
A single-port type surface acoustic wave resonator and a longitudinal mode coupling type surface acoustic wave resonator filter may be used.

[0101]

As described above, according to the present invention, 1
When a plurality of surface acoustic wave filter elements are formed on a chip and they are commonly connected to each other at an input terminal or an output terminal, it is possible to realize a filter device having good characteristics with little characteristic change.

Even if a plurality of filter elements formed on one chip are connected in common, an impedance matching circuit is not required, and the filter device can be made compact.

Further, a complicated phase adjustment circuit which has to be provided outside the chip can be reduced, and the peripheral circuits can be simplified.

In order to eliminate the characteristic change at all, it is necessary to provide an impedance matching circuit outside the chip. However, of the first and second filter elements, the impedance matching circuit is provided on the side having the higher center frequency. The filter device can be miniaturized by connecting.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a composite surface acoustic wave filter device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a composite surface acoustic wave filter device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to a third embodiment of the present invention.

FIG. 4 is a Smith chart of the longitudinal mode coupling type surface acoustic wave resonator filter of the filter 1 viewed from connection points B and B ′.

FIG. 5 is a Smith chart of the filter F1 viewed from connection points A and A ′.

FIG. 6 is a Smith chart of a filter F2 viewed from connection points C and C ′.

FIG. 7 is a Smith chart of the filter F2 viewed from connection points A and A ′.

FIG. 8 is a characteristic diagram of filters F1 and F2 before compounding.

FIG. 9 is a characteristic diagram of filters F1 and F2 after compounding.

FIG. 10 is a diagram showing a configuration of a composite surface acoustic wave filter device according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to a fifth embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to a sixth embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to a seventh embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to an eighth embodiment of the present invention.

FIG. 15 is a view showing a practical mounting form of the composite surface acoustic wave filter device according to the eighth embodiment.

FIG. 16 is a diagram showing a configuration of a composite surface acoustic wave filter device according to a ninth embodiment of the present invention.

FIG. 17 is a view showing a practical mounting form of the composite surface acoustic wave filter device according to the ninth embodiment.

FIG. 18 is a diagram showing a configuration of a composite type surface acoustic wave filter device according to a tenth embodiment of the present invention.

FIG. 19 is a view showing a practical mounting form of the composite type surface acoustic wave filter device according to the tenth embodiment.

FIG. 20 is a Smith chart of a filter F1 before compounding viewed from connection points A and A ′.

FIG. 21 is a Smith chart of a filter F2 before compounding viewed from connection points D and D ′.

FIG. 22 is a Smith chart of the phase shift circuit and the filter F2 before the combination viewed from the connection points A and A ′.

FIG. 23 is a characteristic diagram of filters F1 and F2 before compounding.

FIG. 24 shows a filter F1. The characteristic view of F2.

FIG. 25 is a diagram showing a configuration of a conventional filter having a plurality of independent input / output terminals.

FIG. 26 is a circuit diagram for realizing a conventional common input or common output.

FIG. 27 is a circuit diagram for realizing a conventional common input or common output.

FIG. 28 is a circuit diagram for realizing a conventional common input or common output.

FIG. 29: A filter F is connected to a common connection terminal without adjusting the phase.
FIG. 4 is a characteristic diagram of a filter F1 before and after connection when F1 and F2 are connected.

FIG. 30: Filter F connected to common connection terminal without adjusting phase
FIG. 4 is a characteristic diagram of a filter F2 before and after connection when F1 and F2 are connected.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Chip, 10 and 20 ... Surface acoustic wave resonator filter,
11, 21 ... longitudinal mode coupling type surface acoustic wave resonator filter, A, A '... common connection point, B, B' ... 1-port type surface acoustic wave resonator Rs1 of filter F1 and longitudinal mode coupling type surface acoustic wave resonance. , A connection point between the one-port surface acoustic wave resonator Rs2a of the filter F2 and the longitudinal mode coupling type surface acoustic wave resonator filter 21, F1, F2. f2: center frequency of pass band, Rs1, Rs2a, Rs2b: port type surface acoustic wave resonator, To: common connection terminal, Tin1 to Tin4 ...
Input terminals, Tout 1 to Tout 4 ... output terminals.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J006 JA01 KA02 KA23 LA21 LA24 PB03 5J097 AA11 AA29 BB15 BB17 CC02 FF03 KK02 KK04 LL07

Claims (7)

[Claims] 1. A first chip includes first and second surface acoustic wave resonator filters each having a different center frequency, and at least one of an input end and an output end of the filter is outside or inside the chip. A filter device connected to a common terminal, wherein the filter device is connected in series between the common terminal and the first surface acoustic wave resonator filter, and operates as at least a part of the first surface acoustic wave resonator filter; A first surface acoustic wave resonator that performs phase adjustment with the second surface acoustic wave resonator filter, and a first surface acoustic wave resonator connected in series between the common terminal and the second surface acoustic wave resonator filter; A second surface acoustic wave resonator that operates as at least a part of the second surface acoustic wave resonator filter and adjusts the phase with the first surface acoustic wave resonator filter. Filter apparatus according to claim. 2. A first chip and first and second surface acoustic wave resonator filters having different center frequencies are formed on one chip, and at least one of an input terminal and an output terminal of the filter is outside or inside the chip. In a filter device connected to a common terminal, the first or second surface acoustic wave according to a magnitude relationship of a center frequency between the first surface acoustic wave resonator filter and the second surface acoustic wave resonator filter. A phase adjustment circuit that is connected between one of the wave resonator filters and a common terminal and adjusts a phase with the other, and is connected in series between the common terminal and the first surface acoustic wave resonator filter; A first surface acoustic wave resonator that operates as at least a part of a first surface acoustic wave resonator filter and that operates as at least a part of the phase adjustment circuit; A second elastic member connected in series between the second surface acoustic wave resonator filters and operating as at least a part of the second surface acoustic wave resonator filter and operating as at least a part of the phase adjustment circuit; A filter device comprising: a surface acoustic wave resonator. 3. The filter device according to claim 1, wherein the first and second surface acoustic wave resonators are one-port surface acoustic wave resonators. . 4. The filter device according to claim 1, wherein said first and second surface acoustic wave resonator filters are longitudinal mode coupling type surface acoustic wave resonator filters, and And the second surface acoustic wave resonator is a one-port type surface acoustic wave resonator. 5. The filter device according to claim 1, wherein the first and second surface acoustic wave resonator filters are longitudinal mode coupled surface acoustic wave resonator filters, and Is a one-port surface acoustic wave resonator, and the second surface acoustic wave resonator is formed by connecting a plurality of one-port surface acoustic wave resonators in series. Filter device. 6. The filter device according to claim 2, wherein the phase adjustment circuit is constituted by a circuit including at least an inductor. 7. The filter device according to claim 6, wherein the phase adjustment circuit has the inductor disposed outside the chip.