JPH09214203A - Strip line dual mode filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strip line dual mode filter where a band is wide, the constitution of a multistage filter is easy, a high frequency characteristic is superior and which can easily be constituted on a plane by providing transmission line-type resonators and ring resonators and input/output connection parts only for the transmission line-type resonators. SOLUTION: The transmission line-type resonators 11 and 12 having the length of 1/4 wavelengths are connected to an electric field with connection capacities 13 and 14. The transmission line-type resonators 19 and 20 having the similar wavelengths are connected with connection capacities 21 and 22 by an electric field. Furthermore, terminals for input/output 16, 18, 24 and 26 are provided for the transmission line-type resonators 11, 12, 19 and 20. Since the multistage filter can be constituted with such constitution, the strip line dual mode filter with high attenuation, wide band and without affecting an orthogonal resonance mode and with less noise can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and low-cost stripline dual-mode filter used for communication devices and measuring instruments in the UHF to SHF band.

[0002]

2. Description of the Related Art A stripline ring resonator filter usually uses a one-wavelength stripline ring resonator or the like in order to reduce radiation loss, but it has a drawback that it has a large shape even if the loss is small. To solve the shortcomings of this one wavelength stripline ring resonator filter,
A dual-mode filter that excites two quadrature modes in one resonator has also been proposed, but has not been put to practical use.

A conventional stripline dual mode filter will be described below. FIG. 16 is a configuration diagram of a conventional stripline dual mode filter. This is J. A. 1991 IEEE by Curtis et al.
International Microwave S
ymposium Digest, pp. 443-44
6 (N-1).

In FIG. 16, 601 is a strip line ring resonator of one wavelength (electrical length of 360 °), 602, 6
Reference numeral 03 is an input / output line, and 604 is a strip line resonator 60.
1 and the input / output line 602, the input / output coupling capacitance is obtained by providing the gap 604. Reference numeral 605 denotes a gap provided between the strip line resonator 601 and the input / output line 603. By providing this gap 605, the input / output coupling capacitance is obtained. Reference numeral 606 denotes a stub with an open tip provided on the strip line resonator 601. The angle A between the input / output line 602 and the input / output line 603 is 90 degrees, the angle B between the stub 606 and the center of the input / output line 602 is 135 degrees, and the angle C between the stub 606 and the center of the input / output line 603 is 13 degrees.
It is arranged to be 5 degrees.

The operation of the strip-line dual-mode filter configured as described above will be qualitatively described below based on the concept of a traveling wave (however, the input / output line 6
02 is treated as an input line 602, and the input / output line 603 is treated as an output line 603. ).

First, the traveling wave propagating from the input line 602 is field-coupled to the one-wavelength strip line ring resonator via the gap 604 that realizes the coupling capacitance, and a strong electric field is generated in the vicinity of the input line 602. This electric field propagates in the clockwise and counterclockwise directions as a traveling wave. First, consider the counterclockwise traveling wave. This traveling wave undergoes a 90-degree phase change and reaches the vicinity of the output line 603, but since the electric field is minimum here, it does not couple to the output line 603. If you go further 135 degrees from this, the stub 60 with the tip open will be
Reach position 6. Here, since the line has a discontinuous portion, a part thereof becomes a reflected wave, and the rest propagates to the vicinity of the input line 602 and is coupled to the input line 602 via the gap 604. The reflected wave at the stub 606 retreats 135 ° and reaches the vicinity of the output line 603, but since the phase difference is 270 ° for a round trip, the electric field is maximized here and electric field coupling occurs to propagate the traveling wave to the output line 603. It will be a matter. Similarly, as for the traveling wave in the clockwise direction, only the reflected wave at the stub 606 of the strip line having the open tip is propagated to the output line 603. The magnitude of the reflection is remarkable when the discontinuity is large, so that the magnitude of the traveling wave propagating can be controlled by the line length of the stub 606. When this operation is viewed as a resonator, it means that in the case of the configuration of FIG. 16, there are two orthogonal modes in the resonator, and the coupling degree of the two resonant modes can be controlled by the structure of the stub 606. In other words, it can be considered that the resonator operates as a dual-mode filter and has a function corresponding to a two-stage filter with one resonator, which can be said to contribute to downsizing.

[0007]

However, in the above-mentioned conventional structure, the coupling degree, that is, the pass band width as a filter is adjusted only by the line stub having an open tip, and the pass band cannot be made large. There is a problem that it is difficult to construct the filter.

Further, in the input / output coupling, since the coupling position of the ring resonator is restricted to the position separated by 90 °, it is necessary to configure the electric field coupling by the capacitance and adjust the coupling by the capacitance adjustment. For this reason, when the adjustment range is limited and the coupling capacitance is configured by the parallel coupling line, there is a problem that the shape becomes large, and it becomes difficult to planarize when a chip component is used.

Further, the ring resonator has a higher-order resonance mode that is an integral multiple of the fundamental wave. These unnecessary resonances cause deterioration of the harmonic attenuation characteristics of the filter.

The present invention solves the above-mentioned problems of the prior art. It is a stripline dual-mode filter having a wide band, easy configuration of a multistage filter, excellent harmonic characteristics, and easy configuration on a plane. Is intended to provide.

[0011]

According to the present invention, there are provided four or more transmission line co-mode resonators and one ring resonator having two mutually orthogonal resonance modes which are electric field coupled to the transmission line resonator. As described above, the input / output coupling portion is provided only in the transmission line type resonator.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a ring resonance having first to fourth transmission line type resonators and two resonance modes which are electric field coupled to the transmission line type resonators and are orthogonal to each other. A multi-stage filter by using the first and second transmission line type resonators on the input side and the third and fourth transmission line type resonators on the output side. it can.

According to the second aspect of the present invention, by providing the input / output coupling section in the transmission line type resonator, the input / output section can be configured so as not to affect the orthogonal resonance modes.

In the invention according to claim 3, the ring resonator is
Since the length is one wavelength, a desired resonance frequency can be obtained by defining the length of the ring resonator.

In the invention according to claim 4, a multistage filter can be constructed by providing a plurality of ring resonators and electrically coupling the ring resonators.

In the invention according to claim 5, the ring resonator can be shortened in ring diameter by adding a lumped constant capacitance element to one of the opposing portions for electric field coupling with the transmission line type resonator.

According to the sixth aspect of the present invention, the ring resonator has a ring diameter that can be shortened by adding a transmission line having one open end to one of the opposing portions that are electric field coupled to the transmission line type resonator. .

In the invention according to claim 7, in the ring resonator, the ring diameter of the ring resonator can be shortened by adding the parallel coupling line to one of the opposing portions for electric field coupling with the transmission line type resonator.

According to the eighth aspect of the present invention, the ring resonator can be shortened by adding the same one to one of the opposing portions where electric field coupling with the transmission line type resonator is made.

In the invention according to claim 9, in the ring resonator, the ring diameter of the ring resonator can be shortened by adding a different one from the other to the opposing part that is electric field coupled to the transmission line type resonator. .

According to the tenth aspect of the present invention, the transmission line type resonator is a quarter wavelength resonator by short-circuiting the other end opposite to the side for electric field coupling with the ring resonator to define the length. By doing so, a desired resonance frequency can be obtained.

In the eleventh aspect of the present invention, the transmission line type resonator is made a half-wavelength resonator by opening the other end opposite to the side in which the electric field coupling with the ring resonator is made, and the length is reduced. The desired resonance frequency can be obtained by defining

According to the twelfth aspect of the present invention, the frequencies of the higher-order resonance modes of the transmission line type resonator and the ring resonator are different from each other, so that the influence of the higher-order mode resonance of each resonator unit is filtered. The characteristics can be suppressed.

According to a thirteenth aspect of the present invention, a substrate, a ring resonator formed on the substrate, and first to fourth transmission lines formed on the substrate and electrically coupled to the ring resonator. Type resonator, and the first and second transmission line type resonators are set to the input side, and the third and fourth transmission line type resonators are set to the output side, whereby a multistage filter can be configured. it can.

According to a fourteenth aspect of the present invention, the ring resonator is provided with stubs extending toward the center of the ring resonator, respectively, at the portions facing the first to fourth transmission line type resonators. The ring resonator length can be shortened and the formation area can be reduced.

According to the fifteenth aspect of the present invention, deterioration of the filter characteristics can be prevented by making the stubs facing each other have substantially the same length.

According to the sixteenth aspect of the present invention, since the lumped constant capacitance is provided between the stubs facing each other, the ring resonator length can be shortened and the formation area can be reduced.

In the seventeenth aspect of the present invention, the input / output unit can be configured so as not to affect the orthogonal resonance modes by providing the first to fourth transmission line type resonators with terminals.

According to the eighteenth aspect of the present invention, the ring resonator has a length of one wavelength, so that a desired resonance frequency can be obtained by defining the length of the ring resonator.

According to the nineteenth aspect of the present invention, the transmission line type resonator is provided with portions having different impedances.
The length of the transmission line resonator can be shortened, and higher-order resonance modes can be shifted from the ring resonator.

According to the twentieth aspect of the present invention, the transmission line type resonator is grounded to form a quarter wavelength resonator, and the desired resonance frequency can be obtained by defining the length.

(Embodiment 1) FIG. 1 is a schematic diagram showing a strip line dual mode filter according to Embodiment 1 of the present invention. In FIG. 1, 1, 2, 3 and 4 are ring resonators, and each of the ring resonators 1, 2, 3 and 4 has a length (ring length) corresponding to one wavelength.

Reference numerals 5 and 6 denote ring resonator 1 and ring resonator 2.
Inter-stage coupling capacitors provided between the ring resonator 2 and the ring resonator 3, and inter-stage coupling capacitors 7 and 8 provided between the ring resonator 3 and the ring resonator 4, respectively. Is the inter-stage coupling capacity provided between the two.

Reference numerals 11 and 12 denote transmission line type resonators each having a length of ¼ wavelength.
2 is the coupling capacitance 13 to the ring resonator 1,
Electric field coupling is performed at 14. In addition, the transmission line type resonator 1
1 is grounded, and tap (conductive line) 15
It is electrically connected to the terminal 16 via. Further, the transmission line type resonator 12 is similarly grounded, and is electrically connected to the terminal 18 via the tap (conductive line) 17.

Reference numerals 19 and 20 denote transmission line type resonators each having a length of 1/4 wavelength.
0 is the coupling capacitance 21 to the ring resonator 4 respectively,
Electric field coupling is made at 22. In addition, the transmission line type resonator 1
9 is grounded, and tap (conductive line) 23
It is electrically connected to the terminal 24 via. Further, the transmission line type resonator 20 is similarly grounded, and is electrically connected to the terminal 26 via the tap (conductive line) 25.

The operation of the strip line dual mode filter configured as described above will be described.

When a signal is input from the terminal 16, it is input to the ring resonator 1 through the transmission line type resonator 11 and the coupling capacitor 13. The signal input to the ring resonator 1 is
The ring resonator 1 is divided into a signal transmitted in the arrow A direction (hereinafter abbreviated as A signal) and a signal transmitted in the arrow B direction (hereinafter abbreviated as B signal). When the separated A and B signals resonate at the point P1, the signals are input to the ring resonator 2 through the interstage coupling capacitance 6. The signal input to the ring resonator 2 operates in the same manner as when input to the ring resonator 1,
When resonating at the point P2, the signal is input to the ring resonator 3 through the interstage coupling capacitance 7. The signal input to the ring resonator 3 operates in the same manner as when it is input to the ring resonator 1, and when the signal resonates at the point P3, the signal becomes the interstage coupling capacitance 1
It is input to the ring resonator 4 through 0. The signal input to the ring resonator 4 operates in the same manner as when it is input to the ring resonator 1, and when it resonates at the point P4, the signal passes through the coupling capacitance 21 and is input to the transmission line type resonator 4. , From the terminal 24 to the outside.

As described above, in the first embodiment, the lengths (circumferential lengths) of the ring resonators 1, 2, 3, 4 are specified, and the interstage coupling capacitances 5, 6, 7, 8 are provided. , 9, 10 and the coupling capacitors 13, 14, 21, 22 to the ring resonators 1, 4 are defined in their positions, it is possible to extract only a signal having a predetermined frequency from the input signals.

Similarly, when a signal is input from the terminal 18,
A signal having a predetermined frequency is output to the terminal 26.

As described above, in the first embodiment, the multistage filter can be constructed by electrically coupling the ring resonators 1 and 4 with the transmission line type resonators 11, 12, 19 and 20, respectively. It is possible to provide a high attenuation, broadband stripline dual mode filter.

Further, the transmission line type resonators 11, 12, 19,
20 for input / output terminals 16, 18, 24, 26 respectively
By providing the above, it is possible to provide a stripline dual-mode filter with less noise without affecting the orthogonal resonance modes.

Although the ring resonator has a donut shape in the first embodiment, the same effect can be obtained with an elliptical shape, a polygonal shape, or the like.

Further, in the first embodiment, the number of ring resonators is four.
The case where two ring resonators are provided is explained.
Similar effects can be obtained in the case of three or five or more. When a plurality of ring resonators are used, interstage coupling capacitance is provided between the ring resonators. Note that, as shown in FIG. 2, when the number of ring resonators is one, the interstage coupling capacitance is naturally unnecessary. 2, members given the same reference numerals as those shown in FIG. 1 have the same functions as the constituent members shown in FIG.

The ring diameters of the ring resonators 1, 2, 3 and 4 are defined by the resonance frequency, but one of the opposing portions (FIGS. 3 to 7) which is electric field coupled to the transmission line type resonator.
By adding circuit elements at points I1 and I2), the ring diameter can be shortened without affecting the independent resonance mode. 3 to 7 are diagrams in which only the ring and the inter-stage capacitance section of FIG. 1 are taken out, but in FIG. 3, the resonance frequency of the ring resonator is changed to the ground capacitance by adding a lumped constant capacitance from the points I1 and I2. The resonator length can be shortened because the resonance frequency of the ring can be changed with the constant of. In FIG. 4, a point I2, which is 180 degrees away from the point I1, is connected through a lumped constant capacitance. In this case, the resonator length can be shortened because the resonance frequency of the ring can be changed by lowering the constant of the connection capacitance. Specifically, chip components are used as the lumped constant capacitance. In FIG. 5, open-ended transmission lines (stubs) are connected to points I1 and I2. The equivalent circuit is equivalent to that of FIG. 3 and the resonator length can be shortened with the same effect.
6 is equivalent to FIG. 4 in an equivalent circuit in which points I1 and I2 are connected to the parallel coupling line, and the resonator length can be shortened by the same effect. Normally, in the combination of FIGS. 3, 4, 5 and 6, the same thing is added to two points of I1 and I2 which are 180 degrees apart on the ring, but different things may be added as shown in FIG.

The resonator has a higher-order resonance mode that is an integral multiple of the basic resonance due to its resonator structure, and becomes unnecessary resonance as a filter characteristic. FIG. 8 shows an embodiment in which one ring is used.
A wavelength resonator is used. The half-wave resonator and the ring resonator have high-order resonance at an integral multiple (1, 2, 3, ...) Of the fundamental frequency. In the case of FIG. 2, the transmission line type resonator 1
1, 12, 19, and 20 are short-circuited quarter-wave resonators. The quarter-wave resonator has high-order resonance only at odd multiples (1, 3, 5 ...) Of the fundamental frequency. ing. Even in the same type of resonator, so-called SIR composed of lines with different impedances in the same resonator
The structure can shift the higher-order mode resonance of the resonator having the same impedance line by an integer multiple. As described above, by constructing the filters with resonators having different structures and selecting a combination of the resonators, it is possible to reduce unnecessary resonance between them and improve the filter characteristics.

Next, the external Q in each of the first embodiment and the conventional stripline dual mode filter will be described.

FIG. 8 is a graph showing the relationship between the electrical length from the ground of the first embodiment to the tap (tap 15, 17, 23, 25 in FIG. 1) and the external Q, and FIG. 9 is a parallel diagram of the conventional example. 6 is a graph showing the relationship between the line coupling length (width of the portion of the input / output line facing the ring resonator) and the external Q. As can be seen from FIGS. 8 and 9, when the minimum values of the external Q of the first embodiment and the conventional example are compared, the first embodiment is 1/3 that of the conventional example. Since the coupling degree of the form 1 can be tripled as compared with the conventional example, it is possible to input / output a signal with a large value. Furthermore, since the amount of change in the external Q is doubled in the first embodiment compared to the conventional example, the degree of freedom in the degree of coupling is widened, and the circuit design and the like are very easy to perform.

(Second Embodiment) FIGS. 10 and 11 are a plan view and a perspective view showing a stripline dual mode filter according to a second embodiment of the present invention. The second embodiment shows an example in which the circuit shown in FIG. 2 is configured as an actual element.

In FIGS. 10 and 11, reference numeral 30 denotes a square substrate, and the substrate 30 is preferably made of a dielectric material. Among these dielectric materials, it is preferable to use a ceramic material having particularly good workability and a high dielectric constant. Further, as a specific example of the ceramic material, Ba
O-TiO ₂ -Nd ₂ O ₃ based, ZrO ₂ -SnO ₂ -TiO ₂
System, CaO-MgO-TiO ₂ system, and the like.
Of these, BaO—TiO ₂ —Nb ₂ O ₃ based materials, which have extremely high dielectric constant and can reduce the cavity length, are preferable.

If the surface roughness of the substrate 30 is too large, it affects the filter characteristics and the like. Therefore, the surface roughness of the substrate 30 is preferably 5 μm or less, more preferably 1 μm or less. Most preferably, the surface roughness of the substrate 30 is 0.5 μm or less.

Reference numeral 31 is a ring-shaped ring resonator provided substantially in the center of the main surface of the substrate 30, and the ring resonator 31 has a substantially square shape. In the second embodiment, the substrate 3
Although the ring resonator 31 has a square shape in order to effectively use the principal plane of 0, it may naturally have an annular shape, a polygonal shape, or an elliptical shape. The ring resonator 31 has stubs 31a to 31d extending from the center of each of the four sides toward the center of the ring resonator 31. Therefore, the ring resonator 31 is composed of at least an annular portion and stubs 31a to 31d extending from the annular portion. The stubs 31a to 31d are provided for the purpose of shortening the length of the resonator.

The line width L1 of the annular portion of the ring resonator 31
It is preferable that the width is wider because the Q value of the ring resonator 31 can be increased, but from the viewpoint of ease of manufacturing and cost, it is preferably about 0.5 mm to 2 mm. Further, it is preferable that the line width L3 of the stubs 31a to 31d of the ring resonator 31 is wide, because the Q value of the ring resonator 31 can be increased, but it is 0.2 mm in view of ease of manufacturing and cost. It is preferably about 2 mm.

The stubs 31a facing each other
It is preferable that the stub 31d and the stub 31b and the stub 31c have substantially the same length (L5 = L7, L4 = L6). If the lengths of the two facing stubs are greatly different, the filter characteristics are deteriorated and a problem occurs. Further, in the case of L5 = L7, L4 = L6 and L4 ≠ L5, the filter is used as a filter having two resonance frequencies of the first resonance frequency and the second resonance frequency at the same time.
That is, for example, the first resonant frequency is determined by the lengths of the stubs 31a and 31d, and the second resonant frequency is determined by the lengths of the stubs 31b and c. Furthermore, when L5 = L7, L4 = L6 and L4 = L5,
It is used as a filter having one resonance frequency.

By thus adjusting the lengths of the stubs 31a to 31d, a filter having two or one resonance frequency can be constructed.

Further, focusing on the fact that the resonance frequency can be changed by changing at least one of the length of the annular portion of the ring resonator 31 and the length of the stubs 31a to 31d, the length L4 of each of the stubs 31a to 31d is changed. By changing L7 to L7, the size of the ring resonator 31 (the area where the ring resonator 31 is formed) can be changed (in the case of the second embodiment, for example, the length of the diagonal line of the ring resonator 31 is changed. Can be made). That is, even if the resonance frequency is the same, the length L4 of the stubs 31a to 31d
The size of the ring resonator 31 can be freely set by changing L7.

Further, for example, when the resonance frequency is 1.5 GHz, the length L2 of one side of the square ring resonator 31 is about 6 mm on a substrate having a dielectric constant of about 90. At this time, the lengths L4 to L of the stubs 31a to 31d
Since the length of L2 can be made longer or shorter than 6 mm by changing 7, the degree of freedom in design can be expanded.

At this time, it is preferable that the stub 31a and stub 31d and the stub 31b and stub 31c facing each other have substantially the same length (L5 = L7, L4 = L6).

The ring resonator 31 corresponds to the ring resonator 1 of the circuit shown in FIG. 32, 34, 36,
Reference numeral 38 is a transmission line type resonator having a quarter wavelength, and the transmission line type resonators 32, 34, 36 and 38 are formed at the corners of the substrate 30, respectively. The transmission line resonators 32, 34, 36 and 38 have taps 32a and 3 respectively.
4a, 36a, 38a are provided, and the terminals 32b, 34a, 36a, 38a are provided at the tips of the terminals 32b,
34b, 36b, 38b are connected. Terminal 32
b, 34b, 36b, and 38b are formed in the notches provided in the side portions of the substrate 30, and as shown in FIG.
2b, 34b, 36b and 38b are exposed on the side surface of the substrate 30. At this time, both terminals 32b and 34b are exposed on the side surface 30a of the substrate 30, and both terminals 36b and 38b are exposed on the side surface 30b of the substrate 30. With this configuration, the input side terminals can be placed on one side and the output terminals can be placed on the other side, so this filter has very good workability when mounted on other members. Is improved. Embodiment 2
Then, for example, the terminal 3 exposed on the side surface 30a
2b and 34b as terminals on the input side, and terminals 36b and 38b
Is the terminal on the output side.

Further, the transmission line type resonators 32, 34, 3
6 and 38 are short-circuited parts 3 connected to the ground wire, etc.
2c, 34c, 36c, 38c are provided, and the short-circuit portions 32c, 34c, 36c, 38c are provided up to the side surfaces of the corners of the substrate 30, and as shown in FIG.
The c, 34c, 36c, and 38c are exposed on the side surfaces of the corners of the substrate 30.

The transmission line type resonators 32, 34, 36,
38 is arranged so as to face each side of the ring resonator 31, and a gap 3 is provided between the ring resonator 31 and the transmission line type resonators 32, 34, 36, 38.
3, 35, 37, 39 are provided. Gap 3
3, 35, 37 and 39 form inter-stage coupling capacitors, respectively.

Further, the transmission line type resonators 32, 34, 36,
Numeral 38 indicates a facing portion 32 that faces the ring resonator 31, respectively.
d, 34d, 36d, 38d and the facing portions 32d, 34
The orthogonal portions 32e, 34 that are substantially orthogonal to d, 36d, 38d
e, 36e, 38e, and short-circuited parts 32c, 34
c, 36c, 38c and terminals 32b, 34b, 36b,
38b are orthogonal parts 32e, 34e, 36e, 38, respectively.
connected to e.

The central portions of the facing portions 32d, 34d, 36d and 38d and their vicinity are closest to the ring resonator 31 and have a boomerang type shape which gradually separates from the ring resonator 31 toward the ends. There is. The reason for this is
This is because the facing portions 32d, 34d, 36d, and 38d have a higher degree of coupling as the ends are closer to the ring resonator 31, and the frequency band may become wider than necessary. Of course, if the frequency band is to be made very wide, the facing portion 32
The ends of d, 34d, 36d and 38d are connected to the ring resonator 31.
It is also possible to increase the degree of coupling by approaching to.

Further, the facing portions 32d, 34d, 36d, 3
Since 8d and the orthogonal portions 32e, 34e, 36e, and 38e have different widths facing the ring resonator 31 (width of the opposing portion >> width of the orthogonal portion), the opposing portions 32d, 34d, and 36e.
Since the d and 38d and the orthogonal portions 32e, 34e, 36e, and 38e have different impedances (SIR structure), the transmission line resonators 32, 34, 36, and
Since the length of 38 can be shortened and the resonance mode that is an integral multiple of the fundamental wave can be shifted, the filter characteristics can be improved.

Further, the ring resonator 31, the transmission line type resonators 32, 34, 36, 38 and the like formed on the substrate 30 are made of a conductive thin film made of a conductive material. Examples of the conductive material include copper, silver, aluminum and gold. Examples of the method for forming the conductive thin film include a plating method and a screen printing method, but the screen printing method is preferable in view of productivity and cost. That is, the most preferable method is to apply the metal paste onto a predetermined substrate by screen printing and bake the applied metal paste onto the substrate.
At this time, a silver paste is most preferable as the metal paste in consideration of cost and corrosion resistance.

The filter constructed as described above is mounted on another member so that the terminals 32b, 34b, 36
b and 38b are respectively arranged on the input-side line and the output-side line provided on other members, and further, the short-circuit portion 32c,
34c, 36c and 38c are arranged on an earth line provided on another member. Then, the filter is joined to another member by means of reflow or the like.

Next, the operation will be described. First, when the first and second signals are input from the terminals 32c and 34c, respectively, the first signal is transmitted from the transmission line resonator 32 to the ring resonator 31 via the coupling capacitance formed by the gap 33. If the signal is substantially equal to the resonance frequency determined by the length of the circumference of the annular portion of the ring resonator 31 and the lengths (L4 and L6) of the stubs 31b and 31c, the first signal is composed of the gap 37. It is transmitted to the transmission line type resonator 36 through the coupling capacitance and is output from the terminal 36b.

At the same time, the second signal is transmitted from the transmission line type resonator 34 to the ring resonator 31 via the coupling capacitance formed by the gap 35, and the length of the ring resonator 31 around the annular portion and the stubs 31a, 31d. Length (L7 and L5)
If the signal has a frequency substantially equal to the resonance frequency determined by, for example, the second signal is transmitted to the transmission line resonator 38 via the coupling capacitance formed by the gap 39, and is output from the terminal 38b.

In the filter thus constructed, a multistage filter can be constructed by electrically coupling the transmission line type resonators 32, 34, 36 and 38 to the ring resonator 31, so that a high attenuation can be obtained. , It is possible to provide a wideband stripline dual mode filter.

Further, the transmission line type resonators 32, 34, 36,
Since the terminals 32b, 34b, 36b, and 38b are provided on the 38, respectively, it is possible to provide a stripline dual-mode filter with little noise without affecting the orthogonal resonance modes.

A chip lumped constant capacitance element (such as a capacitor) is provided between at least one of the stub 31b and the stub 31c or between the stub 31a and the stub 31d.
By mounting, the length of the ring resonator 31 can be shortened.

Further, as shown in FIG. 12, the ring resonator 50
It is possible to shorten the length of the ring resonator 50 by bringing at least the stub 51 and the stub 52 out of the stubs 51 to 54 provided in the stub 52 close to each other to cause electric field coupling between the stubs as described above. In this case, the 53 and 54 stubs are set to 0.
When the length is reduced to 1 mm or less, the resonators on the stubs 51 and 52 side can obtain a resonance frequency much lower than that of one resonator. If the ring length is set to a resonance frequency of about 1.5 GHz, a resonance of 800 MHz, which is about 50% lower than that, is obtained.
It is possible to realize a two-frequency filter having a large pass band.

Although the resonators are formed on the substrate in the second embodiment, the resonators may be sandwiched between the dielectric substrates.

FIG. 13 is a frequency characteristic diagram near the pass band of the strip line dual mode filter in the second embodiment. In the figure, S31 shows the pass characteristic from the terminal 32b to the terminal 36b, and S42 shows the pass characteristic from the terminal 34b to the terminal 38b. From this figure, it is possible to obtain good characteristics of the bandpass filter having the pass bands of different frequencies in the second embodiment.

FIG. 14 is a wideband frequency characteristic diagram of a stripline dual mode filter having a conventional structure, and FIG. 15 is a wideband frequency characteristic diagram of the stripline dual mode filter of the second embodiment. In Figure 14, 1.5GH
It can be seen that although it has a pass band in z, it also passes signals having frequencies that are integral multiples of 1.5 GHz, that is, frequencies of 3.0 GHz and 4.5 GHz. Therefore, it is understood that the conventional example cannot obtain a reliable filter characteristic. Also, FIG. 15 also has a pass band at 1.5 GHz, but unlike the characteristics shown in FIG.
Frequency that is an integral multiple of z, namely 3.0 GHz and 4.5
It can be seen that it is difficult to pass a signal having a frequency of GHz. Therefore, in the second embodiment, an unnecessary number of unnecessary modes is suppressed,
The harmonic attenuation characteristics can be improved by about 20 dB compared with the conventional one.

[0075]

According to the first aspect of the present invention, there are provided first to fourth transmission line type resonators, and a ring resonator having two resonance modes which are electrically coupled to the transmission line type resonator and are orthogonal to each other. Since the first and second transmission line type resonators are set to the input side and the third and fourth transmission line type resonators are set to the output side, a multi-stage filter can be configured. It is possible to obtain excellent filter characteristics of wide band and high attenuation.

According to the second aspect of the invention, since the input / output coupling section is provided in the transmission line type resonator, the input / output section can be configured so as not to affect the orthogonal resonance modes. Makes designing easier.

In the invention according to claim 3, the ring resonator is
Since the length is one wavelength, a desired resonance frequency can be obtained by defining the length of the ring resonator, which facilitates circuit design and improves productivity.

According to the fourth aspect of the invention, since a plurality of ring resonators are provided and the ring resonators are electrically coupled to each other, a multi-stage filter can be constructed. Therefore, a filter having excellent broadband and high attenuation can be obtained. The characteristics can be obtained.

In the invention according to claim 5, the ring resonator is
Since the ring length can be shortened by adding a lumped-constant capacitance element to one of the opposing portions where electric field coupling is performed with the transmission line type resonator, the filter itself can be miniaturized.

In the invention according to claim 6, the ring resonator is
Since the ring length can be shortened by adding a transmission line whose one end is open to one of the opposing portions that are electrically coupled to the transmission line type resonator, the size of the filter itself can be reduced.

In the invention according to claim 7, the ring resonator is
Since the length of the ring resonator can be shortened by adding a parallel coupling line to one of the opposing portions that are electrically coupled to the transmission line resonator, the size of the filter itself can be reduced.

The invention according to claim 8 is that the ring resonator is
Since the ring resonator length can be shortened by adding the same part to one of the opposing parts that are electric field coupled to the transmission line type resonator, the size of the filter itself can be reduced.

In the invention according to claim 9, the ring resonator is
Since the ring length can be shortened by adding one different from the other to the one portion facing the transmission line type resonator that is electric-field-coupled, the filter itself can be miniaturized.

According to a tenth aspect of the present invention, the transmission line resonator is a quarter-wave resonator by short-circuiting the other end facing the side for electric field coupling with the ring resonator,
Since the desired resonance frequency can be obtained by defining the length of the resonator, the circuit design becomes easy and the productivity is improved.

According to the eleventh aspect of the present invention, the transmission line type resonator is a half-wavelength resonator by opening the other end opposite to the side for electric field coupling with the ring resonator. Since the desired resonance frequency can be obtained by defining the height, circuit design becomes easy and productivity is improved.

According to the twelfth aspect of the present invention, the transmission line type resonator and the ring resonator are characterized in that the higher-order mode resonance frequencies are different from each other. Since the filter characteristics can be suppressed, it is possible to obtain a filter having excellent harmonic attenuation characteristics.

According to a thirteenth aspect of the present invention, a substrate, a ring resonator formed on the substrate, and first to fourth transmission lines formed on the substrate and electrically coupled to the ring resonator. Type resonator, and the first and second transmission line type resonators are set to the input side, and the third and fourth transmission line type resonators are set to the output side, whereby a multistage filter can be configured. Therefore, it is possible to obtain excellent filter characteristics of wide band and high attenuation.

According to the fourteenth aspect of the present invention, stubs extending toward the center of the ring resonator are provided at portions of the ring resonator facing the first to fourth transmission line type resonators. Since the ring resonator length can be shortened and the formation area can be reduced, the device can be downsized.

According to the fifteenth aspect of the present invention, deterioration of the filter characteristics can be prevented by making the stubs facing each other have substantially the same length.

According to the sixteenth aspect of the present invention, since the lumped constant capacitance is provided between the stubs facing each other, the ring resonator length can be shortened and the formation area can be reduced, so that the device can be downsized.

According to the seventeenth aspect of the invention, since the input / output unit can be configured so as not to affect the orthogonal resonance modes by providing the terminals to the first to fourth transmission line type resonators, the multistage is realized. Filter design becomes easy.

According to the eighteenth aspect of the present invention, since the ring resonator has the length of one wavelength, the desired resonance frequency can be obtained by defining the length of the ring resonator. Design is easier and productivity is improved.

According to the nineteenth aspect of the present invention, the transmission line type resonator is provided with portions having different impedances.
Since the length of the transmission line type resonator can be shortened, the device can be downsized. Furthermore, it becomes possible to shift the higher-order resonance modes from an integer multiple, and it is possible to suppress the influence of the higher-order mode resonance of each resonator alone in the filter characteristics, and obtain a filter with excellent harmonic attenuation characteristics. it can.

According to the twentieth aspect of the present invention, the transmission line type resonator is grounded to be a quarter wavelength resonator, and the desired resonance frequency can be obtained by defining the length of the resonator. Therefore, the circuit design is facilitated and the productivity is improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a stripline dual mode filter according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a stripline dual-mode filter according to Embodiment 1 of the present invention.

FIG. 3 is a schematic diagram showing a stripline dual-mode filter according to Embodiment 1 of the present invention.

FIG. 4 is a schematic diagram showing a stripline dual-mode filter according to Embodiment 1 of the present invention.

FIG. 5 is a schematic diagram showing a stripline dual-mode filter according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram showing a stripline dual-mode filter according to the first embodiment of the present invention.

FIG. 7 is a schematic diagram showing a stripline dual mode filter according to the first embodiment of the present invention.

FIG. 8 is an electrical length from the ground according to the first embodiment to the tap (tap 15, 17, 23, 25 in FIG. 1) and the external Q.
Graph showing the relationship with

FIG. 9 is a graph showing the relationship between the parallel line coupling length (width of the portion of the input / output line facing the ring resonator) and the external Q in the conventional example.

FIG. 10 is a plan view showing a stripline dual mode filter according to a second embodiment of the present invention.

FIG. 11 is a perspective view showing a strip line dual mode filter according to a second embodiment of the present invention.

FIG. 12 is a configuration diagram showing another ring resonator of the stripline dual-mode filter according to the second embodiment of the present invention.

FIG. 13 is a frequency characteristic diagram in the vicinity of the pass band of the strip line dual mode filter according to the second embodiment of the present invention.

FIG. 14 is a wideband frequency characteristic diagram of a stripline dual mode filter having a conventional structure.

FIG. 15 is a wideband frequency characteristic diagram of the stripline dual mode fill of the second embodiment.

FIG. 16 is a block diagram of a conventional stripline dual mode filter.

[Explanation of symbols]

1, 2, 3, 4, 31, 50 Ring resonator 11, 12, 19, 20, 32, 34, 36, 38 Transmission line type resonator 16, 18, 24, 26, 32b, 34b, 36b, 3
8b terminal 13,14,21,22 coupling capacity 5,6,7,8,9,10 inter-stage coupling capacity 30 substrate 31a, 31b, 31c, 31d, 51, 52, 53,
54 stubs

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Moruichi Sagawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (20)

[Claims] 1. A first to a fourth transmission line type resonator, and a ring resonator having two resonance modes which are electrically coupled to the transmission line type resonator and which are orthogonal to each other. The second transmission line resonator is used as the input side, and
A strip line dual mode filter, characterized in that a fourth transmission line type resonator is provided on the output side. 2. The strip line dual mode filter according to claim 1, wherein an input / output coupling section is provided in the transmission line type resonator. 3. The strip line dual mode filter according to claim 1, wherein the ring resonator has a length of one wavelength. 4. A plurality of ring resonators are provided and an electric field is coupled between the ring resonators.
[3] The stripline dual-mode filter according to any one of [3]. 5. The strip line according to claim 1, wherein the ring resonator is provided with a lumped constant capacitance element at one of the opposing portions which are electrically coupled to the transmission line type resonator. Dual mode filter. 6. The strip resonator according to claim 1, wherein the ring resonator has a transmission line whose one end is open, which is added to one of the opposing portions where the transmission line type resonator is electrically coupled to the ring resonator. Line dual mode filter. 7. The strip line dual according to claim 1, wherein the ring resonator has a parallel coupling line added to one of the opposing portions for electric field coupling with the transmission line type resonator. Mode filter. 8. The strip line dual mode according to claim 1, wherein the ring resonator has the same one added to one of the opposing portions which are electrically coupled to the transmission line type resonator. filter. 9. A strip resonator according to claim 1, wherein a ring resonator is different from the other in one of the opposing portions that are in electric field coupling with the transmission line type resonator. Line dual mode filter. 10. The strip line dual mode filter according to claim 8, wherein the transmission line type resonator has a short-circuit at the other end which is opposite to the side electrically coupled to the ring resonator. 11. The strip line dual mode filter according to claim 8, wherein the transmission line type resonator has the other end facing the side for electric field coupling with the ring resonator opened. 12. The strip line dual mode filter according to claim 1, wherein the transmission line type resonator and the ring resonator have different higher order mode resonance frequencies. 13. A substrate, a ring resonator formed on the substrate, and first to fourth transmission line resonators formed on the substrate and electrically coupled to the ring resonator. A strip line dual mode filter, wherein the first and second transmission line type resonators are provided on an input side and the third and fourth transmission line type resonators are provided on an output side. 14. A stub extending toward the center of the ring resonator is provided at a portion of the ring resonator facing the first to fourth transmission line type resonators.
3. The strip line dual mode filter according to item 3. 15. The strip line dual mode filter according to claim 14, wherein the stubs facing each other have substantially the same length. 16. The strip line dual mode filter according to claim 15, wherein a lumped constant capacitance is provided between the stubs facing each other. 17. The strip line dual mode filter according to claim 13, wherein terminals are provided in the first to fourth transmission line type resonators. 18. The strip line dual mode filter according to claim 13, wherein the ring resonator has a length of one wavelength. 19. The strip line dual mode filter according to claim 13, wherein the transmission line resonator is provided with portions having different impedances. 20. The strip line dual mode filter according to claim 13, wherein the transmission line type resonator is grounded.