JPH11205005A - Planar filter and planar filter module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable low-loss characteristics, back lowering and miniaturization by arranging two ring-shaped resonators vertical with respect to a first symmetric axis, electromagnetically coupling them and arranging a signal input/output transmission line to be coupled electromagnetically with the ring-shaped resonators, along the outer peripheries of two ring-shaped resonators. SOLUTION: Planar ring-shaped resonators 101 and 102 are formed by spatially and capacitively coupling two open terminals of a ring-shaped line, which has a line length of 1/2 wavelength, bending and facing opposite axes 103 and 104 passing through the center of the line length as the first symmetric axis. Two ring-shaped resonators 101 and 102 are arranged vertical to the first symmetric axes 103 and 104 and electromagnetically coupled, and signal input/output transmission lines 105 and 106 are formed provided along their outer peripheries. Since the planar ring-shaped resonator is used for a resonator, a radiation loss is reduced, a stable, miniaturized and back-lowered filter is provided, and the reduction of loss is enabled by the use of the signal input/output transmission lines 105 and 106 to be coupled electromagnetically.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar filter and a planar filter module for a high-frequency circuit used in the field of communications such as mobile communications.

[0002]

2. Description of the Related Art A conventional filter realizes a resonator composed of an inductance and a capacitor with a coaxial dielectric or the like as shown in an equivalent circuit diagram of a bandpass filter in FIG.
It was a filter that couples each resonator with a chip capacitor. Further, even the filters using the planar resonators 120 and 121 are filters that input and output signals using the signal input and output taps 122 and 123 as shown in FIG.

[0003]

However, a filter using a coaxial dielectric resonator or the like has a 3G coaxial dielectric resonator itself.
It can only be expected to operate in the normal mode up to about Hz. In addition, 5G is used as a resonator using a semi-rigid cable.
Even if a bandpass filter is formed at a frequency of Hz or more, the capacitance of the coupling capacitor becomes a value of about 0.01 pF to 0.1 pF, and a chip capacitor cannot be used. Therefore, the coupling of the resonators is capacitive coupling in space. However, in the case of capacitive coupling in space, it is difficult to obtain the characteristics of the originally designed bandpass filter due to stray coupling or the like.

Further, in a filter using a dielectric resonator, the size of the resonator itself is large, and the shape of the filter is also large. Further, in a filter using a planar resonator using a signal input / output tap in a signal input / output unit, loss increases due to parasitic capacitance at the tap portion.

In view of the above problems, the present invention does not require a line ground point, is not affected by ground potential, forms a loop by a ring shape, reduces radiation loss, and forms a planar resonator on a substrate. Accordingly, an object of the present invention is to provide a low-profile planar filter and a filter module.

[0006]

In order to achieve the above object, a planar filter according to the present invention has a line length of a half wavelength, and an axis passing through a center point of the line length is defined as a first line. A planar ring resonator formed by spatially capacitively coupling two open ends of a ring line bent and opposed to each other as a symmetric axis;
A signal input / output transmission line provided so that two ring resonators are arranged in a direction perpendicular to the first axis of symmetry and electromagnetically coupled to each other and electromagnetically coupled to the two ring resonators; Wherein the signal input / output transmission line is arranged along the outer periphery of the two ring resonators so as to be electromagnetically coupled to the two ring resonators. According to this configuration, it is possible to realize a stable, compact, low-profile filter and filter module with small radiation loss.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention has a line length of a half wavelength, and is bent and opposed to an axis passing through a center point of the line length as a first symmetric axis. A planar ring resonator formed by spatially capacitively coupling two open ends of a ring-shaped line, and two ring resonators arranged in a direction perpendicular to the first axis of symmetry. A signal input / output transmission line provided so as to be coupled and electromagnetically coupled to the two ring-shaped resonators, and the signal input / output transmission line is configured to be electromagnetically coupled to the two ring-shaped resonators. This is a planar filter which is arranged along the outer circumference of the two ring resonators. By using the ring resonator as the resonator, a stable, small, and low-profile filter with small radiation loss is realized. Along with
The use of the signal input / output transmission line that performs electromagnetic field coupling has the effect of reducing loss.

According to a second aspect of the present invention, a plurality of ring resonators are arranged in a direction perpendicular to the first axis of symmetry, and each of the resonators is electromagnetically coupled to each other. A signal input / output transmission line provided so as to be electromagnetically coupled to two ring-shaped resonators disposed at both ends of the resonator, wherein the signal input / output transmission line is provided with the two ring-shaped resonators; 2 for electromagnetic coupling with
This is a planar filter which is arranged along the outer periphery of two ring-shaped resonators, and is capable of realizing a steeper out-of-passband attenuation characteristic than the planar filter according to the first aspect.

According to a third aspect of the present invention, a line width of a transmission line forming a ring is widened on an open end side, and an opening window surrounded by the ring-shaped transmission line is provided with a first symmetric axis. 2. The flat filter according to claim 1, wherein the filter is formed so as to be left-right symmetrical, wherein the flat filter is a stepped impedance (SIR) resonator that widens the line width on the open end side. It is possible to realize further downsizing than the described invention.

According to a fourth aspect of the present invention, the opening windows of the two ring-shaped resonators are bilaterally symmetric with respect to a second axis of symmetry between the two resonators, and the first symmetry. 4. A planar filter wherein each ring-shaped resonator is asymmetric with respect to the axis and is formed so as to be close to the second symmetric axis, and has the same function as the invention according to claim 3, and has an aperture. By adjusting the window, it is possible to realize a filter having a different pass bandwidth and attenuation pole from the flat filter according to the third aspect of the present invention.

According to a fifth aspect of the present invention, the opening windows of the two ring-shaped resonators are bilaterally symmetric with respect to a second axis of symmetry between the two resonators and the first symmetry. 5. A planar filter, wherein each ring-shaped resonator is asymmetric with respect to the axis and formed so as to be away from the second symmetry axis, and has a different pass bandwidth from the filter according to claim 3 or 4. And a filter having an attenuation pole can be realized.

According to a sixth aspect of the present invention, there is provided a planar filter module in which the ring resonator and the signal input / output transmission line of the planar filter according to the first aspect are formed on a Teflon substrate or an alumina substrate. By forming a resonator on a Teflon substrate or alumina substrate, Q
It is possible to realize a low-loss and low-loss filter module.

According to a seventh aspect of the present invention, the ring-shaped resonator has an opening above the open end so that the length of the open end can be adjusted and the resonance frequency can be varied. The flat filter module according to claim 6, further comprising a shield case covering other than the above. At a frequency of 5 GHz or more, there is a difference between the filter characteristics when the shield case is mounted and the filter characteristics without the shield case. However, by using the shield case having the opening, the laser is mounted in the shield case. It is possible to easily adjust the filter characteristics by using means such as trimming.

According to an eighth aspect of the present invention, there is provided a flat filter module in which the ring resonator and the signal input / output transmission line of the flat filter according to the first embodiment are formed in a dielectric. By using a dielectric having a higher dielectric constant than Teflon or Alumina described in 6 as a sealing material, it is possible to realize a small-sized filter. Further, since the resonator is formed in the dielectric, a shield case is not required.

(Embodiment 1) FIG. 1 shows a configuration diagram of a ring resonator planar filter according to Embodiment 1 of the present invention. In FIG. 1, two open ends of a ring-shaped line having a half-wavelength line length and bent and opposed to each other with axes 103 and 104 passing through a center point of the line length as a first symmetric axis are defined as spaces. Planar ring resonators 101 and 102 formed by capacitive coupling, and two ring resonators 101 and 102 are arranged in a direction perpendicular to first symmetry axes 103 and 104 to perform electromagnetic field coupling and Ring resonator 10
The signal input / output transmission lines 105 and 106 are provided along the outer periphery of the two ring-shaped resonators 101 and 102 so as to be electromagnetically coupled to the ring-shaped resonators 101 and 102.

Here, by using a planar ring-shaped resonator as the resonator, a stable, small and low-profile filter with small radiation loss is realized, and signal input / output transmission lines 105 and 106 for electromagnetic field coupling are used. This makes it possible to reduce the loss. Further, since the half-wavelength line is used, as shown in FIG.
It is possible to realize a filter having attenuation poles 117, 119 below or above 18.

By changing the length of the signal input / output transmission lines 105 and 106 arranged along the two ring resonators 101 and 102 in the present embodiment as shown in FIG. It is possible to change the input / output impedance of the planar filter by changing the degree of electromagnetic field coupling with the filters 101 and 102.

(Embodiment 2) FIG. 3 shows a configuration diagram of a ring resonator planar filter according to Embodiment 2 of the present invention. In FIG. 3, the line has a half wavelength line length,
A planar ring resonator in which two open ends of a ring-shaped line bent and opposed with axes 103 and 104 passing through the center point of the line length as a first axis of symmetry are spatially coupled; A plurality of resonators are arranged in a direction perpendicular to the first symmetry axes 103 and 104, and each of the resonators is electromagnetically coupled. Of the coupled ring resonators electromagnetically coupled,
It comprises signal input / output transmission lines 105 and 106 provided along the outer peripheries of the two ring resonators at the two extreme ends so as to be electromagnetically coupled with the two ring resonators arranged at the two extreme ends. In FIG. 2, by using a plurality of ring resonators, it is possible to realize a steeper out-of-band attenuation characteristic.

(Embodiment 3) FIG. 4 shows a configuration diagram of a ring resonator planar filter according to Embodiment 3 of the present invention. In FIG. 4, the line has a half wavelength line length,
This is a ring-shaped line which is bent and opposed with axes 103 and 104 passing through the center point of the line length as a first symmetric axis.
An open window 108, which is formed of a planar ring-shaped resonator having two open ends spatially coupled, and which is surrounded by a ring-shaped transmission line which is bilaterally symmetric with respect to the first symmetry axis 103, 104. 109 is a flat-type filter formed.

The two ring-shaped resonators 101 and 102 have a stepped impedance (S
By using an IR) resonator, it is possible to further reduce the size compared to the first embodiment.

(Embodiment 4) FIG. 5 shows a configuration diagram of a ring resonator planar filter according to Embodiment 4 of the present invention. In FIG. 5, the line has a half wavelength line length,
This is a ring-shaped line which is bent and opposed with axes 103 and 104 passing through the center point of the line length as a first symmetric axis.
An open window 108, which is formed of a planar ring-shaped resonator having two open ends spatially coupled, and which is surrounded by a ring-shaped transmission line which is bilaterally symmetric with respect to the first symmetry axis 103, 104. 109 is a flat-type filter formed.

Opening windows 108, 1 of two ring resonators
09 is a second axis of symmetry 1 between the two resonators 101 and 102.
10 and a first axis of symmetry 1
03, 104, each ring-shaped resonator 101, 102
Is asymmetric and close to the second axis of symmetry 110, it is possible to realize a filter having a different pass bandwidth and attenuation pole from the planar filter of the third embodiment.

(Embodiment 5) FIG. 6 shows a configuration diagram of a ring resonator planar filter according to Embodiment 5 of the present invention. In FIG. 6, the line has a half wavelength line length,
This is a ring-shaped line which is bent and opposed with axes 103 and 104 passing through the center point of the line length as a first symmetric axis.
An open window 108, which is formed of a planar ring-shaped resonator having two open ends spatially coupled, and which is surrounded by a ring-shaped transmission line which is bilaterally symmetric with respect to the first symmetry axis 103, 104. 109 is a flat-type filter formed.

Opening windows 108, 1 of two ring resonators
09 is a second axis of symmetry 1 between the two resonators 101 and 102.
10 and a first axis of symmetry 1
03, 104, each ring-shaped resonator 101, 102
Is asymmetric and away from the second axis of symmetry 110, it is possible to realize a filter having a pass band width and an attenuation pole different from those of the planar filters of the third and fourth embodiments. .

(Embodiment 6) FIG. 7 shows a configuration diagram of a ring resonator planar filter module according to Embodiment 6 of the present invention. In FIG. 7, axes 103 and 104 having a line length of a half wavelength and passing through a center point of the line length.
Ring-shaped resonators 101 and 102 in which two open ends of a ring-shaped line that are bent and opposed to each other with a first symmetry axis are spatially capacitively coupled;
Two ring-shaped resonators 101 and 102 are arranged in the direction perpendicular to the first symmetry axes 103 and 104 so as to be electromagnetically coupled to each other and to be coupled to the two ring-shaped resonators 101 and 102. , 102 and signal input / output transmission lines 105, 106 provided along the outer circumference of the ring-shaped resonators 101, 102 and the signal input / output transmission lines 10, 102.
5, 106 are formed on a Teflon substrate or an alumina substrate.

Q of a Teflon substrate or an alumina substrate
By forming the resonator on the filter module substrate 111 having a high material, it is possible to realize a low-loss filter module.

(Embodiment 7) FIG. 8 shows a configuration diagram of a ring resonator planar filter module according to Embodiment 7 of the present invention. In FIG. 8, axes 103 and 104 having a line length of a half wavelength and passing through a center point of the line length.
Ring-shaped resonators 101 and 102 in which two open ends of a ring-shaped line that are bent and opposed to each other with a first symmetry axis are spatially capacitively coupled;
Two ring-shaped resonators 101 and 102 are arranged in the direction perpendicular to the first symmetry axes 103 and 104 so as to be electromagnetically coupled to each other and to be coupled to the two ring-shaped resonators 101 and 102. , 102 and signal input / output transmission lines 105 and 106 provided along the outer periphery of the ring-shaped resonator 1.
An opening 114 is provided above the open end 112 so that the resonance frequency can be varied by adjusting the length of the open end 112 of each of the first and second 01 and 102, and a shield case 113 covering portions other than the open end 112.
It is composed of

Here, by using a shield case having an opening for adjusting the resonance frequency, it is possible to easily adjust the filter characteristics by means such as laser trimming with the shield case mounted.

(Eighth Embodiment) FIG. 9 shows a configuration diagram of a ring resonator planar filter module according to an eighth embodiment of the present invention. In FIG. 9, the ring resonators 101 and 102 and the signal input / output transmission line 10 of the ring resonator planar filter according to the first to fifth embodiments are shown.
5 and 106 are formed in the dielectric 115.

Here, by using a dielectric material having a high dielectric constant as a sealing material, it is possible to realize a filter smaller than Embodiments 1 to 7. Further, since the resonator is formed in the dielectric, a shield case is not required.

FIG. 10 shows the characteristics of the planar filter modules according to the sixth to eighth embodiments.
8 denotes a pass band, and 117 and 119 denote attenuation poles.

[0032]

As described above, according to the present invention, a stable ring-shaped planar resonator having a small radiation loss and a signal input / output transmission line which are electromagnetically coupled to the ring-shaped resonator and have a small loss when extracting a signal. By constructing a planar filter by the above, an advantageous effect of reducing the size and height of the filter while maintaining low loss characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a planar filter according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a planar filter according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a planar filter according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a planar filter according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a planar filter according to a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram of a planar filter according to a fifth embodiment of the present invention.

FIG. 7 is a configuration diagram of a planar filter module according to Embodiment 6 of the present invention.

FIG. 8 is a configuration diagram of a planar filter module according to a seventh embodiment of the present invention.

FIG. 9 is a sectional view of a flat filter module according to an eighth embodiment of the present invention.

FIG. 10 is a characteristic diagram of the planar filter module according to the sixth to eighth embodiments of the present invention.

FIG. 11 is a configuration diagram of a conventional flat filter.

FIG. 12 is a configuration diagram of a conventional planar filter.

[Explanation of symbols]

101, 102, 107, 120, 121 Ring resonator 103, 104 First symmetry axis 105, 106 Signal input / output transmission line 108, 109 Opening window 110 Second symmetry axis 111 Filter module substrate 112 Ring resonator open end 113 Shield case 114 Shield case opening 115 Dielectric 116, 118 Pass band 117, 119 Attenuation pole 122, 123 Signal input / output tap

Claims (8)

[Claims] 1. A space-capacitive coupling between two open ends of a ring-shaped line having a line length of a half wavelength and bending and facing an axis passing through a center point of the line length as a first symmetric axis. A planar ring-shaped resonator made up of two ring-shaped resonators arranged in a direction perpendicular to the first axis of symmetry, and electromagnetically coupled to the two ring-shaped resonators; And a signal input / output transmission line provided along the outer circumference of the two ring resonators for electromagnetically coupling with the two ring resonators. A planar filter characterized by the following: 2. A plurality of ring resonators are arranged in the direction perpendicular to the first axis of symmetry, are electromagnetically coupled to each other, and are arranged at the both ends of the coupled ring resonators electromagnetically coupled. A signal input / output transmission line provided so as to be electromagnetically coupled to the two ring-shaped resonators, and the signal input / output transmission line is used to couple the two ring-shaped resonators to the two ring-shaped resonators. The flat filter according to claim 1, wherein the filter is arranged along the outer periphery of the ring resonator. 3. A transmission line forming a ring, the line width of which is widened on an open end side, and an opening window surrounded by the ring-shaped transmission line is formed so as to be bilaterally symmetric on a first axis of symmetry. The flat filter according to claim 1, wherein: 4. Each of the ring resonators has opening windows of the two ring resonators symmetrical with respect to a second axis of symmetry between the two resonators and with respect to the first axis of symmetry. 4. The flat filter according to claim 3, wherein the filter is asymmetric and formed to be close to the second axis of symmetry. 5. Each ring-shaped resonator is provided such that the aperture windows of the two ring-shaped resonators are bilaterally symmetrical with respect to a second axis of symmetry between the two resonators, and each ring-shaped resonator is aligned with respect to the first axis of symmetry. 4. The planar filter according to claim 3, wherein the filter is asymmetric and formed so as to be distant from the second axis of symmetry. 6. A planar filter module according to claim 1, wherein the ring-shaped resonator and the signal input / output transmission line of the planar filter are formed on a Teflon substrate or an alumina substrate. 7. A shield case having an opening above the open end so as to adjust the length of the open end of the ring-shaped resonator and adjust the resonance frequency, and covering a portion other than the adjustment portion. 7. The planar filter module according to 6. 8. A flat filter module, wherein the ring resonator and the signal input / output transmission line of the flat filter according to claim 1 are formed in a dielectric.