JP2007208686A - Ring resonator filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve miniaturization of a filter by achieving reduction of a line length of a ring resonator. <P>SOLUTION: A ring resonator filter consists of a plurality of ring resonators 1-3 arranged to be coupled in parallel. The ring resonators 1-3 are respectively provided with pairs of conductor lines (11, 12), (21, 22), (31, 32) in which their one ends oppose with each other and their other ends oppose with each other, first capacitive elements 13, 23, 33 provided between the one ends opposing with each other, and second capacitive elements 14, 24, 34 provided between the other ends opposing with each other. The pair of conductor lines and the first and second capacitive elements form a loop-like transmission path. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high frequency filter used in various high frequency devices, and more particularly to a ring resonator type filter using a ring resonator.

  The ring resonator has a feature that it does not have a ground point and has little loss, and its resonance frequency is determined so that the electrical length of the ring-shaped transmission line is one wavelength, that is, 360 °. Conventionally, a ring resonator type filter in which a plurality of one-wavelength ring resonators are arranged so as to be coupled in parallel has been proposed (see, for example, Patent Document 1).

FIG. 6 is a configuration diagram of a ring resonator type filter described in Patent Document 1. In FIG.
Three ring resonators 111, 112, and 113 are arranged so that adjacent resonators are coupled in parallel with each other. Each ring resonator 111, 112, 113 has frequency tuning capacitive elements 111a, 112a, 113a connected to both open ends of a conductor line forming a loop-shaped transmission line. An input / output terminal 141 is coupled to the ring resonator 111 at one end via an input / output coupling capacitive element 114. An input / output terminal 142 is coupled to the ring resonator 113 at the other end via an input / output coupling capacitive element 115. High frequency filters such as a low-pass filter, a high-pass filter, and a band-pass filter are constructed by giving the ring resonator type filter desired frequency characteristics.

The ring resonator type filter described above can achieve low loss (high Q) because there is no need to provide grounding for each of the ring resonators 111, 112, 113, and the coupling between the ring resonators is also a parallel coupling. The structure is very simple and good characteristics can be obtained. Further, by connecting the open ends of the conductor lines with concentrated capacitance elements (111a, 112a, 113a), the resonator length can be shortened and the size can be reduced.
JP-A 64-1303

  However, in the conventional ring resonator type filter, the resonator length can be shortened to some extent by connecting the open ends provided in the conductor line of the ring resonator with a concentrated capacitor element. There is a limit only by providing a capacitive element, and further miniaturization has been desired.

  The present invention has been made in view of such points, and by providing capacitive elements at two locations in the loop-shaped transmission line of the ring resonator, the line length of each ring resonator can be shortened and greatly reduced. An object of the present invention is to provide a ring resonator type filter that can be miniaturized.

  The ring resonator type filter of the present invention is arranged at a plurality of ring resonators arranged so as to be coupled in parallel, a first input / output end coupled to a ring resonator arranged at one end, and the other end. A second input / output end coupled to the ring resonator, and at least one of the plurality of ring resonators includes a pair of conductor lines each having an end-shaped conductor pattern, and the pair A first capacitive element provided between one end of one conductor line and one end of the other conductor line, and the other end of one conductor line of the pair of conductor lines; A second capacitive element provided between the other end of the other conductor line, and forming a loop-shaped transmission line with the pair of conductor lines and the first and second capacitive elements. It is a characteristic.

  According to this configuration, since the loop-shaped transmission line in the ring resonator is composed of the pair of conductor lines and the first and second capacitive elements, the capacitive element is interposed at two locations on the loop-shaped transmission line, and resonance occurs. The instrument length can be further shortened.

  According to the present invention, in the ring resonator type filter, the pair of conductor lines have the same length, and a portion where the density of the high-frequency signal propagating through the loop-shaped transmission line is maximum is the pair of conductor lines. It is characterized by being both ends.

  With this configuration, by making the pair of conductor lines the same length, the location where the density of the high-frequency signal propagating through the loop-shaped transmission line is maximized can be the both ends of the pair of conductor lines. The length of the transmission path can be shortened most by disposing the capacitive element at the location where the density is maximized.

  Further, in the ring resonator type filter according to the present invention, one of the pair of conductor lines is provided in a predetermined layer of the multilayer substrate, and the other conductor line is provided in another layer of the multilayer substrate. One end and the other end of one conductor line and the one end and the other end of the other conductor line are arranged to face each other, and one end of one conductor line and one end of the other conductor line are opposite to each other The first capacitive element is configured at a portion where the second capacitive element is formed, and the second capacitive element is configured at a portion where the other end portion of one conductor line and the other end portion of the other conductor line are opposed to each other. .

  With this configuration, the first capacitive element is formed by a portion where one end of one conductor line overlaps with one end of the other conductor line, and the other end of one conductor line and the other end of the other conductor line. Since the second capacitor element is formed by the overlapping portion, the size can be reduced by the amount of overlap between one conductor line and the other conductor line.

  Further, in the ring resonator type filter according to the present invention, at least two adjacent ring resonators are respectively configured by the pair of conductor lines and the first and second capacitive elements that form a loop-shaped transmission line, Of the pair of conductor lines of the ring resonators adjacent to each other, both conductor lines to be coupled are formed in the same layer of the multilayer substrate.

  With this configuration, since the conductor lines to be coupled are formed in the same layer of the multilayer substrate, the coupling force between the ring resonators can be increased, and loss can be reduced.

  In the ring resonator type filter according to the present invention, each of the ring resonators may be configured such that one conductor line of the pair of conductor lines includes a straight portion having a predetermined width and the other conductor at both ends of the straight portion. A pair of rectangular portions respectively formed so as to protrude toward the track side, and the other conductor line of the pair of conductor lines is a straight portion having a predetermined width and one conductor line at both ends of the straight portion. It consists of a pair of square part each formed so that it may protrude to the side.

  With this configuration, since the capacitive element is configured by the square portion formed at the end portion of one conductor line and the square portion formed at the end portion of the other conductor line, a large capacitance can be easily secured. .

  According to the present invention, it is possible to reduce the line length of each ring resonator by providing capacitive elements at two locations on the loop-shaped transmission line of the ring resonator, and to greatly reduce the ring resonator type filter. Is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. An embodiment of a ring resonator type filter that can be applied as a high frequency filter of a transmission / reception device in mobile communication, wireless LAN, or the like will be described.

(Embodiment 1)
FIG. 1 is a configuration diagram of a ring resonator type filter according to Embodiment 1 of the present invention.
The ring resonator type filter shown in FIG. 1 has a configuration in which first to third ring resonators 1 to 3 having a loop-shaped transmission line are arranged so as to be magnetically coupled. The first input / output end 4 is coupled to the first ring resonator 1 positioned on one end side of the ring resonator type filter, and the second ring resonator is positioned on the third ring resonator positioned on the other end side of the filter. The input / output terminal 5 is configured to be coupled. The first and third ring resonators 1 and 3 and the first and second input / output terminals 4 and 5 are coupled by capacitive coupling or magnetic field coupling.

  The first to third ring resonators 1 to 3 have the same configuration. The first ring resonator 1 includes a pair of conductor lines 11 and 12 having the same shape and the same length, and two chip capacitors 13 and 14 serving as first and second capacitive elements. The conductor lines 11 and 12 include linear portions 11a and 12a having a predetermined length and connecting end portions 11b, 11c, 12b, and 12c obtained by bending both ends of the linear portions 11a and 12a at a right angle by a predetermined amount. The connection end 11b of one conductor line 11 and the connection end 12b of the other conductor line 12 are connected via a chip capacitor 13, and the connection end 11c of one conductor line 11 and the other conductor line 12 are connected to each other. By connecting the connection end portion 12c via a chip capacitor 14, a configuration is adopted in which two capacitive elements are interposed in a rectangular loop transmission line serving as a loop-shaped transmission line.

  The second ring resonator 2 and the third ring resonator 3 are also configured similarly to the first ring resonator 1. That is, the second ring resonator 2 includes a pair of conductor lines 21 and 22 and two chip capacitors 23 and 24 serving as first and second capacitor elements, and the conductor lines 21 and 22 and the chip capacitor. 23 and 24 form a square loop transmission line. Similarly, the third ring resonator 3 includes a pair of conductor lines 31 and 32 and two chip capacitors 33 and 34 serving as first and second capacitor elements, and these conductor lines 31 and 32 and the chip capacitor. 33 and 34 form a rectangular loop transmission line.

The operation of the present embodiment configured as described above will be described.
When a high-frequency signal is applied to the first input / output terminal 4, the first input / output terminal 4 and one conductor line 11 of the first ring resonator 1 are coupled by capacitive coupling or electromagnetic coupling. The high-frequency signal propagated to the first ring resonator 1 propagates through a square loop transmission line formed by one conductor line 11, the chip capacitor 13, the other conductor line 12, and the chip capacitor 14. The rectangular loop transmission line forms an LC resonance circuit composed of an inductor component (L) caused by the conductor lines 11 and 12 and a capacitance component (C) including the capacitances of the chip capacitors 13 and 14. L) and resonance at a specific frequency determined by the capacitance component (C).

  At this time, the linear portion 12a of the conductor line 12 in the first ring resonator 1 and the linear portion of the conductor line 21 in the second ring resonator 2 are magnetically coupled, and a high-frequency signal is transmitted to the second ring resonator 2. Propagate. The second ring resonator 2 resonates on the same principle as the first ring resonator 1, and the linear portion of the conductor line 22 in the second ring resonator 2 and the conductor line 31 in the third ring resonator 3. Magnetic field coupling with the straight line portion. Then, the third ring resonator 3 resonates, and a high frequency signal having a specific frequency is output from the second input / output end 5 coupled to the conductor line 32 of the third ring resonator 3.

  In the present embodiment, chip capacitors (13, 14) (23, 24) that are capacitive elements at two locations that divide a square loop transmission line that is a loop-shaped transmission line into two equal parts in each of the ring resonators 1, 2, and 3. (33, 34) are connected to each other. Thereby, a part of the loop-shaped transmission line can be replaced with a capacitor, and the line length of the entire resonator can be greatly reduced.

  Note that the position where the chip capacitors (13, 14) (23, 24) (33, 34) are provided is preferably a place where the density of the high-frequency signal is maximized on the loop-shaped transmission line. Of the nodes and antinodes that appear in one wavelength, the antinode is the position where the density of the high frequency signal is maximum. In the case of this embodiment, it is set so that the antinode portion of one wavelength of the high-frequency signal comes to two places that bisect the rectangular loop transmission line. By providing capacitive elements at two locations where the density of the high-frequency signal is maximized, the transmission path length can be minimized.

According to the present embodiment, the resonator length of the ring resonator can be shortened as follows.
In order to suppress the insertion loss in the ring resonator to 1 dB or less, it is necessary to make the resonator inductive. Therefore, it is considered to set 5.5 GHz as the filter center frequency on condition that the ring resonator becomes inductive. Under such conditions, the capacity value is limited to 1.5 PF, so that the margin is set to 1.2 PF. According to the present embodiment, the line length of the loop-shaped transmission line (the total length of the pair of conductor lines) is 6.4 mm. FIG. 2 is a diagram specifically showing dimensions of each part of the ring resonator type filter according to the present embodiment. The unit of the dimension in the figure is mm.

  On the other hand, in the case of a general ring resonator, assuming that a filter is constructed on a glass epoxy substrate, for example, 15 mm is required as the physical length of the loop-shaped transmission line if it is designed with a physical length of ½ wavelength. is there. Therefore, according to the present embodiment, the resonator length can be reduced to half or less.

  FIG. 3 is a diagram showing the result of simulating the frequency characteristics of the ring resonator type filter according to the present embodiment. As a simulation condition, the center frequency is set to 5.5 GHz, and the input side end and the output side end are each terminated with 50Ω. As shown in the figure, the loss at the center frequency of 5.5 GHz is about 0.5 dB, and good characteristics are realized.

  In this way, chip capacitors (13, 14) (23, 24) (33, 34), which are capacitive elements, were connected to two locations equally dividing the loop-shaped transmission line in the ring resonators 1, 2, and 3, respectively. As a result, the resonator length can be greatly reduced as compared with the conventional ring resonator. Therefore, when a ring resonator type filter is constituted by a plurality of stages of ring resonators 1, 2, 3, the size of the entire filter can be greatly reduced.

  In the first embodiment, a discrete component chip capacitor is used as the capacitive element, but a capacitive element patterned on a substrate may be used. Further, a discrete capacitive element and a patterned capacitive element may be used in appropriate combination.

  In the first embodiment, all the ring resonators 1 to 3 constituting the ring resonator type filter have the same configuration. However, depending on the application and required performance, the ring resonator shown in FIG. It is good also as a structure which combined the ring resonator (1-3) shown.

(Embodiment 2)
The second embodiment is an example of a ring resonator type filter in which the capacitive element is formed of a multilayer substrate and the magnetic field coupling of the filter is performed in the same layer. In the second embodiment, a ring resonator type filter is configured by arranging four ring resonators 51 to 54 constructed on a multilayer substrate so as to be magnetically coupled.

  4 (a) and 4 (b) are plan views showing the configuration of the ring resonator type filter according to the second embodiment. FIG. 4 (a) is a plan view of the first layer as the surface layer, and FIG. ) Is a plan view of the second layer as the inner layer.

  As shown in FIG. 4A, one conductor pattern 61 of the first ring resonator 51 is formed on the first layer 50 a of the multilayer substrate 50. The multilayer substrate 50 is formed of a dielectric material such as glass epoxy or ceramic and has a multilayer structure. The conductor pattern 61 of the first ring resonator 51 is integrally formed so as to protrude to the second ring resonator side (right side in the figure) at both ends of the linear portion 61a having a predetermined width and the linear portion 61a. It is composed of shaped lands 61b and 61c.

  As shown in FIG. 4B, the other conductor pattern 62 of the first ring resonator 51 is formed on the second layer 50 b of the multilayer substrate 50. The conductor pattern 62 has a linear portion 62a formed in parallel to a position shifted by a predetermined distance on the second ring resonator side (right side in the figure). Lands 62b and 62c having the same shape are formed integrally with the straight part 62a at both ends of the straight part 62a and in regions facing the lands 61b and 61c. Thus, the first ring resonator 51 includes one conductor pattern 61 formed on the first layer 50a, the other conductor pattern 62 formed on the second layer 50b, and the land 61b of the first layer 50a. And a capacitor portion formed between the land 62b of the second layer 50b and a capacitor portion formed between the land 61c of the first layer 50a and the land 62c of the second layer 50b. Forming. This loop-shaped transmission line includes two capacitors as in the first embodiment.

  Further, as shown in FIG. 4B, one conductor pattern 63 of the second ring resonator 52 is formed adjacent to the other conductor pattern 62 of the first ring resonator 51 in the second layer 50b. Has been. The conductor pattern 63 includes a straight portion 63a that is arranged in parallel to the straight portion 62a of the conductor pattern 62 of the first ring resonator 51 and is formed so as to be magnetically coupled, and both ends of the straight portion 63a. It is composed of rectangular lands 63b and 63c that are integrally formed so as to protrude to the third ring resonator side (right side in the figure).

  As shown in FIG. 4A, one conductor pattern 64 of the second ring resonator 52 is formed on the first layer 50 a of the multilayer substrate 50. The conductor pattern 64 has a straight line portion 64a formed in parallel to a position shifted by a predetermined distance from the position where the straight line portion 63a is formed to the third ring resonator side (right side in the figure). Lands 64b and 64c having the same shape are formed integrally with the straight line portion 64a at both ends of the straight line portion 64a and in the regions facing the lands 63b and 63c. As described above, the second ring resonator 52 includes one conductor pattern 64 formed on the first layer 50a, the other conductor pattern 63 formed on the second layer 50b, and a land 64b of the first layer 50a. And a capacitive part formed between the land 63b of the second layer 50b and a capacitive part formed between the land 64c of the first layer 50a and the land 63c of the second layer 50b. Forming. Similar to the first ring resonator 51, the loop-shaped transmission line includes two capacitance units.

  As shown in FIGS. 4A and 4B, the third ring resonator 53 and the fourth ring resonator 54 are also configured in the same manner as the first and second ring resonators 51 and 52 described above. . The third ring resonator 53 includes one conductor pattern 65 formed on the first layer 50a, the other conductor pattern 66 formed on the second layer 50b, and lands 65b and 65c on the first layer 50a side. The capacitor portion is formed between the lands 66b and 66c on the second layer 50b side. The fourth ring resonator 54 includes the other conductor pattern 67 formed on the second layer 50b, the one conductor pattern 68 formed on the first layer 50a, and the land 67b on the second layer 50b side. 67c and a capacitor portion formed between the lands 68b and 68c on the first layer 50a side. The third ring resonator 53 is coupled to the other conductor pattern 64 of the second ring resonator 52 in the first layer 50a, and one conductor pattern 67 of the fourth ring resonator 54 in the second layer 50b. Join.

  A first input / output end 71 is provided at one end of the first layer 50a on the first ring resonator 51 side, and a second input / output end 72 is provided at the other end on the fourth ring resonator 54 side. It has been.

  5 is a cross-sectional view taken along line B-B shown in FIG. The multilayer substrate 50 has a three-layer structure of first to third dielectric layers 50-1 to 50-3, and a ground layer 73 is formed on the lower surface of the first dielectric layer 50-1. Yes. In the present embodiment, the first dielectric layer 50-1 is called the inner layer 50a, and the third dielectric layer 50-3 is called the surface layer 50a. As shown in the figure, each of the ring resonators 51 to 54 includes a conductor pattern (61, 64, 65, 68) formed on the first layer 50a side and a conductor pattern (62, 63) formed on the second layer 50b side. , 66, 67) is opposed to the land portion with the second dielectric layer 50-2 interposed therebetween, and forms a capacitor portion C as shown in FIG.

Next, the operation of the present embodiment configured as described above will be described.
In the first ring resonator 51, between one land pattern (61b, 62b) (61c, 62c) between one conductor pattern 61 formed on the first layer 50a and the other conductor pattern 62 formed on the second layer 50b. A loop-shaped transmission line composed of the formed capacitance portion is formed, and the inductor component (L) of the pair of conductor patterns 61 and 62 formed separately in the first layer 50a and the second layer 50b and the land (61b , 62b) (61c, 62c) and resonates at a resonance frequency determined from the capacitance components (C) of the two capacitance portions formed at the two locations.

  The first ring resonator 51 and the second ring resonator 52 are magnetically coupled in the second layer 50b. Thereby, since adjacent loop-shaped transmission lines are coupled in the same layer, the coupling force of electromagnetic coupling is enhanced. As a result, a high-frequency signal efficiently propagates from the straight portion 62a of the other conductor pattern 62 of the first ring resonator 51 to the straight portion 63a of the one conductor pattern 63 of the second ring resonator 52. The second ring resonator 52 resonates in the same manner as described above. Further, the second ring resonator 52 and the third ring resonator 53 are magnetically coupled in the first layer 50 a, and a high frequency signal propagates from the second ring resonator 52 to the third ring resonator 53. The third ring resonator 53 resonates. When the third ring resonator 53 resonates, the third ring resonator 53 and the fourth ring resonator 54 are magnetically coupled in the second layer 50b, and the fourth ring resonator 54 resonates. As a result, a signal having a specific frequency is taken out from the second input / output terminal 72 formed in the first layer 50a.

  According to this embodiment, in each of the ring resonators 51 to 54, the first layer side land (61b, 64b, 65b, 68b) and the second layer side land (62c, 63c, 66c, 67c) are provided. Are stacked on each other with the dielectric layer interposed therebetween to form each capacitor portion. Therefore, the length in the arrangement direction of the ring resonators can be shortened by the amount of overlap.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible. For example, the number of arrangements of ring resonators can be increased or decreased depending on the application and required accuracy. In addition, the shape of the loop-shaped transmission line can be modified.

  The present invention can be applied to a high frequency filter formed by coupling ring resonators.

Configuration diagram of a ring resonator type filter according to Embodiment 1 of the present invention Explanatory drawing which shows the specific dimension of the ring resonator type filter shown in FIG. Characteristics of ring resonator type filter shown in FIG. (A) The top view of the 1st layer of the ring resonator type filter which concerns on Embodiment 2 of this invention, (b) The top view of a 2nd layer (A) AA sectional view taken along line AA shown in FIG. 4, (b) Partial enlarged view of FIG. Configuration of conventional ring resonator type filter

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 1st ring resonator 2,52 2nd ring resonator 3,53 3rd ring resonator 4,71 1st input / output end 5,72 2nd input / output end 11,12,21 , 22, 31, 32 Conductor line 13, 14, 23, 24, 33, 34 Chip capacitor 50 Multilayer substrate 50a First layer (surface layer)
50b Second layer (inner layer)

Claims (5)

A plurality of ring resonators arranged to be coupled in parallel, a first input / output end coupled to the ring resonator disposed at one end, and a second coupled to the ring resonator disposed at the other end With input and output ends,
At least one ring resonator of the plurality of ring resonators is
A pair of conductor lines each consisting of an end-shaped conductor pattern;
A first capacitive element provided between one end of one conductor line and one end of the other conductor line of the pair of conductor lines;
A second capacitive element provided between the other end of one conductor line and the other end of the other conductor line of the pair of conductor lines;
Comprising
A ring resonator type filter comprising a loop-shaped transmission line formed by the pair of conductor lines and the first and second capacitive elements.   The pair of conductor lines have the same length, and the portions where the density of the high-frequency signal propagating through the loop-shaped transmission line is maximum are both ends of the pair of conductor lines. Ring resonator type filter.   One conductor line of the pair of conductor lines is provided in a predetermined layer of the multilayer substrate, the other conductor line is provided in another layer of the multilayer substrate, and one end and the other end of the one conductor line and the other One end and the other end of the conductor line are arranged opposite to each other, and the first capacitive element is configured at a portion where one end of one conductor line and one end of the other conductor line face each other, 3. The ring resonator type according to claim 1, wherein the second capacitor element is configured at a portion where the other end portion of one conductor line and the other end portion of the other conductor line face each other. filter. At least two adjacent ring resonators are respectively configured by the pair of conductor lines and the first and second capacitive elements that form a loop-shaped transmission line,
4. The ring resonator type filter according to claim 3, wherein both conductor lines to be coupled among a pair of conductor lines of adjacent ring resonators are formed in the same layer of the multilayer substrate. Of the pair of conductor lines, one conductor line is composed of a straight portion having a predetermined width and a pair of rectangular portions respectively formed so as to protrude toward the other conductor line at both ends of the straight portion,
The other conductor line of the pair of conductor lines includes a straight portion having a predetermined width and a pair of square portions formed so as to protrude toward one conductor line at both ends of the straight portion. 5. The ring resonator type filter according to claim 3, wherein the ring resonator type filter is provided.

Images