JP7237247B2 - Resonators and high frequency filters - Google Patents

Description

The present disclosure relates to resonators and high frequency filters.

A planar filter using a strip conductor provided on a dielectric substrate is known as a high-frequency filter. For example, Patent Literature 1 describes a bandpass filter having two or more resonators arranged between two input/output terminals in a laminated substrate made up of a plurality of dielectric layers. In this band-pass filter, each resonator is composed of a resonant line and a resonant capacitor connected to one end thereof, and the capacitor electrode and resonant line forming the resonant capacitor form a band-pass filter when viewed from the lamination direction. They are arranged on different dielectric layers via a planar ground electrode that covers the entire part.

By the way, in Patent Document 1, for example, in a transmission line that is a strip conductor having a length of less than a quarter effective wavelength, one end of the transmission line is loaded with a capacitance, and the other end is loaded with a capacitance. A short-circuited resonator is described. In this resonator, when one end of the transmission line is left open without any capacitance, fundamental resonance occurs at a frequency at which the length of the transmission line becomes 1/4 of the effective wavelength. A first-order spurious resonance occurs at a frequency whose length is three-quarters of the effective wavelength. Since the frequency ratio between the fundamental resonance and the first spurious resonance is 3, the first spurious resonance occurs at the frequency _fs1 , which is three times the fundamental resonance frequency _f0 .

Therefore, by loading a capacitance at the open end of the transmission line, it is possible to design a resonator having a frequency ratio of 3 or more between the fundamental resonance frequency _f0 and the primary spurious resonance frequency _fs1 . This means that the planar filter can attenuate unwanted waves over a wider frequency band, that is, improve spurious characteristics.

In order to improve the spurious characteristics of the resonator, it is necessary to increase the value of the capacitance loaded at the end of the strip conductor. For example, there is known a resonator employing an electrode structure (hereinafter referred to as electrode structure A) in which signal conductors and ground conductors are alternately arranged in the lamination direction on a dielectric substrate having a plurality of laminated dielectric layers. ing. In the electrode structure A, the effective electrode area of the capacitor can be increased while suppressing an increase in the area occupied by the capacitor, so that the value of the capacitor increases.

WO2010/018798

In order to achieve a larger capacitance value in the electrode structure A, it is necessary to increase the area of the signal conductor that constitutes the capacitance. However, if the size of the signal conductor that constitutes the capacitor becomes too large to be ignored compared to the effective wavelength of the operating frequency, the electrode structure A itself will cause unnecessary resonance, degrading the spurious characteristics of the resonator. I had a problem.

An object of the present disclosure is to provide a resonator capable of suppressing degradation of spurious characteristics even when the size of a signal conductor is increased, and a high-frequency filter using the resonator.

A resonator according to the present disclosure includes a dielectric substrate on which dielectrics are laminated, a first ground conductor provided on a first surface of the dielectric substrate, and a side opposite to the first surface of the dielectric substrate. a second ground conductor provided on the second surface of the dielectric substrate, a plurality of strip-shaped signal conductors arranged in the lamination direction so as to overlap each other in a planar view in the inner layer of the dielectric substrate, and the inner layer of the dielectric substrate one or more inner layer ground conductors alternately arranged with the signal conductor in the stacking direction, a strip-shaped strip conductor provided in the inner layer of the dielectric substrate, and a first ground conductor provided in the inner layer of the dielectric substrate, , a plurality of first short-circuit conductors for electrically connecting and short-circuiting the second ground conductor and the inner layer ground conductor, an end of the strip conductor opposite to the end to which the first short-circuit conductor is connected, and a signal a first connection conductor electrically connecting the ends of the conductors; a second connection conductor electrically connecting the signal conductors at each end of the plurality of signal conductors; a third connecting conductor for electrically connecting between the signal conductors at each end opposite to the end to which the connecting conductors of the plurality of signal conductors have the same electrical length; The electrical length is smaller than the electrical length of the strip conductor, and the sum of the electrical lengths of the signal conductor and the strip conductor is equal to or less than 1/4 effective wavelength at the resonance frequency.

According to the present disclosure, a plurality of strip-shaped signal conductors arranged in the lamination direction so as to overlap each other in a planar view in the inner layer of the dielectric substrate, and the signal conductors arranged alternately in the lamination direction in the inner layer of the dielectric substrate. electrically connect and short-circuit the one or more inner layer ground conductors, the band-shaped strip conductor provided in the inner layer of the dielectric substrate, the first ground conductor, the second ground conductor, and the inner layer ground conductor. a first connecting conductor electrically connecting a plurality of first short-circuiting conductors, an end of the strip conductor opposite to the end to which the first short-circuiting conductor is connected, and an end of the signal conductor; a second connecting conductor for electrically connecting between the signal conductors at each end of the signal conductors of the plurality of signal conductors, and a signal conductor at each end of the plurality of signal conductors opposite to the end to which the second connecting conductor is connected and a third connection conductor electrically connecting between them. The resonator according to the present disclosure having these components can suppress deterioration of spurious characteristics even when the size of the signal conductor is increased.

1A is a plan view showing the resonator according to Embodiment 1, and FIG. 1B is a cross-sectional arrow diagram showing a cross section of the resonator according to Embodiment 1 taken along line AA in FIG. 1A. is. 2 is a plan view showing the configuration of each layer of the resonator according to Embodiment 1; FIG. 3A is a plan view showing a resonator without a third connection conductor, and FIG. 3B shows a cross section of the resonator without a third connection conductor taken along line BB in FIG. 3A. It is a cross-sectional arrow view. FIG. 4 is a plan view showing the configuration of each layer of a resonator without a third connection conductor; FIG. 4 is a circuit diagram showing an equivalent circuit of a resonator without a third connecting conductor; 4 is a graph showing analysis results of resonance frequencies of a resonator without a third connection conductor; 5 is a graph showing analysis results of the resonance frequency of the resonator according to Embodiment 1; 8A is a plan view showing a high-frequency filter according to Embodiment 2, and FIG. 8B is a cross-sectional arrow diagram showing a cross-section of the high-frequency filter according to Embodiment 2 taken along line CC of FIG. 8A. is. FIG. 9 is a plan view showing the configuration of each layer of the high-frequency filter according to Embodiment 2; 9 is a graph showing analysis results of amplitude characteristics of the high-frequency filter according to Embodiment 2; 11A is a plan view showing a modification of the high-frequency filter according to Embodiment 2, and FIG. 11B is a cross section of the modification of the high-frequency filter according to Embodiment 2 taken along line DD of FIG. 11A. It is a cross-sectional arrow view showing the. FIG. 10 is a plan view showing the configuration of each layer of a modification of the high-frequency filter according to Embodiment 2; 13A is a plan view showing a high-frequency filter according to Embodiment 3, and FIG. 13B is a cross-sectional arrow view showing a cross-section of the high-frequency filter according to Embodiment 3 taken along line EE in FIG. 13A. is. FIG. 10 is a plan view showing the configuration of each layer of the high frequency filter according to Embodiment 3; 10 is a graph showing analysis results of amplitude characteristics of a high-frequency filter according to Embodiment 3;

Embodiment 1.
FIG. 1A is a plan view showing resonator 1 according to Embodiment 1. FIG. FIG. 1B is a cross-sectional arrow diagram showing a cross section of the resonator 1 taken along line AA in FIG. 1A. FIG. 2 is a plan view showing the structure of each layer of the resonator 1. FIG. As shown in FIGS. 1B and 2, the resonator 1 includes a first ground conductor 2a, a second ground conductor 2b, a dielectric substrate 3, an inner layer ground conductor 4, a strip conductor 5, a signal conductor 6, a first A connection conductor 7a, a second connection conductor 7b, a third connection conductor 7c and a first short-circuit conductor 8 are provided.

The dielectric substrate 3 is a dielectric substrate in which dielectrics are laminated, and the first ground conductor 2a is provided on the first surface, which is the principal surface, and the principal surface opposite to the first surface. A second ground conductor 2b is provided on the second surface. The first ground conductor 2a, as shown in FIGS. 1A and 2, is a conductor solid pattern on the first surface, and the second ground conductor 2b is a conductor solid pattern on the second surface. In the example shown in FIGS. 1B and 2, the first surface of the dielectric substrate 3 is the first layer, the second surface is the eighth layer, and between the first and second surfaces has inner layers from the 3rd to the 7th layers.

One or a plurality of inner layer ground conductors 4 are solid patterns of the first to n-th conductors provided in the inner layer of the dielectric substrate 3 . n is an integer of 1 or more. In the examples of FIGS. 1B and 2, the plurality of inner layer ground conductors 4 are inner layer ground conductors 4a and inner layer ground conductors 4b. An opening pattern is formed in the inner layer ground conductor 4a and the inner layer ground conductor 4b so as not to conduct with the second connection conductor 7b and the third connection conductor 7c.

The strip conductor 5 is a strip-shaped conductor pattern provided on the inner layer of the dielectric substrate 3 . In the inner layer of the dielectric substrate 3, the strip conductor 5 functions as a strip transmission line arranged between the second ground conductor 2b and the inner layer ground conductor 4b. The ends of the strip conductor 5 are electrically connected to the first ground conductor 2a, the second ground conductor 2b, the inner layer ground conductor 4a and the inner layer ground conductor 4b by the first short-circuit conductor 8. FIG. That is, the end of the strip conductor 5 is grounded.

The plurality of signal conductors 6 are first to (n+1)-th strip-shaped conductor patterns arranged in the stacking direction so as to overlap each other in a plan view on the inner layer of the dielectric substrate 3. 1B and 2, the plurality of signal conductors 6 are signal conductors 6a, 6b and 6c. The signal conductors 6a, 6b and 6c are arranged in the stacking direction so as to overlap each other when the dielectric substrate 3 is viewed in plan.

The inner layer ground conductors 4a and 4b and the signal conductors 6a, 6b and 6c are alternately arranged in the stacking direction of the dielectric substrate 3. As shown in FIG. That is, as shown in FIG. 1B, the resonator 1 has a dielectric substrate 3 in which a signal conductor 6a is arranged on the second layer, an inner layer ground conductor 4a is arranged on the third layer, and a signal conductor 6b is arranged on the fourth layer. are arranged, the inner layer ground conductor 4b is arranged on the fifth layer, and the signal conductor 6c is arranged on the sixth layer. The electrode structure A functions as a lumped element capacitance.

As shown in FIG. 2, the signal conductor 6a is provided on the second layer of the dielectric substrate 3, has one end connected to the second connection conductor 7b, and has the other end connected to the third connection conductor. 7c is connected. The signal conductor 6b is provided on the fourth layer of the dielectric substrate 3, and, like the signal conductor 6a, has one end connected to the second connection conductor 7b and the other end connected to the third connection conductor 7c. is connected. The signal conductor 6c is provided on the sixth layer of the dielectric substrate 3, and has one end connected to the second connection conductor 7b and the other end connected to the third connection conductor 7b, similar to the signal conductors 6a and 6b. A conductor 7c is connected.

The first connection conductor 7a is a via conductor that electrically connects the end of the strip conductor 5 opposite to the end connected to the first short-circuit conductor 8 and the end of the signal conductor 6c. The second connection conductor 7b is a via conductor that electrically connects the signal conductors at respective ends of the signal conductors 6a, 6b and 6c. The third connection conductor 7c is a via conductor that electrically connects the signal conductors at the ends of the signal conductors 6a, 6b and 6c opposite to the ends to which the second connection conductor 7b is connected.

The first short-circuit conductor 8 is provided in the inner layer of the dielectric substrate 3, and electrically connects and short-circuits the first ground conductor 2a, the second ground conductor 2b, the inner layer ground conductor 4a, and the inner layer ground conductor 4b. It is a via conductor. As shown in FIG. 2, on the dielectric substrate 3, the plurality of first short-circuit conductors 8 are arranged so as to surround the strip conductor 5 and the signal conductors 6a, 6b and 6c in plan view.

3A is a plan view showing the resonator 100 without the third connection conductor 7c, and FIG. 3B is a cross-sectional arrow view showing a cross-section of the resonator 100 taken along line BB in FIG. 3A. be. FIG. 4 is a plan view showing the structure of each layer of the resonator 100. FIG. The resonator 100 includes a first ground conductor 101a, a second ground conductor 101b, a dielectric substrate 102, an inner layer ground conductor 103, a strip conductor 104, a signal conductor 105, a first connection conductor 106a, and a second connection conductor 106b. and a first shorting conductor 107 .

The first ground conductor 101a is a conductor solid pattern provided on the first surface of the dielectric substrate 102, as shown in FIGS. is a solid pattern of conductors provided on the second surface of the . The inner layer ground conductor 103 is a solid pattern of the first to n-th conductors provided in the inner layer of the dielectric substrate 102 . 3B and 4, the plurality of inner layer ground conductors 103 are inner layer ground conductors 103a and inner layer ground conductors 103b. An opening pattern is formed in the inner layer ground conductor 103a and the inner layer ground conductor 103b so as not to conduct with the second connection conductor 106b.

The strip conductor 104 is a strip-shaped conductor pattern provided on the inner layer of the dielectric substrate 102 . In the inner layer of dielectric substrate 102, strip conductor 104 functions as a strip transmission line arranged between second ground conductor 101b and inner layer ground conductor 103b. The ends of the strip conductor 104 are electrically connected to the first ground conductor 101a, the second ground conductor 101b, the inner layer ground conductor 103a and the inner layer ground conductor 103b by the first short-circuit conductor 107. FIG. That is, the ends of the strip conductor 104 are grounded.

The plurality of signal conductors 105 are first to (n+1)-th strip-shaped conductor patterns arranged in the stacking direction so as to overlap each other in a plan view in the inner layer of the dielectric substrate 102 . 3B and 4, the plurality of signal conductors 105 are signal conductors 105a, 105b and 105c. The signal conductors 105a, 105b and 105c are arranged in the stacking direction so as to overlap each other when the dielectric substrate 102 is viewed two-dimensionally.

The inner layer ground conductors 103a and 103b and the signal conductors 105a, 105b and 105c are alternately arranged in the stacking direction of the dielectric substrate 3. As shown in FIG. That is, as shown in FIG. 3B, the resonator 100 has the signal conductor 105a arranged in the second layer and the inner layer ground conductor 103a arranged in the third layer in the dielectric substrate 102, similarly to the resonator 1. It has an electrode structure A in which a signal conductor 105b is arranged on the fourth layer, an inner layer ground conductor 103b is arranged on the fifth layer, and a signal conductor 105c is arranged on the sixth layer.

The resonator 1 is characterized in that in the electrode structure A it comprises a third connection conductor 7c. In contrast, the resonator 100 does not have a component corresponding to the third connection conductor 7c. FIG. 5 is a circuit diagram showing an equivalent circuit of the resonator 100. As shown in FIG. When the electrode structure A is regarded as the capacitance of a lumped constant element, the equivalent circuit of the resonator 100 is expressed as a circuit in which the transmission line 200 and the capacitor 201 are connected at the connection point 202, as shown in FIG.

In the equivalent circuit shown in FIG. 5, the input admittance Y _inA viewed from the connection point 202 toward the transmission line 200 is expressed by the following equation (1). Also, the input admittance Y _inB when the capacitor 201 side is viewed from the connection point 202 is expressed by the following equation (2). In equations (1) and (2) below, Y is the characteristic admittance of the transmission line 200 , θ is the electrical length of the transmission line 200 , and C is the capacitance of the capacitor 201 .
_YinA =jYcotθ (1)
_YinB =jωC (2)

The resonance condition is Y _inA =Y _inB . Applying the resonance condition to the equivalent circuit, the following equation (3) is obtained.
ωC/Y=cot θ ₁ (3)

In the above equation (3), when the capacitance C is set to 0, the resonator ₁₀₀ operates as a quarter-wave resonator. … becomes. Therefore, when the electrical length θ at the fundamental resonance frequency f ₀ is θ ₀ and the electrical length θ at the primary spurious resonance frequency f _s1 is θ _s1 , θ ₀ =π/4 and θ _s1 =3π/4, The ratio of both is 3.

When both the capacitance C and the characteristic admittance Y are positive numbers, the possible range of the electrical length θ ₀ is 0<θ ₀ <π/4, and the possible range of the electrical length θ _s1 is π/2<θ _s1 < 3π/4. Therefore, by loading the capacitance C, the fundamental resonance frequency _f0 and the first spurious resonance frequency _fs1 become lower than the original frequencies. Also, when the value of C/Y is increased, θ ₀ approaches 0 and θ _s1 approaches π/2. Therefore, the frequency ratio (f _s1 /f ₀ ) between the fundamental resonance frequency f ₀ and the primary spurious resonance frequency f _s1 becomes greater than 3, and the spurious characteristics are improved.

However, as the operating frequency becomes higher, the electrode structure A can no longer be regarded as a lumped capacitance. Therefore, at the fundamental resonance frequency _f0 , the resonator designed by regarding the electrode structure A as a lumped constant capacitance is compared to the one designed so that the electrode structure A functions as a transmission line in the high frequency band. may degrade the spurious characteristics. In particular, two of the signal conductors 105a, 105b, and 105c operate as half-wave resonators with both ends open at a frequency where the length of each of the signal conductors 105a, 105b, and 105c is around a quarter wavelength. and the spurious characteristics deteriorate.

FIG. 6 is a graph showing analysis results of the resonance frequency of the resonator 100. As shown in FIG. In FIG. 6, the horizontal axis is the electrode length dl in the electrode structure A. In FIG. The electrodes in the electrode structure A are a signal conductor 105a, an inner ground conductor 103a, a signal conductor 105b, an inner ground conductor 103b and a signal conductor 105c. The length dl of the electrodes is the length normalized by the effective wavelength at the fundamental resonance frequency _f0 when the length of these conductors in the longitudinal direction is 0. The first vertical axis is the fundamental resonance frequency _f0 and the first spurious resonance frequency _fs1 , and the second vertical axis is the frequency ratio between the fundamental resonance frequency _f0 and the first spurious resonance frequency _fs1 ( f _s1 /f ₀ ).

When the value of the electrode length dl in the resonator 100 is increased, the fundamental resonance frequency f ₀ monotonously decreases as shown in FIG. 6, but the frequency ratio (f _s1 /f ₀ ) is dl=0. It reaches a maximum around 025. When the value of dl is further increased, the value of the frequency ratio (f _s1 /f ₀ ) gradually decreases. Therefore, if the value of the electrode length dl in the resonator 100 is increased, the ratio between the fundamental resonance frequency _f0 and the primary spurious resonance frequency _fs1 will decrease, that is, the spurious characteristics will deteriorate.

If the length of the signal conductor in the electrode structure A is set to 1/4 wavelength or less in order to avoid the deterioration of the spurious characteristics described above, the number of signal conductors in the electrode structure A is need to be increased. However, in order to increase the number of signal conductors, it is necessary to increase the number of conductor layers of the dielectric substrate 102, and the manufacturing cost of the dielectric substrate 102 increases. Further, the resonance at the lowest frequency that occurs in the electrode structure A is half-wave resonance that occurs when the path length of the high-frequency current is half the wavelength.

Therefore, in the resonator 1, the open ends of the signal conductors 6a, 6b and 6c are short-circuited by connecting the third connection conductor 7c. As a result, in the spurious resonance mode, the open-ended half-wave resonance occurring in the signal conductors 105a, 105b, and 105c of the resonator 100 can be suppressed, so that the primary spurious resonance frequency _fs1 can be increased. It is possible to shift the frequency band.

In the fundamental resonance mode, the signal conductors 6a, 6b and 6c forming the electrode structure A are at the same potential. Therefore, the resonance frequency of the electrode structure A does not change even if the ends of the signal conductors 6a, 6b and 6c are short-circuited with each other by the third connecting conductor 7c.
Therefore, the resonator 1 has the same area as that of the resonator 100 required for fundamental resonance at the target frequency, but the primary spurious resonance frequency _fs1 can be shifted to a higher frequency band. Therefore, spurious characteristics are improved.

The operation of resonator 1 at the fundamental resonant frequency f ₀ is similar to resonator 100 . That is, the resonator 1 produces fundamental resonance in the range where the electrical length θ of the strip conductor 5 is θ<π/4. In the resonator 1, the electrical length θ _k of the signal conductors 6a, 6b and 6c and the electrical length θ of the strip conductor 5 satisfy the relationships θ _k < θ and θ _k + θ < π/4. The electrical lengths θ _k of the signal conductors 6 a , 6 b and 6 c are equal to each other, and the electrical length θ _k is smaller than the electrical length θ of the strip conductor 5 . θ _k +θ, which is the sum of the electrical lengths of the signal conductor 6 and the strip conductor 5, is equal to or less than 1/4 effective wavelength at the fundamental resonance frequency f ₀ .

FIG. 7 is a graph showing analysis results of the resonance frequency of the resonator 1. In FIG. In FIG. 7, the horizontal axis is the electrode length dl in the electrode structure A. In FIG. The electrodes in the electrode structure A are a signal conductor 6a, an inner ground conductor 4a, a signal conductor 6b, an inner ground conductor 4b and a signal conductor 6c. The length dl of the electrodes is the length normalized by the effective wavelength at the fundamental resonance frequency _f0 when the length of these conductors in the longitudinal direction is 0. The first vertical axis is the fundamental resonance frequency _f0 and the first spurious resonance frequency _fs1 , and the second vertical axis is the frequency ratio between the fundamental resonance frequency _f0 and the first spurious resonance frequency _fs1 ( f _s1 /f ₀ ).

As the value of the electrode length dl increases, the fundamental resonance frequency _f0 monotonously decreases, and the frequency ratio between the fundamental resonance frequency _f0 and the primary spurious resonance frequency _fs1 (f _s1 / _f0 ) monotonically increases in the range of 0<dl<0.07. Comparing the analysis result of FIG. 6 with the analysis result of FIG. 7, the spurious characteristics of the resonator 1 are improved in the range of 0.025<dl<0.07.

As described above, the resonator 1 according to the first embodiment includes the signal conductors 6a, 6b and 6c arranged in the lamination direction so as to overlap each other in a plan view in the inner layer of the dielectric substrate 3, and the dielectric substrate. Inner layer ground conductors 4a and 4b alternately arranged with signal conductors 6a, 6b and 6c in the lamination direction in inner layer 3, strip conductor 5, first ground conductor 2a, second ground conductor 2b and inner layer A first short-circuit conductor 8 for electrically connecting and short-circuiting the ground conductors 4a and 4b, an end of the strip conductor 5 opposite to the end to which the first short-circuit conductor 8 is connected, and signal conductors 6a and 6b. and 6c, a second connection conductor electrically connecting the signal conductors at the ends of the signal conductors 6a, 6b and 6c, and the signal conductor 6a , 6b and 6c for electrically connecting the signal conductors at the ends opposite to the ends to which the second connection conductors 7b are connected. The resonator 1 having these constituent elements can suppress deterioration of spurious characteristics even if the sizes of the signal conductors 6a, 6b and 6c are increased. For example, if the electrode length dl is increased in order to increase the capacitance C of the electrode structure A, the spurious characteristics of the resonator 100 deteriorate. In order to increase the capacitance C of the electrode structure A while suppressing the deterioration of this spurious characteristic, the resonator 100 should have the electrode length dl set to a quarter wavelength or less, and the number of signal conductors in the electrode structure A, that is, the dielectric It was necessary to increase the number of layers of the body substrate 102 . Therefore, miniaturization is restricted. On the other hand, in the resonator 1, even if the length dl of the electrodes is increased, the spurious characteristics are less likely to deteriorate, and excellent spurious characteristics can be realized without increasing the number of layers of the dielectric substrate 3. .

Embodiment 2.
FIG. 8A is a plan view showing high-frequency filter 9 according to Embodiment 2. FIG. In order to make the positions of the resonators 1a-1e in the high-frequency filter 9 visible, FIG. 8A shows a partially transparent first ground conductor 2a. FIG. 8B is a cross-sectional arrow diagram showing a cross section of the high-frequency filter 9 taken along line CC of FIG. 8A. FIG. 9 is a plan view showing the structure of each layer of the high frequency filter 9. As shown in FIG. As shown in FIGS. 8B and 9, the high-frequency filter 9 includes a first ground conductor 2a, a second ground conductor 2b, a dielectric substrate 3, a resonator group 10, an input terminal 11a, an output terminal 11b, a first A connection portion 12a and a second connection portion 12b are provided.

The resonator group 10 consists of m resonators 1 . m is an integer of 2 or more. 8A, 8B and 9, the resonator group 10 consists of resonators 1a, 1b, 1c and 1e. Resonators 1a, 1b, 1c and 1e have the same structure as resonator 1 described in the first embodiment. That is, the resonators 1a, 1b, 1c and 1e have a common first ground conductor 2a, a common second ground conductor 2b, and common inner layer ground conductors 4a and 4b. Furthermore, the resonators 1a, 1b, 1c and 1e each have a strip conductor 5, signal conductors 6a, 6b and 6c, a first connection conductor 7a, a second connection conductor 7b and a third connection conductor 7c. In FIG. 9, the strip conductors 5 of the resonators 1a, 1b, 1c, and 1e are connected to the first short-circuit conductor 8 at the ends on the same side, and are comb-shaped in plan view. .

The resonators 1a, 1b, 1c and 1e are arranged side by side on a common dielectric substrate 3 as shown in FIG. 8A. Adjacent resonators in the row of these resonators are arranged close to each other so as to be electromagnetically coupled. That is, in the row of resonators 1a, 1b, 1c and 1e, two adjacent resonators are electromagnetically coupled to each other.

The input terminal 11a is a terminal to which a high frequency signal to the high frequency filter 9 is input, and the output terminal 11b is a terminal to which the high frequency signal from the high frequency filter 9 is output. The first connecting portion 12a electrically connects the strip conductor 5 of the resonator 1a arranged at the end of the row of the resonators 1a, 1b, 1c and 1e on the dielectric substrate 3 and the input terminal 11a. The second connection portion 12b is a strip conductor of the resonator 1e arranged at the end of the row of the resonators 1a, 1b, 1c and 1e opposite to the resonator 1a to which the first connection portion 12a is connected. 5 and the output terminal 11b are electrically connected.

The first short-circuit conductor 8 is provided in the inner layer of the dielectric substrate 3, and electrically connects and short-circuits the first ground conductor 2a, the second ground conductor 2b, the inner layer ground conductor 4a, and the inner layer ground conductor 4b. It is a via conductor. As shown in FIG. 8A, in the dielectric substrate 3, the plurality of first short-circuit conductors 8 are arranged so as to surround the resonator group 10 in plan view.

The high-frequency filter 9 has a function of filtering a high-frequency signal input to the input terminal 11a and outputting a target high-frequency signal from the output terminal 11b, thereby reflecting high-frequency signals other than the target signal to the input terminal 11a. . For example, when the high-frequency filter 9 is provided in communication equipment or radar equipment, an antenna, an active circuit and a passive circuit are connected to the input terminal 11a and the output terminal 11b. The high frequency filter 9 removes spurious frequency components generated in the active circuit, or removes frequency components other than the target signal received by the antenna.

In a resonator-directed band-pass filter in which a plurality of resonators are electromagnetically coupled, spurious characteristics are mainly spurious characteristics of the resonators themselves constituting the filter, or unintended noise generated inside the dielectric substrate 3. It is determined by the amount of coupling between the input terminal 11a and the output terminal 11b depending on the propagation path. If the amount of coupling between the input terminal 11a and the output terminal 11b is sufficiently small, the spurious characteristics of the high-frequency filter 9 are determined by the spurious characteristics of the single resonator.

FIG. 10 is a graph showing analysis results of amplitude characteristics of the high-frequency filter 9. FIG. In FIG. 10, the horizontal axis indicates the normalized frequency normalized by the center frequency of the high-frequency filter 9, and the vertical axis indicates the amplitude value (dB) of the pass amplitude. The pass amplitude is attenuated in a wide frequency band up to the first-order spurious resonance that occurs around the normalized frequency of 6.8.

FIG. 9 shows the high-frequency filter 9 in which the resonators 1a, 1b, 1c and 1e are arranged so that the ends of the strip conductor 5 connected to the first short-circuit conductor 8 are aligned in the same direction. This is an example. In the high-frequency filter according to the second embodiment, it is sufficient that the resonators are electrically connected to each other by electromagnetic field coupling.

FIG. 11A is a plan view showing a high frequency filter 9A that is a modification of the high frequency filter 9 according to the second embodiment. In order to make the positions of the resonators 1a to 1e in the high frequency filter 9A visible, FIG. 11A shows a partially transparent first ground conductor 2a. FIG. 11B is a cross-sectional arrow diagram showing a modified example of the high-frequency filter 9A taken along line DD of FIG. 11A. FIG. 12 is a plan view showing the structure of each layer of the high frequency filter 9A.

For example, on the seventh layer of the dielectric substrate 3 shown in FIG. It looks like a comb. Similarly, the strip conductors 5 of the resonators 1b and 1e are comb-shaped in plan view, with the ends on the same side connected to the first short-circuit conductors 8 . Further, the comb-shaped strip conductors 5 of the resonators 1a, 1c and 1d and the comb-shaped strip conductors 5 of the resonators 1b and 1e are connected to the first connection conductor 7a as shown in FIG. staggered ends. In the high-frequency filter 9A configured in this manner, the resonators are electrically connected to each other by electromagnetic field coupling.

As described above, the high-frequency filter 9 according to the second embodiment includes the first ground conductor 2a, the second ground conductor 2b, the dielectric substrate 3, the resonator group 10, the input terminal 11a, the output terminal 11b, the first connection portion 12a and a second connection portion 12b. Resonators 1a, 1b, 1c, and 1e forming resonator group 10 are arranged side by side on common dielectric substrate 3, and adjacent resonators are arranged close to each other so as to be electromagnetically coupled. The first connecting portion 12a electrically connects the strip conductor 5 of the resonator 1a arranged at the end of the row of the resonators 1a, 1b, 1c and 1e on the dielectric substrate 3 and the input terminal 11a. The second connection portion 12b is a strip conductor of the resonator 1e arranged at the end of the row of the resonators 1a, 1b, 1c and 1e opposite to the resonator 1a to which the first connection portion 12a is connected. 5 and the output terminal 11b are electrically connected. With these configurations, the high-frequency filter 9 can achieve excellent spurious characteristics.

Embodiment 3.
FIG. 13A is a plan view showing a high frequency filter 9B according to Embodiment 3. FIG. In order to make the positions of the resonators 1a to 1e in the high frequency filter 9B visible, FIG. 13A shows the first ground conductor 2a which is partially transparent. FIG. 13B is a cross-sectional arrow diagram showing a cross section of the high-frequency filter 9B taken along line EE of FIG. 13A. FIG. 14 is a plan view showing the structure of each layer of the high frequency filter 9B. As shown in FIGS. 13B and 14, the high-frequency filter 9B includes a first ground conductor 2a, a second ground conductor 2b, a dielectric substrate 3, a resonator group 10, an input terminal 11a, an output terminal 11b, a first A connection portion 12 a , a second connection portion 12 b and a plurality of second short-circuit conductors 13 are provided.

The resonator group 10 consists of m resonators 1 . 13A, 13B and 14, the resonator group 10 consists of resonators 1a, 1b, 1c and 1e. Resonators 1a, 1b, 1c and 1e have the same structure as resonator 1 described in the first embodiment. That is, the resonators 1a, 1b, 1c and 1e have a common first ground conductor 2a, a common second ground conductor 2b, a common inner layer ground conductor 4a and a common inner layer ground conductor 4b, and Each of the resonators 1a, 1b, 1c and 1e has a strip conductor 5, signal conductors 6a, 6b and 6c, a first connection conductor 7a, a second connection conductor 7b and a third connection conductor 7c, respectively.

The resonators 1a, 1b, 1c and 1e are arranged side by side on a common dielectric substrate 3 as shown in FIG. 13A. Adjacent resonators in the row of resonators are arranged close to each other so as to be electromagnetically coupled. That is, in the row of resonators 1a, 1b, 1c and 1e, two adjacent resonators are electromagnetically coupled with each other.

The input terminal 11a is a terminal for inputting a high frequency signal to the high frequency filter 9B, and the output terminal 11b is a terminal for outputting a high frequency signal from the high frequency filter 9B. The first connecting portion 12a electrically connects the resonator 1a arranged at one end of the row of the resonators 1a, 1b, 1c and 1e on the dielectric substrate 3 and the input terminal 11a. . The second connecting portion 12b electrically connects the resonator 1e arranged at the other end of the row of the resonators 1a, 1b, 1c and 1e to the output terminal 11b.

The first short-circuit conductor 8 is provided in the inner layer of the dielectric substrate 3, and electrically connects and short-circuits the first ground conductor 2a, the second ground conductor 2b, the inner layer ground conductor 4a, and the inner layer ground conductor 4b. It is a via conductor. As shown in FIG. 13A, in the dielectric substrate 3, the plurality of first short-circuit conductors 8 are arranged so as to surround the resonator group 10 in plan view.

13A, 13B and 14, the plurality of second short-circuit conductors 13 are second short-circuit conductors 13a, 13b, 13c and 13d. The second short-circuit conductors 13a, 13b, 13c, and 13d are arranged between resonators adjacent to each other in a plan view on the dielectric substrate 3, and the first ground conductor 2a, the second ground conductor 2b, the inner layer The ground conductors 4a and 4b are electrically connected to each other and short-circuited. For example, the second short-circuit conductor 13 is connected to the first ground conductor 2a and the second ground conductor 2b, and among the plurality of inner layer ground conductors 4, the inner layer ground conductors 4 between adjacent layers on the dielectric substrate 3 are connected to each other. short them by connecting to .

As described in the second embodiment, in a high-frequency filter, electromagnetic waves propagate from the input terminal to the output terminal in the dielectric substrate provided with resonators, which may degrade the spurious characteristics. This is because the dielectric substrate can be regarded as a dielectric medium whose sides are covered with metal, and electromagnetic waves propagate through this dielectric medium as a waveguide. Therefore, by short-circuiting the two surfaces of the waveguide, unwanted propagation of electromagnetic waves can be suppressed. For example, in a rectangular waveguide, an electromagnetic wave propagates at a frequency at which the long side of the section perpendicular to the propagation direction in the rectangular waveguide is equal to or greater than half the wavelength.

Therefore, the plurality of first short-circuit conductors 8 and the plurality of second short-circuit conductors 13 are arranged such that the shortest distance between any two short-circuit conductors on the dielectric substrate 3 is 2 at the highest frequency in the frequency band for designing spurious characteristics. It is placed at a position that is less than 1/1 effective wavelength. Preferably, the interval between the adjacent second short-circuit conductors 13 and the interval between the first short-circuit conductor 8 and the second short-circuit conductor 13 are 4 minutes at the highest frequency in the attenuation frequency band of the high-frequency filter 9B. is less than or equal to one effective wavelength of Note that this is an example. For example, in order to suppress unnecessary propagation of electromagnetic waves, it is desirable that the first short-circuit conductors 8 and the second short-circuit conductors 13 are arranged inside the dielectric substrate 3 at high density.

In the high-frequency filter 9B, the second short-circuit conductor 13 provided between the resonators suppresses unnecessary propagation of electromagnetic waves inside the dielectric substrate 3, so that the attenuation of the electromagnetic waves in the stopband can be improved. is possible.

FIG. 15 is a graph showing analysis results of the amplitude characteristics of the high frequency filter 9B, and also shows analysis results of the amplitude characteristics of the high frequency filter 9B for comparison with the amplitude characteristics of the high frequency filter 9B. In FIG. 15, the horizontal axis indicates the normalized frequency normalized by the center frequency of the high-frequency filter 9B, and the vertical axis indicates the amplitude value (dB) of the pass amplitude. The amplitude characteristic of the high-frequency filter 9 is the dashed-line curve labeled F1, and the amplitude characteristic of the high-frequency filter 9B is the solid-line curve labeled F2.

Compared with the amplitude characteristic of the high frequency filter 9, the amplitude characteristic of the high frequency filter 9B provides a greater amount of attenuation on the high frequency side of the passband. That is, by including the second short-circuit conductor 13, the high-frequency filter 9B can reduce unnecessary propagation of electromagnetic waves in the dielectric substrate 3, and can achieve better attenuation characteristics.

As described above, the high-frequency filter 9B according to the third embodiment is arranged between resonators adjacent to each other in a plan view on the dielectric substrate 3, and the first ground conductor 2a and the second ground conductor 2b, a second short-circuit conductor 13 for electrically connecting and short-circuiting the inner layer ground conductor 4a and the inner layer ground conductor 4b. By including the second short-circuit conductor 13 , the high-frequency filter 9</b>B can reduce unnecessary propagation of electromagnetic waves in the dielectric substrate 3 .

It should be noted that it is possible to combine the embodiments, modify arbitrary constituent elements of each embodiment, or omit arbitrary constituent elements from each embodiment.

The resonator according to the present disclosure can be used, for example, in high-frequency filters used in microwave bands or millimeter wave bands.

1, 1a to 1e resonator, 2a first ground conductor, 2b second ground conductor, 3 dielectric substrate, 4, 4a, 4b inner layer ground conductor, 5 strip conductor, 6, 6a, 6b, 6c signal conductor, 7a first connection conductor 7b second connection conductor 7c third connection conductor 8 first short-circuit conductor 9, 9A, 9B high-frequency filter 10 resonator group 11a input terminal 11b output terminal 12a first connection portion 12b second connection portion 13, 13a, 13b, 13c, 13d second short-circuit conductor 100 resonator 101a first ground conductor 101b second ground conductor 102 dielectric substrate , 103 inner layer ground conductor, 103a inner layer ground conductor, 103b inner layer ground conductor, 104 strip conductor, 105, 105a, 105b, 105c signal conductor, 106a first connection conductor, 106b second connection conductor, 107 first short-circuit conductor , 200 transmission line, 201 capacitor, 202 connection point.

Claims (4)

a dielectric substrate laminated with a dielectric;
a first ground conductor provided on the first surface of the dielectric substrate;
a second ground conductor provided on a second surface of the dielectric substrate opposite to the first surface;
a plurality of strip-shaped signal conductors arranged in a stacking direction so as to overlap each other in a plan view in the inner layer of the dielectric substrate;
one or more inner layer ground conductors arranged alternately with the signal conductor in the lamination direction in the inner layer of the dielectric substrate;
a strip conductor provided in the inner layer of the dielectric substrate;
a plurality of first short-circuit conductors provided in an inner layer of the dielectric substrate for electrically connecting and short-circuiting the first ground conductor, the second ground conductor, and the inner layer ground conductor;
a first connection conductor electrically connecting an end of the strip conductor opposite to the end to which the first short-circuiting conductor is connected and an end of the signal conductor;
a second connection conductor electrically connecting between the signal conductors at each end of the plurality of signal conductors;
a third connection conductor that electrically connects the signal conductors at each end of the plurality of signal conductors opposite to the end to which the second connection conductor is connected ;
The plurality of signal conductors have equal electrical lengths,
the electrical length of the signal conductor is smaller than the electrical length of the strip conductor;
The sum of the electrical lengths of the signal conductor and the strip conductor is equal to or less than 1/4 effective wavelength at the resonance frequency.
A resonator characterized by: a dielectric substrate laminated with a dielectric;
a first ground conductor provided on the first surface of the dielectric substrate;
a second ground conductor provided on a second surface of the dielectric substrate opposite to the first surface;
a plurality of strip-shaped signal conductors arranged in the lamination direction so as to overlap each other in a plan view in the inner layer of the dielectric substrate; a plurality of inner-layer ground conductors, strip-shaped strip conductors provided in the inner layer of the dielectric substrate, and the first ground conductor, the second ground conductor and the inner-layer ground conductor provided in the inner layer of the dielectric substrate; a plurality of first short-circuit conductors for electrically connecting and short-circuiting, electrically connecting an end of the strip conductor opposite to the end to which the first short-circuit conductors are connected and an end of the signal conductor; a first connection conductor for connecting, a second connection conductor for electrically connecting between the signal conductors at each end of the plurality of signal conductors, and the second connection conductor in the plurality of signal conductors for connection a plurality of resonators each having a third connection conductor electrically connecting between the signal conductors at each end opposite to the end where the resonator is connected;
an input terminal provided on the dielectric substrate to which a high-frequency signal is input;
an output terminal provided on the dielectric substrate for outputting a high frequency signal;
a first connection portion electrically connecting the input terminal and the resonator;
a second connection portion electrically connecting the output terminal and the resonator;
with
a plurality of the resonators arranged side by side on the dielectric substrate;
the first connecting portion electrically connects the strip conductor of the resonator arranged at the end of the array of the plurality of resonators on the dielectric substrate and the input terminal;
The second connection portion is arranged in the row of the plurality of resonators on the dielectric substrate at an end opposite to the resonator to which the first connection portion is connected. electrically connecting the strip conductor and the output terminal ;
The plurality of signal conductors have equal electrical lengths,
the electrical length of the signal conductor is smaller than the electrical length of the strip conductor;
The sum of the electrical lengths of the signal conductor and the strip conductor is equal to or less than 1/4 effective wavelength at the resonance frequency.
A high frequency filter characterized by: In the dielectric substrate, the first ground conductor, the second ground conductor, and the inner layer ground conductor are arranged between the resonators that are adjacent to each other in plan view, and are electrically connected to each other. 3. The high-frequency filter according to claim 2 , further comprising a second short-circuit conductor for short-circuiting. The distance between the adjacent second short-circuit conductors and the distance between the first short-circuit conductor and the second short-circuit conductor are 1/4 effective at the highest frequency in the attenuation frequency band of the high-frequency filter. 4. The high-frequency filter of claim 3 , wherein the wavelength is less than or equal to the wavelength.

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