EP2688137A1 - Hyperfrequency resonator with impedance jump, in particular for band-stop or band-pass hyperfrequency filters - Google Patents

Abstract

The resonator i.e. stepped impedance resonator (803) has a high characteristic impedance line comprising determined length, and a low characteristic impedance line (8033). The high characteristic impedance line has a line cut (8031A), and a first link wire (8031B) with determined length to ensure determined impedance at the line cut. The line cut is produced at one third of overall length of a resonator body from a side of an end of the high characteristic impedance line opposite to another end of the high characteristic impedance line situated on a side of low characteristic impedance line. An independent claim is also included for a method for producing a microwave resonator.

Description

The present invention relates to microwave impedance jump resonators. Such resonators may in particular be included in microwave filters, for example microwave filters of the rejection or notch type, or of the band-pass type.

Devices operating in so-called microwave frequency bands typically use microwave filters. Among the microwave filters, there are in particular rejector or "band-stop" type filters, the function of which is to reject signals whose frequency is within a determined frequency band, as well as so-called "bandpass filters". , allowing only signals whose frequency is within a certain frequency band.

• lorsque les filtres hyperfréquence présentent une ou plusieurs bandes de fréquences coupées à basse fréquence, situées dans une bande passante globale relativement large, ce premier cas étant illustré par la figure 1 décrite en détails ci-après ;
• lorsque les filtres hyperfréquence sont intégrés dans des structures de substrats multicouches, notamment dans le cas où les filtres sont intégrés dans un sous-système monolithique comprenant en outre un grand nombre d'éléments. Dans un tel cas, un filtre dont les performances se situent en dehors des spécifications souhaitées implique la mise au rebut du sous-système complet, et partant un rendement de fabrication réduit. Lorsqu'une pluralité de filtres hyperfréquences sont intégrés dans un même module, la réduction du rendement de fabrication est d'autant plus critique ;

• lorsque les filtres hyperfréquence comprennent des via. Un tel cas se présente particulièrement lorsque les filtres hyperfréquence comprennent des résonateurs dont une extrémité est court-circuitée vers une masse, ainsi que cela est le cas pour les filtres hyperfréquence faisant l'objet de la présente invention ;
• lorsque les filtres sont des filtres hyperfréquence compacts réalisés sur des substrats à forte permittivité et/ou perméabilité, particulièrement sensibles aux tolérances de réalisation et aux paramètres électriques tels que la permittivité et la perméabilité ;
• lorsque les filtres hyperfréquence sont utilisés dans des systèmes pour lesquels il est nécessaire d'effectuer un réglage du filtre dans son contexte applicatif ;
• lorsque les filtres hyperfréquence forment des multiplexeurs.

Microwave filters may include planar transmission lines and resonators formed by discrete components such as auto-inductors and capacitors. Microwave filters are constrained by the tolerances of the elements which constitute them, in particular the thickness of the substrate on which the transmission lines are made, the permittivity and the permeability of the substrate, as well as by the performance tolerances of the discrete components used. The variability of all the aforementioned parameters can lead to insufficient manufacturing yields or to overly random overall performance, more particularly in the following cases:

• when the microwave filters have one or more low-frequency cut-off frequency bands located in a relatively wide overall bandwidth, this first case being illustrated by the figure 1 described in detail below;
• when the microwave filters are integrated in structures of multilayer substrates, especially in the case where the filters are integrated in a monolithic subsystem further comprising a large number of elements. In such a case, a filter whose performance is outside the specifications desired involves the scrapping of the complete subsystem, and hence a reduced manufacturing efficiency. When a plurality of microwave filters are integrated in the same module, the reduction of the manufacturing efficiency is all the more critical;

• when the microwave filters include via. Such a case occurs particularly when the microwave filters include resonators whose one end is short-circuited to a ground, as is the case for the microwave filters subject of the present invention;
• when the filters are compact microwave filters made on substrates with high permittivity and / or permeability, particularly sensitive to production tolerances and electrical parameters such as permittivity and permeability;
• when the microwave filters are used in systems for which it is necessary to adjust the filter in its application context;
• when the microwave filters form multiplexers.

A major problem in the design of microwave filters occurs when the cut strips are located at relatively low frequencies with respect to the highest frequencies that the microwave filter has to pass, ie the frequency of high cutoff of the overall bandwidth of the filter. For what follows, the term "fundamental resonance frequency" denotes the first resonance frequency of a microwave resonator around which the cut strip is located in the case of a notch filter, or in a manner similar bandwidth in the case of a bandpass filter, the following resonant frequencies determining the overall bandwidth of the filter.

With the aim of producing a microwave filter, for example of the rejection type, having a narrow cut-off frequency band at a relatively low frequency, in a large overall bandwidth, it is possible, according to techniques known per se, to produce the filter microwaves by means of a so-called "mixed" technology, that is to say on the one hand with localized elements, typically capacitors and / or self-inductances, and secondly distributed elements: typically parallel lines coupled, as is illustrated by the figure 4 , described in detail below. The self-inductances and capacitors used may be "CMS" type components, the acronym designating the terms "Surface Mounted Component". The available CMS type self-inductors typically have resonant frequencies, quality coefficients, and insufficient tolerances. Also, to a lesser extent, CMS type capacitors typically have the same disadvantages. Self-inductors in the form of air coils offer better performance than their monolithic counterparts of the CMS type, but present problems related to a delicate implementation: that is to say a delicate transfer and placement , as well as performance problems related to micro-phonic phenomena, that is to say by which vibrations of the structure can cause a displacement of the turns of the coil, and thus the generation by it of signals parasites.

The performance of such mixed structures is further limited in the high frequency domain, in particular by the localized components. Furthermore, the tolerances of these components and their implementation introduce significant dispersions in the performance of the microwave filter. These dispersions limit their performance and can lead to insufficient production yields.

According to another technique known in itself, the microwave filters can be made without discrete localized elements such as self-inductance or SMD capacitors. According to this technique, the microwave filters may comprise so-called impedance jump resonators, commonly referred to by the acronym SIR corresponding to the English terminology "Stepped Impedance Resonator". Such resonators typically have resonance frequencies higher than the fundamental resonant frequency, different from multiples of this fundamental frequency. Such resonators are illustrated by the figure 7 , described in detail below.

A so-called "invariant" resonator, that is to say without characteristic impedance jump, consisting of a so-called "half-wave" line section, that is to say delimited by two short-circuits or by two open circuits, has a fundamental resonance frequency f0, and higher resonant frequencies equal to the multiples of the fundamental resonance frequency F0, ie 2F0, 3F0, etc., as illustrated by the figure 5 , described below.

An invariant type resonator consisting of a simple segment of a line called "quarter-wave", that is to say delimited by a short-circuit and an open circuit, has a first resonant frequency f0, and higher resonance frequencies equal to the odd multiples of the first resonance frequency F0, ie 3F0, 5F0, etc., as illustrated by the figure 6 , described below. Each of the higher resonant frequencies results in "replicas" of the fundamental response, i.e. bandwidths or parasitic cut bands, depending on the type of response of the filter.

An SIR resonator of the so-called "quarter-wave" type with two sections as illustrated by the figure 7 allows to discard the first resonance frequency f0 and the second resonance frequency denoted Fres2. The second resonant frequency is typically well above 3f0. The second resonant frequency is even higher than the characteristic impedance ratio of the two sections of the resonator is high.

However, the planar line technologies have achievable minimum and maximum characteristic impedance limits which limit the ratio between the second resonance frequency and the first resonance frequency Fres2 / FO, and therefore the bandwidth of the microwave filter, denoted BPG. .

In addition, SIR resonators are sensitive to manufacturing tolerances and tolerances of the materials used.

The present invention aims to overcome the aforementioned drawbacks by providing band-cut microwave filters comprising adjustment means for better control of their performance.

For this purpose, the subject of the invention is an impedance jump resonator, comprising at least one high impedance line of characteristic length and a low impedance line. characteristic, at least the characteristic high impedance line comprising a first line break, a first connection wire of a determined length ensuring a determined impedance at the first line break, said first line cut being substantially realized to the third the total length of the microwave resonator from the side of one end of the characteristic high impedance line opposite the end of the characteristic high impedance line on the side of the characteristic low impedance line.

In one embodiment of the invention, the microwave resonator may comprise a second line cutoff, a second connection wire of a determined second impedance providing an electrical connection for the passage of the signal on either side of the second line break.

In one embodiment of the invention, the second line cutoff can be located between a characteristic high impedance line and a characteristic low impedance line.

In one embodiment of the invention, the first line cut can be made substantially midway along the characteristic high impedance line.

In one embodiment of the invention, said at least one characteristic high-impedance line and a characteristic low-impedance line may be embodied as printed metal tracks on a substrate, in the form of plane-type line segments. ribbon or micro-ribbon.

In one embodiment of the invention, the characteristic low impedance line may be formed by a butterfly type stub.

In one embodiment of the invention, the characteristic low impedance line may be formed by a capacitor mounted on the surface of the substrate, a first armature of which is connected to said second connecting wire, and a second armature is connected to a second electrode. reference.

In one embodiment of the invention, the characteristic low impedance line, the characteristic high impedance line and the capacitor may be located on an upper face of the substrate, the reference electrode being a ground electrode located on a lower face of the substrate, said second armature of the capacitor being connected to the reference electrode by means of a via passing through the substrate.

In one embodiment of the invention, the microwave resonator can be made in a multilayer type structure made in the substrate, the capacitor being integrated into the multilayer structure.

The present invention also relates to a band rejection type microwave filter, characterized in that it comprises a transmission line, coupled to a plurality of microwave resonators according to any one of the embodiments described.

• une première étape de réalisation d'une structure comprenant ladite au moins une ligne de haute impédance caractéristique, ladite au moins une ligne de basse impédance caractéristique, et au moins une coupure de ligne,
• une deuxième étape de caractérisation des performances de la structure réalisée à la première étape,
• une troisième étape de réglage au cours de laquelle les spécifications d'au moins un fils de liaison sont définies en fonction des résultats de la caractérisation effectuée lors de la deuxième étape et en fonction des spécifications de performances du résonateur hyperfréquence escomptées,
• une étape de réalisation du câblage lors de laquelle est réalisé le câblage des fils de liaison suivant les spécifications définies à la troisième étape sur la structure réalisée à la première étape.

The present invention also relates to a method for producing a microwave resonator or a microwave filter according to any one of the embodiments described, characterized in that it comprises a sequence of at least the following steps:

• a first step of producing a structure comprising said at least one characteristic high impedance line, said at least one characteristic low impedance line, and at least one line cutoff,
• a second stage of characterization of the performances of the structure carried out at the first step,
• a third adjustment step during which the specifications of at least one bonding wire are defined according to the results of the characterization performed in the second step and according to the performance specifications of the expected microwave resonator,
• a step of performing the wiring in which is performed the wiring of the connecting son according to the specifications defined in the third step on the structure made in the first step.

The microwave filter structure proposed by the present invention uses SIR resonators in an advantageous manner. allowing both to optimize and expand the bandwidth, and to adjust in the production phase the cut band notch filter.

A microwave filter according to the embodiments of the present invention also has the advantage of being able to be achieved by conventional manufacturing means commonly used in the field of microelectronics, such as the laying of wires and / or conductor ribbons. unrolled length and position mastered. The response of the filter can be adjusted by varying the dimensions and attachment points of the wires and / or conductive ribbons.

This adjustment method is particularly suitable for high production volumes because it can be fully automated.

This adjustment method also makes it possible to adjust the response of the microwave filter as close to the need as possible, with very low residual dispersions linked to the materials and to the embodiment.

This adjustment method also makes it possible to adjust the filtering in situ, that is to say according to the characteristics of the environment of the microwave filter, or even according to several applications envisaged, several filtering functions being feasible from a same microwave filter structure.

Another advantage of the present invention is related to the fact that the response performance of a microwave filter according to the present invention can be adjusted after integration of the assembly, allowing in particular to release the tolerances and manufacturing constraints for a plurality of stages of realization of the microwave filter.

Another advantage of the present invention is that it makes it possible to obtain higher impedance ratios than on known impedance jump resonators, and thus to obtain optimized filter performance.

• la figure 1, une courbe caractérisant les performances typiques d'un filtre coupe-bande connu de l'état de la technique ;
• la figure 2, un schéma illustrant de manière simplifiée la structure d'un exemple de filtre coupe-bande à résonateurs de type quart d'onde connu de l'état de la technique ;
• la figure 3, un schéma illustrant de manière simplifiée la structure d'un premier exemple alternatif de filtre coupe-bande à résonateurs de type quart d'onde connu de l'état de la technique ;
• la figure 4, un schéma illustrant de manière simplifiée la structure d'un second exemple alternatif de filtre coupe-bande à résonateurs de type mixte connu de l'état de la technique ;
• la figure 5, une courbe caractérisant les performances typiques d'un filtre coupe-bande à résonateurs de type demi-onde connu de l'état de la technique ;
• la figure 6, une courbe caractérisant les performances typiques d'un filtre coupe-bande à résonateurs de type quart d'onde connu de l'état de la technique ;
• la figure 7, un schéma illustrant de manière simplifiée la structure d'un résonateur SIR de type quart d'onde, en elle-même connue de l'état de la technique ;
• la figure 8, un schéma illustrant la structure d'une cellule pour filtre hyperfréquence comprenant un résonateur selon un exemple de réalisation de la présente invention ;
• la figure 9, un schéma illustrant de manière simplifiée un filtre hyperfréquence comprenant une pluralité de cellules pour filtre hyperfréquence suivant un mode de réalisation alternatif de la présente invention ;
• la figure 10, un schéma illustrant la structure d'un filtre hyperfréquence coupe-bande comprenant une pluralité de résonateurs selon un exemple de réalisation de la présente invention ;
• la figure 11, des courbes caractérisant les performances d'un exemple de filtre hyperfréquence coupe-bande tel qu'illustré par la figure 10 ;
• la figure 12, un diagramme illustrant un procédé de réalisation d'un résonateur hyperfréquence, dans un exemple de réalisation de la présente invention.

Other features and advantages of the invention will appear on reading the description, given by way of example, with reference to the appended drawings which represent:

• the figure 1 a curve characterizing the typical performances of a notch filter known from the state of the art;
• the figure 2 a diagram schematically illustrating the structure of an exemplary quarter-wave resonator band-stop filter known from the state of the art;
• the figure 3 a diagram schematically illustrating the structure of a first alternative example of a quarter-wave resonator band-stop filter known from the state of the art;
• the figure 4 , a diagram illustrating in a simplified manner the structure of a second alternative example of mixed type resonator band-stop filter known from the state of the art;
• the figure 5 a curve characterizing the typical performances of a half-wave resonator band-stop filter known from the state of the art;
• the figure 6 , a curve characterizing the typical performance of a quarter-wave resonator band-stop filter known from the state of the art;
• the figure 7 , a diagram illustrating in a simplified manner the structure of a quarter-wave type SIR resonator, itself known from the state of the art;
• the figure 8 , a diagram illustrating the structure of a microwave filter cell comprising a resonator according to an exemplary embodiment of the present invention;
• the figure 9 a schematic diagram illustrating in a simplified manner a microwave filter comprising a plurality of microwave filter cells according to an alternative embodiment of the present invention;
• the figure 10 , a diagram illustrating the structure of a band-cut microwave filter comprising a plurality of resonators according to an exemplary embodiment of the present invention;
• the figure 11 , curves characterizing the performance of an example of a band-cut microwave filter as illustrated by FIG. figure 10 ;
• the figure 12 , a diagram illustrating a method for producing a microwave resonator, in an exemplary embodiment of the present invention.

The microwave filters which are the subject of the present invention may comprise parallel lines coupled with quarter-wave resonators as illustrated by the FIG. figures 2 and 3 . Compared with other notch filter technologies, such as surface acoustic wave filter technologies, commonly referred to as the SAW acronym for Surface Acoustic Wave, or volume acoustic wave, commonly referred to by the acronym BAW corresponding to the English terminology "Bulk Acoustic Wave", such microwave filters have the advantage of offering lower insertion losses, higher power outages and the possibility of operating at different frequencies. higher frequencies.

Compared to notch filters consisting of cavities or coaxial resonators, these filters have the advantage of offering a reduced size and weight.

The embodiments of the present invention described below are based on micro-ribbon type lines, conventionally made on a single substrate or integrated into a stack of substrates, for example in a tri-plate type technology. or made on a suspended substrate. It should be noted that the present invention applies similarly to other known embodiments.

It should also be observed that the exemplary embodiments described below applying to band-cut microwave filters can be transposed to bandpass microwave filters.

The figure 1 presents a curve characterizing the typical performances of a notch filter known from the state of the art.

The curve illustrated by the figure 1 is represented in a Cartesian frame whose ordinate axis carries the insertion losses, for example expressed in dB, and the abscissa axis carries the frequencies. The curve shown is characteristic of a notch filter whose cut strip is in the example illustrated a narrow band around a fundamental resonance frequency F0. The filter provides a first bandwidth BP1 comprising the frequencies below the fundamental resonance frequency F0, and a second bandwidth BP2 comprising the frequencies beyond the fundamental resonant frequency F0, and below a Fres2 resonance frequency. The frequencies below the resonance frequency Fres2 thus define a global bandwidth BPG of the filter. The frequency Fres2 is a parasitic resonance frequency, and it is desirable that it be as far as possible from the fundamental resonance frequency F0. It is thus one of the technical problems that the present invention proposes to solve, namely to maximize the second bandwidth BP2, the overall bandwidth BPG, and the ratio between the resonance frequency Fres2 and the fundamental resonant frequency F0, namely: Fres2 / F0.

The figure 2 is a schematic diagram illustrating in simplified manner the structure of an exemplary quarter-wave resonator band-stop filter known from the state of the art.

A notch filter 200 comprises a planar transmission line 201 comprising an input E and an output S, between which a microwave signal flows. A plurality of resonators 203, three in the example illustrated by the figure 2 , are arranged in parallel with the transmission line 201, thus coupled to the latter. Typically, the transmission line 201 may have an impedance of 50 Ohms.

The filter structure illustrated by the figure 2 is simplified: in particular, the resonators 203 are arranged linearly, in parallel with a straight transmission line. In practice, the transmission line 201 may be formed by a plurality of line sections, for example perpendicular to each other, and whose lengths are chosen so as to define the characteristics of the filter. Resonators are then arranged in parallel with certain line sections.

In the example illustrated by the figure, the resonators 203 are quarter-wave type resonators. A portion of the transmission line 201 coupled to a resonator may be designated a "cell" for a microwave filter. The characteristics of the different filter resonators are chosen to define the cut-off band of the filter, or in a similar manner the bandwidth when the filter is a band-pass filter. Resonators may for example have resonance frequencies equal to improve the rejection in a very thin band around this resonance frequency; resonators may have resonant frequencies slightly different so as to broaden the band of frequencies rejected, etc., according to configurations themselves known to those skilled in the art. The resonators 203 may be formed by line sections, one end of which is connected to a range, the range being connected to a via 2030 making it possible to establish a short circuit with a reference electrode, for example a ground electrode.

The transmission line 201 and the resonators 203 may be made by metallization on an upper face of a substrate 210, the ground electrode being for example made by a metallization on the underside of the substrate 210.

The figure 3 shows a diagram illustrating in a simplified manner the structure of a first alternative example of a quarter-wave resonator band-stop filter known from the state of the art.

In a similar way to the structure illustrated by the figure 2 described above, a microwave filter 300 may be formed by a transmission line 301 comprising an input E and an output S, and a plurality of resonators 303, three in the example illustrated by FIG. figure 3 , made on a substrate 310. Unlike the structure illustrated by the figure 2 the resonators 303 may be formed by spurs, commonly referred to as "spurlines", directly inserted into the transmission line 301.

The figure 4 presents a schematic diagram illustrating in a simplified manner the structure of a second alternative example of mixed-type resonator band-stop filter known from the state of the art.

A resonator is called a mixed type when it consists of a transmission line and localized elements. In a similar way to the structure illustrated by the figure 3 described above, a microwave filter 400 may be formed by a transmission line 401 comprising an input E and an output S, and a plurality of resonators 403, three in the example illustrated by FIG. figure 4 , made on a substrate 410. In the example illustrated by the figure 4 the resonators 403 may be formed by line sections arranged in parallel with the transmission line 401 and connected to the transmission line 401 via resonators formed by discrete components connected in series, typically a self-inductance L and a capacitor C.

The figure 5 presents a curve characterizing the typical performances of a half-wave resonator band-stop filter known from the state of the art.

In a similar way to the curve presented by the figure 1 previously described, the curve illustrated by the figure 5 is represented in a Cartesian frame whose ordinate axis carries the insertion losses, for example expressed in dB, and the abscissa axis carries the frequencies. The curve shown is characteristic of a notch filter whose cut strip is in the example illustrated a narrow band around a fundamental resonance frequency F0. As described above, such a microwave filter has a fundamental resonance frequency F0, and higher resonant frequencies equal to the multiples of the fundamental resonance frequency F0, ie 2F0, 3F0, 4F0, 5F0, and so on. Thus the resonance frequency Fres2 delimiting the overall bandwidth of the microwave filter is in the case of such a filter equal to 2F0.

The figure 6 presents a curve characterizing the typical performances of a quarter-wave resonator band-stop filter known from the state of the art.

In a similar way to the curve presented by the figure 5 described above, the curve illustrated by the figure 6 is represented in a Cartesian frame whose ordinate axis carries the insertion losses, for example expressed in dB, and the abscissa axis carries the frequencies. The curve shown is characteristic of a notch filter whose cut strip is in the example illustrated a narrow band around a fundamental resonance frequency F0. As described above, such a microwave filter has a fundamental resonant frequency F0, and higher resonance frequencies equal to the odd multiples of the fundamental resonance frequency F0, ie 3F0, 5F0, and so on. Thus, the resonance frequency Fres2 delimiting the overall bandwidth of the microwave filter is in the case of such an equal filter at 3F0. A microwave filter comprising quarter-wave resonators thus has advantageous performance with respect to a microwave filter comprising half-wave resonators, particularly in terms of overall bandwidth and Fres2 / F0 ratio.

The figure 7 presents a diagram illustrating in a simplified manner the structure of a quarter-wave type SIR resonator, itself known from the state of the art.

A two-section quarter-wave type SIR resonator 703 in the example illustrated by the figure typically comprises a high-impedance line section Zc1 of a determined length, directly connected to a low-impedance line section Zc2. . The high impedance line section may be connected to a ground electrode. More generally, an SIR resonator comprises a plurality of sections, that is to say at least one high impedance section and at least one low impedance section. For example, a half-wave type SIR resonator, not shown in the figures, comprises a first low-impedance section directly connected to a high impedance section at a first end of the latter, the second end of the latter being directly connected to a second low impedance section.

It is proposed according to the present invention, an advantageous structure of a resonator SIR as illustrated by the figure 7 .

The figure 8 shows a diagram illustrating the structure of a microwave filter cell comprising a resonator according to an exemplary embodiment of the present invention.

A cell 800 may be formed on a substrate 810, and comprises a transmission line 801 having an input E and an output S between which a microwave signal flows. The cell 800 also comprises a resonator SIR 803 according to an exemplary embodiment of the invention, coupled to the transmission line 801. A microwave filter can be formed by a cell 800 or by placing in series a plurality of cells 800. The SIR 803 resonator and the 801 transmission line can be made on a substrate 810, for example in the form of ribbon or micro-ribbon type planar transmission lines.

The resonator SIR 803 comprises, in the example illustrated by the figure 8 a characteristic high-impedance line 8031 of a given length, and a characteristic low-impedance line 8033.

The characteristic low impedance line 8033 may advantageously be formed by a so-called "stub" line section, for example a butterfly type stub, as in the example illustrated by the figure. Such a structure makes it possible in particular to obtain a low impedance in a relatively small bulk.

According to a specificity of the present invention, the high impedance line 8031 may comprise a first line break 8031A, typically an absence of metallization, separating the high impedance line 8031 into two non-electrically connected line sections. The resonator 803 further comprises a first link wire 8031B of a determined length providing a determined impedance at the first line break 8031A.

The location of the first line break 8031A may be chosen to coincide with the area of greatest current amplitude of the characteristic high impedance line 8031 at the first resonance frequency, i.e. substantially short-circuit side 8030 and with the lower current region at the second resonance frequency, in the presence of the first line break 8031A and the first wire 8031B.

For example, the first line break 8031A may be substantially mid-length of the characteristic high impedance line 8031.

The first line cut-off 8031A is made substantially at one-third of the total length of the microwave resonator 803, starting from the side of one end of the characteristic high-impedance line 8031 opposite the end of the characteristic high-impedance line 8031 located on the 8033. In particular, to obtain the widest possible bandwidth, above the cut band, a cut and a wire are introduced into the resonator at a position corresponding to a maximum of current, again called current belly, for the first resonance and at a minimum of current, also called current node, for the second resonance. This position corresponds to approximately 1/3 of the total length of the resonator from the 8030 short circuit.

Advantageously, the resonator 803 may comprise a second line break 8033A. In this case, the first line break 8031A may be shifted to the short circuit 8030 so as to locate the two line breaks 8031A, 8033A in the area which corresponds to the highest current amplitude at the first resonance frequency and at the lowest current amplitude at the second resonance frequency. Since in practice the maximum usable length for the wires is limited by reliability constraints, such as shock resistance, vibration, power, etc., constraints and realization constraints, such as the need for In a coupling, it may be advantageous to use a plurality of pairs of link wires / line breaks, for example two or three. It is observed that a second pair of line break / wire link provides more opportunities to optimize the structure and provides better results in impedance matching. As the case may be, the second line break 8033A may be located at the junction between the characteristic high impedance line 8031 and the characteristic low impedance line 8033. In a similar manner, a second link wire 8033B provides the link electrical signal for passing the signal between the characteristic high impedance line 8031 and the characteristic low impedance line 8033.

Advantageously, the resonator 803 may comprise a via providing an electrical connection between a range disposed at one end of the characteristic high impedance line, and a reference electrode located for example on the underside of the substrate 810.

The optimum dimensions of the high impedance 8031 and 8033 low impedance lines, 8031A, 8033A line breaks, and 8031B, 8033B link wires can be determined by design to meet the performance requirements of the filter.

An advantage provided by the 8031B, 8033B connection wires is related to the fact that they not only make it possible to optimize the response of the cell 800 comprising the resonator 803, but also to allow a production adjustment of the response characteristics of cell 800 in a relatively simple manner. It suffices, for example, to adapt the length of the first connection wire 8031B to adjust the impedance, for example, of the characteristic high-impedance line 8031 accordingly. This can be achieved during a process for producing a microwave filter, during a step provided for this purpose, this step being able to follow the steps of producing the various components of the filter, as described above. afterwards with reference to the figure 12 . One advantage provided by this embodiment is that it makes it possible to reduce the manufacturing tolerances for the production of the elements constituting the microwave filter. Another advantage is that it makes it possible to produce different microwave filters, having distinct performance characteristics, on a common hardware basis, the distinct performance characteristics that can be obtained from the common base by appropriate choices of the connecting wires.

The required level of rejection for a microwave filter comprising a plurality of cells 800 can be obtained by multiplying the number of cells 800 and adjusting their resonance frequencies appropriately. In a similar manner, a plurality of cut strips for a notch filter can be obtained by serializing a plurality of cells 800.

The figure 9 schematically illustrating a microwave filter comprising a plurality of microwave filter cells according to an alternative embodiment of the present invention.

A microwave filter 900 as shown in the example illustrated by the figure 9 may comprise a transmission line 901 comprising an input E and an output S, in parallel with which are disposed a plurality of resonators 903, related to the quarter-wave type and three in number in the example illustrated by the figure, coupled to the transmission line 901, all of which can be made on the upper surface of a substrate 910.

The resonators 903 are in this example similar to the resonators 803 included in the cell for microwave filter 800 described above with reference to the figure 8 with the exception that the high impedance lines formed by stubs in the embodiment illustrated by FIG. figure 8 can be replaced by capacitors 9033, for example discrete components of the CMS type. Moreover, each resonator 903 comprises, like the example illustrated by the figure 8 a high impedance line 9031 comprising a first line break 9031A, a first link wire 9031B ensuring the passage of the signal on either side of the first line break 9031A. Each capacitor 9033 may for example be arranged on a connection pad formed by a metallization surface, and comprise a first armature welded to a second wire 9033B, and a second armature connected for example by means of a via 9030 to a reference electrode, for example a mass formed on the underside of the substrate 910.

Advantageously, a multilayer structure may be formed by metallization surfaces on and in the substrate 910. Thus, the capacitors 9033 may comprise reinforcements formed by metallization surfaces opposite, located on different layers of the multilayer structure, one of the reinforcements can be formed on the surface of the substrate 910, and connected to the second wire 9033B.

Advantageously, it is possible, in all the examples of structures described above, to reinforce the coupling between the transmission line and the high-impedance line of the SIR resonators, for example by superimposing these lines in a multilayer structure, or by subdividing these lines and nesting them, like a structure of a coupler called Lange coupler.

A microwave filter structure may comprise a plurality of cells according to various embodiments described above.

The figure 10 shows a diagram illustrating the structure of a band-cut microwave filter comprising a plurality of resonators according to an exemplary embodiment of the present invention.

In the example illustrated by the figure 10 a microwave filter 1000 may comprise a plurality, six in the illustrated example, of resonators 1003 according to one of the embodiments described above, coupled to a transmission line 1001 comprising an input E and an output S, these elements being made on the surface of a substrate 1010. The transmission line 1001 may have a zigzag structure, that is to say comprising a plurality sections of line perpendicular to each other. The characteristic lengths and impedances of the different line segments can be adjusted according to the performance specifications of the microwave filter 1000. The scale is presented in figure 10 : the sections can typically have lengths of the order of 3 millimeters, and the large dimension of the entire structure of the microwave filter can be of the order of a centimeter: these are dimensions provided for non-limiting examples of the present invention.

The figure 11 presents curves characterizing the performances of an exemplary band-stop microwave filter as illustrated by the figure 10 .

With reference to the figure 11 a first curve 1101 represents the insertion losses of the microwave filter, for example expressed in dB, as a function of the frequency on the abscissa, and a second curve 1103 represents the adaptation of the microwave filter, for example expressed in dB, in frequency function.

As illustrated by the curves 1101 and 1103, such a microwave filter structure makes it possible to obtain a fundamental resonance frequency F0 of the order of 5 GHz, and a first Fres2 resonance frequency greater than 25 GHz. The fundamental resonance frequency F0 can be varied by adjusting the connecting wires included in the resonators. When a line cutoff / link wire pair coincides with a minimum of current amplitude at the second resonance frequency and a maximum of current amplitude at the first resonance frequency then the length of the bond wire allows adjustment the fundamental resonance frequency F0 with maximum efficiency and a very small modification of the first resonance frequency Fres2.

The figure 12 presents a diagram illustrating a method for producing a microwave resonator, in an exemplary embodiment of the present invention.

The realization of a microwave resonator according to one of the embodiments described above, and by extension of a cell for a microwave filter or a microwave filter structure, may comprise a first step 1201 for producing the main constituents, that is to say ie lines of high and low characteristic impedance, line breaks, transmission line, via and reference electrodes where appropriate. The first step 1201 may be carried out by realization techniques known per se, for example by metallizations on a substrate, for example by ribbon or micro-ribbon type technologies, possibly forming multilayer structures as described previously.

The first step 1201 may be followed by a second step 1203 for characterizing the performance of the structure of the microwave resonator or of the cell or filter thus obtained. Since this structure is not functional at the end of the first step 1201, since the connecting wires are not yet placed, the characterization of the performances can be carried out by means of a dimensional characterization.

The second step 1203 can then be followed by a third adjustment step 1205 during which the specifications of the bonding wires can be defined, according to the results of the characterization performed during the second step 1203 described above, and according to the expected performance specifications.

A step of making the wiring 1207 can then consist in making the final wiring of the microwave filter (s) with the optimal dimensions as determined in the previous steps.

Claims (11)

An impedance jump resonator (803) comprising at least one characteristic high-impedance line (8031) of a determined length and a characteristic low impedance line (8033), characterized in that at least the high impedance line feature (8031) includes a first line break (8031A), a first link wire (8031B) of a determined length providing a determined impedance at the first line break (8031A), said first line break (8031A). ) being substantially one-third of the total length of the microwave resonator (803) extending from one end of the characteristic high-impedance line (8031) opposite the end of the characteristic high-impedance line (8031) of the side of the characteristic low impedance line (8033). Microwave resonator (803) according to Claim 1, characterized in that it comprises a second line break (8033A), a second connection wire (8033B) of a second determined impedance providing an electrical connection for the passage of the signal of both sides of the second line break (8033A). Microwave resonator (803) according to claim 2, characterized in that the second line break (8033A) is located between a characteristic high impedance line (8031) and a characteristic low impedance line (8033). A microwave resonator (803) according to claim 1, characterized in that said first line break (8031A) is substantially mid-length of the characteristic high-impedance line (8031). Microwave resonator (803) according to one of the preceding claims, characterized in that said at least one characteristic high-impedance line (8031) and a characteristic low-impedance line (8033) are formed in the form of tracks. metal printed on a substrate (810), in the form of sections of ribbon or micro-ribbon type planar lines. Microwave resonator (803) according to Claim 5, characterized in that the characteristic low impedance line (8033) is formed by a butterfly type stub, also called a radial stub. Microwave resonator (803, 903) according to Claim 5, characterized in that the characteristic low impedance line (8033) is formed by a capacitor (9033) mounted on the surface of the substrate (810, 910), of which a first armature is connected said second connecting wire (8033B, 9033B), and a second armature is connected to a reference electrode. Microwave resonator (803, 903) according to Claim 7, characterized in that the characteristic low impedance line (8033), the characteristic high impedance line (8031, 9031) and the capacitor (9033) are located on an upper surface of the substrate (810, 910), the reference electrode being a ground electrode on a lower face of the substrate (810, 910), said second armature of the capacitor being connected to the reference electrode by means of a via ( 9030) passing through the substrate (810, 910). Microwave resonator (803, 903) according to Claim 8, characterized in that it is produced in a multilayer type structure made in the substrate (810, 910), the capacitor being integrated in the multilayer structure. Microwave frequency filter (200, 900, 1000) of the strip rejector type, characterized in that it comprises a transmission line (201, 901, 1001), coupled to a plurality of microwave resonators (203, 903, 1003) according to the any preceding claim. Process for producing a microwave resonator (803, 903) according to any one of the preceding claims, characterized in that it comprises a sequence of at least the following steps: A first step (1201) for producing a structure comprising said at least one characteristic high-impedance line (8031), said at least one characteristic low-impedance line (8033), and at least one line-out (8031A) , A second step (1203) for characterizing the performances of the structure carried out in the first step (1201), A third adjustment step (1205) during which the specifications of at least one bonding wire (8031B, 8033B) are defined according to the results of the characterization performed during the second step (1203) and according to the performance specifications of the microwave resonator (803, 903) expected, A step of carrying out the wiring (1207) during which the wiring of the connecting wires is carried out according to the specifications defined in the third step (1205) on the structure produced in the first step (1201).

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