Frequency tunable resonator

Abstract

The present application relates to a frequency tunable resonator (100) comprising a dielectric block (110) having a surface coated with a conductive layer (112). The frequency tunable resonator (100) further comprises a conductive tuning pattern (114) of the surface of the dielectric block (110), the conductive tuning pattern (114) being delimited by an opening (120) in the conductive layer (112). An electrically controllable switch (130) is used to electrically connect the conductive tuning pattern (114) to the conductive structure (112; 142). Thus, when the electrically controllable switch (130) is operated in a non-activated state, the frequency tunable resonator (100) will resonate at a first frequency (F1), and when the electrically controllable switch (130) is operated in an activated state, the frequency tunable resonator (100) will resonate at a second frequency (F2).

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to frequency tunable resonators, for example, frequency tunable resonators for filter applications in communication devices. BACKGROUND

[0002] Tunable radio frequency (RF) components are of great interest due to the increasing number of frequency bands that modern communication systems need to support and the demand for miniaturization, which leads to design constraints. Due to these requirements, multi-band and / or multi-standard systems are desirable features for any RF front-end component such as RF filters in communication devices.

[0003] The basic building block of an RF filter is a so-called resonator, which is configured to pass RF signals within a frequency passband while rejecting signals outside the passband. The resonant frequency of an RF resonator determines the filter passband, and by using multiple tunable resonators, a frequency tunable filter can be realized. A tunable filter can increase flexibility and support more frequency bands without significantly increasing size by using a single filter with tuning elements that can shift the filter frequency response to cover a larger range of frequency bands.

[0004] In order to perform well in a tunable filter, a tunable resonator needs to fulfill several desirable characteristics such as high-Q resonator (i.e., low power loss), low power consumption, wide tuning range, fast tuning speed, good linearity, high power handling, and small tuning element footprint (i.e., small size).

[0005] There are several conventional tuning filter schemes, but none of them can exhibit all of these desirable characteristics. This limits the use of tunable filters in practice. SUMMARY

[0006] It is an object of embodiments of the present application to provide a scheme to reduce or solve the drawbacks and problems of conventional schemes.

[0007] It is a further object of embodiments of the present application to provide a resonator scheme that is easy to produce and easy to implement in multiple filter applications.

[0008] The above and other objects are achieved by the subject matter claimed in the independent claims. Further embodiments of the present application are provided in the dependent claims.

[0009] According to an aspect of the present application, the above and other objects are achieved by a frequency tunable resonator, comprising:

[0010] a dielectric block comprising a surface coated with a conductive layer;

[0011] an input port for receiving an input signal;

[0012] an output port for outputting an output signal;

[0013] a resonator arranged within the dielectric block and electromagnetically connected to the input port and the output port, respectively;

[0014] at least one dielectric opening in the electrically conductive layer, the dielectric openings defining an electrically conductive tuning pattern at the surface of the dielectric block;

[0015] at least one electrically controllable switch for electrically conductively connecting the electrically conductive tuning pattern to an electrically conductive structure when operating in an active state; the frequency tunable resonator is configured to:

[0016] resonate at a first frequency when the electrically controllable switch is operating in an inactive state;

[0017] resonate at a second frequency when the electrically controllable switch is operating in an active state.

[0018] The electrically controllable switch being in an active state can be understood as the electrically controllable switch being electrically conductive, i.e. an electrical signal can pass through the switch. This is in contrast to the electrically controllable switch being in an inactive state, in which case an electrical signal cannot pass through the switch. The electrically controllable switch can be any type of switch having suitable properties.

[0019] An advantage of the frequency tunable resonator according to the first aspect is that the frequency tunable resonator can be used as a building block in any type of filter to achieve tunable properties. Furthermore, the present frequency tunable resonator also provides a very small form factor, space-occupying system that can be easily implemented on any substrate using existing methods of making dielectric opening slots in electrically conductive layers. Furthermore, the tuning structure disclosed herein can be easily applied to any currently or previously designed filter without significant modification of topology or resonator placement. Any type of controllable switch can be used, enabling the resonator to be configured with switch types according to performance requirements. The frequency tunable resonator according to the first aspect is easily modified according to specifications, e.g. frequency tuning range, and switches are interchangeable according to priority of reduced insertion loss or increased switch speed.

[0020] In one implementation of the frequency tunable resonator according to the aspect of the present application, the electrically conductive tuning pattern comprises a first electrically conductive part connected to a second electrically conductive part by at least one additional electrically controllable switch.

[0021] An advantage of this implementation is that by adding additional controllable switches, the number of tuning states is increased, where the number of achievable tuning states is 2 nwhere n is the number of switches in a particular configuration.

[0022] In one implementation of the frequency tunable resonator according to the aspect of the application, the second conductive portion is circumferentially arranged around the first conductive portion.

[0023] This implementation has the advantage that small incremental tuning steps can be achieved without significantly increasing the footprint of the tuning element.

[0024] In one implementation of the frequency tunable resonator according to the aspect of the application, the conductive tuning pattern comprises a single conductive portion.

[0025] This implementation has the advantage that a very simple configuration can be provided for low cost applications.

[0026] In one implementation of the frequency tunable resonator according to the aspect of the application, the conductive tuning pattern is arranged coaxially with respect to the resonator in the dielectric block.

[0027] This implementation has the advantage that the tunability of the resonator is improved since the tuning pattern is arranged at a point of strongest electromagnetic field.

[0028] In one implementation of the frequency tunable resonator according to the aspect of the application, the resonator is a resonant cavity comprising an opening extending inwardly from the surface of the dielectric block.

[0029] In one implementation of the frequency tunable resonator according to the aspect of the application, the opening of the resonant cavity and the conductive tuning pattern are arranged on opposite surfaces of the dielectric block.

[0030] This implementation has the advantage that the tunability of the resonator is improved since the tuning pattern is arranged at a point of strongest electromagnetic field.

[0031] In one implementation of the frequency tunable resonator according to the aspect of the application, the dielectric block has a cuboid or rectangular cuboid shape.

[0032] In one implementation of the frequency tunable resonator according to the aspect of the application, the electrically controllable switch is a semiconductor, a variable capacitance or a variable inductance.

[0033] This implementation has the advantage that a large number of different components can be used in this regard, thereby providing a wider selection of designs.

[0034] In one implementation of the frequency tunable resonator according to the aspect of the application, the electrically controllable switch is mounted at the dielectric block.

[0035] The advantage of this implementation is that by mounting the electrically controllable switch at the dielectric block, the space occupation can be greatly reduced.

[0036] In one implementation of the frequency tunable resonator according to the aspect of the application, the electrically conductive layer is the electrically conductive structure.

[0037] The advantage of this implementation is that the controllable switch can be connected to the electrically conductive ground without the need of additional structures or components.

[0038] In one implementation of the frequency tunable resonator according to the aspect of the application, the frequency tunable resonator comprises a dielectric layer arranged at the dielectric block, and the electrically controllable switch is mounted at the dielectric layer.

[0039] The advantage of this implementation is that by moving the switch reference plane and mounting position to an external dielectric layer / substrate, the controllable switch and the feed network can be designed without being limited by the size of the resonator.

[0040] In one implementation of the frequency tunable resonator according to the aspect of the application, the electrically controllable switch is connected to the electrically conductive tuning pattern through an electrically conductive interface.

[0041] The advantage of this implementation is that by moving the switch reference plane and mounting position to an external dielectric layer / substrate, the controllable switch and the feed network can be designed without being limited by the size of the resonator.

[0042] In one implementation of the frequency tunable resonator according to the aspect of the application, the electrically conductive structure is arranged at or connected to the dielectric layer.

[0043] The advantage of this implementation is that by moving the switch reference plane and mounting position to an external dielectric layer / substrate, the controllable switch and the feed network can be designed without being limited by the size of the resonator.

[0044] In one implementation of the frequency tunable resonator according to the aspect of the application, the frequency tunable resonator comprises at least one second resonator, at least one second electrically conductive tuning pattern and at least one second controllable switch; and the resonator and the second resonator are electromagnetically coupled to each other.

[0045] The advantage of this implementation is that multiple resonators can be connected in cascade or arbitrarily arranged to form a tunable radio frequency filter.

[0046] In one implementation of the frequency tunable resonator according to the aspect of the application, the frequency tunable resonator comprises at least one inner cavity coated with a conductive layer and forming a wall portion extending inside the dielectric block and at least partially between the resonator and the second resonator.

[0047] This implementation has the advantage of breaking the symmetry of the radio frequency, thus allowing the design of a tunable radio frequency filter.

[0048] Other applications and advantages of embodiments of the application will be apparent from the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0049] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application.

[0050] Figure 1 A frequency tunable resonator according to embodiments of the application is shown;

[0051] Figure 2 A conductive tuning pattern according to embodiments of the application is shown;

[0052] Figure 3 A conductive tuning pattern according to further embodiments of the application is shown;

[0053] Figure 4 A design geometry of a frequency tunable resonator according to embodiments of the application is shown;

[0054] Figure 5 A design geometry of a frequency tunable resonator according to further embodiments of the application is shown;

[0055] Figure 6 and Figure 7 A frequency tunable resonator comprising a dielectric layer according to embodiments of the application is shown in top view and perspective view, respectively;

[0056] Figure 8 An exemplary topology of a frequency tunable resonator comprising a plurality of resonators is shown;

[0057] Figure 9 A frequency tunable resonator comprising a plurality of resonators according to embodiments of the application is shown;

[0058] Figure 10 Performance results of a frequency tunable filter 100 according to embodiments of the application are shown. DETAILED DESCRIPTION

[0059] The main difference between a single-band filter and a tunable filter is the addition of tuning elements in the tunable filter. Depending on the tuning scheme, this will have a significant impact on the overall system performance of the filter. In particular, the quality (Q) factor value of the tunable filter is lower, which is a consequence related to the losses in the resonator due to the addition of the tuning elements. Thus, the performance of a high Q factor resonator can be severely degraded by the addition of tuning elements. Therefore, it is desirable that the tuning elements have a small impact on the resonator Q factor.

[0060] Furthermore, while the tuning of cavity filters is a well-explored field, the tuning of ceramic block filters has not been explored as much. The ceramic block filter limits the selection of tuning elements due to its solid structure by itself. Most tunable filters have an air cavity into which the tuning elements can be simply inserted. This is naturally not possible in a ceramic block filter, and thus some traditional tuning approaches are not physically feasible.

[0061] Therefore, embodiments of the present application explore a new scheme for tuning a ceramic block resonator that achieves a good trade-off between the desired requirements for a tunable filter through a new type of tunable resonator structure. Among other things, a miniaturized tunable filter can thus be achieved. In a ceramic block filter, previous tunable schemes were based on mechanical tuning with low tuning speed or varactor diodes with low Q factor. The scheme presented herein instead utilizes controllable switches, without the need for low Q factor varactor diodes, while still providing a fast response time. Furthermore, the present frequency tunable resonator can be optimized in terms of losses and tuning speed based on component selection.

[0062] Figure 1 A top view of a frequency tunable resonator 100 according to embodiments of the present application is shown. The frequency tunable resonator 100 comprises a solid dielectric block 110, e.g. a high Q ceramic with a large relative permittivity, which in turn comprises a surface coated with a conductive layer 112. The frequency tunable resonator 100 further comprises an input port 102 for receiving an input signal S In and an output port 104 for outputting an output signal S Out . The output signal S Out is a processed input signal S In . The input signal S In and the output signal S Out may comprise high frequency signals, e.g. RF signals, and such RF signals can be used as communication signals in different types of communication systems.

[0063] The frequency tunable resonator 100 further comprises a resonator 106 (shown with dashed lines) arranged inside the dielectric block 110 and electromagnetically connected to the input port 102 and the output port 104, respectively. As Figure 1As shown, the resonator 106 can be a resonant cavity filled with air. However, the resonator 106 as used herein does not have to be a resonant cavity. For example, in other examples, the resonator 106 can refer to the dielectric block itself without additional structures, and other propagation modes than the fundamental mode can be utilized.

[0064] The frequency tunable resonator 100 further comprises at least one dielectric opening 120 in the electrically conductive layer 112, which dielectric opening bounds the electrically conductive tuning pattern 114 at a surface of the dielectric block 110. The frequency tunable resonator 100 further comprises at least one electrically controllable switch 130, 130’ for electrically conductively connecting the electrically conductive tuning pattern 114 to the electrically conductive structure 112 when operating in an active state. Thus, the frequency tunable resonator 100 is configured to resonate at a first frequency Fi when the electrically controllable switch 130 is operating in an inactive state, and to resonate at a second frequency F2when the electrically controllable switch 130 is operating in an active state. The first frequency Fi and the second frequency F2are different, thus providing a tunable resonator.

[0065] The dielectric block 110 can be molded or produced in any other suitable way. The dielectric block 110 can be a ceramic dielectric block wrapped in an electrically conductive coating, such as a silver or copper coating. However, any other dielectric substrate and conductor can be used as the dielectric block with the same effect. The dielectric block 110 is designed to resonate at one or more design frequencies as desired. The dielectric block 110 can have any shape and any internal structure without affecting the basic functionality of the resonator solution disclosed herein.

[0066] In embodiments of the present application, the electrically conductive layer 112 is the electrically conductive structure itself. This means that in this case, the electrically conductive layer 112 acts as a ground for the resonator 100 and is interrupted by the dielectric openings 120 in the electrically conductive layer 112. By introducing a direct ceramic-dielectric interface in the form of the dielectric openings 120 in the electrically conductive layer 112, the electrical properties of the resonator 100 change with perturbations of the internal electric field. The dielectric openings 120 in the electrically conductive layer 112 form and define the electrically conductive tuning pattern 114, where a point on the electrically conductive layer 112 is separated from another point on the electrically conductive layer 112 by a dielectric opening in the electrically conductive ground. Both points can still be connected to the electrically conductive layer 112 and the ground plane of the resonator 100. By this separation, the surface currents have to use a different path through the electrically conductive layer 112 to connect the two points. One or more of these points can be electrically connected to an electrically conductive ground that is not part of the conductor housing. This electrically conductive ground can be mounted on the dielectric substrate, which in turn can be connected to one or more controllable switches 130. Thus, a new electrical path is introduced for the electromagnetic coupling between the surface currents on the electrically conductive layer 112 and the internal electric field of the resonator 100. The electrical path can be connected to a common ground that is separated by the controllable switches 130.Figure 6 and Figure 7 Embodiments using a dielectric substrate are described.

[0067] The introduction of an alternative electrical path from the conductive layer 112 to the external tuning element enables the capacitance seen by the resonator 100 to be changed by selecting the controllable switch 130 and the conductive tuning pattern 114. The change in capacitance is a perturbation effect on the internal electric field. Thus, the resonant frequency of the resonator 100 can be changed in a predictable and controllable manner by changing the characteristics of the external conductor path, for example, by changing the resonant frequency of the resonator 100 by closing or opening one or more controllable switches 130 connecting the external conductor to the ground plane.

[0068] Another advantage of the present resonator structure compared to conventional solutions is that a fast switching speed tuning network can be achieved using conventional off-the-shelf RF controllable switches. By tuning with controllable switches instead of capacitor banks or variable capacitors, the negative effects of the tuning elements are reduced, especially in the off state of the controllable switches, i.e. when the controllable switches are not conductive. Thus, embodiments of the present application comprise controllable switches 130, and the basic functionality of the frequency tunable resonator 100 does not change with the selection of the controllable switches. Thus, the electrically controllable switches 130 can be any suitable controllable switch known in the art. For example, a semiconductor, a variable capacitance or a variable inductance.

[0069] In embodiments of the present application, and also disclosed in Figure 1 Electrically controllable switches 130 can be mounted directly at the dielectric block 110. However, in other proposed embodiments, the electrically controllable switches 130 can be provided at a dielectric layer separate from the dielectric block 110, which will be referred to in the disclosure below with reference to Figure 6 and Figure 7 detailed description.

[0070] Figure 2 A top view of a conductive tuning pattern 118 according to embodiments of the present application is shown. In the disclosed example, the conductive tuning pattern 118 comprises a single conductive portion 118. A controllable switch 130 is provided in a portion between the single conductive portion 118 and the surrounding conductive layer 112, which portion can be referred to in the following as a bridging portion due to the fact that it bridges the conductive portion 118 to the surrounding conductive layer 112. The single conductive portion 118 is delimited or defined by an opening 120 in the conductive layer 112. The controllable switch 130 can operate in an active state, i.e. conductive, or in an inactive state, i.e. non-conductive. Depending on whether a surface current can pass through the controllable switch 130 or not, the frequency passband of the resonator 100 will change, thus providing a tunable resonator functionality as described above.

[0071] Figure 3A conductive tuning pattern 114 according to another embodiment of this application is shown, which instead includes a plurality of conductive portions. In this example, the conductive tuning pattern 114 includes a first conductive portion 118 connected to a second conductive portion 118' via at least one additional electrically controllable switch 130. Figure 3 The example includes four controllable switches 130, two of which connect a first conductive portion 118 to a second conductive portion 118', while the other two controllable switches 130 connect the second conductive portion 118' to the surrounding conductive layer 112 via bridging portions. Alternatively... Figure 3 As shown, the second conductive portion 118' can be arranged circumferentially around the first conductive portion 118 so that the surface of the dielectric block 110 completely surrounds the first conductive portion 118.

[0072] However, it can be recognized that this conductive tuning pattern 114 can include any number of conductive portions 118 connected via one or more electrically controllable switches in the bridging portion to achieve suitable frequency tuning characteristics. Therefore, a large number of different frequency configurations can be provided depending on the number of conductive portions 118, the shape of the conductive portions 118, the interconnection structure, the number of controllable switches 130, the position of the controllable switches 130, etc. Thus, an unlimited number of different frequency passbands F1, F2, up to Fn can be configured using this scheme.

[0073] also, Figure 4 A perspective view showing the geometry of a frequency-tunable resonator 100 according to an embodiment of this application is provided. On the other hand, Figure 5 It shows the relationship with Figure 4 The resonator shown is compared to the frequency-tunable resonator 100, which has a slightly different geometry. In these examples, the controllable switch 130 is directly surface-mounted on the dielectric block 110. Even though the two bridging portions are directly connected to ground, the controllable switch 130 introduces a shift in the resonant frequency. This means that any arbitrary shape is possible as long as at least one controllable switch 130 as a tuning element and a conductive tuning pattern 114 are present.

[0074] exist Figure 4 In this configuration, conductive pattern 114 includes an inner conductive portion surrounded by an outer conductive portion. The inner and outer conductive portions are defined by an opening in conductive layer 112 and connected to each other via two controllable switches 130, allowing surface current to flow in two different ways depending on the states of the two controllable switches. An additional structure includes an opening 120 in conductive layer 112, exposing the internal electromagnetic field at the interface between dielectric block 110 and surrounding air. The opening 120 in conductive layer 112 can be obtained through any milling process or manually. A bridging portion connecting the intermediate conductive portion to ground is also shown, illustrating the principle of connecting two separate points on the conductive layer.Figure 4 and Figure 5 It can be clear that the electrical path changes with the opening or closing of the controllable switches 130. In Figure 5 the conductive pattern 114 comprises a single conductive portion, which is also delimited with respect to the surrounding conductive layer 112 by the opening 120 in the conductive layer. The single conductive portion is connected with the surrounding conductive layer 112 by four bridge portions. Two controllable switches 130 are provided at two bridge portions.

[0075] In Figure 4 and Figure 5 the two examples shown, the conductive tuning pattern 114 is provided coaxially with respect to the resonant cavity 106 in the dielectric block 110. This can be understood as that both the conductive tuning pattern 114 and the resonant cavity 106 are symmetrically provided around an axis A extending through the dielectric block 110. This axis can be defined as a central axis as shown in the examples, but in not shown examples, the axis can be misaligned or offset from the center of the dielectric block 110.

[0076] Furthermore, a common point for the two examples disclosed in Figure 4 and Figure 5 is that the resonant cavity 106 comprises an opening 108 extending inwardly from a surface of the dielectric block 110. It can also be noted that the opening 108 of the resonant cavity 106 and the conductive tuning pattern 114 are provided on opposite surfaces of the dielectric block 110. The interior of the resonant cavity 106 is coated with a conductive layer to provide suitable conductive properties. In Figure 4 and Figure 5 the examples disclosed in and

[0077] the dielectric block 110 has a basic cuboid or rectangular cuboid shape. However, the general shape of the dielectric block 110 can vary depending on the application. The same applies to the shape of the resonant cavity 106. Figure 6 Figure 7 Figure 6 and Figure 7 respectively in a top view (Fig. 1) and a perspective view (Fig. 2).) shows a frequency tunable resonator 100 comprising an additional dielectric layer 140 according to embodiments of the present application. The frequency tunable resonator 100 comprises a dielectric layer 140 arranged at the dielectric block 110. The dielectric layer 140 can be a so-called PCB layer or any other suitable dielectric layer. The dielectric layer 140 can comprise a conductor. The separate dielectric layer 140 can be attached to the dielectric block 110 using soldering, adhesive or any other suitable attachment technique. In these examples, the electrically controllable switch 130 is mounted at the dielectric layer 140 instead of being mounted directly at the dielectric block 110 as shown before. The controllable switch 130 can be attached to either side of the dielectric layer 140, i.e. on the surface of the dielectric layer 140 facing towards the dielectric block 110 or on the surface of the dielectric layer 140 pointing in the opposite direction away from the dielectric block 110.

[0078] Furthermore, a conductive structure 142 can be arranged at or connected to the dielectric layer 140. Furthermore, the electrically controllable switch 130 can be connected to the conductive tuning pattern 114 through a conductive interface 144, again as shown in Figure 6 and Figure 7 By overlapping the conductor to connect the dielectric layer 140 and the conductive tuning pattern 114 enables to control the frequency of the resonator 100 through the controllable switch 130.

[0079] Using the dielectric layer 140, the direct connection of the controllable switch 130 to the resonator ground can be removed. It is additionally disclosed to achieve a reference plane shift of the controllable switch 130 by connecting the dielectric layer 140 to the tuning pattern. The controllable switch 130 will act as an on-off connection between the ground of the dielectric layer 140 and the conductive tuning pattern 114. The ground of the dielectric layer 140 is stacked on top of the resonator ground. The input port 102 and the output port 104 are also shown in Figure 6 and Figure 7 .

[0080] In Figure 6 and Figure 7The configuration disclosed in the middle enables a very flexible placement of the controllable switch 130. By moving the tuning elements away from the surface mount setup on top of the conductive filter coating, an easier installation process and a more flexible resonator design can be achieved. Furthermore, a signal feed network (not shown) can be easily implemented in the resonator 100, as the use of the dielectric layer 140 removes the spatial constraints of a directly mounted controllable switch. The signal feed network is used to turn on / off or activate / deactivate the controllable switch 130, but can also be used to feed and / or bias the controllable switch 130. However, the shift in the reference plane of the controllable switch 130 introduces a small insertion loss compared to when the controllable switch 130 is directly mounted on the dielectric block 110. On the other hand, the configuration with the dielectric layer 140 enables the selection of components without the strict size and spatial constraints of the resonator 100 including the dielectric layer 140. Thus, the optimization of the resonator 100 by selection of the controllable switch can be simplified. Furthermore, when the dielectric-air interface is replaced by a dielectric-dielectric interface, a shift in the center frequency is introduced and can be re-optimized to shift the center frequency back. It is also possible to increase the tuning range of the resonator 100 by introducing the dielectric layer 140, as the range of switch selection is wider, but also by changing the tuning pattern.

[0081] Figure 8 A system topology of a frequency tunable resonator 100 comprising multiple resonant cavities connected to each other is shown, where (a) shows a 5-pole straight inline filter structure and (b) shows a 6-pole filter structure with a triplet section creating transmission zeros. The different resonant cavities are shown as circles, numbered 1 to 5 in (a) or 1 to 6 in (b), and are arranged between the input port 102 and the output port 104 of the frequency tunable resonator 100. The electromagnetic coupling between the resonant cavities is indicated with lines connecting the circles. The 5-pole straight inline structure shows a very simple setup with symmetric tuning elements. On the other hand, the 6-pole shows a system topology where the resonant cavities can be geometrically shifted with respect to a straight line or row. Both examples can be implemented with a dielectric layer 140 as discussed above.

[0082] Typically, a frequency-tunable resonator 100 for multi-resonator applications includes at least one second resonator 106', at least one second conductive tuning pattern 114', and at least one second controllable switch 130'. The resonators 106 and 106' are electromagnetically coupled to each other. Therefore, the frequency-tunable resonator 100 can be realized by cascading any number of resonant cavities in any configuration through electromagnetic coupling between the resonators. The design methodology for manufacturing the multi-resonator is no different from that of conventionally synthesized and designed filters, as the basic ceramic filter can be designed to incorporate a tuning element, i.e., the controllable switch 130, in the final manufacturing step. Therefore, adding the controllable switch 130 to existing ceramic block filter designs is readily achievable. Tuning the on and off positions of the switch can be simplified by selecting certain symmetries.

[0083] Figure 9 As shown Figure 8 (b) shows a system architecture for a frequency-tunable resonator 100 comprising multiple resonators. The frequency-tunable resonator 100 includes six interconnected resonant cavities disposed between an input port 102 and an output port 104 of the resonator 100. In this particular example, resonant cavities 106, 106' are disposed within a single dielectric block. To achieve electromagnetic coupling between the different resonant cavities, the frequency-tunable resonator 100 may also include at least one inner cavity 160 coated with a conductive layer and forming a wall portion extending within the dielectric block 110. Such a wall portion helps guide electromagnetic coupling between the resonant cavities of the multi-cavity resonator 100, especially when the cavity layout is not in a straight line or row arrangement. The tuning range of the resonator 106 can be adjusted by modifying the size and shape of the conductive tuning pattern 114. Each subsequent conductive tuning pattern 114' can be modified individually to obtain the desired tuning range for each corresponding resonator 106'.

[0084] In this configuration, each resonator 106 has two controllable switches 130. However, without departing from the scope of this application, any number of controllable switches 130 may be used. For example, the controllable switches 130 can be electrically controlled by sending control signals and / or bias currents through a signal feed network to change the state of the controllable switches. For example, the signal feed network may include a microcontroller or central processing unit (CPU), control lines, etc. Furthermore, in other configurations, this frequency-tunable resonator 100 may include a conductive tuning pattern 114 that interacts with multiple resonators, etc.

[0085] Figure 10 The simulated response of a ceramic passband filter including a resonator according to an embodiment of this application is shown, wherein, for example, Figure 9The same filter structure is shown, with the center frequency specified to be 3.5 GHz, and a bandwidth of 200 MHz (active state), with a second passband at 3.4 GHz (inactive state). The x-axis shows frequency in GHz, and the y-axis shows the scattering parameter in dB. The upper passband shows the filter characteristics in the active switch state, while the lower passband shows the response of the filter in the inactive switch state, illustrating the principle of a tunable filter made up of multiple tunable resonators 100. The increased part of the low passband mismatch is partly due to the fact that the absolute bandwidth is kept constant over the tuning range.

[0086] The frequency tunable resonator 100 can be implemented and used in many different applications. Non-limiting examples are in communication devices and communication equipment configured for different communication systems, such as 3GPP 5G, WiFi, etc. For example, the communication devices and communication equipment can be part of a network access node or a client device.

[0087] A client device herein can be denoted a user device, user equipment, UE, an internet of things, IoT, device, a sensor device, a wireless terminal and / or a mobile terminal, enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UE can further be a wireless-enabled mobile phone, cell phone, a tablet or a laptop, for example. A UE in the present context can be, for example, a portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and / or data, with another entity, like another receiver or a server, through a radio access network, RAN. The UE can also be a station, STA, i.e. any device that comprises a medium access control, MAC, and physical layer, PHY, interface to the wireless medium, WM, in compliance with IEEE 802.11. The UE can be used for communication in 3GPP related long term evolution, LTE, LTE-Advanced, fifth generation, 5G, wireless systems, e.g. new radio, NR, and evolution thereof, as well as IEEE related Wi-Fi, worldwide interoperability for microwave access, WiMAX, and evolution thereof.

[0088] The network access node herein can also be denoted a radio network access node, an access network access node, an access point (AP), or a base station (BS), e.g., a radio base station (RBS), which in some networks can be referred to as transmitter, "gNB", "gNode B", "eNB", "eNode B", "Node B" or "B node", depending on the standard, technology and terminology used. The radio network access node can be of different classes or types such as a macro eNodeB, a home eNodeB or a relay node, based on transmission power and thereby cell size. The radio network access node can also be a station (STA), which is any device that includes an IEEE 802.11 -conformant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM). The radio network access node can be configured to communicate in 3GPP related long term evolution (LTE), LTE-Advanced, fifth generation (5G) wireless systems, e.g., new radio (NR) and evolution thereof, as well as IEEE related Wi-Fi, worldwide interoperability for microwave access (WiMAX) and evolution thereof.

[0089] Finally, it is to be understood that the application is not limited to the embodiments described above, but also encompasses all embodiments within the scope of the appended claims.

Claims

1. A frequency-tunable resonator (100), characterized in that, The frequency-tunable resonator (100) includes: A dielectric block (110) comprising a surface coated with a conductive layer (112); Input port (102) is used to receive input signals (S) In ); Output port (104) is used to output output signal (S) Out ); A resonator (106) is disposed within the dielectric block (110) and electromagnetically connected to the input port (102) and the output port (104), respectively. At least one dielectric opening (120) in the conductive layer (112) defines a conductive tuning pattern (114) on the surface of the dielectric block (110). At least one electrically controllable switch (130) is used to electrically connect the conductive tuning pattern (114) to the conductive structure (142) when operating in the active state; the frequency-tunable resonator (100) is used for: When the electrically controllable switch (130) is in the inactive state, it resonates at a first frequency (F1); When the electrically controllable switch (130) is in the active state, it resonates at the second frequency (F2); The frequency-tunable resonator (100) includes a dielectric layer (140) disposed on the dielectric block (110), and the electrically controllable switch (130) is mounted on the dielectric layer (140); The electrically controllable switch (130) is connected to the conductive tuning pattern (114) via a conductive interface (144).

2. The frequency-tunable resonator (100) according to claim 1, characterized in that, The conductive tuning pattern (114) includes a first conductive portion (118), which is connected to a second conductive portion (118') via at least one additional electrically controllable switch (130).

3. The frequency-tunable resonator (100) according to claim 2, characterized in that, The second conductive portion (118') is arranged circumferentially around the first conductive portion (118).

4. The frequency-tunable resonator (100) according to claim 1, characterized in that, The conductive tuning pattern (114) includes a single conductive portion (118).

5. The frequency-tunable resonator (100) according to any one of claims 1 to 4, characterized in that, The conductive tuning pattern (114) is arranged coaxially with respect to the resonator (106) in the dielectric block (110).

6. The frequency-tunable resonator (100) according to any one of claims 1 to 4, characterized in that, The resonator (106) is a resonant cavity, which includes an opening (108) extending inward from the surface of the dielectric block (110).

7. The frequency-tunable resonator (100) according to claim 6, characterized in that, The opening (108) of the resonant cavity and the conductive tuning pattern (114) are disposed on opposite surfaces of the dielectric block (110).

8. The frequency-tunable resonator (100) according to any one of claims 1 to 4, characterized in that, The dielectric block (110) has a cubic or cuboid shape.

9. The frequency-tunable resonator (100) according to any one of claims 1 to 4, characterized in that, The electrically controllable switch (130) is a semiconductor, a variable capacitor, or a variable inductor.

10. The frequency-tunable resonator (100) according to any one of claims 1 to 4, characterized in that, The electrically controllable switch (130) is installed at the dielectric block (110).

11. The frequency-tunable resonator (100) according to claim 10, characterized in that, The conductive layer (112) is the conductive structure (142).

12. The frequency-tunable resonator (100) according to any one of claims 1 to 4, characterized in that, The conductive structure (142) is disposed at or connected to the dielectric layer (140).

13. The frequency-tunable resonator (100) according to any one of claims 1 to 4, characterized in that, The frequency-tunable resonator (100) includes at least one second resonator (106'), at least one second conductive tuning pattern (114'), and at least one second controllable switch (130'); and the resonator (106) and the second resonator (106') are electromagnetically coupled to each other.

14. The frequency-tunable resonator (100) according to claim 13, characterized in that, The frequency-tunable resonator (100) includes at least one cavity (160) coated with a conductive layer and forming a wall portion extending inside the dielectric block (110) and at least partially located between the resonator (106) and the second resonator (106').

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