The present disclosure relates to a frequency tunable resonator e.g., for a filter application in a communication device.
Tunable radio frequency (RF) components are of great interest as an ever-increasing number of frequency bands need to be supported in modern communication system while the demand for miniaturization result in design constraints due to size limitations. Because of these requirements, multiband and/or multi-standard systems are a desirable property in any RF front end components, such as RF filters, in communication devices.
The basic building block of RF filters is so-called resonators which are arranged in such a way to pass an RF signal in a frequency passband while rejecting signals outside of the passband. The resonance frequency of the RF resonators determines the filter passband and by using a number of tunable resonators, a frequency tunable filter can be realized. Tunable filters have the potential to add higher flexibility and support more frequency bands without a significant increase in size by using a single filter with tuning elements able to shift the frequency response of the filter so as to cover a larger range of frequency bands.
There are several desirable properties which tunable resonators need to satisfy to perform well in tunable filters, such as high Q resonators (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).
Several conventional solutions of tuning filters exist but there are few if any which display many of these desirable properties. This limits the usage of tunable filters in practice.
The present disclosure provides solutions that mitigate drawbacks or solve problems of conventional solutions.
The present disclosure provides a resonator solution that is simple to produce and easy to implement in multiple filter applications.
According to an aspect of the present disclosure, a frequency tunable resonator is provided comprising:
That the electrically controllable switch is in its active state may be understood such that the electrically controllable switch is conductive meaning that an electrical signal can pass through the switch. This is contrary to the case when the electrically controllable switch is in its non-active state in which an electrical signal cannot pass through the switch. The electrically controllable switch can be any type of switch having the suitable properties.
An advantage of the frequency tunable resonator according to the first aspect is that the frequency tunable resonator may be utilized as a building block in any type of filter to realize tunable properties. Further, the present frequency tunable resonator provides a very low profile and small footprint system which is simple to realize on any substrate with existing methods for producing dielectric openings slots in the conductive layer. In addition, the tuning structure herein disclosed can easily be applied to any current or previously designed filters without having to modify the topology or resonator positions significantly. Any type of controllable switch can be used which makes the resonator configurable with regards to switch type depending on performance requirements. The frequency tunable resonator according to the first aspect is easy to modify according to specifications, such as the frequency tuning range, and further the switches are interchangeable depending on priority in reducing insertion loss or increasing switching speed.
In an implementation form of a frequency tunable resonator, the conductive tuning pattern comprises a first conductive section connected to a second conductive section via at least one additional electrically controllable switch.
An advantage with this implementation form is that by adding additional controllable switches, the number of tuning states increases where the number of tuning states achievable is 2n where n is the number of switches in a certain configuration.
In an implementation form of a frequency tunable resonator, the second conductive section is circumferentially arranged around the first conductive section.
An advantage with this implementation form is that a small incremental tuning step can be implemented without significantly increasing the footprint of the tuning element.
In an implementation form of a frequency tunable resonator, the conductive tuning pattern comprises a single conductive section.
An advantage with this implementation form is that a very simple configuration may be provided for low cost applications.
In an implementation form of a frequency tunable resonator, the conductive tuning pattern is coaxially arranged in relation to the resonator in the dielectric block.
An advantage with this implementation form is that since the tuning pattern is arranged at the point of strongest electromagnetic field, the tunability of the resonator is increased.
In an implementation form of a frequency tunable resonator, the resonator is a resonator cavity comprising an opening extending inwards from the surface of the dielectric block.
In an implementation form of a frequency tunable resonator, the opening of the resonator cavity and the conductive tuning pattern are arranged on opposite surfaces of the dielectric block.
An advantage with this implementation form is that since the tuning pattern is arranged at the point of strongest electrical field, the tunability of the resonator is increased.
In an implementation form of a frequency tunable resonator, the dielectric block has a cubic or a cuboid shape.
In an implementation form of a frequency tunable resonator, the electrically controllable switch is a semiconductor, a variable capacitance, or a variable inductance.
An advantage with this implementation form is that a large number of different components may be used in this respect thereby providing a wider range of design choices.
In an implementation form of a frequency tunable resonator, the electrically controllable switch is mounted at the dielectric block.
An advantage with this implementation form is that the footprint is greatly reduced by mounting the electrically controllable switch at the dielectric block.
In an implementation form of a frequency tunable resonator, the conductive layer is the conductive structure.
An advantage with this implementation form is that the controllable switch can be connected to the conductive ground, eliminating the need for additional structures or components.
In an implementation form of a frequency tunable resonator, the frequency tunable resonator comprises a dielectric layer arranged at the dielectric block, and wherein the electrically controllable switch is mounted at the dielectric layer.
An advantage with this implementation form is that the controllable switches and feed network can be designed without size restrictions of the resonator by shifting the switch reference plane and mounting position to an external dielectric layer/substrate.
In an implementation form of a frequency tunable resonator, the electrically controllable switch is connected to the conductive tuning pattern via a conductive interface.
An advantage with this implementation form is that the controllable switches and feed network can be designed without size restrictions of the resonator by shifting the switch reference plane and mounting position to an external dielectric layer/substrate.
In an implementation form of a frequency tunable resonator, the conductive structure is arranged at the dielectric layer or connected to the dielectric layer.
An advantage with this implementation form is that the controllable switches and feed network can be designed without size restrictions of the resonator by shifting the switch reference plane and mounting position to an external dielectric layer/substrate.
In an implementation form of a frequency tunable resonator, the frequency tunable resonator comprises at least one second resonator, at least one second conductive tuning pattern, and at least one second controllable switch; and wherein the resonator and the second resonator are electromagnetically coupled to each other.
An advantage with this implementation form is that a cascade or an arbitrary arrangement of several resonators can be connected to form a tunable radio frequency filter.
In an implementation form of a frequency tunable resonator, the frequency tunable resonator comprises at least one inner cavity coated with a conductive layer and forming a wall section extending inside the dielectric block and at least partially between the resonator and the second resonator.
An advantage with this implementation form is that the symmetry of a radio frequency is broken and a tunable radio frequency filter can hence be designed.
Further applications and advantages of embodiments of the of the present disclosure will be apparent from the following detailed description.
The appended drawings are intended to clarify and explain different embodiments, in which:
A main difference between a single band filter and a tunable filter is the addition of tuning elements in the tunable filter. Depending on tuning solution this will have a major impact on the overall system performance of the filter. In particular, tunable filters suffer from low quality (Q) factor values related to losses in the resonator as an effect of added tuning elements. High Q factor resonators can therefore have a severely reduced performance due to the addition of tuning elements. Therefore, the tuning elements should preferably have a small impact on the resonators Q factor.
In addition, while the tuning of cavity filters is a well explored area, the tuning of ceramic block filters is fairly unexplored. Ceramic block filters restrict the choice of tuning elements due to the solid structure of the filter itself. Most tunable filters operate with an air cavity where tuning elements can simply be inserted into the air cavity. This is naturally not possible in ceramic block filters and therefore some of the conventional ways of tuning are physically not feasible.
The present disclosure therefore provides a new solution of tuning ceramic block resonators which achieves a good compromise between the desired requirements for tunable filters by a new type of tunable resonator structure. Among other things, miniaturized tunable filters may therefore be realized. In ceramic block filters the previous tunable solutions have been based on mechanical tuning with slow tuning speed or varactors with low Q factor. The solution herein presented instead utilizes controllable switches which eliminates the need for low Q factor varactors while still providing fast response time. Further, the present frequency tunable resonator can be optimized with regards to loss and tuning speed based on component choice.
The frequency tunable resonator 100 further comprises a resonator 106 (illustrated with dashed lines) arranged inside the dielectric block 110 and being electromagnetically connected to the input 102 and the output 104, respectively. The resonator 106 may as shown in
The frequency tunable resonator 100 further comprises at least one dielectric opening 120 in the conductive layer 112 delimiting a conductive tuning pattern 114 at the surface of the dielectric block 110. The frequency tunable resonator 100 further comprises at least one electrically controllable switch 130, 130′ configured to conductively connect the conductive tuning pattern 114 to a conductive structure 112 when operating in its active state. The frequency tunable resonator 100 is hence configured to: resonate at a first frequency F1 when the electrically controllable switch 130 is operating in its non-active state, and resonate at a second frequency F2 when the electrically controllable switch 130 is operating in its active state. The first frequency F1 is different to the second frequency F2, hence a tunable resonator is provided.
The dielectric block 110 may be moulded or produced in any other suitable way. The dielectric block 110 may be a ceramic dielectric block encased in a conductive coating such as silver or copper coating. However, any other dielectric substrate and conductor can be used as a dielectric block with the same effect. The dielectric block 110 is designed so as to resonate at a desired design frequency or frequencies. The dielectric block 110 can have any shape and with any internal structures present without affecting the basic functionality of the herein disclosed resonator solution.
In embodiments, the conductive layer 112 is the conductive structure itself. This implies that the conductive layer 112 in this case act as a ground of the resonator 100 and is interrupted by dielectric openings 120 in the conductive layer 112. By introducing a direct ceramic-to-dielectric interface in the form of dielectric openings 120 in the conductive layer 112, the electrical property of the resonator 100 is changed with the perturbation of the internal electrical fields. The dielectric openings 120 in the conductive layer 112 form and define a conductive tuning pattern 114, where a point located on the conductive layer 112 is separated from another point on the conductive layer 112 by a dielectric opening in the conducting ground. Both points may still be connected to the conductive layer 112 and the ground plane of the resonator 100. By this separation, a surface current has to use a different path through the conductive layer 112 to connect the two points. One or more of these points may be electrically connected to a conducting ground not part of the conductor casing. This conducting ground may be mounted on a dielectric substrate which in turn may be connected to one or more controllable switches 130. Thereby, a new electrical path is introduced for the surface current on the conductive layer 112 and electromagnetic coupling between the internal electrical fields of the resonator 100. The electrical path may be connected to a common ground separated by a controllable switch 130. The embodiment using dielectric substrate is described with reference to
The introduction of an alternative electrical path from the conductive layer 112 to an external tuning element allows for a change of capacitance seen by the resonator 100 by a choice of controllable switches 130 and conductive tuning pattern 114. The change of capacitance is an effect perturbing the internal electrical field. The resonance frequency of the resonator 100 can thus be changed in a predictable and controllable way by changing the properties of the external conductor path, e.g., by the closing or opening of one or more controllable switches 130 which connects the external conductor to the ground plane.
An additional advantage of the present resonator structure compared to conventional solutions is that by using conventional readily available RF controllable switches a fast switching speed tuning network can be realized. By utilizing controllable switches for tuning, instead of capacitor banks or variable capacitors, the negative impact of the tuning elements is reduced, especially in the off-state of the controllable switch, i.e., when the controllable switch is not conductive. Hence, embodiments comprise controllable switches 130 and the basic functionality of the frequency tunable resonator 100 does not change with the choice of controllable switch. Therefore, the electrically controllable switch 130 may be any suitable controllable switch known in the art. For example, a semiconductor, a variable capacitance, or a variable inductance.
In embodiments, and also disclosed in
However, it is realised that the present conductive tuning pattern 114 may comprise any number of conductive sections 118 connected via one or more electrically controllable switches at bridge sections to achieve suitable frequency tuning properties. Hence, depending on the number of conductive sections 118, the shape of the conductive sections 118, the interconnecting structure, number of controllable switches 130, the location of the controllable switches 130, etc. a huge number of different frequency configurations may be provided. Thus, unlimited number of different frequency passbands F1, F2, . . . , Fn may be configured using the present solution.
Furthermore,
In
In both examples shown in
Furthermore, common for both disclosed examples in
Further, a conductive structure 142 may be arranged at the dielectric layer 140 or connected to the dielectric layer 140. Moreover, the electrically controllable switch 130 may be connected to the conductive tuning pattern 114 via a conductive interface 144 as also shown
By using a dielectric layer 140, the controllable switches 130 can be removed from direct connection with the resonator ground. The shift in reference plane for the controllable switches 130 by the connection of the dielectric layer 140 to the tuning pattern is also disclosed. The controllable switches 130 will act as an opening and closing 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 ground of the resonator ground. Input 102 and output 104 ports are also shown in
The configuration as disclosed in
In general terms, the frequency tunable resonator 100 for multi resonator applications comprises at least one second resonator 106′, at least one second conductive tuning pattern 114′, and at least one second controllable switch 130′. The resonator 106 and the second resonator 106′ are electromagnetically coupled to each other. The frequency tunable resonator 100 can thus be realized by cascading an arbitrary number of resonator cavities in an arbitrary configuration with electromagnetic coupling therebetween. The design method for manufacturing multi-pole resonators may not differ to traditionally synthesized and designed filters in the sense that a basic ceramic filter can be designed to introduce the tuning elements, i.e., controllable switches 130, in a last manufacturing step. Therefore, adding controllable switches 130 to already existing ceramic block filter designs is simple to implement. Tuning of open and closed switch positions can be simplified by choosing certain symmetries.
In this configuration there are two controllable switches 130 per resonator 106. However, any number of controllable switches 130 can be used without deviating from the scope of the present disclosure. The controllable switches 130 may be controlled electrically for example by a signal feed network sending control signals and/or biasing current to change the state of the controllable switches. The signal feed network may e.g., comprise a microcontroller or a central processing unit (CPU), control lines, etc. Further, in other configurations, the present frequency tunable resonator 100 may comprise one conductive tuning pattern 114 interacting with multiple resonators, etc.
The frequency tunable resonator 100 may be implemented and used in a number of different applications. A non-limiting example is in a communication device and a communication equipment configured for different communication system, such as 3GPP 5G, WiFi, etc. The communication device and communication equipment may e.g., be a part of a network access node or a client device.
A client device herein may be denoted as a user device, a user equipment (UE), a mobile station, an internet of things (IoT) device, a sensor device, a wireless terminal and/or a mobile terminal, and is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UEs may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in this context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via a radio access network (RAN), with another communication entity, such as another receiver or a server. The UE may further be a station (STA), which is any device that contains an IEEE 802.11-conformant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM). The UE may be configured for communication in 3GPP related long term evolution (LTE), LTE-advanced, fifth generation (5G) wireless systems, such as new radio (NR), and their evolutions, as well as in IEEE related Wi-Fi, worldwide interoperability for microwave access (WiMAX) and their evolutions.
A network access node herein may also be denoted as 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 may be referred to as transmitter, “gNB”, “gNodeB”, “eNB”, “eNodeB”, “NodeB” or “B node”, depending on the standard, technology and terminology used. The radio network access nodes may be of different classes or types such as e.g., macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby the cell size. The radio network access node may further be a station (STA), which is any device that contains an IEEE 802.11-conformant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM). The radio network access node may be configured for communication in 3GPP related long term evolution (LTE), LTE-advanced, fifth generation (5G) wireless systems, such as new radio (NR) and their evolutions, as well as in IEEE related Wi-Fi, worldwide interoperability for microwave access (WiMAX) and their evolutions.
Finally, it should be understood that the disclosure is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended claims.
This application is a continuation of International Application No. PCT/EP2022/069986, filed on Jul. 18, 2022, the disclosure of which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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Parent | PCT/EP2022/069986 | Jul 2022 | WO |
Child | 19025872 | US |