A phase shifter and frequency multiplier circuit and a method for operating such a circuit

Abstract

A phase shifter and frequency multiplier circuit, comprising a resonant tank tuned to a harmonic of an injection signal, a plurality of parallel cascaded switch banks, wherein each of said plurality of switch banks is arranged to receive a distinct phase shifted variation of said injection signal (Q+, Q-, I+, I-), wherein each of said plurality of switch banks comprises a contribution unit wherein said contribution unit comprises a non-linear element for receiving said distinct phase shifted variation of said injection signal (Q+, Q-, I+, I-) and for providing a harmonic of said corresponding received distinct phase shifted variation of said injection signal, a switch connected in series with said non-linear element and connected to said resonant tank and a controller arranged for controlling said switches of said contribution units of each of said plurality of switch banks.

Description

[0001] A PHASE SHIFTER AND FREQUENCY MULTIPLIER CIRCUIT AND A METHOD FOR OPERATING SUCH A CIRCUIT

[0002] Technical field

[0003] The present disclosure generally relates to the field of frequency multiplier circuits and, more specifically, to circuitry that is able to implement frequency multiplications as well as phase shifting.

[0004] Background

[0005] In the context of wireless communication technologies, particularly in the context of 6G networks, the utilization of higher frequencies such as millimeter-wave, mm- wave, and sub-terahertz, sub-THz, may pose certain technical challenges. One challenge arises in the generation of local oscillator, LO, signals , which becomes increasingly difficult at these higher frequencies with existing technologies.

[0006] To address this issue, frequency multipliers are commonly employed. These devices allow for the generation of higher-frequency signals by taking the output of an oscillator operating at a sub-harmonic of the desired LO frequency and feeding it into a frequency multiplier circuit.

[0007] Among the various techniques for frequency multiplication, injection locking multipliers have raised attention, particularly in the context of high frequencies, owing to their current efficiency. This efficiency may be of importance in ensuring improved performance and power utilization in the demanding landscape of advanced wireless communication.

[0008] Moreover, the use of frequency multipliers introduces a level of flexibility in synthesizer design, as a single design can be adapted for use across different frequency bands by combining it with various multiplication factors.

[0009] As the frequencies involved increase, the power amplifier's output power tends to decrease. To overcome this limitation and enhance radiated power, front-ends are often aggregated to form an antenna array system. This system allows for the concentration of radiated power into a focused beam, enabling efficient communication over longer distances - so-called “beamforming”. However, to manipulate the direction of this beam, phase control functionality becomes important in the front-end. Implementing phase control in the front-end can be achieved through either the LO path or the radio frequency, RF, path. Both approaches have their benefits, but low loss phase control circuits in the RF path present a particular challenge. The inherent difficulties in designing such circuits at higher frequencies often require additional amplifications, introducing energy inefficiencies into the system.

[0010] In scenarios where the LO is generated centrally and then fed to multiple multipliers, incorporating a phase shifter directly before or after frequency multiplication may become of importance. However, phase shifters are inherently lossy components, and compensatory amplification is frequently required. This arrangement, while addressing the phase control requirements, contributes to a more energy-inefficient circuit, especially at the elevated frequencies associated with 6G networks.

[0011] The transition to higher frequencies, for example in 6G networks, introduces several technical challenges, including the generation of LO frequencies, power amplification issues, and the implementation of efficient phase control in front-end systems.

[0012] While frequency multipliers offer a solution to LO generation challenges, their integration with phase control circuits may require consideration of energy efficiency, especially in the context of RF path phase control where low loss is challenging to achieve.

[0013] Summary

[0014] It is an object of the present disclosure to provide for a circuit that is able to implement phase shifting as well as frequency multiplication. Further objects include associated devices as well as associated methods.

[0015] In a first aspect of the present disclosure, there is provided a phase shifter and frequency multiplier circuit.

[0016] The phase shifter and frequency multiplier circuit comprises a resonant tank tuned to a harmonic of an injection signal.

[0017] The phase shifter and frequency multiplier circuit further comprises a plurality of parallel cascaded switch banks, wherein each of said plurality of switch banks is arranged to receive a distinct phase shifted variation of said injection signal (Q+, Q-, l+, I-), wherein each of said plurality of switch banks comprises a contribution unit. The contribution unit comprises a non-linear element for receiving said distinct phase shifted variation of said injection signal (Q+, Q-, l+, I-) and for providing a harmonic of said corresponding received distinct phase shifted variation of said injection signal, and a switch connected in series with said non-linear element and connected to said resonant tank. The phase shifter and frequency multiplier circuit further comprises a controller arranged for controlling said switches of said contribution units of each of said plurality of switch banks.

[0018] The inventors have found that it may be beneficial to create a circuit that is able to do phase shifting and frequency multiplication simultaneously. This is accomplished by the introduction of the plurality of parallel cascaded switch banks. Each of the switch banks is arranged to receive a distinct phase shifted variation of an injection signal.

[0019] The distinct phase shifted variations of the injection signal may correspond to quadrature, Q, and in-phase, I, signals. The signals Q+, Q-, l+, and I- are often associated with specific phases in a signal.

[0020] In detail, the in-phase component l+ may represent the signal aligned with a reference signal, denoting 0 degrees phase. Simultaneously, the in-phase component I- may denote a signal with the same amplitude but in phase opposition, corresponding to 180 degrees phase.

[0021] On the quadrature side, the Q+ component may denote a signal 90 degrees ahead of the reference, while Q- may represent a signal 90 degrees behind the reference, equivalent to 270 degrees phase.

[0022] It is noted that the above example is directed to specific I and Q examples, but any phase variation may work in accordance with the present disclosure.

[0023] Each switch bank comprises at least one contribution unit. The contribution unit comprises a non-linear element for receiving the corresponding distinct phase shifted variation of the invention signal and for providing a harmonic of the received distinct phase shifted variation of the injection signal.

[0024] The non-linear element may, for example, be a transistor like a Field Effect Transistor, FET, or a Bipolar Junction Transistor, or anything alike. The generation of harmonics in a transistor can be explained by the nonlinear characteristics of the transistor's input-output relationship. In electronic devices like transistors, the behaviour is typically described by linear or nonlinear models. When dealing with nonlinear components, such as transistors, the input-output relationship is not a simple linear function.

[0025] In nonlinear systems like transistors, the relationship between input and output is not proportional, leading to the generation of harmonics.

[0026] When an input signal is applied to a transistor, especially at high amplitudes, the nonlinearities in the transistor's characteristics cause it to produce harmonics of the input signal. Harmonics are multiples of the fundamental frequency of the input signal. For instance, if the input signal has a frequency of f, the second harmonic would be 2*f, the third harmonic 3*f, and so on.

[0027] The generation of harmonics can be explained by the nonlinear distortion of the input signal waveform as it passes through the transistor. The nonlinear transfer characteristic of the transistor causes the output signal to contain additional frequency components beyond the original input frequency. These additional components manifest as harmonics.

[0028] The switch bank further comprises a switch connected in series with said nonlinear element and connected to said resonant tank. By utilizing the switch, it can be determined whether the corresponding harmonic(s) of said corresponding received distinct phase shifted variation of said injection signal, i.e. generated by the non-linear element, are provided to the resonant tank.

[0029] Finally, a controller is provided that is arranged for controlling the switches of said contribution units of each of said plurality of switch banks.

[0030] A resonant tank, in the context of electronic circuits, is a combination of inductor(s) and capacitor(s) arranged in a way that creates a resonant circuit. This resonant circuit has a natural or resonant frequency at which it exhibits maximum energy storage and transfer. The term "tank" is used because this circuit can store and release energy in a manner analogous to a tank storing and dispensing liquid.

[0031] In a frequency multiplier circuit, the resonant tank is used to generate a periodic waveform, such as a sinusoidal signal. Specifically, the Radio Frequency, RF, carrier may be generated. The combination of the inductor and capacitor allows energy to oscillate between them, creating the desired waveform. This resonant frequency is determined by the values of the inductor and capacitor.

[0032] The non-linear element, i.e. a transistor, will thus generate harmonics of the injection signal. The fundamental frequency, i.e. the sub-harmonic frequency originating from the oscillator, as well as its harmonic frequencies are generated and provided to the resonant tank, if the corresponding switch of the switch bank is activated / enabled. The resonant tank is, for example, tuned to the 3rdor 5thharmonic frequency. For example, if the resonant tank is tuned to the 3rdharmonic, then a frequency multiplication of three is realized. If the resonant tank is tuned to the 5thharmonic, then a frequency multiplication of five is realized.

[0033] The introduction of the harmonic signal from the non-linear element into the resonant tank, via a switch of the switch banks, thus initiates a resonance effect, contributing to the generation of a multiplied frequency. This frequency multiplication is an aspect of the overall operation of the circuit, allowing it to produce an output signal with a frequency that is a multiple of the original input signal.

[0034] Non-linear elements like transistors, specifically Field-Effect Transistors, FETs, or Bipolar Junction Transistors, BJTs, may be employed due to their ability to amplify and manipulate electrical signals effectively. These transistors function by nonlinearly amplifying the input signal, resulting in the creation of harmonics. Nonlinear devices, such as transistors, generate harmonics due to the distortion introduced during signal amplification. The resonant tank is then “tuned” to a specific harmonic content of the input signal.

[0035] In an example, each of said plurality of switch banks comprises a plurality of parallel cascaded contribution units, wherein each of said contribution units comprises a non-linear element for receiving said distinct phase shifted variation of said injection signal (Q+, Q-, l+, I-) and for providing a harmonic of said corresponding received distinct phase shifted variation of said injection signal; a switch connected in series with said non-linear element and connected to said resonant tank.

[0036] The inventors have found that it may be beneficial if each switch bank comprises a plurality of parallel cascaded contribution units. Each contribution unit within a switch bank is provided with the same phase shifted variation of the injection signal.

[0037] In the most basic version of the phase shifter and frequency multiplier circuit in accordance with the present disclosure, a single switch of a switch bank may be activated / enabled to provide the harmonics of a distinct phase shifted variation of the injection signal to the resonant tank. The distinct phase shifted variation is, for example, a 0 degree phase shifted variation of the injection signal, a 90 degrees phase shifted variation of the injection signal, a 180 degrees phase shifted variation of the injection signal or a 270 degrees phase shifted variation of the injection signal.

[0038] Utilizing the phase shifter and frequency multiplier circuit in accordance with the example provided above, it is possible to create four different phase shifts.

[0039] The inventors have found that it may be beneficial to have more granularity in the phase shifts. In order to accomplish that, it was found to introduce multiple contributions units within a single switch bank. The controller may then select / enable one or more switches of a switch bank. This is best explained with an example.

[0040] Let’s consider a first phase shifted variation of the injection signal being a 0 degree phase shifted variation, and a second phase shifted variation of the injection signal being a 90 degree phase shifted variation. If a phase shift of 0 degrees is to be generated, then the controller may enable / activate all switches of the switch bank corresponding to the first phase shifted variation of the injection signal.

[0041] If a phase shift of 90 degrees is to be generated, then the controller may enable / activate all switches of the switch bank corresponding to the second phase shifted variation of the injection signal.

[0042] If a phase shift of 45 degrees is to be generated, then the controller may enable / activate the same number of switches in the switch bank corresponding to the first phase shifted variation of the injection signal as the number of switches in the switch bank corresponding to the second phase shifted variation of the injection signal.

[0043] If a phase shift of somewhere between 0 degrees to 45 degrees is to be generated, then the controller may active / enable more switches in the switch bank corresponding to the first phase shifted variation of the injection signal compared to the number of switches in the switch bank corresponding to the second phase shifted variation of the injection signal.

[0044] If a phase shift of somewhere between 45 degrees and 90 degrees is to be generated, then the controller may activate / enable more switches in the switch bank corresponding to the second phase shifted variation of the injection signal compared to the number of switches in the switch bank corresponding to the first phase shifted variation of the injection signal.

[0045] So, for phase shifts between 45 and 90 degrees, the controller may adjust the number of activated switches for the second variation relative to the first variation. This method offers a flexible and nuanced approach to generating specific phase-shifted variations in signals within a switch bank configuration.

[0046] It is noted that a benefit of phase shifting before multiplication by M is that since the signal is multiplied in frequency then applying the phase shift at lower frequency reduces the overall required phase tuning range by a factor of M, where M is the frequency multiplication ratio, i.e. with a multiply-by-2, only 180°phase tuning range is required at the input to cover a full 360° turn at the output of the multiplier.

[0047] In an example, the phase shifter and multiplier circuit further comprises: a tuneable phase shifter circuit arranged for adding a phase shift to said selected harmonic of said corresponding distinct phase shifted variations of said injection signal. The inventors have found that it may be beneficial to implement a tuneable phase shifter circuit. The tuneable phase shifter may introduce an additional phase to the harmonics provided to the resonant tank.

[0048] Here below, the above described example if explained with reference to a practical implementation.

[0049] Let’s consider a situation wherein the controller is arranged to activate / enable the switch(es) of one switch bank at a time. This would mean that harmonics are generated from one input signal, i.e. one distinct phase shifted variation of the injection signal. If there are four different switch banks, then that would mean that the controller is able to select one out of four phases, for example 0 degrees or 90 degrees or 180 degrees or 270 degrees.

[0050] The granularity of these selected phases may not be sufficient. As such, the inventors have found that it may be beneficial to implement a tuneable phase shifter circuit. The tuneable phase shifter circuit may be implemented such that it is able to provide an additional phase shift of between 0 degrees - 90 degrees.

[0051] The tuneable phase shifter circuit may be implemented using a T network of an inductor-capacitor-inductor. The capacitor may be a tuneable capacitor to implement the phase shift.

[0052] In a specific example, the controller is arranged controlling said switches of said contribution units of each of said plurality of switch banks thereby select said corresponding distinct phase shifted variations of said injection signal for provisioning to said resonant tank.

[0053] The controller may further be arranged to control the tuneable phase shifter circuit to generate a specific phase shift to the harmonics provided to the resonant tank.

[0054] In a further example, the phase shifter and multiplier circuit comprises four in parallel cascaded switch banks, wherein each of said plurality of switch banks is arranged to receive said distinct phase shifted variation of said injection signal, being: a first signal; a second having a 180-degree phase shift compared to said first signal; a third signal having a 90-degree phase shift compared to said first; a fourth signal having a 270-degree phase shift compared to said first signal.

[0055] In a further example, said non-linear elements comprised within one of said plurality of switch banks comprise any of: heterogeneous non-linear elements; homogeneous non-linear elements. The same type of non-linear elements may be used within a switch bank. This would result in that each of the non-linear elements have the same contribution to the signal provided to the resonant tank. Another option is that different types of non-linear elements, or a mixture of the same and different types, may be used within a switch bank. This would result in that the non-linear elements may effect a different contribution to the signal provided to the resonant tank.

[0056] In a further example, the phase shifter and multiplier circuit further comprises: a notch filter tuned to a frequency of said injection signal.

[0057] The advantage of using a notch filter is that the effect of feedthrough from the injected signals can be mitigated. The notch filter may be designed at the frequency of the injected signal.

[0058] In another example, the controller is further arranged for: selecting a phase shift of said harmonic at an output of said resonant tank; controlling said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

[0059] In yet another example, the controller is further arranged for: selecting a phase shift of said harmonic at an output of said resonant tank; enabling one of said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

[0060] In an example, the tuneable phase shifter is arranged to add said phase shift of between 0 and 90 degrees.

[0061] In a further example, the tuneable phase shifter comprises: two in series connected inductances; a tuneable capacitor connected to ground and to a node in between said two in series connected inductances.

[0062] In a second aspect of the present disclosure, there is provided a method of operating a phase shifter and frequency multiplier circuit in accordance with any of the previous examples, wherein said method comprises the steps of: receiving, by each of said plurality of switch banks, a distinct phase shifted variation of said injection signal, controlling, by said controller, said switches of said contribution units of each of said plurality of switch banks thereby controlling a contribution of each of said provided harmonics of said corresponding distinct phase shifted variations of said injection signal to said resonant tank.

[0063] It is noted that the advantages as explained with reference to the first aspect of the present disclosure, being the phase shifter and frequency multiplier circuit, are also applicable to the second aspect of the present disclosure, being the method of operating the phase shifter and frequency multiplier circuit.

[0064] In an example, the method of receiving comprises: receiving, by a first of said plurality of switch banks, a first signal; receiving, by a second of said plurality of switch banks, a second signal having a 180-degree phase shift compared to said first signal; receiving, by a third of said plurality of switch banks, a third signal having a 90-degree phase shift compared to said first signal; receiving, by a fourth of said plurality of switch banks, a fourth signal having a 270-degree phase shift compared to said first signal.

[0065] The provided example describes a signal reception method through multiple switch banks, each designed to handle signals with specific phase characteristics. The first signal, considered as in-phase+, is received by the initial switch bank. Subsequent switch banks process signals with distinct phase shifts: the in-phase- signal with a 180-degree phase shift, the quadrature+ signal with a 90-degree phase shift, and the quadrature- signal with a 270-degree phase shift. This approach reflects a strategy commonly employed in communication systems, particularly in modulation schemes, where signals are categorized based on their phase relationships to a reference signal. Precise control over these phase components may be of importance for various applications, such as achieving accurate signal representation or manipulation.

[0066] In an example, the non-linear elements comprised within one of said plurality of switch banks comprise any of: heterogeneous non-linear elements; homogeneous non-linear elements.

[0067] In a further example, the phase shifter and multiplier circuit further comprises a notch filter, and wherein said method comprises the step of: filtering, by said notch filter, a frequency of said injection signal.

[0068] In another example, the method comprises the steps of: selecting a phase shift of said harmonic at an output of said resonant tank; controlling said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

[0069] In a further example, the method comprises the steps of: selecting a phase shift of said harmonic at an output of said resonant tank; enabling one of said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

[0070] In yet another example, the tuneable phase shifter is arranged to add said phase shift of between 0 to 90 degrees.

[0071] In an example, the tuneable phase shifter comprises: two in series connected inductances; a tuneable capacitor connected to ground and to a node in between said two in series connected inductances.

[0072] In a third aspect of the present disclosure, there is provided an electronic apparatus comprising a phase shifter and frequency multiplier circuit in accordance with any of the examples as provided above.

[0073] The electronic apparatus may, for example, be a communication apparatus.

[0074] In a further example, the communication apparatus is a User Equipment, UE, for a cellular communications system or a radio base station for a cellular communications system, like a gNodeB or an eNodeB.

[0075] In the appended figures, similar components and / or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0076] The above and other aspects of the disclosure will be apparent from and elucidated with reference to the examples described hereinafter.

[0077] Brief description of the drawings

[0078] Figure 1 discloses an Antenna Array System, AAS, arrangement variant with an Local Oscillator synthesizer that also includes phase shifting functionality; Figure 2 discloses an AAS arrangement variant with a central frequency feeding multiple phase shifters and each then drives a multiply by M circuit to feed a frondend;

[0079] Figure 3a discloses an illustration of vector summation and figure 3b discloses a high level overview of a phase shifter and frequency multiplier circuit;

[0080] Figure 4 discloses a specific implementation of a phase shifter and frequency multiplier circuit;

[0081] Figure 5 discloses another specific implementation of a phase shifter and frequency multiplier circuit;

[0082] Figure 6 discloses an example of an electronic apparatus in accordance with the present disclosure.

[0083] Detailed description

[0084] It is noted that in the description of the figures, same reference numerals refer to the same or similar components performing a same or essentially similar function.

[0085] A more detailed description is made with reference to particular examples, some of which are illustrated in the appended drawings, such that the manner in which the features of the present disclosure may be understood in more detail. It is noted that the drawings only illustrate typical examples and are therefore not to be considered to limit the scope of the subject matter of the claims. The drawings are incorporated for facilitating an understanding of the disclosure and are thus not necessarily drawn to scale. Advantages of the subject matter as claimed will become apparent to those skilled in the art upon reading the description in conjunction with the accompanying drawings.

[0086] The ensuing description above and below provides preferred exemplary embodiment(s) only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements, including combinations of features from different embodiments, without departing from the scope of the disclosure.

[0087] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0088] Figure 1 discloses an Antenna Array System, AAS, arrangement with a Local Oscillator synthesizer that also includes phase shifting functionality locally for each frondend.

[0089] In antenna array systems the Local Oscillator path is often chosen to add phase control functionality. An example of an implementation is shown in figure 1 , where each front-end has an associated local Phased Locked Loop, PLL, system with phase shifting capability and a frequency multiplier afterwards.

[0090] This solution may be expensive in terms of chip area as each local PLL would fill a large footprint. An attractive solution would be then to have one central PLL generating a continuous wave for all the front-ends. This is shown in figure 2.

[0091] The phase control functionality is implemented by adding a phase shifter before or after the frequency multiplier. Figure 2 shows a phase shifter connected to the output of the PLL. To compensate for the phase shifter loss, buffers and amplifiers are usually inserted to boost signal levels. A benefit of phase shifting before multiplication is that the phase shift is multiplied as well, i.e. the phase shift that is applied at the lower frequency is times M at the higher frequency, wherein M is the frequency multiplication ratio. This reduces the required phase tuning range at the lower frequency by a factor M.

[0092] Figure 3a discloses an illustration of vector summation and figure 3b discloses a high level overview of a phase shifter and frequency multiplier circuit. This is explained in more detail here below.

[0093] Operating an oscillator at higher frequencies such as mm-wave and sub-THz planned for 6G, may become difficult. Frequency multipliers are then typically used, wherein the oscillator operates at a sub-harmonic of the desired frequency and its output is fed to a frequency multiplication circuit.

[0094] Injection locking multipliers are attractive at high frequencies thanks to their higher current efficiency. The use of multipliers is also beneficial in that one synthesizer design may be used for several different frequency bands when combining with different multiplication factors, offering large flexibility.

[0095] Due to increased propagation losses at higher frequencies, front-ends are grouped together to form an antenna array system with increased radiated power forming a beam. To be able to focus the beam at different directions phase control functionality must be employed in the front-end. The phase control can be implemented in the LO path or the Radio Frequency, RF, path. Although both options are viable, low loss phase control circuits in the RF path are challenging.

[0096] If the LO to be multiplied is generated centrally and fed to several multipliers, then a phase shifter may be used directly before or after frequency multiplication. Phase shifters are lossy, and amplification is often needed making such circuit arrangement more energy inefficient at high frequencies.

[0097] The present disclosure is directed to a phase shifter and frequency multiplier circuit that is able to perform both phase shifting and frequency multiplication.

[0098] The present disclosure is directed to embedding the phase shifting and the multiplication features in one circuitry. This is achieved using either vector summation of in phase and quadrature signals, of which a detailed implementation is shown in figure 4, and / or using physical phase shifters in series inside the multiplier core, which is shown in figure 5.

[0099] This is energy efficient especially when injection locked multipliers are used. The injection locked multiplier locks to a signal source and produces large signal levels even if phase shifting is slightly lossy. Reducing the required range of phase shifting results in low loss phase shifters making the combination highly efficient.

[0100] A preferred solution including phase control is shown in figure 4. Each phase of the quadrature signal is injected into one switch bank respectively and then the switches may be programmed depending on the desired phase shift accordingly.

[0101] Consider that each of the switch banks is binary weighted with 4 bits. Suppose a phase shift of 0° is to be generated, then the first signal, i.e. I+, is activated with the binary weight 15, while the second signal, the third signal and the fourth signal, being I-, Q+ and Q-, respectively, are deactivated with the binary weight 0 respectively.

[0102] In similar way, if 90° is desired, then Q+ is set to 15 while l+, I- and Q- are set to 0. To achieve intermediate phases, for example a phase between 0° and 90°, set l+ to k and then Q+ to 15-k, while I- and Q- are set to 0. For example, if about 4° is desired then set l+ to 14 and Q+ to 1 , and if 9° is desired l+ is set to 13 and Q+ is set to 2. By activating l+ and Q+ with different binary weights, while I- and Q- are deactivated, the phase range between 0° and 90° is covered.

[0103] Similarly, the other quadrants are covered by activating another pair of the quadrature signal. If l+ and Q- are activated, while I- and Q+ are deactivated, the phase range between 270° and 07360° is covered. To mitigate the effect of feedthrough from the injected signals, a notch filter at the injection frequency can be used.

[0104] It is noted that the above described example may change based on the multiplication factor. As mentioned above, phase shifting may be performed before frequency multiplication. This would mean that the phase tuning range is also reduced by the multiplication factor. For example, for a frequency multiplication ratio of 2, only 180 degrees phase tuning range is required at the input to cover a full 360 degrees phase shift at the output.

[0105] Another example to implement the phase shifting functionality is shown in figure 5. A physical phase shifter, i.e. a tuneable phase shifter, may be constructed e.g., using a T network of inductor-capacitor-inductor. With this arrangement, a range of 90° phase shift may be achieved by using a tuneable capacitor.

[0106] To be able to cover a full 360° then one of the four signals quadrants is selected by switching in one of the four switch banks. As mentioned above, these four signals may be the quadrature signals l+, I-, Q+ or Q-. This is achieved by setting / enabling / activating one of the switches SW1 , SW2, SW3 or SW4 of the corresponding switch bank, as shown in figure 5. If only differential signals are available, then 180° shifters are required.

[0107] Figure 6 discloses an example of an electronic apparatus in accordance with the present disclosure.

[0108] The electronic apparatus 42 comprises an input terminal 44, an input device 43, an output terminal 46 and an output device 45.

[0109] The electronic apparatus may further comprise a processor 47 connected to a memory 48.

[0110] On top of the above, the electronic apparatus may comprise a phase shifter and frequency multiplier circuit in accordance 49 with any of the examples provided above.

[0111] The electronic apparatus may be a communication apparatus such as a User Equipment, UE, or a base station like an eNodeB or a gNodeB.

[0112] It should be noted that the above-mentioned examples illustrate rather than limit the idea, and that those skilled in the art will be able to design many alternative examples without departing from the scope of the appended claims. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims. Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

CLAIMS:1 . A phase shifter and frequency multiplier circuit, comprising: a resonant tank tuned to a harmonic of an injection signal; a plurality of parallel cascaded switch banks, wherein each of said plurality of switch banks is arranged to receive a distinct phase shifted variation of said injection signal (Q+, Q-, l + , I-), wherein each of said plurality of switch banks comprises a contribution unit wherein said contribution unit comprises: a non-linear element for receiving said distinct phase shifted variation of said injection signal (Q+, Q-, l+, I-) and for providing a harmonic of said corresponding received distinct phase shifted variation of said injection signal; a switch connected in series with said non-linear element and connected to said resonant tank; a controller arranged for controlling said switches of said contribution units of each of said plurality of switch banks.

2. A phase shifter and frequency multiplier circuit in accordance with claim 1 , wherein each of said plurality of switch banks comprises a plurality of parallel cascaded contribution units, wherein each of said contribution units comprises a non-linear element for receiving said distinct phase shifted variation of said injection signal (Q+, Q-, l+, I-) and for providing a harmonic of said corresponding received distinct phase shifted variation of said injection signal; a switch connected in series with said non-linear element and connected to said resonant tank.

3. A phase shifter and frequency multiplier circuit in accordance with claim 1 , wherein said phase shifter and multiplier circuit further comprises: a tuneable phase shifter circuit arranged for adding a phase shift to said selected harmonic of said corresponding distinct phase shifted variations of said injection signal.

4. A phase shifter and frequency multiplier circuit in accordance with claim 3, wherein said controller is arranged controlling said switches of said contribution units of each of said plurality of switch banks thereby select said corresponding distinct phase shifted variations of said injection signal for provisioning to said resonant tank.

5. A phase shifter and frequency multiplier circuit in accordance with claim 1 , wherein said phase shifter and multiplier circuit comprises four in parallel cascaded switch banks, wherein each of said plurality of switch banks is arranged to receive said distinct phase shifted variation of said injection signal, being: a first signal; a second signal having a 180-degree phase shift compared to said first signal; a third signal having a 90-degree phase shift compared to said first; a fourth signal having a 270-degree phase shift compared to said first signal.

6. A phase shifter and frequency multiplier circuit in accordance with any of the previous claims and at least in accordance with claim 2, wherein said switches comprised within one of said plurality of switch banks comprise any of: heterogeneous non-linear elements; homogeneous non-linear elements.

7. A phase shifter and frequency multiplier circuit in accordance with any of the previous claims, wherein said phase shifter and multiplier circuit further comprises: a notch filter tuned to a frequency of said injection signal.

8. A phase shifter and frequency multiplier circuit in accordance with any of the previous claims and at least in accordance with claim 2, wherein said controller is further arranged for: selecting a phase shift of said harmonic at an output of said resonant tank; controlling said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

9. A phase shifter and frequency multiplier circuit in accordance with any of the previous claims and at least in accordance with claim 3, wherein said controller is further arranged for: selecting a phase shift of said harmonic at an output of said resonant tank;enabling one of said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

10. A phase shifter and frequency multiplier circuit in accordance with any of the previous claims and at least in accordance with claim 3, wherein said tuneable phase shifter is arranged to add said phase shift of between 0 and 90 degrees.

11. A phase shifter and frequency multiplier circuit in accordance with any of the previous claims and at least in accordance with claim 3, wherein said tuneable phase shifter comprises: two in series connected inductances; a tuneable capacitor connected to ground and to a node in between said two in series connected inductances.

12. A method of operating a phase shifter and frequency multiplier circuit in accordance with any of the previous claims, wherein said method comprises the steps of: receiving, by each of said plurality of switch banks, a distinct phase shifted variation of said injection signal, controlling, by said controller, said switches of said contribution units of each of said plurality of switch banks thereby controlling a contribution of each of said provided harmonics of said corresponding distinct phase shifted variations of said injection signal to said resonant tank.

13. A method in accordance with claim 12, wherein said method of receiving comprises: receiving, by a first of said plurality of switch banks, a first signal; receiving, by a second of said plurality of switch banks, a second signal having a 180-degree phase shift compared to said first signal; receiving, by a third of said plurality of switch banks, a third signal having a 90-degree phase shift compared to said first signal; receiving, by a fourth of said plurality of switch banks, a fourth signal having a 270-degree phase shift compared to said first signal.

14. A method in accordance with any of the claims 12 - 13, wherein said nonlinear elements comprised within one of said plurality of switch banks comprise any of:heterogeneous non-linear elements; homogeneous non-linear elements.

15. A method in accordance with any of the claims 12 - 14, wherein said phase shifter and multiplier circuit further comprises a notch filter, and wherein said method comprises the step of: filtering, by said notch filter, a frequency of said injection signal.

16. A method in accordance with any of the claims 12 - 15, wherein said method comprises the steps of: selecting a phase shift of said harmonic at an output of said resonant tank; controlling said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

17. A method in accordance with any of the claims 12 - 15, wherein said method comprises the steps of: selecting a phase shift of said harmonic at an output of said resonant tank; enabling one of said switches of said contribution units of each of said plurality of switch banks based on said selected phase shift.

18. A method in accordance with any of the claims 12 - 16, wherein said tuneable phase shifter is arranged to add said phase shift of between 0 to 90 degrees.

19. A method in accordance with any of the claims 12 - 18, wherein said tuneable phase shifter comprises: two in series connected inductances; a tuneable capacitor connected to ground and to a node in between said two in series connected inductances.

20. An electronic apparatus comprising a phase shifter and frequency multiplier circuit in accordance with any of the claims 1 - 11.

21. An electronic apparatus in accordance with claim 20, wherein the electronic apparatus is a communication apparatus.

22. An electronic apparatus in accordance with claim 21 , wherein the communication apparatus is a User Equipment, UE, for a cellular communications system.

23. An electronic apparatus in accordance with claim 21 , wherein the communication apparatus is a radio base station for a cellular communications system.

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