linearizer

Abstract

To provide a linearizer that compensates for the frequency dependency of distortion components of power amplifiers for transmission waves in high frequency bands of 100 GHz or more and wide bands of several GHz or more.SOLUTION: A linearizer 1, which compensates for the nonlinear characteristics of a power amplifier 900, includes N predistorters 12 and N filters 14 connected one-to-one to the N predistorters 12. The i-th predistorter 12-i of the N predistorters 12 compensates for the frequency dependency of a distortion component contained in a radio signal in the i-th divided bandwidth among N divided bandwidths obtained by dividing the bandwidth of a radio signal in the sub-terahertz band of 100 GHz or higher by N in the frequency domain. The i-th filter 14-i of the N filters 14 passes the radio signal from the i-th predistorter 12-i in the i-th divided bandwidth.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a linearizer for the sub-terahertz band. [Background technology]

[0002] In telecommunications, especially wireless communications, amplifiers are required to boost the power of transmitted waves in order to ensure the required signal-to-noise ratio (SNR). Nonlinear distortion (especially third-order intermodulation distortion: IM3) generated by amplifiers can cause degradation of signal quality (specifically, a decrease in SNR).

[0003] Linearizers are known as electronic circuits that compensate for distortion, and are applied to cellular amplifiers that use the hundreds of MHz to several GHz band. Non-Patent Documents 1 and 2 disclose digital predistorter technology that compensates for the frequency dependency of distortion components with a continuous spectrum. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-121881 [Non-patent literature]

[0005] [Non-Patent Document 1] "Control Method of Frequency Suppression Compensator of Digital Predistorter for Compensating Frequency Dependence of Distortion Components with Continuous Spectrum," Shinji Mizuta et al., IEICE Electronics Society Conference, C-2-15, 2005. [Non-patent document 2] "Fast Calculation Method of Frequency Response Compensator Function in Digital Predistorter for Compensating Frequency Dependence of Distortion Components," Junya Okawara et al., IEICE Technical Report MW2008-152 (2008-12). Summary of the Invention [Problem to be solved by the invention]

[0006] Research and development of sixth-generation mobile communication systems (hereinafter referred to as 6G) as the next-generation mobile communication system is progressing worldwide. 6G is expected to use not only the conventional cellular band below 6 GHz, but also the sub-terahertz band above 100 GHz. Sub-terahertz band transmitters, like cellular band transmitters, are also required to suppress intermodulation distortion components generated in amplifiers, thereby improving frequency utilization efficiency and transmission quality by reducing guard bands. For these reasons, it is expected that linearizers will be used in sub-terahertz band transmitters as well, just like cellular band transmitters. As shown in Patent Document 1, a sub-terahertz band linearizer using a diode is being considered.

[0007] Sub-terahertz band linearizers are expected to compensate for the frequency dependence of distortion components, similar to cellular band linearizers, from the perspective of spectral efficiency and transmission characteristics. However, to achieve the 100 Gbps or higher throughput required for 6G, the modulation bandwidth of the sub-terahertz band transmission wave is expected to be several GHz. Although the frequency dependence of distortion components in cellular band linearizers is inverted using digital signal processing, the modulation bandwidth is only about 100 MHz at most, which is not suitable for several GHz. Supporting a modulation bandwidth of several GHz using digital signal processing requires a digital-to-analog converter and a processor such as an FPGA (field-programmable gate array) with an operating speed at least six times the modulation bandwidth. Such a digital-to-analog converter and a processor such as an FPGA have not yet been realized, and even if they were realized, a significant increase in power consumption would be expected, making them unrealistic. Analog circuits could avoid the power consumption issue.

[0008] To compensate for the frequency dependency of distortion components in an analog circuit, one possible configuration is to configure a filter bank and control the gain and phase at its input or output using a vector adjuster. Commonly known coefficient control methods include the perturbation method and a control method using a reference signal (see Non-Patent Documents 1 and 2). However, compensating for the frequency dependency of wideband distortion components that arise when amplifying sub-terahertz band transmission waves involves a problem: the out-of-band attenuation characteristics of the filter are limited, so frequency components between filters become visible to each other, and there is strong interdependence between multiple coefficients, requiring a relatively long time for the control operation.

[0009] The present disclosure provides a linearizer that compensates for the frequency dependency of distortion components of a power amplifier for transmission waves in high frequency bands of 100 GHz or higher and wide bands of several GHz or higher. [Means for solving the problem]

[0010] The technical matters described herein are not intended to explicitly or implicitly limit the invention described in the claims, nor to enable anyone other than those who benefit from the invention (e.g., the applicant and the right holder) to limit the invention described in the claims, but are provided simply to facilitate understanding of the gist of the invention. The outline of the invention from other perspectives can be understood, for example, from the claims at the time of filing of this patent application. The linearizer of the present disclosure is a linearizer connected to an input terminal of a power amplifier, and includes a predistorter and a filter connected to an output terminal of the predistorter, and the filter is characterized by having an out-of-band attenuation characteristic with a sufficiently large roll-off. [Effects of the Invention]

[0011] The linearizer of the present disclosure can compensate for the frequency dependency of distortion components of a power amplifier for transmission waves in high frequency bands of 100 GHz or more and wide bands of several GHz or more. [Brief explanation of the drawings]

[0012] [Figure 1] 1 shows the configuration of a linearizer according to a first embodiment. [Figure 2] 1A and 1B are diagrams for explaining division of a bandwidth, in which (a) is a schematic diagram showing the relationship between bandwidth B and power, and (b) is a schematic diagram showing divided bandwidths Bd obtained by dividing bandwidth B. [Figure 3] 10 shows the configuration of a linearizer according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the linearizer of the present disclosure will be described with reference to the drawings. Hereinafter, unless otherwise specified, N is a predetermined integer satisfying 2≦N, and i represents an integer satisfying 1 or more and N or less. Furthermore, in order to clarify the gist of the embodiment, illustrations and descriptions of components (such as a power supply unit and an intermediate amplifier) ​​that are actually necessary or potentially necessary but are considered non-essential to the embodiment will be omitted. In each figure, the reference numerals and other symbols of some components may be omitted to avoid complexity.

[0014] First Embodiment The linearizer 1 of the first embodiment shown in FIG. 1 is connected to an input terminal (not shown) of a power amplifier 900, and compensates for the nonlinear characteristics of the power amplifier 900.

[0015] The linearizer 1 includes a divider 10 , N predistorters 12 , N filters 14 connected to the N predistorters 12 in a one-to-one relationship, and a mixer 16 .

[0016] The divider 10 divides the input radio signal into N equal parts. The radio signal is an analog signal. The frequency band of the radio signal is the sub-terahertz band of 100 GHz or higher, for example, a frequency band of 100 GHz or higher and 300 GHz or lower, or a frequency band included in that frequency band.

[0017] The i-th predistorter 12-i among the N predistorters 12 divides the bandwidth B (for example, several GHz to several tens of GHz) of the above-mentioned radio signal into N divided bandwidths B d In the i-th split bandwidth of the d (See Fig. 2(b) for details) compensates for the frequency dependency of the distortion components contained in the radio signal. d is a bandwidth in which the predistorter 12 can perform distortion compensation, and is, for example, about several tens of MHz to several hundreds of MGHz. In other words, N is not an arbitrary value, but is a value obtained by dividing the bandwidth B of the radio signal by the (average) divided bandwidth B in which the predistorter 12 can perform distortion compensation. d This is a value close to the value obtained by dividing by . Scintera Networks' Adaptive RF Power Amplifier Linearizer SC1889 is known as a predistorter that compensates for the frequency characteristics of distortion components by adaptively changing the amplitude and phase applied to a radio signal in the analog signal domain (see references). In this way, the distortion compensation frequency band of the ith predistorter 12-i and the distortion compensation frequency band of the jth (where i ≠ j) predistorter 12-j are different from each other. (References) "Adaptive RF Power Amplifier Linearizer and Dual RMS Power Measurement Unit," https: / / www.analog.com / media / en / technical-documentation / data-sheets / sc1889.pdf

[0018] The i-th filter 14-i among the N filters has the i-th division bandwidth B iIn this case, the radio signal from the i-th predistorter 12-i passes through. As mentioned above, if the frequency components of the filters are mutually visible, it becomes impossible to distinguish between the radio signals that require coefficient control for distortion compensation. For this reason, it is desirable that the strength of the radio signal passing through one of the adjacent filters 14 is at least 10 dB lower than that of the radio signal passing through the other adjacent filter. Therefore, it is desirable that each filter 14 has out-of-band attenuation characteristics with a sufficiently large roll-off. The larger the roll-off (i.e., attenuation slope) of each filter 14, the better. For example, if the passband width of the filter 14 for a radio signal with a center frequency of 100 GHz is 10 GHz and the adjacent bandwidth is 10 GHz, considering that a roll-off of 1 dB / GHz will provide 10 dB of attenuation, the roll-off should preferably be 1 dB / GHz or greater, and more preferably 2 dB / GHz or greater.

[0019] The mixer 16 mixes the radio signals from the N filters 14 and outputs a single frequency signal. The radio signal from the mixer 16 is input to a power amplifier 900.

[0020] Second Embodiment The linearizer 2 of the second embodiment shown in FIG. 3 has a configuration in which a directional coupler 22, a measuring device 24, and a controller 26 are added to the configuration of the linearizer 1 of the first embodiment.

[0021] The radio signal from power amplifier 900, which has been branched by directional coupler 22, enters measuring device 24. Measuring device 22 measures the distortion components of the radio signal from power amplifier 900.

[0022] The controller 26 identifies amplitude and phase control amounts to be set for each of the N predistorters 14 so that the distortion components measured by the measuring instrument 24 are minimized in each of the N divided bandwidths described above, and sets the identified amplitude and phase control amounts for each of the N predistorters 14. Identification of the amplitude and phase control amounts can be achieved, for example, by the following process. The controller 26 prepares in advance three different combinations of amplitude control amount and phase control amount, and sets the amplitude control amount and phase control amount for each of the three combinations for the i-th predistorter 12-i at a certain frequency included in the i-th divided bandwidth, and the measuring instrument 24 measures the distortion components corresponding to each of the three combinations. Using the distortion components corresponding to each of the three combinations, the controller 26 fits the amplitude with a quadratic function and the phase with a sinusoidal function, and identifies the amplitude control amount and phase control amount when each function is minimized. This process is performed for each of a finite number of frequencies selected, for example, at equal intervals from the i-th divided bandwidth. Furthermore, the controller 26 may perform this process for a selected finite number of frequencies in the order from frequencies closest to the center frequency of the i-th division bandwidth to frequencies farthest from the center frequency, or in the order from frequencies farthest from the center frequency of the i-th division bandwidth to frequencies close to the center frequency.

[0023] <Addendum> Each aspect / embodiment described in the present disclosure may be any of the following: LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (x is, for example, an integer or decimal number)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE The present invention may be applied to at least one of systems using 802.20, UWB (Ultra-Wideband), Bluetooth (registered trademark), or other appropriate systems, and next-generation systems that are extended, modified, created, or defined based on these systems. The present invention may also be applied to a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A with 5G).

[0024] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0025] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0026] The determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0027] Instructions, information, etc. may be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired and / or wireless technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared and microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0028] The terms "determining" and "determining" can encompass a wide variety of actions. "Determining" can include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and so forth. "Determining" can also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and so forth. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0029] The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0030] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0031] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0032] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0033] Where articles are added by translation, such as a, an and the in English, the disclosure may include that the noun following these articles is in the plural form.

[0034] The technical features disclosed in the various embodiments and their modifications described above are not necessarily mutually exclusive, and technical features of one embodiment or its modifications may be applied to technical features of another embodiment or its modifications, provided that there is no contradiction from a technical viewpoint.

[0035] While the present invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the invention. Furthermore, many modifications can be made to adapt a particular system, device, or component thereof to the teachings of the present invention without departing from the essential scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but rather that the invention will include all embodiments falling within the scope of the appended claims.

[0036] Furthermore, the use of terms such as "first," "second," and the like (ordinal numerals), if any, does not denote order or importance; terms such as "first," "second," and the like (ordinal numerals) are used to distinguish elements. The terminology used herein is for the purpose of describing embodiments and is not intended to limit the invention in any way. The term "comprises" and its conjugations, when used in this specification and / or the appended claims, reveal the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The term "and / or" includes any and all combinations of one or more of the associated listed elements, if any. In the claims and the specification, unless otherwise specified, the use of words such as "connected," "coupled," "joined," "connected," or cognate words and all forms thereof does not necessarily negate the presence of one or more intermediate elements between two items, e.g., "connected" or "coupled" to each other or "connected" to each other. In the claims and the specification, the term "optional", if any, unless otherwise specified, should be understood as a term that represents the same meaning as the universal symbol ∀.

[0037] Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art and this disclosure, and should not be interpreted ideally or excessively formally unless explicitly defined.

[0038] It will be understood that in describing the present invention, many techniques and steps are disclosed. Each of these has distinct advantages, and each can be used in combination with one or more, or in some cases all, of the other disclosed techniques. Therefore, to avoid cluttering, this specification will refrain from describing every possible combination of individual techniques or steps. Nevertheless, the specification and claims should be read with the understanding that such combinations are fully within the scope of the present invention and claims.

[0039] The corresponding structure, material, acts, and equivalents of all functional elements combined with means or steps in the following claims are intended to include the structure, material, or acts, if any, that perform the function in combination with other elements.

[0040] Although the present invention has been described above with reference to exemplary embodiments, it is not limited to these embodiments. Various modifications and variations are possible without departing from the spirit of the present invention. The selected and described embodiments are intended to illustrate the principles of the present invention and its practical application. The present invention may be used in various embodiments with various modifications and variations, which are determined according to the expected use. All such modifications and variations are intended to be included within the scope of the present invention, as defined by the appended claims, and are intended to be accorded the same protection when interpreted in accordance with the breadth that is fairly, legally, and equitably to be given. [Explanation of symbols]

[0041] 1 Linearizer 10 distributor 12 Predistorter 14 Filters 16 Mixer 22 Directional coupler 24 Measuring instruments 26 Controller

Claims

1. A linearizer connected to an input terminal of a power amplifier to compensate for nonlinear characteristics of the power amplifier, N predistorters, where N is a predetermined integer satisfying 2≦N; N filters connected to the N predistorters in a one-to-one relationship; Including, an i-th predistorter among the N predistorters compensates for frequency dependence of a distortion component included in a radio signal in an i-th divided bandwidth among N divided bandwidths obtained by dividing a bandwidth of a radio signal in a sub-terahertz band of 100 GHz or more by N in the frequency domain, where i represents an integer greater than or equal to 1 and less than or equal to N; an i-th filter among the N filters passes the radio signal from the i-th predistorter in the i-th division bandwidth; the radio signal input to the power amplifier is the radio signal obtained by mixing the radio signals from the N filters; Linearizer.

2. 2. The linearizer according to claim 1, a measuring device for measuring distortion components of the radio signal from the power amplifier, a controller that specifies control amounts of amplitude and phase to be set in the N predistorters so that the distortion components measured by the measuring instrument are minimized in each of the N divided bandwidths, and sets the specified control amounts of amplitude and phase in the N predistorters; Contains A linearizer characterized by:

3. 3. The linearizer according to claim 2, The controller specifies the control amounts of the amplitude and phase to be set in the i-th predistorter in order from the frequency closest to the center frequency of the i-th division bandwidth to the frequency farthest from the center frequency. A linearizer characterized by:

4. 3. The linearizer according to claim 2, The controller specifies the control amounts of the amplitude and phase to be set in the i-th predistorter in order from the frequency farthest from the center frequency of the i-th division bandwidth to the frequency close to the center frequency. A linearizer characterized by:

5. 5. The linearizer according to claim 1, wherein: The roll-off of each of the N filters is 1 dB / GHz or greater. A linearizer characterized by:

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