Mlinc

Abstract

A multilevel linear amplifier with nonlinear components, MLINC (1), for a radio-frequency transmitter, the MLINC (1) comprising a first outphasing amplifier (2) designed to receive a first set of input signals (S11, S12) and to provide a first intermediate signal (S1) having a stepped envelope, which is dependent on a controlled part (θc1) of a phase modulation in the first set of input signals (S11, S12); a second outphasing amplifier (3) designed to receive a second set of input signals (S21, S22) and to provide a second intermediate signal (S2) having a stepped envelope, which is dependent on a controlled part (θc2) of a phase modulation in the second set of input signals (S21, S22); and a combining device (6) designed to combine the first intermediate signal and the second intermediate signal (S2) to form an output signal (Sout) having an envelope which is linearized on account of a phase symmetry of the first and second intermediate signals (S1, S2).

Description

[0001] Description

[0002] MLINC

[0003] TECHNICAL FIELD

[0004] The invention relates to a multi-stage linear amplifier with non-linear components (MLINC) having the features of the preamble of claim 1 and a method for operating an MLINC.

[0005] The following background is intended only to provide information necessary to understand the context of the inventive ideas and concepts disclosed herein. Therefore, this background section may contain patentable subject matter and should not be considered prior art.

[0006] BACKGROUND

[0007] The demand for high-data-rate wireless communications is constantly growing. To increase the data rate, both the linearity and bandwidth of the circuits in radio-frequency transmitters must be increased. This leads to increasing power consumption of the associated mobile phones and base stations, as there is an inherent trade-off between linearity and power efficiency in the power amplifiers (PAs), which are typically the most power-consuming part of the entire radio-frequency transmitter.

[0008] The present invention resolves the trade-off between linearity and power efficiency while enabling high-bandwidth modulation.

[0009] The invention is based on the object of improving the trade-off between linearity and power efficiency. This can provide simultaneous high-bandwidth modulation. SUMMARY

[0010] This summary is intended to introduce a selection of features and concepts of embodiments of the invention that are explained further in the specification. This summary is not intended to identify important or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0011] According to the invention, the above-mentioned object is achieved by the features of the independent claims.

[0012] Specifically, the task is solved by a multi-stage linear amplifier with non-linear components (also called MLINC) for a high-frequency transmitter or a high-frequency transmitter.

[0013] The MLINC includes a first phase-out amplifier. The first phase-out amplifier is configured to receive a first set of input signals. The first phase-out amplifier is configured to provide a first intermediate signal. The first intermediate signal may be based solely on the first set of input signals. The first intermediate signal has a stepped envelope. The stepped shape or envelope of the first intermediate signal depends on a (first) controlled portion of a (first) phase modulation in the first set of input signals.

[0014] The MLINC comprises a second phase-out amplifier. The second phase-out amplifier is configured to receive a second set of input signals. The second phase-out amplifier is configured to provide a second intermediate signal. The second intermediate signal can be based solely on the second set of input signals. The second intermediate signal has a stepped envelope. The stepped shape or envelope of the second intermediate signal depends on a (second) controlled part of a (second) phase modulation in the second set of input signals. The MLINC comprises a combining device. The combining device is configured to combine the first and second intermediate signals to form a (particularly common) output signal. The output signal has an envelope that is linearized due to a phase symmetry of the first and second intermediate signals.

[0015] The invention has the advantage of providing an improved compromise between linearity and power efficiency of the MLINC. In addition, it can provide high-bandwidth modulation.

[0016] It is to be understood in particular that the respective input signals are already phase-modulated by the (e.g., first and second) phase modulation before they are received by the MLINC described herein. Within the MLINC described herein, for example, no (further) modulation, namely amplitude modulation or phase modulation, may be provided.

[0017] The phase symmetry of the first and second intermediate signals can be understood as meaning that the (first and second) phase modulation is adjusted in such a way that the first and second phase-out amplifiers at the output have phase shifts of the same magnitude but different from each other, i.e. opposite phase shifts.

[0018] The first set of input signals may differ in phase and / or amplitude from the second set of input signals such that the two intermediate signals are equal in magnitude. For example, the first and second sets of input signals may be symmetrical but phase-shifted in opposite directions, for example by means of opposite phasing angles. The input signals of the first set of input signals may also be symmetrical but phase-shifted in opposite directions, for example by means of opposite first and second controlled parts of the (first) phase modulation. The same may apply to the input signals of the second set of input signals. These may be symmetrical but phase-shifted in opposite directions, for example by means of opposite first and second controlled parts of the (second) phase modulation.

[0019] The stepped shape or stepped envelope can be understood to mean that a dedicated envelope level can be set by the controlled part of the phase modulation. The controlled part can be the same in the first and second sets of input signals. In particular, the first and second controlled parts can, for example, each be the same. The term "controlled" can be understood to mean that programming takes place during operation or prior to operation of the MLINC in the radio-frequency transmitter. In one example, this can be carried out in the sense of a software-defined radio or other processor units mentioned below.

[0020] Advantageous embodiments of the invention are specified in the subclaims.

[0021] The input signals of the first and second sets of input signals may have equal amplitudes.

[0022] This simplifies the wiring of the MLINC or the high-frequency transmitter, resulting in cost savings.

[0023] The input signals of the first set of input signals may have the same (first) constant envelope. The input signals of the second set of input signals may have the same (second) constant envelope. The input signals of the first and second sets of input signals may have the same (first and second) constant envelope.

[0024] This also simplifies the wiring of the MLINC or the high-frequency transmitter and thus saves operating costs.

[0025] The first set of input signals and the second set of input signals may contain phase-modulated input signals. For example, the input signals of the first and second sets of input signals may be purely, i.e., exclusively, phase-modulated.

[0026] This can also save costs for interconnection and increase system performance.

[0027] The controlled part of the phase modulation in the first set of input signals may be equal to the controlled part of the phase modulation in the second set of input signals.

[0028] This allows circuit symmetry to be improved and circuit complexity to be reduced.

[0029] The first phase-out amplifier and the second phase-out amplifier may be non-isolating phase-out amplifiers.

[0030] This ensures effective coupling in the respective phase-out amplifiers, which can facilitate symmetrical phase matching.

[0031] The first phase-out amplifier and the second phase-out amplifier can each have (e.g., two) input nodes and one output node. The input nodes can form the inputs of the MLINC. Furthermore, the first and second phase-out amplifiers can each have a Chireix combiner. Each of the Chireix combiners can have passive components. The passive components can be complementary to each other. The passive components can have complex conjugate admittances. Each of the Chireix combiners can have 4-leads referenced to a carrier frequency of the radio-frequency transmitter.

[0032] The X / 4 lines referenced to the carrier frequency of the radio-frequency transmitter can each be connected between the output node and a corresponding input node. The passive components can each be connected between a corresponding input node and ground. The X / 4 lines referenced to the carrier frequency of the radio-frequency transmitter and the passive components can each share a common connection node.

[0033] Alternatively, the X / 4 lines referenced to the carrier frequency of the radio-frequency transmitter and the passive components can each be connected in series in the signal direction, for example, between the respective input nodes and output nodes. The X / 4 lines referenced to the carrier frequency of the radio-frequency transmitter and the passive components can each share a common connection node.

[0034] In an alternative, for example, instead of the Chireix combiner, a respective non-isolating combiner structure can be used. The respective non-isolating combiner structure can be configured to change a load impedance of the respective amplifier element across a phase of the respective input signal. As an example, the non-isolating combiner structure of the structure T 2 P in Fig.9 from IEEE Transactions On Circuits And Systems-I: Regular Papers, Vol. 64, No. 5, May 2017; Özen et al. : “A Generalized Combiner Synthesis Technique for Class-E Outphasing Transmitters”.

[0035] The combiner may have (two) input nodes. The input nodes of the combiner may each be connected to one of the output nodes of the first and second phase-out amplifiers. The combiner may have an output node. The output node may form an output of the MLINC. The combiner may have an isolating power combiner. The isolating power combiner may be a Wilkinson combiner. The power combiner may have a resistive element. The resistive element may be connected between the (two) input nodes of the combiner. The power combiner may have 4×4 lines referenced to the carrier frequency of the radio-frequency transmitter. The 4×4 lines referenced to the carrier frequency of the radio-frequency transmitter may each be connected between the output node of the combiner and the (two) input nodes of the combiner.

[0036] The MLINC can be an integrated circuit, for example a chip. The MLINC can be manufactured at least partially using stripline technology. For example, the striplines used can comprise a microstrip line, a symmetrical stripline, a coplanar line, or a symmetrical / asymmetrical double-strip line. For example, the λ / 4 lines related to the carrier frequency of the radio-frequency transmitter can each have essentially the same line width. The stripline technology can be adapted to a Zo system, for example a 50 ohm system, so that the λ / 4 lines related to the carrier frequency of the radio-frequency transmitter (at least of the power combiner) can each have λ2 Zo, for example approximately 71 ohms. The line width orThe characteristic impedance of the respective k / 4 lines referenced to the carrier frequency of the radio-frequency transmitter can be set to a characteristic impedance value, V2 Zo, for example, approximately 71 ohms. For example, the respective k / 4 lines referenced to the carrier frequency of the radio-frequency transmitter (at least the Chireix combiner) can be set to a characteristic impedance value, Zo, for example, approximately 50 ohms.

[0037] The characteristic impedance of the striplines can depend on the stripline substrate used for the MLINC and / or the stripline width, or can be adjusted accordingly. The aforementioned resistor of the power combiner can have a resistance of 2Zo, for example, 100 ohms.

[0038] This makes it possible to provide a simple circuit arrangement that can be manufactured cost-effectively.

[0039] The first phase-out amplifier may have a first set of amplifier elements. The second phase-out amplifier may have a second set of amplifier elements. The first set of amplifier elements may have the same number and / or type of amplifier elements. The second set of amplifier elements may have the same number and / or type of amplifier elements. The first set of amplifier elements and the second set of amplifier elements may have the same number and type of amplifier elements.

[0040] This allows the symmetry and circuit complexity of the MLINC to be improved.

[0041] A respective amplifier element of the first and second sets of amplifier elements can be connected downstream of a corresponding one of the input nodes of the first and second phase-out amplifiers in the signal direction. For example, a respective amplifier element of the first and second sets of amplifier elements can be connected between a corresponding one of the input nodes of the first and second phase-out amplifiers and a corresponding one of the passive components of the first and second Chireix combiners. Thus, a respective amplifier element can be connected between a corresponding input node and a corresponding connection node of one of the first and second phase-out amplifiers.

[0042] This results in an optimized phasing structure.

[0043] In one example, a voltage supply may be provided for the amplifier elements of the first and second phase-out amplifiers. The voltage supply may be symmetrical. For example, the voltage supply may be the same for all amplifier elements of the first and second phase-out amplifiers, in particular, it may provide the same power / voltage. An arrangement of voltage supply points may also be the same for all amplifier elements of the first and second phase-out amplifiers.

[0044] Individual circuit blocks, for example, the first and / or second phase-out amplifiers and / or the power combiner of the MLINC, can be arranged symmetrically. This can provide a simplified circuit.

[0045] All input signals can contain an information part that represents the data to be transmitted.

[0046] The above-mentioned object is also achieved by a method for operating a multi-stage linear amplifier with non-linear components (MLINC) of a radio frequency transmitter or for a radio frequency transmitter.

[0047] The method comprises receiving a first and second set of input signals. The receiving preferably occurs simultaneously.

[0048] The method comprises providing first and second intermediate signals, each with a stepped envelope dependent on a controlled portion of a phase modulation in a corresponding one of the first and second sets of input signals. The provision preferably occurs simultaneously. The first set of input signals is preferably provided as a single common first intermediate signal. The second set of input signals is preferably provided as a single common second intermediate signal.

[0049] The method comprises combining the first and second intermediate signals into a common output signal having a linearized envelope due to a phase symmetry of the first and second intermediate signals. The combining preferably occurs simultaneously. The first and second intermediate signals are preferably combined into a single common output signal.

[0050] In other words, the invention relates to the use of highly efficient, non-isolating PAs in a multi-stage LINC architecture. This allows the transmission waveform to be controlled solely by phase modulation. This approach increases the possible modulation bandwidth and makes signal generation significantly simpler and cheaper compared to the prior art. In particular, the radio-frequency transmitter presented here can be integrated into mobile network infrastructure or mobile phones.

[0051] Although some of the aspects described above have been described with reference to the method, these aspects may also apply to the MLINC. Likewise, the aspects described above with reference to the MLINC may apply to the method accordingly.

[0052] It will be apparent to those skilled in the art that the explanations presented herein may be implemented using hardware circuits, software means, or a combination thereof. The software means may be associated with programmed microprocessors, ASICs (application-specific integrated circuits), and / or DSPs (digital signal processors).

[0053] In one example, the MLINC and the radio frequency transmitter may be implemented at least in part as a computer, logic circuit, FPGA (field programmable logic gate array), microprocessor, microcontroller, vector processor, processor-integrated core, CPU (e.g., with multiple cores), coprocessor (microprocessor supporting the CPU), GPU (graphics processing unit), and / or DSP.

[0054] In the MLINC and the radio-frequency transmitter in general, for example, methods can be applied that are related to pipelining the data to be transmitted or the corresponding components, such as the information component, the controlled component, and / or the other components of the phase modulation listed in the detailed description. Instead of processing an entire instruction in one clock cycle of the processor used in the MLINC or the radio-frequency transmitter, only a sub-task of it, e.g., a portion of the data to be transmitted or one or more parts of the phase modulation, is processed. The various sub-tasks of several instructions are processed simultaneously.Furthermore, methods in the sense of multithreading can be applied to the data to be transmitted or to one or more parts of the phase modulation and further developments thereof, for example simultaneous multithreading of the data to be transmitted or one or more parts of the phase modulation. This allows for better utilization of the processors due to the parallel use of multiple processor cores. The processor contained in the MLINC or the radio-frequency transmitter can be connected to a buffer memory of the MLINC or the radio-frequency transmitter, which can temporarily store the data to be transmitted or one or more parts of the phase modulation before and / or after the processing of the data to be transmitted or the part thereof, or one or more parts of the phase modulation. The buffer memory can be in a volatile memory device of the MLINC or the radio-frequency transmitter, e.g.A DRAM or a non-volatile memory device of the MLINC or the radio-frequency transmitter, e.g., an SSD, can be integrated. This can increase the performance of the MLINC or the radio-frequency transmitter.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the meaning generally understood by one skilled in the art in the field of high-frequency or ultra-high-frequency technology relevant to the present disclosure; they are neither too broad nor too narrow. If technical terms are used incorrectly and thus do not express the technical idea of ​​the present disclosure, they should be replaced with technical terms that provide a correct understanding to those skilled in the art. The general terms used herein are to be interpreted based on the definition found in the dictionary or according to technical slang.

[0056] Although terms such as "first" or "second," etc., may be used to describe different components, these components are not limited to these terms. The above terms are intended solely to distinguish one component from another. For example, a first component may be referred to as a second component, and a second component may be referred to as a first component.

[0057] In this context, if a component is "connected" or "communicates" with another component, this may mean that it is directly connected or communicates with it; however, it should be noted that another component may be present in between. On the other hand, if a component is "directly connected" or "directly communicates" with another component, this means that there are no other components in between.

[0058] The process steps described herein should not be interpreted as requiring them to be performed in a particular order, unless expressly or implicitly stated otherwise, for example, if these process steps cannot be interchanged for technical reasons. The process steps described herein may also be performed directly, sequentially, continuously, and / or successively. However, other process steps may also be included in between.

[0059] BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Further objects, features, advantages, and possible applications will become apparent from the following description of non-limiting embodiments with reference to the accompanying drawings. The same or similar elements in the drawings are always provided with the same or similar reference numerals. Detailed explanations of well-known functions and structures are omitted if they would detract from the invention.

[0061] The invention is explained in more detail using embodiments with reference to the attached schematic figures.

[0062] In these show:

[0063] FIG. 1 shows a view of an MLINC;

[0064] FIG. 2 is a view of an input signal of the MLINC;

[0065] FIG. 3 shows a view of an intermediate signal of the MLINC; FIG. 4 shows a view of the output signal of the MLINC;

[0066] FIG. 5 shows a comparison view between the MLINC and a conventional Chireix amplifier; and

[0067] FIG. 6 is a view of a method of operating the MLINC.

[0068] DETAILED DESCRIPTION

[0069] The MLINC 1 and the method S60 therefor will now be described with reference to the embodiments. Without being limited thereto, specific details are explained to provide a deeper understanding of the invention.

[0070] To increase the data rate in wireless communications, either the modulation order or the modulation bandwidth must be increased. High modulation order requires circuits with high linearity, and high modulation bandwidth requires circuits with high bandwidth. Both requirements must be met by high-performance radio frequency (RF) power amplifiers (PAs). When designing RF PAs for mobile phones and base stations, there is an inherent trade-off between linearity and efficiency.

[0071] Modern high-data-rate communication standards require linear amplification of the transmitted signal to utilize complex modulation formats such as QAM and OFDM. To achieve the peak-to-average power ratio required for these modulation formats, the power amplifiers must be turned down from their maximum output power, resulting in poor power efficiency. Typically, the power amplifiers are one of the most power-hungry components of the radio frequency transmitter, as they generate the high-power signal for transmission. Therefore, increasing the power efficiency of the power amplifiers leads to longer battery life for mobile phones and lower operating costs for cellular network base stations.

[0072] Such a compromise between linearity and efficiency is achieved by the MLINC 1 of Fig. 1, which uses linear amplification with nonlinear components (LINC) to ensure linear amplification and to achieve efficiency by introducing discrete amplitude stages (cf. Fig. 3).

[0073] Fig. 1 shows a schematic diagram of an MLINC 1 with a combining device, such as a Wilkinson combiner. The amplitude stages are not generated by changing the supply voltage or the input amplitude of the PAs. To ensure linear amplification with increased modulation bandwidth, the control of the stages and the control of the phase-out angle (also referred to herein as the phase-out section) must be synchronized. The control of the stages and the control of the phase-out angle are not performed via two different paths, which would complicate synchronization and limit the maximum modulation bandwidth. Here, control is performed in phase modulation, and thus efficiency is not limited to the maximum efficiency of, for example, a conventional Doherty amplifier. Pure phase modulation without amplitude modulation eliminates the need for linear driver stages (with poor efficiency).

[0074] The MLINC 1 uses non-isolating phase-out amplifiers 2 and 3 to generate the stages for the MLINC 1. The stages are controlled by a discrete set of phases that can be calibrated before operation. Between two stages, the output amplitude is linearly controlled via LINC. In this way, the output can be linearly controlled over the entire dynamic range. Fig. 1 shows the implementation of the stage generator using two phase-out amplifiers 2 and 3, preferably Chireix amplifiers, although these can generally be implemented using any non-isolating phase-out amplifier structure. Figs. 2 to 4 show typical waveforms for corresponding signals at different tapping points (input and output nodes) of the MLINC 1 using any 4-stage design (cf. Fig. 3).The architecture of the MLINC 1 allows both the phase-out section 4>o and the tap-adjustment section(s) 0ci - 0c2 to be controlled by the same phase-modulated input signals Sn - S22 provided to the amplifier elements PAn - PA22, and they are therefore synchronized from the outset, enabling broadband modulation. Furthermore, the non-isolating phase-out amplifiers 2 and 3 are potentially more efficient than Doherty amplifiers, and therefore the MLINC 1 is more efficient than a conventional Doherty MLINC. This is clearly shown in Fig. 5, which compares efficiency curves for an arbitrary 21-stage MLINC 1 design with a conventional Chireix amplifier circuit. This demonstrates the high efficiency of the MLINC 1 described herein.

[0075] Fig. 6 describes the method S60 for operating the MLINC 1 of Fig. 1. Here, the method S60 comprises receiving S61 a first set of input signals Sn and S12, with Sn = cn e i(e+e ° +ecl) and S12 = C12 e i(e+eo ' ecl) , and a second set of input signals S21 and S22, with S21 = C21 e i(e ' e ° +ec2) and S22 = C22 e i(e ' e °- 0c2 ) j n einem For example, both the constant input components cn, C12, C21 and C22 can be the same. In this example, the step adjustment components 0ci and 0 C 2 also be the same.

[0076] At S62, the respective signals Sn to S22 (see signal curve in Fig. 2) are amplified by the respective amplifier elements PAn to PA22 of the phase-out amplifiers 2 and 3. Chireix combiners 4 and 5 are used to provide first and second intermediate signals S1 and S2 from the amplified signals of the first and second sets of input signals Sn to S22, with Si = Ai v ii(0ci)e i(<l ' +<l ' o) and S2 = Aivi2(0c2)e i(<l '' <l ' o) The first and second intermediate signals Si and S2 each have a stepped envelope with the amplitudes of the intermediate signals Aivii(Oci) and Aivi2(0c2). The envelope depends on a controlled part 0ci and / or 0 C2 of a phase modulation in the input signals Sn to S22. For this purpose, a Chireix combiner 4 and 5 is used, each of which has two complex conjugate passive components with respective admittance values ​​B and connected X / 4 lines. At S63, the first and second intermediate signals Si and S2 are combined to form an output signal S ou t combined with S ou t = Ae*®. The combination is carried out via the combining device 6, which in Fig. 1 has a Wilkinson combiner with a resistor R for isolation and two X / 4 lines. The output signal Sout has a linearized envelope due to the phase symmetry of the first and second intermediate signals Si and S2 (cf. e i(<l ' o) and e' ( ' <l ' o) ).

[0077] For a better understanding of the invention, the phase modulation components are shown below. These components are described herein as phase modulation components and represent corresponding time-normalized phase angles. The output phase control section 9 represents the output phase control component, with 0 = cf> + 4>ivi,cm, where c|) represents the phase information of the symbol to be transmitted, i.e., the information portion of the data to be transmitted. 4>i v i,cm forms the phase compensation of the stage-dependent phase distortion, which is the same for both phase-out amplifiers 2 and 3 (common mode). 0 O represents an output amplitude control part that sets the output amplitude A, with 0 O = $0 + $ivi,dm, where represents the phase-out part at the input of the insulating combining device 6. 4>i vi,dm forms the phase compensation of the stage-dependent phase distortion, which is different for the two phase-out amplifiers 2 and 3 (differential mode).

[0078] Since both the control of the stages AMI-A 2 and the phase-out angle or phase-out part s 4>o is carried out by a phase-modulated signal, the entire signal generation is simplified, since the RF circuits only have to process constant envelope signals.

[0079] Due to the advantages described in the previous section, this invention enables wider-band modulation with greater power efficiency while simplifying signal generation. This can increase the data rate of wireless communication standards and reduce the power consumption of radio-frequency transmitters. It should be noted that all of the above-described components, viewed individually and in any combination, particularly the details shown in the drawings, are claimed as essential to the invention. Modifications will be apparent to those skilled in the art.

[0080] LIST OF REFERENCE SYMBOLS

[0081] 1 MLINC

[0082] 2 First phase-out amplifier

[0083] 3 Second phase-out amplifier

[0084] 4 First Chireix combiner

[0085] 5 Second Chireix combiner

[0086] 6 Combining device

[0087] B Admittance amount

[0088] R resistance

[0089] PA11 - PA12 amplifier elements

[0090] S11 - S12 First set of input signals

[0091] S21 - S22 Second set of input signals

[0092] S1 First intermediate signal

[0093] S2 Second intermediate signal en - C22 constant input components

[0094] Alvll- A1V12 amplitudes of the intermediate signals

[0095] A Output amplitude

[0096] 0 Output phase control part

[0097] 0o Output amplitude control part

[0098] 0C1- 0C2 step adjustment parts

[0099] * Information section

[0100] C|>o phasing part

Claims

Claims 1. A multi-stage linear amplifier with nonlinear components, MLINC (1), for a radio frequency transmitter, comprising MLINC (1): a first phase-out amplifier (2) configured to receive a first set of input signals (Sn, S12) and provide a first intermediate signal (Si) with a stepped envelope dependent on a controlled part (0ci) of a phase modulation in the first set of input signals (Sn, S12); a second phase-out amplifier (3) configured to receive a second set of input signals (S21, S22) and provide a second intermediate signal (S2) with a stepped envelope dependent on a controlled part (0c2) of a phase modulation in the second set of input signals (S21, S22);and a combining device (6) configured to combine the first and second intermediate signals (S2) into an output signal (Sout) which has a linearized envelope due to a phase symmetry of the first and second intermediate signals (Si, S2).

2. MLINC (1) according to claim 1, characterized in that the input signals of the first and second set of input signals (Sn, S12, S21, S22) have the same amplitudes.

3. MLINC (1) according to claim 1 or 2, characterized in that the input signals of the first set of input signals (Sn, S12, S21, S22) and / or second set of input signals (Sn, S12, S21, S22) have the same constant envelope.

4. MLINC (1) according to one of the preceding claims, characterized in that the first set of input signals (Sn, S12) and the second set of input signals (S21, S22) contain phase-modulated input signals.

5. MLINC (1) according to one of the preceding claims, characterized in that the controlled part (0ci) of the phase modulation in the first set of input signals (Sn, S12) is the same as the controlled part (0c2) of the phase modulation in the second set of input signals (S21, S22).

6. MLINC (1) according to any of the preceding claims, characterized in that the first phase-out amplifier (2) and the second phase-out amplifier (3) are non-isolating phase-out amplifiers. MLINC (1) according to one of the preceding claims, characterized in that the first phase-out amplifier (2) and the second phase-out amplifier (3) each have input nodes forming inputs of the MLINC (1) and an output node, and each further each have a Chireix combiner (4, 5), and each of the Chireix combiners (4, 5) comprises: passive components having complex conjugate admittances (- jB, jB) to each other and each connected between a corresponding input node and ground; and / or k / 4 lines referenced to a carrier frequency of the radio frequency transmitter, each connected between the output node and a corresponding input node.MLINC (1) according to claim 7, characterized in that the combining device (6) has input nodes, each connected to one of the output nodes of the first and second phase-out amplifiers (3), an output of the output node forming the MLINC (1), and an isolating power combiner. MLINC (1) according to any of the preceding claims, characterized in that the first phase-out amplifier (2) has a first set of amplifier elements (PAn, PAn) and the second phase-out amplifier (3) has a second set of amplifier elements (PA21, PA22), and the first set of amplifier elements (PAn, PA12) and / or the second set of amplifier elements. (PA2I, PA22) has the same amplifier elements in number of amplifier elements and / or type of amplifier elements.

10. Method (S60) for operating a multi-stage linear amplifier with non-linear components, MLINC (1), for a high-frequency transmitter, comprising the method (S60): Receiving (S61) a first and second set of input signals (Sn, S12, S21, S22); Providing (S62) a first and second intermediate signal (Si, S2) each with a stepped envelope that depends on a controlled part (0ci, 0c2) of a phase modulation in a corresponding part of the first and second sets of input signals (Sn, S12, S21, S22); and Combining (S63) the first and second intermediate signals (Si, S2) to form an output signal (S O ut), which has a linearized envelope due to a phase symmetry of the first and second intermediate signals (Si, S2).

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