An apparatus for improving linearity of an ultra-wideband radio frequency amplification link

Abstract

The application discloses a device for improving the linearity of an ultra-wideband radio frequency amplification link, and belongs to the radio frequency technical field. The device comprises an ultra-wideband in-phase power division network, a harmonic suppression network and an ultra-wideband in-phase synthesis network which are sequentially arranged. The ultra-wideband in-phase power division network is used for dividing a radio frequency input signal into three radio frequency signals with the same amplitude and phase. The harmonic suppression network comprises three wideband radio frequency amplification branches, and the three radio frequency signals are respectively amplified and phase-shifted through one wideband radio frequency amplification branch. The ultra-wideband in-phase synthesis network is used for synthesizing the three amplified radio frequency signals into one radio frequency output signal. The application starts from the radio frequency link architecture, introduces a high-order harmonic suppression branch, optimizes the phase shift amount of multiple suppression branches, ensures the maximum synthesis of the fundamental wave signal, realizes the maximum suppression of the second-order, third-order and other high-order harmonics, and can adjust the optimization parameters according to the parasitic bar amplitude parameters of the fixed phase shifter, so as to meet the actual circuit design requirements.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency technology, specifically relating to a device for improving the linearity of an ultra-wideband radio frequency amplification link. Background Technology

[0002] In many fields such as wireless communication (5G / 6G base stations), radar detection, electronic countermeasures, and satellite navigation, broadband or even ultra-wideband radio frequency (RF) amplification links serve as the core structure for signal transmission, and their performance directly affects the system's communication distance, signal quality, anti-interference capability, and detection range. With technological advancements, systems are placing higher demands on RF amplification links: operating bandwidth must cover multiple frequency bands or even extend to multiple octaves (e.g., from Sub-6GHz to millimeter waves), and output power must meet the requirements for long-distance transmission (e.g., radar pulse power can reach kilowatt levels).

[0003] Wideband amplifiers generate high-order harmonics due to their nonlinear characteristics during operation, leading to intermodulation distortion and consequently causing adverse effects such as signal waveform distortion, reduced signal-to-noise ratio, and decreased efficiency. Therefore, wideband or ultra-wideband systems require RF links to balance high linearity with low harmonic distortion to avoid signal distortion and spectral leakage, thereby improving system performance.

[0004] On the one hand, power back-off technology can directly improve the nonlinear characteristics of the amplifier, thereby enhancing the linearity of the system. However, this sacrifices output power, leading to a significant reduction in the overall system efficiency. On the other hand, while ensuring high-efficiency amplifier output, phase synthesis techniques such as balanced amplifier circuits can improve higher harmonics to some extent. For example, in patent CN114285429, a 180° phase shift of a broadband balun is used to cancel the second harmonic, but ultimately only 30dBc of suppression is achieved for the second harmonic, with no improvement for harmonics above the third order. The suppression effect is limited, and the improvement in system linearity is also limited.

[0005] To address the aforementioned requirements, it is imperative to improve the linearity of the ultra-wideband RF amplification link without compromising amplifier efficiency. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a device for improving the linearity of ultra-wideband radio frequency (RF) amplification links. Starting from the RF link architecture, this invention introduces higher harmonic suppression branches and optimizes the phase offset of multiple suppression branches. This ensures maximum synthesis of the fundamental signal while maximizing the suppression of second, third, and other higher harmonics. Furthermore, the optimized parameters can be adjusted based on the parasitic amplitude parameters of the fixed phase shifter to meet practical circuit design requirements.

[0007] The technical solution adopted in this invention is as follows:

[0008] An apparatus for improving the linearity of an ultra-wideband radio frequency amplifier link, characterized in that it comprises: an ultra-wideband in-phase power divider network, a harmonic suppression network, and an ultra-wideband in-phase synthesizer network;

[0009] The ultra-wideband in-phase power divider network is used to divide the radio frequency input signal into three radio frequency signals with equal amplitude and the same initial phase, and then transmit them to the harmonic suppression network.

[0010] The harmonic suppression network comprises three broadband RF amplification branches. The three RF signals are transmitted to the ultra-wideband in-phase synthesis network after passing through one broadband RF amplification branch respectively. The first broadband RF amplification branch includes a first ultra-wideband amplifier. The second broadband RF amplification branch includes a fixed phase shifter ΔP1, a second ultra-wideband amplifier, and a fixed phase shifter ΔP3 cascaded in sequence. The third broadband RF amplification branch includes a fixed phase shifter ΔP2, a third ultra-wideband amplifier, and a fixed phase shifter ΔP4 cascaded in sequence. The phase shifts of the fixed phase shifters ΔP1, ΔP2, ΔP3, and ΔP4 are ΔP1, ΔP2, ΔP3, and ΔP4, respectively, and the values ​​of ΔP1, ΔP2, ΔP3, and ΔP4 are relative offsets relative to the links before and after the first ultra-wideband amplifier.

[0011] The ultra-wideband in-phase synthesis network is used to synthesize the three radio frequency signals output by the harmonic suppression network into one radio frequency output signal, thereby achieving maximum amplitude synthesis of the fundamental signal and cancellation suppression of higher harmonics, thus improving the linearity of the overall radio frequency amplification link.

[0012] Preferably, the first ultra-wideband amplifier, the second ultra-wideband amplifier, and the third ultra-wideband amplifier are the same ultra-wideband amplifier.

[0013] Preferably, without considering the parasitic amplitude modulation of the phase shifter and the individual differences of the ultra-wideband amplifier, a typical optimal combination of phase shifters is: ΔP1 = 120°, ΔP2 = 240°, ΔP3 = 240°, ΔP4 = 120°. Under this condition, the harmonic suppression of the RF output signal is optimal.

[0014] Preferably, the optimization process for the phase shift amounts ΔP1, ΔP2, ΔP3, and ΔP4 is as follows:

[0015] a) Establish a parameterized nonlinear model of the ultra-wideband amplifier;

[0016] b) Determine the expression of the RF signal before each ultra-wideband amplifier; let the phase shifts of fixed phase shifters ΔP1, ΔP2, ΔP3, and ΔP4 be ΔP1, ΔP2, ΔP3, and ΔP4, respectively. Combine the parameterized nonlinear model to obtain the expression of the RF signal after amplification by the ultra-wideband amplifier, and the expression of the final synthesized RF output signal.

[0017] c) Based on the higher harmonic components in the RF output signal expression, establish the expressions for the second harmonic suppression ratio H2 and the third harmonic suppression ratio H3;

[0018] d) Using phase shifts ΔP1, ΔP2, ΔP3, and ΔP4 as optimization variables, the optimization objective is to maximize the minimum value among the second harmonic suppression ratio H2 and the third harmonic suppression ratio H3. Through iterative optimization using the optimization algorithm, the optimal combination of phase shifts at each stage is output.

[0019] Preferably, the optimization process for the phase shift amounts ΔP1, ΔP2, ΔP3, and ΔP4 further includes:

[0020] Because the phase shifter has parasitic amplitude modulation, after step d), the expression of the radio frequency signal in step b) is corrected according to the stage-optimal phase shift amount, and steps c) and d) are repeated until convergence, and the optimal phase shift amount combination is output.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) The structure is simple, only 4 fixed phase shifters are added, and the high harmonic suppression of ultra-wideband signals can be greatly improved by optimizing their phase shift amount, while ensuring the maximum amplitude synthesis of the fundamental signal. Ideally, the suppression of the second harmonic can reach 133dBc and the third harmonic can reach 117.8dBc.

[0023] (2) The parasitic amplitude modulation parameter of the phase shifter is considered in the optimization process of the phase shifter. The optimization design can be carried out according to the actual phase shifter parameters, thereby ensuring the maximum harmonic suppression of the final designed link and improving the overall link linearity. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a block diagram illustrating the principle of a device for improving the linearity of an ultra-wideband radio frequency amplification link according to the present invention.

[0026] Figure 2 This is a flowchart of the optimization process for the fixed phase shift offset of the harmonic suppression branch in this invention.

[0027] Figure 3 This is a block diagram of a simulation model of the device according to an embodiment of the present invention;

[0028] Figure 4 This is a simulation model diagram of a conventional RF amplification link;

[0029] Figure 5 The simulation output spectrum component results of a conventional RF amplification link are shown in the figure.

[0030] Figure 6 This is a simulation output spectrum component result diagram of the device in an embodiment of the present invention;

[0031] Figure 7 This is a graph showing second harmonic suppression data under different phase shift errors according to an embodiment of the present invention.

[0032] Figure 8 This is a graph showing the third harmonic suppression data under different phase shift errors according to an embodiment of the present invention. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described implementation examples are only a part of the implementation examples of the present invention, not all of them. All other implementation examples obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This embodiment provides a device for improving the linearity of an ultra-wideband radio frequency amplification link, such as... Figure 1 As shown, the device consists of an ultra-wideband in-phase power divider network (101), a harmonic suppression network (102), and an ultra-wideband in-phase synthesis network (103); wherein, the harmonic suppression network (102) consists of four fixed phase shifters with different phase offsets and three ultra-wideband amplifiers.

[0035] The ultra-wideband in-phase power divider (101) divides the RF input signal into three RF signals with the same amplitude and initial phase, which are then fed into the harmonic suppression network (102).

[0036] The harmonic suppression network (102) includes three branches. In the first broadband RF amplification branch, the RF signal is output after passing through an ultra-wideband amplifier (104). In the second broadband RF amplification branch, the RF signal is output after passing through a fixed phase shifter ΔP1 (105), an ultra-wideband amplifier (104), and a fixed phase shifter ΔP2 (106) in sequence. In the third broadband RF amplification branch, the RF signal is output after passing through a fixed phase shifter ΔP3 (107), an ultra-wideband amplifier (104), and a fixed phase shifter ΔP4 (108) in sequence. The phase shifts of the fixed phase shifters in the second and third branches are ΔP1, ΔP2, ΔP3, and ΔP4, respectively, and are all relative to the links before and after the ultra-wideband amplifier (104) in the first branch.

[0037] Figure 3 The following is a block diagram of the simulation model of the device in this embodiment. The simulation parameters set in the simulation model are as follows: the RF input signal frequency is 800MHz and the power is 10dBm; the power divider and combiner are both ideal power dividers to achieve lossless, in-phase output or synthesis of three RF signals; the ultra-wideband amplifier adopts a packaged model, and its typical gain at 800MHz frequency is about 14.2dB.

[0038] In this embodiment, the optimization process for the optimal phase shift values ​​of phase shift quantities ΔP1, ΔP2, ΔP3, and ΔP4 is as follows:

[0039] a) Establish a parameterized nonlinear model of the ultra-wideband amplifier in Matlab numerical analysis software: Where x(t) represents the input signal, y(t) represents the output signal, and α1, α2, and α3 represent nonlinear parameters. In this embodiment, the nonlinear parameters corresponding to the packaged amplifier model are: α1=6, α2=0.02255, and α3=0.224.

[0040] b) Let the phase shifts of fixed phase shifters ΔP1, ΔP2, ΔP3, and ΔP4 be ΔP1, ΔP2, ΔP3, and ΔP4, respectively; assume that the three RF signals output by the ultra-wideband in-phase power divider network are all... Where A represents the RF signal amplitude and ω represents the RF signal frequency; then the RF signals input to the ultra-wideband amplifier in the first, second, and third branches are respectively , , Where c1 and c2 are the parasitic amplitude modulation effects of the second and third branch phase shifters on the radio frequency signal, respectively;

[0041] Taking the first branch as an example, the RF signal output by the first branch can be obtained through series expansion as follows:

[0042] (1)

[0043] Similarly, the RF signals output by the second and third branches can be obtained as shown in equations (2) and (3), respectively:

[0044] (2)

[0045] (3)

[0046] Based on equations (1), (2), and (3) above, the final synthesized radio frequency output signal is obtained as follows:

[0047] (4)

[0048] c) The second and third harmonic suppression ratios H2 and H3 of the final RF synthesized output signal can be obtained according to the expression in equation (4), as shown in equations (5) and (6) below.

[0049] (5)

[0050] (6)

[0051] It can be seen from equations (5) and (6) that there exists an optimal combination of phase shifts ΔP1, ΔP2, ΔP3, and ΔP4 that maximizes the second and third harmonic suppression ratios H2 and H3. In other words, the method of this invention can achieve high-order harmonic suppression of the RF output signal.

[0052] d) Using phase shifters ΔP1, ΔP2, ΔP3, and ΔP4 as optimization variables, the optimization objective is to maximize the minimum value of the second and third harmonic suppression ratios of the RF output signal (i.e., to ensure optimal suppression of higher harmonics). The optimal combination of phase shifters is obtained by using a genetic algorithm.

[0053] In this embodiment, the parasitic amplitude modulation parameters are set to c1 = c2 = 1, and the optimal phase shift combination is finally obtained as ΔP1 = 120°, ΔP2 = 240°, ΔP3 = 240°, ΔP4 = 120°.

[0054] exist Figure 3 In the simulation model shown, the optimal combination of phase shifts is input for simulation, and the following results can be obtained: Figure 6 The output spectral component results are shown in the figure. From Figure 6As can be seen, with an input power of 10dBm and a frequency of 800MHz at the RF input port, the final output signal power of this embodiment is 24.3dBm@800MHz, -110dBm@1.6GHz, and -92.8dBm@2.4GHz, respectively. Based on the output spectrum results, the second and third harmonic suppression degrees of the output signal at the current input frequency can be calculated to be 133dBc and 117.8dBc, respectively.

[0055] In contrast, such as Figure 4 As shown, a conventional RF amplification link using the same packaged amplifier model is established in the simulation software as a comparative simulation model, and its simulation parameters are the same as those of the conventional RF amplification link. Figure 3 All the simulation models shown are identical.

[0056] Figure 5 The output spectrum results of the comparative simulation model are given: when the RF input signal is 800MHz and the input power is 10dBm, the link output signal power is 24.3dBm@800MHz, -30.1dBm@1.6GHz, -16.5dBm@2.4GHz, -27.7dBm@3.2GHz, and -24.9dBm@4GHz, respectively. Based on the output spectrum results, the second, third, fourth, and fifth harmonic suppression of the packaged amplifier at the current input frequency can be calculated to be 54.4dBc, 40.8dBc, 52dBc, and 49.2dBc, respectively.

[0057] contrast Figure 5 , Figure 6 The simulation spectrum results show that, compared to the previous embodiment, this embodiment... Figure 4 The conventional amplification link shown in the figure improved the suppression of second, third, fourth, and fifth harmonics by 78.6 dB, 77 dB, 9.3 dB, and 35.2 dB, respectively, indicating that the present invention can significantly improve the overall suppression of higher harmonics.

[0058] Considering the phase error of the phase shifter in practical applications, according to Figure 3 The simulation model shown underwent optimal value error analysis. By adjusting the phase shift of the four fixed phase shifters within a range of ±20° from the optimal value, the second and third harmonic suppression levels of the final link under different error conditions were obtained as follows: Figure 7 , Figure 8 As shown. From Figure 7It can be seen that when the phase shifts ΔP1, ΔP2, ΔP3, and ΔP4 vary within an error range of ±10°, the highest suppression level for the second harmonic is 133dBc, and the lowest is 78dBc; for the third harmonic, the highest suppression level is 117.8dBc, and the lowest is 63.6dBc. Compared to conventional single-channel RF amplification links, this invention can still achieve a high level of high-order harmonic suppression within a larger error range.

[0059] As can be seen, the method and apparatus for improving the linearity of an ultra-wideband radio frequency amplification link provided by the present invention effectively improves the suppression of high-order harmonics in the radio frequency amplification link and has good tolerance, which can meet the usage requirements of ultra-wideband radio frequency amplification links.

Claims

1. A device for improving the linearity of an ultra-wideband radio frequency amplification link, characterized in that, include: Ultra-wideband in-phase power divider network, harmonic suppression network, ultra-wideband in-phase synthesizer network; The ultra-wideband in-phase power divider network is used to divide the radio frequency input signal into three radio frequency signals with equal amplitude and the same initial phase, and then transmit them to the harmonic suppression network. The harmonic suppression network comprises three broadband RF amplification branches. The three RF signals are transmitted to the ultra-wideband in-phase synthesis network after passing through one broadband RF amplification branch respectively. The first broadband RF amplification branch includes a first ultra-wideband amplifier. The second broadband RF amplification branch includes a fixed phase shifter ΔP1, a second ultra-wideband amplifier, and a fixed phase shifter ΔP3 cascaded in sequence. The third broadband RF amplification branch includes a fixed phase shifter ΔP2, a third ultra-wideband amplifier, and a fixed phase shifter ΔP4 cascaded in sequence. The phase shifts of the fixed phase shifters ΔP1, ΔP2, ΔP3, and ΔP4 are ΔP1, ΔP2, ΔP3, and ΔP4, respectively, and the values ​​of ΔP1, ΔP2, ΔP3, and ΔP4 are relative offsets relative to the links before and after the first ultra-wideband amplifier. The ultra-wideband in-phase synthesis network is used to synthesize the three radio frequency signals output by the harmonic suppression network into one radio frequency output signal, thereby achieving maximum amplitude synthesis of the fundamental signal and cancellation suppression of higher harmonics, thus improving the linearity of the overall radio frequency amplification link.

2. The apparatus for improving the linearity of an ultra-wideband radio frequency amplification link as described in claim 1, characterized in that, The first ultra-wideband amplifier, the second ultra-wideband amplifier, and the third ultra-wideband amplifier are the same ultra-wideband amplifier.

3. The apparatus for improving the linearity of an ultra-wideband radio frequency amplification link as described in claim 2, characterized in that, The optimal combination of phase shifters is: ΔP1 = 120°, ΔP2 = 240°, ΔP3 = 240°, ΔP4 = 120°.

4. The apparatus for improving the linearity of an ultra-wideband radio frequency amplification link as described in claim 2, characterized in that, The optimization process for the phase shifts ΔP1, ΔP2, ΔP3, and ΔP4 is as follows: a) Establish a parameterized nonlinear model of the ultra-wideband amplifier; b) Determine the expression of the RF signal before each ultra-wideband amplifier; let the phase shifts of fixed phase shifters ΔP1, ΔP2, ΔP3, and ΔP4 be ΔP1, ΔP2, ΔP3, and ΔP4, respectively. Combine the parameterized nonlinear model to obtain the expression of the RF signal after amplification by the ultra-wideband amplifier, and the expression of the final synthesized RF output signal. c) Based on the higher harmonic components in the RF output signal expression, establish the expressions for the second harmonic suppression ratio H2 and the third harmonic suppression ratio H3; d) Using phase shifts ΔP1, ΔP2, ΔP3, and ΔP4 as optimization variables, the optimization objective is to maximize the minimum value among the second harmonic suppression ratio H2 and the third harmonic suppression ratio H3. Through iterative optimization using the optimization algorithm, the optimal combination of phase shifts at each stage is output.

5. The apparatus for improving the linearity of an ultra-wideband radio frequency amplification link as described in claim 4, characterized in that, The optimization process for the phase shifts ΔP1, ΔP2, ΔP3, and ΔP4 also includes: Because the phase shifter has parasitic amplitude modulation, after step d), the expression of the radio frequency signal in step b) is corrected according to the stage-optimal phase shift amount, and steps c) and d) are repeated until convergence, and the optimal phase shift amount combination is output.

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