Solid-state high-power amplitude modulation short wave transmitter circuit with digital pre-distortion function
By designing a circuit with digital predistortion function in a high-power amplitude modulation short-wave transmitter, and using digital signal processing and feedback paths to predistort processing and adjustment of radio frequency signals, the problems of difficulty in debugging RF signal performance indicators and increase equipment volume are solved, and high-quality small-volume RF signal output is achieved.
Patent Information
- Application Number
- CN202421292078.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-06
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2034-06-06
AI Technical Summary
Currently, high-power amplitude modulation short-wave transmitters are difficult to debug performance indicators of output RF signals, and the multifunctional structure increases the equipment volume, resulting in a decrease in the quality of RF signals.
Design a solid-state high-power amplitude modulation short-wave transmitter circuit with digital predistortion function, including a digital signal processor, transmission path, feedback path, power amplifier unit and coupler. The initial baseband signal is input through the digital signal processor, the transmission path is modulated, the power amplifier unit amplifies, the coupler outputs the radio frequency signal and feedbacks the signal, the feedback path demodulates and adjusts the initial baseband signal to realize the pre-distortion processing of the radio frequency signal.
Through predistortion processing and amplification of multi-layer processes, high-quality RF signals are guaranteed to be output. At the same time, due to the merger of the added module and the original structure, the transmitter volume does not increase, and small-volume high-quality RF signals are output.
Smart Images
Figure CN222602405U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of amplitude modulation shortwave transmitters, and in particular to a solid-state high-power amplitude modulation shortwave transmitter circuit with a digital predistortion function. Background Art
[0002] In the civilian field, wireless shortwave transmitters are widely used in radio and television and mobile communication base stations; in the military field, wireless shortwave transmitters are used in target radar detection, data links, and electronic countermeasure equipment. As an important part of wireless communication systems, high-power AM shortwave transmitters are widely used, such as in broadcasting, power suppression, anti-interference and other fields.
[0003] A high-power AM shortwave transmitter is mainly composed of an excitation unit and a power amplifier unit. It has a simple structure and a relatively large transmission power. If you need to adjust the performance indicators of the output RF signal, such as the power consumption, distortion, positive and negative peak imbalance of the RF signal, etc., you need to add corresponding functional structures. The more performance indicators you want to adjust, the more functional structures you need to add. Multiple functional structures will not only increase the size of the AM shortwave transmitter, but also increase the interference components of the output RF signal after it is processed by multiple functional structures, and the quality of the output RF signal will decrease.
[0004] Therefore, it is currently difficult to debug the performance indicators of the radio frequency signal output by the shortwave transmitter. Utility Model Content
[0005] In order to reduce the difficulty of debugging the performance indicators of the RF signal output by the shortwave transmitter and improve the quality of the RF signal output by the AM shortwave transmitter, the present application provides a solid-state high-power AM shortwave transmitter circuit with a digital predistortion function, which specifically adopts the following technical solutions:
[0006] A solid-state high-power amplitude modulation shortwave transmitter circuit with digital pre-distortion function, comprising a digital signal processor, a transmission path, a feedback path, a power amplifier unit and a coupler;
[0007] The digital signal processor is used to output an initial baseband signal;
[0008] The input end of the transmitting path is connected to the output end of the digital signal processor, the output end of the transmitting path is connected to the input end of the power amplifier unit, and the transmitting path is used to obtain a modulated signal according to the initial baseband signal;
[0009] The output end of the power amplifier unit is connected to the input end of the coupler, and the coupler is used to obtain a radio frequency signal and a feedback signal according to the modulated signal;
[0010] The input end of the feedback path is connected to the coupling end of the coupler, the output end of the feedback path is connected to the input end of the transmission path, and the feedback path is used to obtain a target baseband signal according to the feedback signal;
[0011] The transmitting path is also used to obtain a final baseband signal according to the initial baseband signal and the target baseband signal.
[0012] By adopting the above technical solution, the digital signal processor inputs the initial baseband signal into the transmission path, the transmission path modulates the initial baseband signal to obtain the modulated signal, and the modulated signal is amplified by the power amplifier unit to obtain a high-power modulated signal. The high-power modulated signal enters the coupler, and the coupler outputs most of the energy as a radio frequency signal outside the transmitter, and the remaining energy enters the feedback path as a feedback signal. The feedback path demodulates the feedback signal to obtain the target baseband signal, and returns the target baseband signal to the transmission path. The transmission path adjusts the initial baseband signal according to the difference between the initial baseband signal and the target baseband signal to obtain the final baseband signal, and finally outputs the radio frequency signal corresponding to the final baseband signal. On the one hand, the radio frequency signal output by the transmitter will undergo multiple processes such as pre-distortion processing and amplification processing to ensure the output of high-quality radio frequency signals; on the other hand, the added modules and devices are all in the original structure and are integrated with the original structure, so the volume of the transmitter itself will not increase, so that a small-volume transmitter can output high-quality radio frequency signals.
[0013] Optionally, the transmission path includes a digital predistortion module, a digital-to-analog conversion module, a first filtering module and a first mixer connected in series in sequence;
[0014] The digital-to-analog conversion module includes a first digital-to-analog converter and a second digital-to-analog converter, the first filtering module includes a first low-pass filter and a second low-pass filter, the first digital-to-analog converter and the first low-pass filter are connected in series to form a first transmission path, the first transmission path is used to transmit an I signal, the second digital-to-analog converter and the second low-pass filter are connected in series to form a second transmission path, the second transmission path is used to transmit a Q signal, and the I signal and the Q signal constitute an initial baseband signal.
[0015] By adopting the above technical solution, the digital predistortion module can adjust the initial baseband signal according to the difference between the initial baseband signal and the target baseband signal to obtain the final baseband signal. The final baseband signal is then subjected to digital-to-analog conversion, filtering and modulation processing to obtain a modulated signal corresponding to the final baseband signal, so that the subsequent power amplifier unit can perform power amplification operation on the modulated signal corresponding to the final baseband signal, thereby obtaining a high-power modulated signal.
[0016] Optionally, the digital predistortion module includes a synchronization submodule, a gain submodule, a phase submodule, a predistortion coefficient submodule and a predistortion processing submodule;
[0017] The input end of the predistortion processing submodule is respectively connected to the output end of the digital signal processor and the output end of the predistortion coefficient submodule, and the output end of the predistortion processing submodule is respectively connected to the first digital-to-analog converter and the second digital-to-analog converter;
[0018] The input end of the synchronization submodule is connected to the output end of the feedback path, and the output end of the synchronization submodule is connected to the input end of the predistortion processing submodule through the gain submodule, the phase submodule and the predistortion coefficient submodule respectively.
[0019] By adopting the above technical solution, the digital pre-distortion module can perform operations such as synchronization design, gain processing and phase adjustment on the target baseband signal input into the feedback path, and then adjust the initial baseband signal according to the difference between the initial baseband signal and the target baseband signal to continuously correct the output final baseband signal, thereby providing technical guarantee for improving the quality of the RF signal output by the transmitter.
[0020] Optionally, the transmitting path further includes a first adjustment module disposed at the output end of the first mixer, and the first adjustment module includes a variable gain amplifier, a first attenuator and a driving amplifier connected in series in sequence.
[0021] By adopting the above technical solution, the final baseband signal needs to undergo gain, attenuation and power amplification before entering the power amplifier unit, so that the power amplifier unit can perform further amplification processing.
[0022] Optionally, the power amplifier unit includes a power divider, a first power amplifier, a second power amplifier, a third power amplifier, a fourth power amplifier, a first combiner, a second combiner and a third combiner;
[0023] The input end of the power divider is connected to the output end of the transmitting path, and the output end of the power divider is respectively connected to the input end of the first power amplifier, the input end of the second power amplifier, the input end of the third power amplifier, and the input end of the fourth power amplifier. The output end of the first power amplifier and the output end of the second power amplifier are both connected to the input end of the first combiner, the output end of the third power amplifier and the output end of the fourth power amplifier are both connected to the input end of the second combiner, the output end of the first combiner and the output end of the second combiner are both connected to the input end of the third combiner, and the output end of the third combiner is connected to the input end of the coupler.
[0024] By adopting the above technical solution, the power divider divides the modulated signal into 4 signals with equal amplitudes and phase differences less than 3°. After the 4 signals are amplified by the power amplifier and combined by the combiner in turn, the output power of the modulated signal is greater than the original modulated signal, thereby obtaining a high-power modulated signal. The high-power modulated signal then enters the coupler and is output by the coupler as a radio frequency signal, that is, a high-power, high-quality radio frequency signal is output.
[0025] Optionally, the feedback path includes a second adjustment module, a second mixer, a second filtering module and an analog-to-digital conversion module;
[0026] The input end of the second adjustment module is connected to the coupling end of the coupler, and the output end of the second adjustment module is connected to the input end of the second mixer;
[0027] The second filtering module includes a fourth low-pass filter and a fifth low-pass filter, the analog-to-digital conversion module includes a first analog-to-digital converter and a second analog-to-digital converter, the fourth low-pass filter is connected in series with the first analog-to-digital converter to form a first input path, the fifth low-pass filter is connected in series with the second analog-to-digital converter to form a second input path, and the first input path and the second input path are arranged in parallel at the output end of the second mixer.
[0028] Optionally, the second adjustment module includes a second attenuator and a third low-pass filter connected in series.
[0029] By adopting the above technical solution, the feedback signal is attenuated and filtered, and then demodulated by the second mixer to obtain the target baseband signal. The target baseband signal is then filtered and converted into a digital signal before entering the transmission path, so that the transmission path can adjust the initial baseband signal according to the difference between the initial baseband signal and the target baseband signal to obtain the final baseband signal.
[0030] Optionally, a signal generator is further included, wherein the signal generator is respectively connected to the digital signal processor, the transmission path and the feedback path, and the signal generator is used to output a local oscillator signal.
[0031] By adopting the above technical solution, the digital signal processor controls the signal generator to provide local oscillator signals for the first mixer in the transmission path and the second mixer in the feedback path, ensuring that the modulation process of the first mixer and the demodulation process of the second mixer are mutually reversible processes, thereby ensuring that an accurate final baseband signal is obtained subsequently.
[0032] Optionally, the power amplifier unit further includes a harmonic filter, and the harmonic filter is arranged on the output end of the coupler.
[0033] By adopting the above technical solution, the radio frequency signal output from the coupler needs to be filtered by the harmonic filter before being output outside the transmitter, so as to ensure the output of high-quality radio frequency signal.
[0034] In summary, the present application includes the following beneficial technical effects:
[0035] The digital signal processor inputs the initial baseband signal into the transmission path, and the transmission path modulates the initial baseband signal to obtain a modulated signal. The modulated signal is amplified by the power amplifier unit to obtain a high-power modulated signal. The high-power modulated signal enters the coupler, and the coupler outputs most of the energy as an RF signal outside the transmitter, and the remaining energy enters the feedback path as a feedback signal. The feedback path demodulates the feedback signal to obtain the target baseband signal, and inputs the target baseband signal into the front end of the transmission path. The transmission path adjusts the initial baseband signal according to the difference between the initial baseband signal and the target baseband signal to obtain the final baseband signal, and finally outputs the RF signal corresponding to the final baseband signal. On the one hand, the RF signal output by the transmitter will undergo multiple processes such as pre-distortion processing and amplification processing to ensure the output of high-quality RF signals; on the other hand, the added modules and devices are all in the original structure and are integrated with the original structure, so the volume of the transmitter itself will not increase, so that a small-volume transmitter can output high-quality RF signals. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Figure 1 It is an overall system diagram of a solid-state high-power amplitude modulation shortwave transmitter circuit with digital pre-distortion function according to an embodiment of the present application.
[0037] Figure 2 It is a circuit diagram of a transmission path and a feedback path in a solid-state high-power amplitude modulation shortwave transmitter circuit with a digital pre-distortion function according to an embodiment of the present application.
[0038] Figure 3 It is a circuit diagram of a power amplifier unit and a coupler in a solid-state high-power amplitude modulation shortwave transmitter circuit with a digital pre-distortion function according to an embodiment of the present application.
[0039] Explanation of the accompanying drawings: 1. digital signal processor; 2. transmission path; 21. digital pre-distortion module; 22. digital-to-analog conversion module; 23. first filtering module; 24. first mixer; 25. first adjustment module; 3. feedback path; 31. second adjustment module; 32. second mixer; 33. second filtering module; 34. analog-to-digital conversion module; 4. power amplifier unit; 5. coupler; 6. harmonic filter. DETAILED DESCRIPTION
[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0041] The following is combined with Figure 1-3 This application is described in further detail.
[0042] The embodiment of the present application discloses a solid-state high-power amplitude modulation shortwave transmitter circuit with a digital pre-distortion function. Figure 1 The solid-state high-power amplitude modulation shortwave transmitter circuit with digital pre-distortion function includes a digital signal processor 1, a transmission path 2, a feedback path 3, a power amplifier unit 4 and a coupler 5. The digital signal processor 1, the transmission path 2 and the feedback path 3 can also be collectively referred to as an excitation unit. The excitation unit is mainly used to generate and correct the modulation signal, the power amplifier unit 4 is used to improve the gain of the modulation signal, and the coupler 5 is used to output most of the energy of the modulation signal as a radio frequency signal, and then return the remaining energy to the excitation unit as a feedback signal to assist the excitation unit in correcting the modulation signal.
[0043] The digital signal processor 1 is connected to a signal source, which outputs a baseband signal. The digital signal processor 1 is used to generate an I signal and a Q signal according to the baseband signal. Here, the signal composed of the I signal and the Q signal is called an initial baseband signal, that is, the signal output by the digital signal processor 1 is called an initial baseband signal. Therefore, the digital signal processor 1 can be an I / Q modem chip, or an electronic device such as a DSP chip that can convert a baseband signal into an I signal and a Q signal.
[0044] Reference Figure 2 The transmission path 2 includes a digital pre-distortion module 21, a digital-to-analog conversion module 22, a first filtering module 23, a first mixer 24 and a first adjustment module 25. The digital pre-distortion module 21 serves as the front end of the transmission path 2 and is connected to the digital signal processor 1 and the feedback path 3 respectively; the first adjustment module 25 serves as the back end of the transmission path 2 and is connected to the power amplifier unit 4 for adjusting the signal output by the transmission path 2 so that the signal matches the power amplifier unit 4.
[0045] Specifically, the digital predistortion module 21 includes a synchronization submodule, a gain submodule, a phase submodule, a predistortion coefficient submodule and a predistortion processing submodule, wherein the predistortion processing submodule and the synchronization submodule are respectively used as two input terminals of the digital predistortion module 21, wherein the input terminal of the predistortion processing submodule is respectively connected to the output terminal of the digital signal processor 1 and the output terminal of the predistortion coefficient submodule, the output terminal of the predistortion processing submodule is connected to the input terminal of the digital-to-analog conversion module 22, and the initial baseband signal is connected from the predistortion processing submodule. The input terminal of the synchronization submodule is connected to the output terminal of the feedback path 3, and the output terminal of the synchronization submodule is connected to the input terminal of the predistortion processing submodule through the gain submodule, the phase submodule and the predistortion coefficient submodule in sequence, so the signal connected from the synchronization submodule will eventually flow into the predistortion processing submodule. In a specific example, the digital predistortion module 21 can be used as an integral processing chip, and the synchronization submodule, gain submodule, phase submodule, predistortion coefficient submodule and predistortion processing submodule are used as virtual modules inside the module. The synchronization submodule uses autocorrelation technology to synchronize the signal output by the feedback path 3 and the initial baseband signal; the gain submodule uses normalization technology to normalize the amplitude of the signal output by the feedback path 3 and the initial baseband signal; the phase submodule adjusts the phase difference between the signal output by the feedback path 3 and the initial baseband signal; the predistortion coefficient submodule is used to fit the nonlinearity of the power amplifier and adjust the algorithm model in the predistortion processing submodule, such as adjusting the MP model, so that the predistortion processing submodule can adjust the initial baseband signal according to the MP model.
[0046] It should be noted that the technologies in the synchronization submodule, gain submodule, phase submodule, predistortion coefficient submodule and predistortion processing submodule are all set in advance, and the technologies used are also mature technologies in related fields.
[0047] The digital-to-analog conversion module 22 includes a first digital-to-analog converter and a second digital-to-analog converter. Figure 2 DAC1 and DAC2 are used in the figure. The first filtering module 23 includes a first low-pass filter and a second low-pass filter. Figure 2 In the figure, LPF1 and LPF2 are used to represent them respectively. The first digital-to-analog converter DAC1 and the first low-pass filter LPF1 are connected in series to form a first transmission path, and the first transmission path is used to transmit the I signal; the second digital-to-analog converter DAC2 and the second low-pass filter LPF2 are connected in series to form a second transmission path, and the second transmission path is used to transmit the Q signal.
[0048] The first transmission path and the second transmission path are arranged in parallel between the digital predistortion module 21 and the first mixer 24. Figure 2The first mixer 24 is represented by MIX1. Specifically, the input end of the first mixer MIX1 is respectively connected to the output end of the first low-pass filter LPF1 and the output end of the second low-pass filter LPF2, and the output end of the first mixer MIX1 is connected to the input end of the first adjustment module 25. The first mixer MIX1 is also connected to a signal generator, which is represented by LO. The signal generator LO is also connected to the digital signal processor 1, so the signal generator LO can be the signal source introduced above, or it can be a separate signal generator LO, as long as it can provide a local oscillator signal for the first mixer MIX1. In actual work, the first mixer MIX1 modulates the initial baseband signal into a modulation signal using the local oscillator signal.
[0049] In order to adjust the modulation signal so that the modulation signal is more matched with the power amplifier unit 4, the first adjustment module 25 includes a variable gain amplifier, a first attenuator and a driving amplifier connected in series in sequence. Figure 2 In the figure, they are represented by VGA, DSA1 and MSR respectively. The variable gain amplifier VGA is arranged close to the first mixer MIX1, specifically, the input end of the variable gain amplifier VGA is connected to the output end of the first mixer MIX1, and the output end of the driving amplifier MSR is connected to the input end of the power amplifier unit 4. It should be noted that the variable gain amplifier VGA is also controlled by the digital signal processor 1.
[0050] Reference Figure 3 The power amplifier unit 4 includes a power divider, a first power amplifier, a second power amplifier, a third power amplifier, a fourth power amplifier, a first combiner, a second combiner and a third combiner. The input end of the power divider is connected to the output end of the driving amplifier MSR, and the output end of the power amplifier is respectively connected to the input end of the first power amplifier, the input end of the second power amplifier, the input end of the third power amplifier and the input end of the fourth power amplifier, the output end of the first power amplifier and the output end of the second power amplifier are both connected to the input end of the first combiner, the output end of the third power amplifier and the output end of the fourth power amplifier are both connected to the input end of the second combiner, the output end of the first combiner and the output end of the second combiner are both connected to the input end of the third combiner, and the output end of the third combiner is connected to the input end of the coupler 5.
[0051] In actual operation, the power divider divides the modulated signal into four signals with equal amplitudes and phase differences less than 3°. After the four signals are amplified by the power amplifier and combined by the combiner in turn, the output power of the modulated signal is greater than that of the original modulated signal, thereby obtaining a high-power modulated signal, which enters the coupler 5.
[0052] The input end of the coupler 5 is connected to the output end of the third combiner, and a harmonic filter 6 or a low-pass filter is provided on the output end of the coupler 5. In this example, the harmonic filter 6 is used as an example. The coupling end of the coupler 5 is connected to the input end of the feedback path 3. In actual use, the coupler 5 uses most of the energy of the modulated signal as a radio frequency signal, and outputs it from the output end after being processed by the harmonic filter 6 or the low-pass filter, and the remaining energy enters the feedback path 3 as a feedback signal.
[0053] Reference Figure 2 The feedback path 3 includes a second adjustment module 31, a second mixer 32, a second filtering module 33 and an analog-to-digital conversion module 34. The second adjustment module 31 includes a second attenuator and a third low-pass filter. Figure 2 In the figure, DSA2 and LPF3 are used to represent them respectively, and the second mixer 32 is represented by MIX2. The input end of the second attenuator DSA2 is connected to the coupling end of the coupler 5, and the output end of the second attenuator DSA2 is connected to the input end of the second mixer MIX2 through the third low-pass filter LPF3. The second mixer MIX2 is connected to the signal generator LO. The second mixer MIX2 and the first mixer MIX1 are connected to the same signal generator LO, and the local oscillator signal input to the first mixer MIX1 and the second mixer MIX2 needs to ensure the same clock source. Specifically, the clock chip built into the digital signal processor 1 is driven by the clock chip to control the signal generator LO to provide the first mixer MIX1 and the second mixer MIX2 with a local oscillator signal with the same clock source. The second filtering module 33 includes a fourth low-pass filter and a fifth low-pass filter, which are represented by LPF4 and LPF5 respectively. The analog-to-digital conversion module 34 includes a first analog-to-digital converter and a second analog-to-digital converter, which are represented by ADC1 and ADC2 respectively. The fourth low-pass filter LPF4 is connected in series with the first analog-to-digital converter ADC1 to form a first input path, the fifth low-pass filter LPF5 is connected in series with the second analog-to-digital converter ADC2 to form a second input path, the first input path and the second input path are arranged in parallel between the second mixer MIX2 and the digital pre-distortion module 21, and the input ends of the first input path and the second input path are both connected to the output end of the second mixer MIX2.
[0054] In practical applications, the second mixer MIX2 uses the local oscillator signal to demodulate the feedback signal into a target baseband signal. The I signal of the target baseband signal is transmitted to the digital predistortion module 21 through the first input path, and the Q signal of the target baseband signal is transmitted to the digital predistortion module 21 through the second input path.
[0055] Finally, the target baseband signal enters the pre-distortion processing submodule after synchronization design processing by the synchronization submodule, gain adjustment by the gain submodule, and phase adjustment by the phase submodule. The pre-distortion processing submodule uses the MP model to adjust the initial baseband signal according to the target baseband signal to obtain the final baseband signal. The final baseband signal is then processed by the transmission path 2, the power amplifier unit 4 and the coupler 5, and then output as a radio frequency signal.
[0056] In summary, the implementation principle of a solid-state high-power amplitude modulation shortwave transmitter circuit with a digital predistortion function in the embodiment of the present application is as follows: the digital signal processor 1 inputs the initial baseband signal into the transmission path 2, the transmission path 2 first performs digital-to-analog conversion and filtering processing on the initial baseband signal, and then modulates to obtain a modulated signal, and the modulated signal enters the power amplifier unit 4 after gain processing, attenuation processing and power amplification processing, and the power amplifier unit 4 performs further amplification processing to obtain a high-power modulated signal. The high-power modulated signal enters the coupler 5, and the coupler 5 outputs most of the energy as a radio frequency signal outside the transmitter, and the remaining energy enters the feedback path 3 as a feedback signal, and the feedback path 3 first performs attenuation and filtering processing on the feedback signal, and then demodulates to obtain a target baseband signal, and inputs the target baseband signal to the front end of the transmission path 2, and the transmission path 2 adjusts the initial baseband signal according to the difference between the initial baseband signal and the target baseband signal to obtain a final baseband signal, and finally outputs a radio frequency signal corresponding to the final baseband signal. From this, we can see that the RF signal output by the transmitter will undergo multiple processes such as pre-distortion processing, filtering processing and amplification processing to ensure the output of high-quality RF signals. Moreover, the added modules and devices are all in the original structure and integrated with the original structure, so the volume of the transmitter itself will not increase, allowing a small-volume transmitter to output high-quality RF signals.
[0057] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the aforementioned disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) by each other to form a technical solution.
Claims
1. A solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function, characterized in that: It comprises a digital signal processor (1), a transmission path (2), a feedback path (3), a power amplifier unit (4) and a coupler (5); The digital signal processor (1) is used to output an initial baseband signal; The input end of the transmitting path (2) is connected to the output end of the digital signal processor (1), the output end of the transmitting path (2) is connected to the input end of the power amplifier unit (4), and the transmitting path (2) is used to obtain a modulated signal according to the initial baseband signal; The output end of the power amplifier unit (4) is connected to the input end of the coupler (5), and the coupler (5) is used to obtain a radio frequency signal and a feedback signal according to the modulated signal; The input end of the feedback path (3) is connected to the coupling end of the coupler (5), the output end of the feedback path (3) is connected to the input end of the transmission path (2), and the feedback path (3) is used to obtain a target baseband signal according to the feedback signal; The transmitting path (2) is also used to obtain a final baseband signal according to the initial baseband signal and the target baseband signal.
2. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 1, characterized in that: The transmitting path (2) comprises a digital predistortion module (21), a digital-to-analog conversion module (22), a first filtering module (23) and a first mixer (24) which are connected in series in sequence; The digital-to-analog conversion module (22) comprises a first digital-to-analog converter and a second digital-to-analog converter, the first filtering module (23) comprises a first low-pass filter and a second low-pass filter, the first digital-to-analog converter and the first low-pass filter are connected in series to form a first transmission path, the first transmission path is used to transmit an I signal, the second digital-to-analog converter and the second low-pass filter are connected in series to form a second transmission path, the second transmission path is used to transmit a Q signal, and the I signal and the Q signal constitute an initial baseband signal.
3. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 2, characterized in that: The digital predistortion module (21) comprises a synchronization submodule, a gain submodule, a phase submodule, a predistortion coefficient submodule and a predistortion processing submodule; The input end of the predistortion processing submodule is respectively connected to the output end of the digital signal processor (1) and the output end of the predistortion coefficient submodule, and the output end of the predistortion processing submodule is respectively connected to the first digital-to-analog converter and the second digital-to-analog converter; The input end of the synchronization submodule is connected to the output end of the feedback path (3), and the output end of the synchronization submodule is connected to the input end of the predistortion processing submodule through the gain submodule, the phase submodule and the predistortion coefficient submodule respectively.
4. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 2, characterized in that: The transmitting path (2) further comprises a first adjustment module (25) arranged at the output end of the first mixer (24), wherein the first adjustment module (25) comprises a variable gain amplifier, a first attenuator and a driving amplifier which are sequentially connected in series.
5. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 1, characterized in that: The power amplifier unit (4) comprises a power distributor, a first power amplifier, a second power amplifier, a third power amplifier, a fourth power amplifier, a first combiner, a second combiner and a third combiner; The input end of the power divider is connected to the output end of the transmitting path (2); the output end of the power divider is respectively connected to the input end of the first power amplifier, the input end of the second power amplifier, the input end of the third power amplifier, and the input end of the fourth power amplifier; the output end of the first power amplifier and the output end of the second power amplifier are both connected to the input end of the first combiner; the output end of the third power amplifier and the output end of the fourth power amplifier are both connected to the input end of the second combiner; the output end of the first combiner and the output end of the second combiner are both connected to the input end of the third combiner; and the output end of the third combiner is connected to the input end of the coupler (5).
6. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 1, characterized in that: The feedback path (3) comprises a second adjustment module (31), a second mixer (32), a second filtering module (33) and an analog-to-digital conversion module (34); The input end of the second adjustment module (31) is connected to the coupling end of the coupler (5), and the output end of the second adjustment module (31) is connected to the input end of the second mixer (32); The second filtering module (33) comprises a fourth low-pass filter and a fifth low-pass filter, the analog-to-digital conversion module (34) comprises a first analog-to-digital converter and a second analog-to-digital converter, the fourth low-pass filter is connected in series with the first analog-to-digital converter to form a first input path, the fifth low-pass filter is connected in series with the second analog-to-digital converter to form a second input path, and the first input path and the second input path are arranged in parallel at the output end of the second mixer (32).
7. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 6, characterized in that: The second adjustment module (31) comprises a second attenuator and a third low-pass filter which are connected in series.
8. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 1, characterized in that: It also comprises a signal generator, which is respectively connected to the digital signal processor (1), the transmission path (2) and the feedback path (3), and is used to output a local oscillation signal.
9. The solid-state high-power AM shortwave transmitter circuit with digital pre-distortion function according to claim 1, characterized in that: It also comprises a harmonic filter (6), which is arranged at the output end of the coupler (5).