Filtering structure for improving output power of broadband power amplifier

Abstract

The utility model relates to the technical field of broadcast transmitters, and provides a filtering structure for improving the output power of a broadband power amplifier, which comprises a radio frequency input module used for receiving radio frequency signals from a signal source; the broadband power amplification module is used for performing power amplification on the radio frequency signal; the output end of the power amplifier matching module is connected with the input end of the filtering module, and the power amplifier matching module is used for optimizing impedance matching between the broadband power amplifier module and the filtering module; the output end of the filtering module is connected with the input end of the radio frequency output module, and the filtering module is used for improving output power and signal quality; and the output end of the radio frequency output module is connected with an external load, and the radio frequency output module is used for outputting the filtered radio frequency signal to the external load. Therefore, the problems that an existing low-pass filter is poor in harmonic linearity, a power amplifier tube cannot meet the requirement for full-band stable work, and consequently power of a system cannot be stably output in the full band are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of broadcast transmitters, and more specifically, to a filtering structure for improving the output power of a broadband power amplifier. Background Art

[0002] At present, all-solid-state FM transmitters, with their advantages of strong anti-interference ability, stable signals, and wide frequency bands, are an indispensable part of the field of broadcast transmitters. The key lies in the technology of stable power output of high-power FM broadband power amplifiers. The broadband FM power amplifier is the core part of a broadband transmitter. The key is to ensure stable output across the entire frequency band. Currently, most FM transmitter power amplifiers, in pursuit of high efficiency, do not consider linearity indicators. As a result, the harmonic linearity of the power amplifier is very poor. The unstable output of a single-module power amplifier will cause the inability to synthesize power in some frequency bands during the power combination of the broadband power amplifier, directly affecting the overall power combination of the transmitter.

[0003] In the prior art, the main solution is to add a low-pass filter behind the power amplifier module to improve the harmonic characteristics. The characteristic of this low-pass filter is that it allows the in-band signal to pass through with as little insertion loss as possible and does not process the reflected signals outside the passband. This will cause all the reflected signals outside the passband to return to the broadband power amplifier. Since the power amplifier tubes used in all-solid-state FM transmitters, in pursuit of high power and high efficiency, already have poor harmonic linearity, and with the addition of the signals reflected by the low-pass filter, the power amplifier tubes will directly fail to operate stably or even burn out due to overheating, directly affecting the stability of the transmitter. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a filtering structure for improving the output power of a broadband power amplifier, aiming to solve the problem that the existing low-pass filter has poor harmonic linearity, the power amplifier tubes cannot meet the requirements of stable operation across the entire frequency band, resulting in the inability to stably output power across the entire frequency band of the system.

[0005] The embodiments of the utility model are realized through the following technical solutions:

[0006] A filtering structure for improving the output power of a broadband power amplifier, comprising:

[0007] A radio frequency input module, used to receive radio frequency signals from a signal source;

[0008] A broadband power amplifier module, the input end of the broadband power amplifier module is connected to the radio frequency input module, and the output end of the broadband power amplifier module is connected to the input end of the power amplifier matching module, used to amplify the power of the radio frequency signal;

[0009] A power amplifier matching module, the output end of the power amplifier matching module is connected to the input end of the filtering module, used to optimize the impedance matching between the broadband power amplifier module and the filtering module;

[0010] A filtering module, the output end of the filtering module is connected to the input end of the radio frequency output module, and is used to improve the output power and signal quality;

[0011] A radio frequency output module, the output end of the radio frequency output module is connected to an external load, and is used to output the filtered radio frequency signal to the external load.

[0012] Optionally, the filtering module is provided with a load end, and an absorption component is arranged at the load end of the filtering module; wherein, the absorption component is used to absorb signals with a signal frequency higher than the cut-off frequency.

[0013] Optionally, the cut-off frequency from the input end to the output end of the filtering module is the same as the cut-off frequency from the input end to the load end of the filtering module.

[0014] Optionally, the order from the input end to the output end of the filtering module is the same as the order from the input end to the load end of the filtering module.

[0015] Optionally, the filtering module includes:

[0016] A signal conduction circuit, including the circuit from the input end to the output end of the filtering module, and is used to transfer radio frequency signals with a frequency lower than the cut-off frequency from the power amplifier matching module to the radio frequency output module;

[0017] A signal absorption circuit, including the circuit from the input end to the load end of the filtering module, and is used to transfer radio frequency signals with a frequency higher than the cut-off frequency from the power amplifier matching module to the absorption component.

[0018] Optionally, the signal conduction circuit is connected in parallel with the signal absorption circuit.

[0019] Optionally, the signal conduction circuit is a low-pass π-type filtering circuit, the signal absorption circuit is a high-pass π-type filtering circuit, and the order of the signal conduction circuit is the same as the order of the signal absorption circuit.

[0020] Optionally, the signal conduction circuit is a cascade of four second-order low-pass filtering circuits, and the signal absorption circuit is a cascade of four second-order high-pass filtering circuits.

[0021] Optionally, the absorption component is a resistor.

[0022] Optionally, the full-band characteristic impedance of the power amplifier matching module is 50 ohms.

[0023] The technical solution of the embodiment of the present utility model has at least the following advantages and beneficial effects:

[0024] Through a carefully designed filtering module, the output power of the broadband power amplifier is effectively improved. The filtering module not only optimizes the quality of the signal during transmission, but also ensures the effective amplification and transmission of the signal within the specified frequency range through its unique signal conduction and absorption mechanism, thereby significantly increasing the overall output power.

[0025] The signal conduction circuit in the filtering module can accurately screen and transmit radio frequency signals below the cut-off frequency, while the signal absorption circuit effectively absorbs stray signals above the cut-off frequency. This dual effect significantly improves the quality of the output signal, reduces harmonic distortion and noise interference, making the output signal purer and more stable.

[0026] The characteristic impedance of the full frequency band of the power amplifier matching module is set to 50 ohms. This design ensures good impedance matching between the broadband power amplifier module and the filtering module, reduces signal reflection and loss during transmission, and further improves power transmission efficiency and signal integrity.

[0027] The filtering structure in this utility model adopts a modular design, including a radio frequency input module, a broadband power amplifier module, a power amplifier matching module, a filtering module and a radio frequency output module. The modules are tightly connected and easy to replace or upgrade. This design not only facilitates maintenance, but also provides users with the flexibility to adjust the system configuration according to actual needs.

[0028] The absorption component set at the load end of the filtering module effectively absorbs signals above the cut-off frequency, prevents the influence of these useless signals on the system performance, reduces the thermal loss of the system at the same time, and improves the overall working efficiency.

[0029] By precisely controlling the cut-off frequency and order of the filtering module, and adopting a parallel signal conduction circuit and signal absorption circuit, while maintaining the system stability, the efficient processing of radio frequency signals is realized, ensuring the reliable operation of the system under various working conditions. Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of the filtering structure for improving the output power of the broadband power amplifier provided in the embodiment of this utility model;

[0031] Figure 2 It is a schematic structural diagram of the filter provided in Embodiment 3 of this utility model;

[0032] Figure 3 It is a schematic diagram of the output spectrum of the broadband power amplifier in the prior art;

[0033] Figure 4 It is a schematic diagram of the output spectrum of the broadband power amplifier when using this utility model;

[0034] Figure 5Characteristic impedance schematic diagram of the power amplifier matching module provided by the embodiment of the present utility model;

[0035] Icon: 1 - RF input module, 2 - broadband power amplifier module, 3 - power amplifier matching module, 4 - filtering module, 5 - RF output module. Specific implementation manners

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some but not all of the embodiments of the present utility model. Usually, the components of the embodiments of the present utility model described and illustrated herein can be arranged and designed in various different configurations.

[0037] Embodiment 1

[0038] Refer to Figure 1 , a filtering structure for improving the output power of a broadband power amplifier, comprising:

[0039] An RF input module 1, configured to receive RF signals from a signal source; in this embodiment, the RF input module is the starting point of the entire filtering structure, and its main function is to receive RF signals from a signal source. The RF signals come from various wireless communication devices, radar systems or other RF sources. The RF input module can stably and accurately receive these signals and transmit them to the subsequent broadband power amplifier module for processing.

[0040] A broadband power amplifier module 2, the input end of the broadband power amplifier module 2 is connected to the RF input module 1, and the output end of the broadband power amplifier module 2 is connected to the input end of the power amplifier matching module 3, configured to amplify the power of the RF signals; in this embodiment, the broadband power amplifier module can provide stable gain within a relatively wide frequency range to meet the amplification requirements of signals in different frequency bands, and has good heat dissipation performance to ensure stable operation even in a high-temperature environment.

[0041] A power amplifier matching module 3, the output end of the power amplifier matching module 3 is connected to the input end of the filtering module 4, configured to optimize the impedance matching between the broadband power amplifier module and the filtering module; in this embodiment, the characteristic impedance of the entire frequency band of the power amplifier matching module 3 is 50 ohms. The characteristic impedance of the power amplifier matching module 3 in this embodiment is as shown in Figure 5 . Adjusting the length of the microstrip line on the power amplifier matching module 3 can improve the frequency offset caused by its addition to the filtering structure in this embodiment. The power amplifier matching module 3 can reduce the reflection and loss of signals during transmission through precise impedance matching, and improve the power transmission efficiency.

[0042] Filtering module 4, the output end of the filtering module 4 is connected to the input end of the radio frequency output module 5, which is used to improve the output power and signal quality;

[0043] In this embodiment, the filtering module 4 is provided with a load end, and an absorption component is arranged at the load end of the filtering module 4. The absorption component can be a resistor. Among them, the absorption component is used to absorb signals with frequencies higher than the cut-off frequency. The cut-off frequency from the input end to the output end of the filtering module 4 is the same as the cut-off frequency from the input end to the load end of the filtering module 4. The order from the input end to the output end of the filtering module 4 is the same as the order from the input end to the load end of the filtering module 4. By precisely controlling the cut-off frequency, it is ensured that only signals within a specific frequency range can pass through. Signals with frequencies less than the cut-off frequency are transmitted through the input end to the output end of the filtering module 4, and signals with frequencies greater than the cut-off frequency are transmitted through the input end to the load end of the filtering module 4. In this way, within the entire frequency band, the radio frequency signal can pass through the input end to the output end of the filtering module 4 with a very small insertion loss in the passband, and the harmonic waves reflected outside the band can be absorbed by the absorption component from the input end to the load end of the filtering module 4. The filtering module 4 can improve the power of the effective signal and suppress the interference of the reflected signal, thereby reducing the impact of the reflected signal on the broadband power amplifier, ensuring the normal and stable operation of the broadband power amplifier, and improving the output ability of the broadband power amplifier.

[0044] Radio frequency output module 5, the output end of the radio frequency output module 5 is connected to an external load, which is used to output the filtered radio frequency signal to the external load. In this embodiment, the external load can be an antenna, other communication devices, or test equipment, etc.

[0045] Embodiment 2

[0046] Refer to Figure 1 , based on the filtering structure for improving the output power of the broadband power amplifier in the above-mentioned Embodiment 1, in this embodiment, the filtering module 4 includes: a signal conduction circuit and a signal absorption circuit. The signal conduction circuit includes the circuit from the input end to the output end of the filtering module 4, which is used to transfer the radio frequency signal with a frequency less than the cut-off frequency from the power amplifier matching module 3 to the radio frequency output module 5. The signal absorption circuit includes the circuit from the input end to the load end of the filtering module 4, which is used to transfer the radio frequency signal with a frequency greater than the cut-off frequency from the power amplifier matching module 3 to the absorption component. The signal conduction circuit and the signal absorption circuit are connected in parallel.

[0047] In this embodiment, the signal conduction circuit is a low-pass π-type filtering circuit, and the signal absorption circuit is a high-pass π-type filtering circuit. The order of the signal conduction circuit is the same as that of the signal absorption circuit.

[0048] Embodiment 3

[0049] Reference Figure 1 and Figure 2 , based on the filtering structure for improving the output power of a broadband power amplifier in the above-mentioned Embodiment 1 and Embodiment 2, in this embodiment, the signal conduction circuit is composed of four cascaded second-order low-pass filtering circuits, and the signal absorption circuit is composed of four cascaded second-order high-pass filtering circuits. As Figure 2 shown, the signal conduction circuit is composed of inductors L1, L2, L3, L4 and capacitors C1, C2, C3, C4, and the signal absorption circuit is composed of inductors L5, L6, L7, L8 and capacitors C5, C6, C7, C8; as Figure 3 and Figure 4 shown, compared with the prior art, in this embodiment, the insertion loss from the input end of the RF input module 1 to the output end of the RF output module 5 is very small, and the influence on the power output of the broadband power amplifier is relatively small, so that the harmonics of the broadband power amplifier are significantly improved, and the influence of the reflected signal on the broadband power amplifier is reduced.

[0050] Table 1 Composite Power Performance Table of Broadband Power Amplifier in Prior Art

[0051] Frequency (MHz) Power (W) Current (A) Supply Voltage of Power Amplifier Tube (V) Temperature of Power Amplifier Tube (℃) 87 810 31.5 45 125 90 850 31 45 118 93 900 31 45 110 96 950 30.5 45 101 99 1000 30.2 45 90 102 1050 30.5 45 81 105 1100 30.7 45 82 108 1100 31 45 83

[0052] Table 2 Composite Power Performance Table of Broadband Power Amplifier in this Embodiment (without Adding Power Amplifier Matching Module)

[0053]

[0054]

[0055] Table 3 Composite Power Performance Table of Broadband Power Amplifier in this Embodiment (with Adding Power Amplifier Matching Module)

[0056] Frequency (MHz) Power (W) Current (A) Supply Voltage of Power Amplifier Tube (V) Temperature of Power Amplifier Tube (℃) 87 1100 30.5 45 82 90 1100 30.2 45 81 93 1100 30 45 80 96 1100 29.8 45 80 99 1100 29.6 45 78 102 1100 30 45 79 105 1100 30.1 45 80 108 1100 30.3 45 81

[0057] Generally, the standard output power of the RF output end is required to be 1100W. Referring to Table 1, Table 2 and Table 3, in the prior art, to achieve the standard output power of 1100W at the RF output end, it is restricted by frequency, while the broadband power amplifier in this embodiment can meet the standard requirements at multiple frequencies; it is obvious that after adding the power amplifier matching module 3 and the filtering module 4, the output power of the broadband power amplifier is significantly improved, the temperature of the power amplifier tube is significantly reduced, and the expected power output requirement is met.

[0058] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A filter structure for improving the output power of a broadband power amplifier, characterized in that: include: A radio frequency input module (1), used for receiving a radio frequency signal from a signal source; A broadband power amplifier module (2), wherein the input end of the broadband power amplifier module (2) is connected to the radio frequency input module (1), and the output end of the broadband power amplifier module (2) is connected to the input end of the power amplifier matching module (3), and is used to amplify the power of the radio frequency signal; A power amplifier matching module (3), the output end of the power amplifier matching module (3) is connected to the input end of the filter module (4), and is used to optimize the impedance matching between the broadband power amplifier module and the filter module; A filter module (4), wherein the output end of the filter module (4) is connected to the input end of the radio frequency output module (5) to improve the output power and signal quality; A radio frequency output module (5), the output end of which is connected to an external load, and is used to output the filtered radio frequency signal to the external load.

2. The filtering structure for improving the output power of a broadband power amplifier according to claim 1, characterized in that: The filter module (4) is provided with a load end, and the load end of the filter module (4) is provided with an absorption component; wherein the absorption component is used to absorb signals with a frequency higher than a cut-off frequency.

3. The filtering structure for improving the output power of a broadband power amplifier as claimed in claim 2, characterized in that: The cut-off frequency from the input end of the filter module (4) to the output end of the filter module (4) is the same as the cut-off frequency from the input end of the filter module (4) to the load end of the filter module (4).

4. The filter structure for improving the output power of a broadband power amplifier as claimed in claim 2, characterized in that: The order from the input end of the filter module (4) to the output end of the filter module (4) is the same as the order from the input end of the filter module (4) to the load end of the filter module (4).

5. The filter structure for improving the output power of a broadband power amplifier as claimed in claim 3, characterized in that: The filtering module (4) comprises: A signal conduction circuit, comprising a circuit from the input end of the filter module (4) to the output end of the filter module (4), used for transmitting a radio frequency signal with a frequency lower than a cut-off frequency from the power amplifier matching module (3) to the radio frequency output module (5); The signal absorption circuit comprises a circuit from the input end of the filter module (4) to the load end of the filter module (4), and is used to transmit a radio frequency signal greater than a cut-off frequency from the power amplifier matching module (3) to the absorption component.

6. The filtering structure for improving the output power of a broadband power amplifier as claimed in claim 5, characterized in that: The signal conducting circuit is connected in parallel with the signal absorbing circuit.

7. The filtering structure for improving the output power of a broadband power amplifier as claimed in claim 6, characterized in that: The signal transmission circuit is a low-pass π-type filter circuit, the signal absorption circuit is a high-pass π-type filter circuit, and the order of the signal transmission circuit is the same as the order of the signal absorption circuit.

8. The filter structure for improving the output power of a broadband power amplifier as claimed in claim 6, characterized in that: The signal conduction circuit is a cascade of four second-order low-pass filter circuits, and the signal absorption circuit is a cascade of four second-order high-pass filter circuits.

9. The filtering structure for improving the output power of a broadband power amplifier according to any one of claims 2 to 8, characterized in that: The absorption component is a resistor.

10. The filtering structure for improving the output power of a broadband power amplifier according to any one of claims 1 to 8, characterized in that: The full-band characteristic impedance of the power amplifier matching module (3) is 50 ohms.

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