Frequency adjusting device of power amplifier and short wave therapy apparatus

Abstract

This invention discloses a frequency adjustment device for a power amplifier and a shortwave therapy device, applicable to the field of power amplification. It includes a power amplifier, a frequency selection module, and a first inductor. The power amplifier is used to turn on its first and second terminals according to a control terminal. The first inductor isolates the AC current at the power output terminal. The impedance of the first inductor and the load at the target frequency is the actual output impedance of the power amplifier at the target frequency. The frequency selection module adjusts the input impedance of the power amplifier to the ideal input impedance at the target frequency, where the ratio of the ideal input impedance to the actual output impedance at the target frequency is -1. By adjusting the input impedance of the power amplifier to a ratio of -1 to the actual output impedance through the frequency selection module, the amplitude and phase of the input and output impedances are balanced. At this point, the input and output impedances are matched, allowing the power amplifier to achieve higher frequencies.

Description

Technical Field

[0001] This invention relates to the field of power amplification, and in particular to a frequency adjustment device for a power amplifier and a shortwave therapy device. Background Technology

[0002] Shortwave therapy devices use power amplifiers to amplify signals, but existing power amplifiers cannot operate at high frequencies due to the Miller effect, which affects their normal operation. Summary of the Invention

[0003] The purpose of this invention is to provide a frequency adjustment device for a power amplifier and a shortwave therapy device. By using a frequency selection module, the input impedance of the power amplifier is adjusted to a ratio of -1 to the actual output impedance. The amplitude and phase of the input impedance and output impedance are balanced. At this time, the input impedance and output impedance are matched, and the power amplifier can achieve a higher frequency.

[0004] To solve the above-mentioned technical problems, the present invention provides a frequency adjustment device for a power amplifier, comprising a power amplifier, a frequency selection module and a first inductor;

[0005] The power supply is connected to the first terminal of the first inductor. The second terminal of the first inductor is connected to the first terminal of the load, the first terminal of the frequency selection module, and the first terminal of the power amplifier. The second terminal of the frequency selection module is connected to the control terminal of the power amplifier. The second terminal of the power amplifier is connected to the second terminal of the load and then grounded. The power amplifier is used to turn on the first terminal and the second terminal of the power amplifier according to the control terminal.

[0006] The first inductor is used to isolate the AC current at the power supply output terminal; the impedance of the first inductor and the load at the target frequency is the actual output impedance of the power amplifier at the target frequency;

[0007] The frequency selection module is used to adjust the input impedance of the power amplifier to the ideal input impedance at the target frequency, wherein the ratio of the ideal input impedance to the actual output impedance at the target frequency is -1.

[0008] Preferably, it further includes a filtering module, wherein a first end of the filtering module is connected to the power supply, and a second end of the filtering module is connected to the first end of the first inductor;

[0009] The filtering module is used to filter out the harmonics of the power supply output.

[0010] Preferably, the filtering module includes a first capacitor module, a second inductor, and a second capacitor module;

[0011] The first end of the first capacitor module serves as the first end of the filter module, the second end of the first capacitor module is connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second capacitor module, and the second end of the second capacitor serves as the second end of the filter module.

[0012] Preferably, it also includes a DC bias module, which is connected to the control terminal of the power amplifier;

[0013] The DC bias module is used to assist in starting the oscillation of the power amplifier.

[0014] Preferably, it further includes an input impedance matching module, the first end of which is connected to the control terminal of the power amplifier, and the input impedance matching module is used to perform impedance matching between the signal output by the frequency selection module and the power amplifier.

[0015] Preferably, it further includes an output impedance matching module, wherein a first terminal of the output impedance matching module is connected to a first terminal of the power amplifier, and a second terminal of the output impedance matching module is connected to a first terminal of the load. The output impedance matching module is used to perform impedance matching between the signal output by the power amplifier and the load.

[0016] Preferably, when the power amplifier is an NPN transistor, the base of the NPN transistor serves as the control terminal of the power amplifier, the collector of the NPN transistor serves as the first terminal of the power amplifier, and the emitter of the NPN transistor serves as the second terminal of the power amplifier.

[0017] Preferably, the frequency selection module includes a third inductor and a first capacitor;

[0018] The first end of the first capacitor serves as the first end of the frequency selection module, and the second end of the first capacitor is connected to the first end of the third inductor. The second end of the third inductor serves as the second end of the frequency selection module.

[0019] Preferably, the equivalent impedance of the first inductor and the load is the actual output impedance Zo = RL + jX2, where RL is the impedance of the load and jX2 is the impedance of the first inductor.

[0020] The ideal input impedance of the frequency selection module and the power amplifier is Zin = -r - jX1, where -r is the impedance of the power amplifier and -jX1 is the impedance of the frequency selection module.

[0021] The relationship between the ideal input impedance and the actual output impedance is Zin / Zo = -1.

[0022] To address the aforementioned technical problems, the present invention also provides a shortwave therapy device, including the frequency adjustment device of the power amplifier described above.

[0023] This application provides a frequency adjustment device for a power amplifier and a shortwave therapy device, applicable to the field of power amplification. It includes a power amplifier, a frequency selection module, and a first inductor. The power amplifier is used to turn on its first and second terminals according to a control terminal. The first inductor is used to isolate the AC current at the power output terminal. The impedance of the first inductor and the load at the target frequency is the actual output impedance of the power amplifier at the target frequency. The frequency selection module is used to adjust the input impedance of the power amplifier to the ideal input impedance at the target frequency, where the ratio of the ideal input impedance to the actual output impedance at the target frequency is -1. By adjusting the input impedance of the power amplifier to a ratio of -1 to the actual output impedance through the frequency selection module, the amplitude and phase of the input and output impedances are balanced. At this point, the input and output impedances are matched, and the power amplifier can achieve higher frequencies. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of a frequency adjustment device for a power amplifier provided by the present invention;

[0026] Figure 2 This is a schematic diagram of another frequency adjustment device for a power amplifier provided by the present invention. Detailed Implementation

[0027] The core of this invention is to provide a frequency adjustment device for a power amplifier and a shortwave therapy device. By using a frequency selection module, the input impedance of the power amplifier is adjusted to a ratio of -1 to the actual output impedance. The amplitude and phase of the input impedance and output impedance are balanced. At this time, the input impedance and output impedance are matched, and the power amplifier can achieve a higher frequency.

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Figure 1 A schematic diagram of the structure of a frequency adjustment device for a power amplifier 1 provided by the present invention includes a power amplifier 1, a frequency selection module 2 and a first inductor L1;

[0030] The power supply is connected to the first terminal of the first inductor L1. The second terminal of the first inductor L1 is connected to the first terminal of the load, the first terminal of the frequency selection module 2, and the first terminal of the power amplifier 1. The second terminal of the frequency selection module 2 is connected to the control terminal of the power amplifier 1. The second terminal of the power amplifier 1 is connected to the second terminal of the load and then grounded. The power amplifier 1 is used to turn on the first terminal and the second terminal of the power amplifier 1 according to the control terminal.

[0031] The first inductor L1 is used to isolate the AC current at the power supply output terminal; the impedance of the first inductor L1 and the load at the target frequency is the actual output impedance of power amplifier 1 at the target frequency.

[0032] The frequency selection module 2 is used to adjust the input impedance of the power amplifier 1 to the ideal input impedance at the target frequency. The ratio of the ideal input impedance to the actual output impedance at the target frequency is -1.

[0033] In practical applications, shortwave therapy can be very effective in treating users. The final stage of the power amplifier 1 in the shortwave therapy device amplifies the signal. Considering that power amplifier 1 needs to continuously operate in the amplification region to amplify the signal and output it to the load, the Miller effect exists between the first terminal and the control terminal of power amplifier 1, such as MOSFETs and transistors. The Miller effect prevents power amplifier 1 from reaching the target power during operation, affecting its normal use. This application provides a frequency adjustment device for power amplifier 1, including a frequency selection module 2. The frequency selection module 2 is used to cancel the Miller capacitance equivalent to the Miller effect, making the ratio of the equivalent impedance of the frequency selection module 2 and power amplifier 1 to the actual output impedance at the target frequency -1. At this point, phase balance and amplitude balance are satisfied, and power amplifier 1 can operate at the target frequency, exhibiting better amplification. Considering that some AC current may exist in the power supply output current, an inductor is provided to isolate this AC current.

[0034] Specifically, the impedance output from the first terminal of power amplifier 1 at the target frequency is taken as the actual output impedance, i.e., the impedance of the first inductor L1 and the load. The impedance between power amplifier 1 and frequency selection module 2 at the target frequency is taken as the ideal input impedance. The function of frequency selection module 2 is to adjust the actual input impedance of power amplifier 1 to the ideal input impedance.

[0035] In summary, this application provides a frequency adjustment device for a power amplifier 1, applied in the field of power amplification. It includes a power amplifier 1, a frequency selection module 2, and a first inductor L1. The power amplifier 1 is used to turn on its first and second terminals according to a control terminal. The first inductor L1 is used to isolate the AC current at the power supply output terminal. The impedance of the first inductor L1 and the load at the target frequency is the actual output impedance of the power amplifier 1 at the target frequency. The frequency selection module 2 is used to adjust the input impedance of the power amplifier 1 to the ideal input impedance at the target frequency, where the ratio of the ideal input impedance to the actual output impedance at the target frequency is -1. By adjusting the input impedance of the power amplifier 1 to a ratio of -1 to the actual output impedance through the frequency selection module 2, the amplitude and phase of the input and output impedances are balanced. At this point, the input and output impedances are matched, and the power amplifier 1 can achieve higher frequencies.

[0036] Based on the above embodiments:

[0037] In a preferred embodiment, the system further includes a filter module 3, with a first end connected to a power supply and a second end connected to the first end of a first inductor L1.

[0038] Filter module 3 is used to filter out harmonics in the power supply output.

[0039] Considering that the power supply will output not only a portion of AC current but also some harmonics, it is insufficient to process the output current through the first inductor L1. Therefore, a filter module 3 is set up to filter out some of the harmonics output by the power supply.

[0040] The filter module 3 processes the current output from the power supply and works in conjunction with the first inductor L1 to better process the current so that it can be amplified by the subsequent power amplifier 1.

[0041] In a preferred embodiment, the filter module 3 includes a first capacitor module 31, a second inductor L2, and a second capacitor module 32;

[0042] The first end of the first capacitor module 31 serves as the first end of the filter module 3. The second end of the first capacitor module 31 is connected to the first end of the second inductor L2. The second end of the second inductor L2 is connected to the first end of the second capacitor module 32. The second end of the second capacitor serves as the second end of the filter module 3.

[0043] This application employs a π-type filter, which consists of a first capacitor module 31, a second inductor L2, and a second capacitor module 32 to filter out harmonics.

[0044] Specifically, the first capacitor module 31 and the second capacitor module 32 can be composed of multiple capacitors connected in parallel. The specific number of capacitors can be adjusted according to actual requirements, and this application does not impose any restrictions here.

[0045] Harmonics are filtered out by building a π-type filter, and with the first inductor L1, the current input to the power amplifier 1 is sufficient for the normal operation of the power amplifier 1.

[0046] In a preferred embodiment, it also includes a DC bias module 4, which is connected to the control terminal of the power amplifier 1;

[0047] The DC bias module 4 is used to assist in starting the oscillation of the power amplifier 1.

[0048] Considering that power amplifier 1 is used for power amplification of the entire circuit, it needs to oscillate to achieve amplification. A DC bias circuit was set up to accelerate the establishment and start-up of the oscillation of power amplifier 1.

[0049] Specifically, power amplifier 1 needs to operate at a frequency of 27.12MHz, and the DC bias circuit is used to provide a frequency of 27.12MHz for the oscillation of power amplifier 1.

[0050] In a preferred embodiment, an input impedance matching module 5 is also included. The first end of the input impedance matching module 5 is connected to the control end of the power amplifier 1. The input impedance matching module 5 is used to perform impedance matching between the signal output by the frequency selection module 2 and the power amplifier 1.

[0051] Considering that the power can reach its maximum value when the input impedance is matched with the impedance of power amplifier 1, but in practical applications the input impedance is often mismatched with the impedance of power amplifier 1, this application sets up an input impedance matching module 5 to match the signal output from frequency selection module 2 with the impedance of power amplifier 1, so as to achieve higher power. This reduces energy loss during transmission, enabling power amplifier 1 to achieve higher power.

[0052] It should be noted that the specific components and connections of the input impedance matching module 5 are not limited in this application; the goal is simply to achieve input impedance matching.

[0053] In a preferred embodiment, the system further includes an output impedance matching module 6. The first end of the output impedance matching module 6 is connected to the first end of the power amplifier 1, and the second end of the output impedance matching module 6 is connected to the first end of the load. The output impedance matching module 6 is used to perform impedance matching between the signal output by the power amplifier 1 and the load.

[0054] Considering that the power can reach its maximum value when the output impedance is matched with the impedance of power amplifier 1, but in practical applications the output impedance is often mismatched with the load impedance, this application sets up an output impedance matching module 6 to match the impedance of the signal output by power amplifier 1 with the load, so as to achieve higher power. This reduces energy loss during the transmission process between power amplifier 1 and the load, allowing the load to receive higher power.

[0055] It should be noted that the specific components and connections of the output impedance matching module 6 are not limited in this application; the goal is simply to achieve input impedance matching.

[0056] In a preferred embodiment, when the power amplifier 1 is an NPN transistor, the base of the NPN transistor serves as the control terminal of the power amplifier 1, the collector of the NPN transistor serves as the first terminal of the power amplifier 1, and the emitter of the NPN transistor serves as the second terminal of the power amplifier 1.

[0057] When power amplifier 1 is an NPN transistor, the base of the transistor is used as the control terminal, the collector as the first terminal, and the emitter as the second terminal. The Miller effect exists between the base and the collector of the transistor.

[0058] Furthermore, the power amplifier 1 includes, but is not limited to, transistors, and also includes MOSFETs. A Miller capacitance exists between the gate and drain of the MOSFET. The gate of the MOSFET serves as the control terminal, the drain as the first terminal, and the source as the second terminal. This application does not impose excessive limitations on the specific model of the power amplifier 1.

[0059] When the voltage applied to the emitter junction of a transistor is greater than the forward voltage of the PN junction, and is at a certain appropriate value, the emitter junction is forward biased and the collector junction is reverse biased. At this time, the base current controls the collector current, giving the transistor current amplification. Therefore, the transistor can be used as a power amplifier (op-amp).

[0060] In a preferred embodiment, the frequency selection module 2 includes a third inductor L3 and a first capacitor C1;

[0061] The first terminal of the first capacitor C1 serves as the first terminal of the frequency selection module 2, and the second terminal of the first capacitor C1 is connected to the first terminal of the third inductor L3. The second terminal of the third inductor L3 serves as the second terminal of the frequency selection module 2.

[0062] Frequency selection module 2 is used to adjust the equivalent impedance of frequency selection module 2 and power amplifier 1 to a state where the ratio of the equivalent impedance to the actual output impedance is -1. The actual output impedance needs to be obtained in advance, and then the value of the ideal input impedance needs to be calculated. The values ​​of the third inductor L3 and the first capacitor C1 are then adjusted to cancel out the equivalent impedance of the Miller capacitor.

[0063] Specifically, depending on the model of power amplifier 1, the value of the equivalent Miller capacitance will also be different, and the values ​​of the third inductor L3 and the first capacitor C1 will also need to be adjusted accordingly. This application will not impose any further restrictions here.

[0064] It should be noted that the specific components of the frequency selection module are not limited in this application, but are based on the equivalent capacitance that cancels out the Miller capacitance.

[0065] By setting a third inductor L3 and a first capacitor C1, the Miller capacitance of power amplifier 1 is canceled, reducing the defects caused by the Miller effect and enabling power amplifier 1 to reach a higher frequency.

[0066] In a preferred embodiment, the equivalent impedance of the first inductor L1 and the load is the actual output impedance Zo = RL + jX2, where RL is the impedance of the load and jX2 is the impedance of the first inductor L1.

[0067] The ideal input impedance of frequency selection module 2 and power amplifier 1 is Zin = -r - jX1, where -r is the impedance of power amplifier 1 and -jX1 is the impedance of frequency selection module 2.

[0068] The relationship between the ideal input impedance and the actual output impedance is Zin / Zo = -1.

[0069] When Zin / Zo=-1, the input impedance and output impedance satisfy the amplitude balance condition and the phase balance condition. The equivalent impedance of the first inductor L1 and the load is obtained in advance, and then the ideal input impedance of the frequency selection module 2 and the power amplifier 1 is calculated. By adjusting the impedance of the frequency selection module 2, the actual impedance of the frequency selection module 2 and the power amplifier 1 is adjusted to the ideal input impedance.

[0070] Specifically, using a vector network analyzer, the first terminal of power amplifier 1 is disconnected from the first inductor L1 and the load. The vector network analyzer is then connected to the common terminal connecting the second terminal of the first inductor L1 and the first terminal of the load to obtain the equivalent impedance of the first inductor L1 and the load. The vector network analyzer is then connected to the first terminal of power amplifier 1 to obtain the actual input impedance. The impedance of frequency selection module 2 and power amplifier 1 is then adjusted to the calculated ideal input impedance using frequency selection module 2. Where jX2 = jX1 * The impedance jX2 of the first inductor L1 is equal to the conjugate of the impedance jX1 of the frequency selection module 2, satisfying phase balance; R L +(-r)=0, where -r is the impedance of power amplifier 1, R L Given the impedance of the load, and satisfying amplitude balance, power amplifier 1 exhibits negative resistance characteristics.

[0071] In summary, the frequency selection module 2 cancels the Miller effect equivalent of the Miller capacitance of the power amplifier 1, so that the power amplifier 1 exhibits negative resistance characteristics. At the same time, after the Miller effect is canceled, the power amplifier 1 can operate at a higher frequency.

[0072] This application also provides a shortwave therapy device, including the frequency adjustment device of the power amplifier 1 described above.

[0073] Please refer to the above embodiments for a description of the shortwave therapy device provided in this application, and it will not be repeated here.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0075] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0076] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A frequency adjustment device for a power amplifier, characterized in that, Includes a power amplifier, a frequency selection module, and a first inductor; The power supply is connected to the first terminal of the first inductor. The second terminal of the first inductor is connected to the first terminal of the load, the first terminal of the frequency selection module, and the first terminal of the power amplifier. The second terminal of the frequency selection module is connected to the control terminal of the power amplifier. The second terminal of the power amplifier is connected to the second terminal of the load and then grounded. The power amplifier is used to turn on the first terminal and the second terminal of the power amplifier according to the control terminal. The first inductor is used to isolate the AC current at the power supply output terminal; the impedance of the first inductor and the load at the target frequency is the actual output impedance of the power amplifier at the target frequency; The frequency selection module is used to adjust the input impedance of the power amplifier to the ideal input impedance at the target frequency, wherein the ratio of the ideal input impedance to the actual output impedance at the target frequency is -1. The frequency selection module includes a third inductor and a first capacitor; The first terminal of the first capacitor serves as the first terminal of the frequency selection module, and the second terminal of the first capacitor is connected to the first terminal of the third inductor. The second terminal of the third inductor serves as the second terminal of the frequency selection module. The equivalent impedance of the first inductor and the load is the actual output impedance Zo = RL + jX2, where RL is the impedance of the load and jX2 is the impedance of the first inductor. The ideal input impedance of the frequency selection module and the power amplifier is Zin = -r - jX1, where -r is the impedance of the power amplifier and -jX1 is the impedance of the frequency selection module. The relationship between the ideal input impedance and the actual output impedance is Zin / Zo = -1; It also includes a DC bias module, which is connected to the control terminal of the power amplifier; The DC bias module is used to provide the operating frequency of the power amplifier and assist in starting the oscillation of the power amplifier.

2. The frequency adjustment device for a power amplifier as described in claim 1, characterized in that, It also includes a filtering module, the first end of which is connected to the power supply, and the second end of which is connected to the first end of the first inductor; The filtering module is used to filter out the harmonics of the power supply output.

3. The frequency adjustment device for a power amplifier as described in claim 2, characterized in that, The filtering module includes a first capacitor module, a second inductor, and a second capacitor module; The first end of the first capacitor module serves as the first end of the filter module, the second end of the first capacitor module is connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second capacitor module, and the second end of the second capacitor serves as the second end of the filter module.

4. The frequency adjustment device for a power amplifier as described in claim 1, characterized in that, It also includes an input impedance matching module, the first end of which is connected to the control terminal of the power amplifier. The input impedance matching module is used to perform impedance matching between the signal output by the frequency selection module and the power amplifier.

5. The frequency adjustment device for a power amplifier as described in claim 1, characterized in that, It also includes an output impedance matching module, the first end of which is connected to the first end of the power amplifier, and the second end of which is connected to the first end of the load. The output impedance matching module is used to perform impedance matching between the signal output by the power amplifier and the load.

6. The frequency adjustment device for a power amplifier as described in claim 1, characterized in that, When the power amplifier is an NPN transistor, the base of the NPN transistor serves as the control terminal of the power amplifier, the collector of the NPN transistor serves as the first terminal of the power amplifier, and the emitter of the NPN transistor serves as the second terminal of the power amplifier.

7. A shortwave therapy device, characterized in that, Includes the frequency adjustment device for the power amplifier as described in any one of claims 1 to 6.

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