Radio frequency and pulse radio frequency switchable power amplification circuit

Abstract

The invention discloses a radio frequency and pulse radio frequency switchable power amplification circuit which comprises a crystal oscillator circuit, a radio frequency signal amplification circuit, a radio frequency and pulse radio frequency switching control circuit, an E-type control signal amplification circuit, two parallel AB-type power amplification circuits and a power synthesis and filter circuit. A radio frequency signal is generated by the crystal oscillator, and a pulse radio frequency signal or a radio frequency signal is output by adjusting the frequency and the duty ratio of the pulse control signal. Subsequently, the signals are amplified by the E-type power amplification circuit and are divided into a group of AB-type power amplification circuit control signals with equal amplitude and 180-degree phase difference by the transmission line transformer. The AB type power amplification circuit is formed by connecting two paths in parallel, each path is composed of four sets of AB type push-pull output modules, and each set is composed of two radio frequency MOSFETs to form AB type push-pull output. And finally, the power synthesis magnetic device performs power synthesis and filtering output. According to the high-power radio-frequency power supply, rapid switching between a high-power power supply radio-frequency mode and a pulse radio-frequency mode is realized, stable output under different output modes is ensured, and the applicability of the high-power radio-frequency power supply under complex conditions is improved.

Description

Technical Field

[0001] The invention relates to a plasma radio frequency source, in particular to a radio frequency and pulse radio frequency switchable power amplifier circuit. Background Art

[0002] With the continuous development of modern electronic technology, power amplifier circuits have also been rapidly developed and applied. In particular, the progress of semiconductor technology has enabled power amplifier circuits to continue to develop in the direction of modularization, miniaturization, and integration.

[0003] Power amplifiers can be divided into two categories according to the working state of transistors: linear power amplifiers and nonlinear power amplifiers. The transistors in linear power amplifiers are in the amplification state, such as Class A, Class B, Class C, and Class AB. Linear power amplifiers improve their working efficiency by reducing the conduction angle. Under normal operation of this type of amplifier, when the power transistor is in the on state, the drain voltage and drain current output waveforms overlap, that is, they work at the same time. The transistor in a nonlinear power amplifier is equivalent to a switch, such as Class D, Class E, etc.

[0004] The frequency range of radio frequency is generally from 1kHz to 10MHz, while the operating frequency of radio frequency discharge is generally maintained at 2-60MHz. Since the frequency in this area is close to radio waves, it is named radio frequency discharge. In order to avoid interference with radio wave propagation, radio frequency discharge is generally fixed at 13.56MHz, 27.12MHz or 40.68MHz internationally. According to load classification, radio frequency discharge is divided into capacitively coupled radio frequency discharge and inductive radio frequency discharge. Capacitively coupled discharge has been widely used in the fields of material etching, surface modification, catalyst preparation, etc. The representative capacitively coupled discharge is capacitively coupled plasma (CCP). This technology has been widely used in etching, deposition, cleaning and other fields in the semiconductor industry. The most typical representative of inductive radio frequency discharge is inductively coupled plasma (ICP). ICP has been combined with a spectrometer or mass spectrometer as an excitation source / ionization source and is widely used in the qualitative and quantitative analysis of elements. Both discharge devices require the output of RF power to convert DC power into RF power with a frequency of 27.12 MHz and transmit it to the load. ICP ignites and maintains plasma discharge by applying a high-frequency electric field to the load coil.

[0005] In the prior art, CCP applies radio frequency power to the plate and needle tip for discharge, thereby realizing the excitation research of non-metallic solids, which easily causes a large amount of heat accumulation in the sample, leading to melting and affecting the analysis.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a radio frequency and pulse radio frequency switchable power amplifier circuit to solve the above-mentioned technical problems existing in the prior art.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] The radio frequency and pulse radio frequency switchable power amplifier circuit of the present invention comprises: a crystal oscillator circuit, a radio frequency signal amplifying circuit and a control signal conditioning circuit;

[0010] The control signal conditioning circuit includes a radio frequency and pulse radio frequency switching control circuit, and an E-type control signal amplifying circuit, and the E-type control signal amplifying circuit is connected to a class AB power amplifying circuit, a power synthesis and filtering circuit in sequence;

[0011] The crystal oscillator circuit includes a 27.12MHz crystal oscillator signal source and an oscillator starting circuit;

[0012] The radio frequency signal amplifying circuit comprises a triode amplifying circuit;

[0013] The RF and pulse RF switching control circuit includes a pulse generation module, a soft switch and a physical switch;

[0014] The class E control signal amplification circuit includes a radio frequency MOSFET and a transmission line transformer;

[0015] The class AB power amplifier circuit is formed by two parallel paths, each path includes 4 groups of class AB push-pull output modules, and each group of modules consists of two radio frequency MOSFETs to form a class AB push-pull output;

[0016] The power synthesis and filtering circuit comprises a power synthesis magnetic ring and a filtering circuit.

[0017] Compared with the prior art, the RF and pulse RF switchable power amplifier circuit provided by the present invention has an RF and pulse RF dual-mode output circuit, which makes the output power and pulse frequency duty cycle adjustable. The power supply is suitable for a variety of output conditions. Therefore, a pulse RF power signal is required to achieve the maximum excitation efficiency of the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the overall structure of a radio frequency and pulsed radio frequency switchable power amplifier circuit provided in an embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of a radio frequency signal amplifying circuit, a radio frequency, a pulse radio frequency switching control circuit, and a class E control signal amplifying circuit according to an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a radio frequency and pulsed radio frequency output switching circuit according to an embodiment of the present invention;

[0021] Figure 4 1 is a pulsed RF output diagram of an embodiment of the present invention, in which: (a) the pulse signal frequency is 100 Hz and the duty cycle is 50%; (b) a 27.12 MHz pulsed RF signal is output at 100 Hz and the duty cycle is 50%;

[0022] Figure 5 AB class power amplifier circuit structure diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0024] First, the terms that may be used in this article are explained as follows:

[0025] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0026] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0027] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0028] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0029] The radio frequency and pulse radio frequency switchable power amplifier circuit of the present invention comprises: a crystal oscillator circuit, a radio frequency signal amplifying circuit and a control signal conditioning circuit;

[0030] The control signal conditioning circuit includes a radio frequency and pulse radio frequency switching control circuit, and an E-type control signal amplifying circuit, and the E-type control signal amplifying circuit is connected to a class AB power amplifying circuit, a power synthesis and filtering circuit in sequence;

[0031] The crystal oscillator circuit includes a 27.12MHz crystal oscillator signal source and an oscillator starting circuit;

[0032] The radio frequency signal amplifying circuit comprises a triode amplifying circuit;

[0033] The RF and pulse RF switching control circuit includes a pulse generation module, a soft switch and a physical switch;

[0034] The class E control signal amplification circuit includes a radio frequency MOSFET and a transmission line transformer;

[0035] The class AB power amplifier circuit is formed by two parallel paths, each path includes 4 groups of class AB push-pull output modules, and each group of modules consists of two radio frequency MOSFETs to form a class AB push-pull output;

[0036] The power synthesis and filtering circuit comprises a power synthesis magnetic ring and a filtering circuit.

[0037] The RF and pulse RF switching control circuit switches the output mode through manual control or automatic control:

[0038] The single-chip microcomputer generates a pulse signal with adjustable frequency and duty cycle, and uses it as the control signal of the analog switch chip to realize the pulse output of the previous stage RF signal to meet the requirements of pulse RF output;

[0039] The manual control or automatic control switching output mode is switched by a switch to three modes: pulse radio frequency, radio frequency, and stop signal output;

[0040] The frequency and the duty cycle of each cycle of the pulse signal with adjustable duty cycle are set by the outside of the key and displayed by the digital tube.

[0041] The class E control signal amplifier circuit uses a transmission line transformer to divide the previous stage control signal into a group of signals with equal amplitude and 180° phase difference and drives a pair of radio frequency MOSFETs to make their push-pull outputs serve as control signals for subsequent class AB power amplifier circuits;

[0042] The mutual induction principle is adopted to make the front-stage sinusoidal signal pass through a 1:1 transmission line transformer to produce a group of signals with equal amplitude and 180° phase difference on the secondary side.

[0043] The transmission line transformer is composed of a hydroxyl magnetic ring and a 17Ω coaxial cable. The formula is:

[0044] Calculate the required number of turns;

[0045] Where: A L Indicates the inductance, L 0 Indicates the corresponding inductance, N 0 Indicates the number of turns of the coil.

[0046] The total power of the class AB power amplifier circuit is synthesized and output by 16 power tubes.

[0047] The power synthesis and filtering circuit synthesizes two parallel AB class power amplifier circuits using a balancing resistor and a power synthesis magnetic ring, and standardizes the waveform through a T-type filtering circuit.

[0048] From the above, it can be seen that the RF and pulse RF switchable power amplifier circuit of the embodiment of the present invention is suitable for the power amplifier circuit topology of a high-power RF and pulse RF switchable power supply. The RF signal is generated by a crystal oscillator, and a pulse RF signal or a RF signal is output by adjusting the pulse control signal frequency and duty cycle. Subsequently, the signal is amplified by a Class E power amplifier circuit and divided into a group of Class AB power amplifier circuit control signals with equal amplitudes and a phase difference of 180° by a transmission line transformer. The Class AB power amplifier circuit is composed of two parallel paths, each of which is composed of 4 groups of Class AB push-pull output modules, and each group is composed of two RF MOSFETs to form a Class AB push-pull output. Finally, the power synthesis magnetic device is used for power synthesis and filtering output. The present invention realizes the rapid switching of the high-power power supply RF and pulse RF dual modes, ensures stable output under different output modes, and improves the applicability of the high-power RF power supply in complex situations.

[0049] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0050] like Figures 1 to 5 As shown:

[0051] A radio frequency and pulse radio frequency switchable power amplifier circuit with linear output power, stable output frequency, strong anti-interference ability, and suitable for various different needs such as ICP and CCP. The power amplifier circuit includes: a crystal oscillator circuit, a radio frequency signal amplifier circuit, a radio frequency and pulse radio frequency switching control circuit, an E-class control signal amplifier circuit, two parallel AB-class power amplifier circuits, and a power synthesis and filtering circuit.

[0052] The crystal oscillator circuit includes an active crystal oscillator and a resistor and capacitor filter network.

[0053] The filtering network is a circuit used to make the crystal oscillator output waveform smoother, and the control and filtering parameters can be adjusted according to actual needs to optimize the quality and stability of the radio frequency signal.

[0054] The RF signal amplifier circuit is used to amplify the weak signal in the input circuit for subsequent circuit processing. It is characterized by using triodes to form a common emitter amplifier circuit, which has a relatively high voltage gain and can amplify the RF signal generated by the crystal oscillator several times.

[0055] The transistor adopts 2N3866A, and the characteristic frequency of the transistor is 800MHz, which meets the RF output requirements. Its amplification factor can be up to 200 times, and the crystal oscillator signal can be stably amplified by using common emitter amplification.

[0056] The RF and pulse RF switching control circuit is composed of a single-chip microcomputer, an analog switch chip, a toggle switch, a button, and an LCD display screen. The pulse output of the single-chip microcomputer is used as a control signal to control the action of the analog switch chip to output a pulse RF signal. The toggle switch can switch between RF output and pulse RF output to be suitable for a variety of RF output environments.

[0057] The pulse output can be realized by programming a single chip microcomputer, and the output pulse frequency and duty cycle can be adjusted by using an external IO interface, thereby changing the RF output energy.

[0058] Furthermore, the analog switch chip adopts DG202, and the switching frequency of this chip can reach up to 1MHz, which can meet the control requirements in most scenarios.

[0059] The class E control signal amplifying circuit is composed of a radio frequency power amplifier, a transmission line transformer and a balun transformer, and divides the preceding stage sinusoidal radio frequency signal into two control signals as the subsequent class AB power amplifier circuit control signals.

[0060] The transmission line transformer is composed of two hydroxy iron powder magnetic rings wrapped with twisted pair wires, and its secondary side divides the sinusoidal signal into two half-wave signals as a drive for the radio frequency power amplifier. The power amplifier operates in a Class E operating mode with low output power, low loss and high efficiency.

[0061] The class AB power amplifier circuit is formed by two parallel paths, each path is composed of 4 groups of class AB push-pull output modules, and each group is composed of two RF MOSFETs to form a class AB push-pull output. Compared with the traditional power amplifier composed of a group of power amplifier devices for push-pull output, multi-path parallel connection greatly reduces the working pressure of a single device and reduces the failure rate.

[0062] Each power amplifier network is composed of four groups of class AB power amplifier networks connected in parallel, and the outputs are synthesized by a balun transformer, and the total output is the sum of the power outputs of each group.

[0063] The balun transformer is composed of a nickel zinc iron powder magnetic ring and a 17Ω coaxial wire, is suitable for frequencies below 50MHz, and can synthesize single-channel power.

[0064] The power synthesis and filtering circuit is composed of a balancing resistor and a power synthesis magnetic ring. The balancing resistor is used to ensure that half of the output power can be absorbed in the output unbalanced state. The RF power resistor is selected, and its resistance is twice the characteristic impedance, that is, 100Ω. The power synthesis magnetic ring synthesizes the two output powers and superimposes their powers to achieve the final required output power.

[0065] In one embodiment, Figure 1 As shown, an overall structure of RF and pulse RF power output control is proposed, and the system includes a crystal oscillator circuit, an RF signal amplification circuit, an RF and pulse RF switching control circuit, an E-class control signal amplification circuit, two parallel AB-class power amplifier circuits, and a power synthesis and filtering circuit. Among them, the system generates an RF signal by a crystal oscillator, and outputs a pulse RF signal or an RF signal by adjusting the frequency and duty cycle of the pulse control signal. Subsequently, the signal is amplified by the E-class power amplifier circuit and divided into a group of AB-class power amplifier circuit control signals with equal amplitude and 180° phase difference by a transmission line transformer. The AB-class power amplifier circuit is composed of two parallel paths, each of which is composed of 4 groups of AB-class push-pull output modules, and each group is composed of two RF MOSFETs to form an AB-class push-pull output. Finally, the power synthesis and filtering output are performed by the power synthesis magnet.

[0066] In one embodiment, Figure 2 As shown, a radio frequency signal amplifying circuit, a radio frequency, a pulse radio frequency switching control circuit, and a class E control signal amplifying circuit are described.

[0067] Specifically, Figure 2As shown, the crystal oscillator signal is a crystal oscillator signal after capacitor and resistor filtering, and the RF signal amplification circuit includes a triode common emitter amplifier circuit, which is used to amplify the crystal oscillator signal to reduce distortion during transmission and improve the circuit driving capability. The complex amplitude of the amplified voltage can be changed by adjusting the triode drain voltage to be suitable for the subsequent amplification circuit input. After the signal is amplified, the RF and pulsed RF signals can be switched according to the output required by the load. The Class E amplifier circuit performs output power control when a DC power control signal is applied.

[0068] The radio frequency and pulse radio frequency switching control circuit is as follows: Figure 3 As shown in the figure, it consists of a single-chip microcomputer, an analog switch chip, a toggle switch, a button, and an LCD display. The pulse output of the single-chip microcomputer is used as a control signal to control the action of the analog switch chip to output a pulsed RF signal. The toggle switch can switch between RF output and pulsed RF output to suit a variety of RF output environments.

[0069] The pulse output can be realized by programming the single chip microcomputer, and the output pulse frequency and duty cycle can be adjusted by using the external IO interface, so that the RF output energy can be changed. It is used as the analog switch chip control signal to output an adjustable pulse RF signal.

[0070] According to one embodiment of the present invention, Figure 4 As shown, the pulse signal frequency and duty cycle can be set by the microcontroller or host computer. Figure 4 In (a), the output frequency is set to 100 Hz through the host computer, and the duty cycle of a single cycle is 50%, that is, 100 outputs per second, and the high-level output is 5ms. Through the control of the single-chip microcomputer, high-precision and low-oscillation output can be achieved. Figure 4 (b) is a pulsed RF output signal. The pulse control signal controls the on and off of the analog switch chip, and modulates the continuously output RF signal into a pulsed RF signal. The pulse frequency and duty cycle are the same as the pulse signal. When the pulse signal is high, the output frequency is a 27.12MHz RF signal.

[0071] The E-type control signal amplifier circuit is a switch type amplifier circuit, which is characterized by high efficiency and low output power. It is more suitable as the first-stage signal amplification. Its drain is supplied with DC power through a choke coil, and a previous-stage RF signal is applied to its gate. When the DC power control signal reaches the conduction voltage, the power amplifier circuit outputs an amplified sinusoidal signal. The final output power depends on the amplitude of the sinusoidal signal, that is, the power control signal voltage.

[0072] Furthermore, since the selected MOSFET is SD2918, which can achieve good linearity at around 30MHz, the output power can be linearly adjusted according to the power control signal. After the MOSFET amplifies the signal, it is divided into two drive signals with equal amplitude and opposite phase through the transmission line transformer to provide drive voltage for the subsequent class AB amplifier.

[0073] One of the AB class power amplifier circuits is as follows Figure 5 As shown, it consists of two channels, each channel consists of four groups of push-pull MOSFET power amplifiers, whose gates are connected to the power amplifier circuits to output RF signals or pulsed RF signals with a phase difference of 180°. When one side of the power amplifier circuit is turned on, the other side is turned off, and its output power is indirectly controlled by a power control DC signal.

[0074] According to one embodiment of the present invention, a 0-5V analog control signal is used to realize linear control of the rated maximum output of the power supply of 2000W. If the output is 1000W, each device will output 1 / 16, that is, 62.5W, which greatly reduces the thermal effect of the device and prolongs the service life. On the control side, the DC component needs to be set to a linear correspondence, that is, half of the maximum output.

[0075] Exemplarily, the power synthesis and filtering circuit is composed of a balanced resistor and a power synthesis magnetic ring, and the sinusoidal power signals of the two AB class power amplifier circuits with the same amplitude and phase are superimposed to achieve the effect of multi-channel synthesis output. The two output power lines are twisted into a twisted pair to reduce interference. Finally, the required RF or pulse RF power output is output after filtering.

[0076] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

[0077] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A radio frequency, pulsed radio frequency switchable power amplifier circuit, characterized in that: include: Crystal oscillator circuit, radio frequency signal amplification circuit and control signal conditioning circuit; The control signal conditioning circuit includes a radio frequency and pulse radio frequency switching control circuit, and an E-type control signal amplifying circuit, and the E-type control signal amplifying circuit is connected to a class AB power amplifying circuit, a power synthesis and filtering circuit in sequence; The crystal oscillator circuit includes a 27.12MHz crystal oscillator signal source and an oscillator starting circuit; The radio frequency signal amplifying circuit comprises a triode amplifying circuit; The RF and pulse RF switching control circuit includes a pulse generation module, a soft switch and a physical switch; The class E control signal amplification circuit includes a radio frequency MOSFET and a transmission line transformer; The class AB power amplifier circuit is formed by two parallel paths, each path includes 4 groups of class AB push-pull output modules, and each group of modules consists of two radio frequency MOSFETs to form a class AB push-pull output; The power synthesis and filtering circuit comprises a power synthesis magnetic ring and a filtering circuit.

2. The radio frequency and pulse radio frequency switchable power amplifier circuit according to claim 1, characterized in that: The RF and pulse RF switching control circuit switches the output mode through manual control or automatic control: The single-chip microcomputer generates a pulse signal with adjustable frequency and duty cycle, and uses it as the control signal of the analog switch chip to realize the pulse output of the previous stage RF signal to meet the requirements of pulse RF output; The manual control or automatic control switching output mode is switched by a switch to three modes: pulse radio frequency, radio frequency, and stop signal output; The frequency and the duty cycle of each cycle of the pulse signal with adjustable duty cycle are set by the outside of the key and displayed by the digital tube.

3. The radio frequency and pulse radio frequency switchable power amplifier circuit according to claim 2, characterized in that: The class E control signal amplifier circuit uses a transmission line transformer to divide the previous stage control signal into a group of signals with equal amplitude and 180° phase difference and drives a pair of radio frequency MOSFETs to make their push-pull outputs serve as control signals for subsequent class AB power amplifier circuits; The mutual induction principle is adopted to make the front-stage sinusoidal signal pass through a 1:1 transmission line transformer to produce a group of signals with equal amplitude and 180° phase difference on the secondary side. The transmission line transformer is composed of a hydroxyl magnetic ring and a 17Ω coaxial cable. The formula is: Calculate the required number of turns; Where: A L represents the inductance, L0 represents the corresponding inductance, and N0 represents the number of turns of the coil.

4. The radio frequency and pulse radio frequency switchable power amplifier circuit according to claim 3, characterized in that: The total power of the class AB power amplifier circuit is synthesized and output by 16 power tubes.

5. The radio frequency and pulse radio frequency switchable power amplifier circuit according to claim 4, characterized in that: The power synthesis and filtering circuit synthesizes two parallel AB class power amplifier circuits using a balancing resistor and a power synthesis magnetic ring, and standardizes the waveform through a T-type filtering circuit.

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