Radio-frequency and pulsed-radio-frequency switchable power amplifier circuit for mass spectrometry signal enhancement

Abstract

A radio-frequency and pulsed-radio-frequency switchable power amplifier circuit, comprising: a crystal oscillator circuit, a radio frequency signal amplifier circuit, and a control signal conditioning circuit, wherein the control signal conditioning circuit comprises a radio-frequency and pulsed-radio-frequency switching control circuit and a class-E control signal amplifier circuit, the class-E control signal amplifier circuit being connected to a class-AB power amplifier circuit and a power combining and filtering circuit in sequence; a radio frequency signal is generated by means of a crystal oscillator, and a pulsed radio frequency signal or a radio frequency signal is output by means of adjusting the frequency and duty cycle of a pulse control signal; subsequently, the signal is amplified by means of the class-E power amplifier circuit, and the amplified signal is split by means of a transmission line transformer into a group of class-AB power amplifier circuit control signals having equal amplitudes and a phase difference of 180°; the class-AB power amplifier circuit is formed by two paths that are connected in parallel, each path consisting of four class-AB push-pull output modules, and two radio-frequency MOSFETs in each module forming a class-AB push-pull output; and finally, a power-combining magnetic device performs power combining and filtering output. Quick switching between a radio-frequency mode and a pulsed-radio-frequency mode of a high-power power supply is realized, thereby ensuring stable output in different output modes, and improving the applicability of a high-power radio frequency power supply in complex situations.

Description

A switchable RF / pulse RF power amplifier circuit for mass spectrometry signal enhancement Technical Field

[0001] This invention relates to a plasma radio frequency source, and more particularly to a radio frequency and pulse radio frequency switchable power amplifier circuit for mass spectrometry signal enhancement. Background Technology

[0002] With the continuous development of modern electronic technology, power amplifier circuits have also developed and been applied rapidly. In particular, the advancement of semiconductor technology has led to the continuous development of power amplifier circuits towards modularization, miniaturization, and integration.

[0003] Power amplifiers can be broadly classified into two categories based on the operating state of their transistors: linear power amplifiers and nonlinear power amplifiers. In linear power amplifiers, the transistors are in amplification mode, such as Class A, Class B, Class C, and Class AB. Linear power amplifiers improve efficiency by reducing the conduction angle. Under normal operating conditions, when the power transistors are in the conduction state, the drain voltage and drain current output waveforms overlap, meaning they operate simultaneously. In nonlinear power amplifiers, the transistors function like switches, such as Class D and Class E.

[0004] Radio frequency (RF) typically ranges from 1 kHz to 10 MHz, while RF discharge operating frequencies are generally maintained between 2 and 60 MHz. Because this frequency range is close to that of radio waves, it is named RF discharge. To avoid interference with radio wave propagation, internationally, RF discharge frequencies are generally fixed at 13.56 MHz, 27.12 MHz, or 40.68 MHz. Based on the load, RF discharge is classified into capacitively coupled RF discharge and inductively coupled RF discharge. Capacitively coupled RF discharge has been widely used in materials etching, surface modification, and catalyst preparation, with capacitively coupled plasma (CCP) being a representative example. This technology is widely used in etching, deposition, and cleaning processes in the semiconductor industry. The most typical example of inductively coupled RF discharge is inductively coupled plasma (ICP). ICP has been widely used as an excitation / ionization source in conjunction with spectrometers or mass spectrometers for qualitative and quantitative elemental analysis. Both discharge devices require the output of radio frequency power to convert DC power into radio frequency power at a frequency of 27.12MHz and transmit it to the load. ICP ignites and sustains plasma discharge by applying a high-frequency electric field to the load coil.

[0005] In existing technologies, CCP applies radio frequency power to the plate electrode and needle tip to discharge, thereby achieving the excitation study of non-metallic solids. This method is prone to generating 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 hereby proposed. Summary of the Invention

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

[0008] The objective of this invention is achieved through the following technical solution:

[0009] The radio frequency (RF) and pulse RF switchable power amplifier circuit of the present invention includes: a crystal oscillator circuit, an RF signal amplification 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 a Class E control signal amplification circuit. The Class E control signal amplification circuit is connected in sequence with a Class AB power amplification circuit, a power combining and filtering circuit.

[0011] The crystal oscillator circuit includes a 27.12MHz crystal oscillator signal source and its oscillation circuit;

[0012] The radio frequency signal amplification circuit includes a transistor amplification circuit;

[0013] The radio frequency and pulse radio frequency switching control circuit includes a pulse generation module, a soft switch, and a physical switch.

[0014] The Class E control signal amplification circuit includes an RF MOSFET and a transmission line transformer;

[0015] The Class AB power amplifier circuit consists of two parallel circuits, each of which includes four Class AB push-pull output modules. Each module consists of two radio frequency MOSFETs forming a Class AB push-pull output.

[0016] The power combining and filtering circuit includes a power combining magnetic ring and a filtering circuit.

[0017] Compared with existing technologies, the RF / pulse RF switchable power amplifier circuit provided by this invention, through the design of a dual-mode RF / pulse RF output circuit, allows for adjustable output power and adjustable pulse frequency duty cycle. This makes the power supply suitable for various output conditions. Therefore, a pulse RF power signal is required to achieve the maximum excitation efficiency of the sample. Attached Figure Description

[0018] Figure 1 is a schematic diagram of the overall structure of the switchable RF and pulse RF power amplifier circuit provided in an embodiment of the present invention.

[0019] Figure 2 is a schematic diagram of the radio frequency signal amplification circuit, radio frequency, pulse radio frequency switching control circuit, and Class E control signal amplification circuit according to an embodiment of the present invention.

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

[0021] Figure 4 is a pulse radio frequency output diagram of an embodiment of the present invention. In the figure: (a) the pulse signal frequency is 100Hz and the duty cycle is 50%; (b) a 27.12MHz pulse radio frequency signal is output at 100Hz with a duty cycle of 50%.

[0022] Figure 5 is a structural diagram of a Class AB power amplifier circuit according to an embodiment of the present invention. Detailed Implementation

[0023] 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 a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0024] First, the following explanations are provided for the terms that may be used in this article:

[0025] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0026] The terms "comprising," "including," "containing," "having," or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction conditions, processing conditions, parameter, algorithm, signal, data, product or article of manufacture, etc.) should be interpreted as including not only the expressly listed technical feature element, but also other technical feature elements that are not expressly listed and are well-known in the art.

[0027] The term "composed of" excludes any technical features not expressly listed. When used in a claim, it closes the claim to exclude all technical features other than those expressly listed, except for associated conventional impurities. If the term appears only in a clause of a claim, it limits the claim to the elements expressly listed in that clause; elements recited in other clauses are not excluded from the overall claim.

[0028] The contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments used in the embodiments of this invention are not specified, they are all conventional products that can be purchased commercially.

[0029] The radio frequency (RF) and pulse RF switchable power amplifier circuit of the present invention includes: a crystal oscillator circuit, an RF signal amplification 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 a Class E control signal amplification circuit. The Class E control signal amplification circuit is connected in sequence with a Class AB power amplification circuit, a power combining and filtering circuit.

[0031] The crystal oscillator circuit includes a 27.12MHz crystal oscillator signal source and its oscillation circuit;

[0032] The radio frequency signal amplification circuit includes a transistor amplification circuit;

[0033] The radio frequency and pulse radio frequency switching control circuit includes a pulse generation module, a soft switch, and a physical switch.

[0034] The Class E control signal amplification circuit includes an RF MOSFET and a transmission line transformer;

[0035] The Class AB power amplifier circuit consists of two parallel circuits, each of which includes four Class AB push-pull output modules. Each module consists of two radio frequency MOSFETs forming a Class AB push-pull output.

[0036] The power combining and filtering circuit includes a power combining magnetic ring and a filtering circuit.

[0037] The aforementioned radio frequency and pulse radio frequency switching control circuit switches the output mode via manual or automatic control:

[0038] A pulse signal with adjustable frequency and duty cycle is generated by a microcontroller and used as a control signal for an analog switch chip to achieve pulse output of the front-end RF signal, thereby meeting the requirements of pulse RF output.

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

[0040] The frequency and duty cycle of the duty-cycle adjustable pulse signal are set externally by the button and displayed by the digital tube.

[0041] The Class E control signal amplification circuit uses a transmission line transformer to divide the preceding control signal into a group of signals with equal amplitude and 180° phase difference, and drives a pair of RF MOSFETs to push-pull output the signal as the control signal for the subsequent Class AB power amplifier circuit.

[0042] Using the principle of mutual inductance, the sinusoidal signal from the front stage is mutually induced on the secondary side by a 1:1 transmission line transformer to generate a set of signals with equal amplitude and 180° phase difference;

[0043] The transmission line transformer is composed of a hydroxyl magnetic ring and a 17Ω coaxial cable wound together, as shown by the formula:

[0044] The required number of turns is calculated;

[0045] In the formula: Indicates the inductance coefficient. This indicates the corresponding inductance. Indicates the number of turns in the coil.

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

[0047] The power combining and filtering circuit uses a balancing resistor and a power combining magnetic ring to combine two parallel AB class power amplifier circuits, and uses a T-type filter circuit to standardize the waveform.

[0048] In summary, the RF / pulse RF switchable power amplifier circuit of this invention is suitable for the power amplifier circuit topology of high-power RF / pulse RF switchable power supplies. It generates an RF signal using a crystal oscillator and outputs a pulse RF signal or RF signal by adjusting the frequency and duty cycle of the pulse control signal. The signal is then amplified by a Class E power amplifier circuit and split into a set of Class AB power amplifier control signals with equal amplitude and a 180° phase difference by a transmission line transformer. The Class AB power amplifier circuit consists of two parallel circuits, each composed of four Class AB push-pull output modules, each consisting of two RF MOSFETs forming the Class AB push-pull output. Finally, a power combining magnetron performs power combining and filtering for the output. This invention achieves rapid switching between RF and pulse RF modes in high-power power supplies, ensuring stable output in different output modes and improving the applicability of high-power RF power supplies under complex conditions.

[0049] To more clearly demonstrate the technical solution and its effects provided by the present invention, the embodiments of the present invention will be described in detail below with reference to specific examples.

[0050] As shown in Figures 1 to 5:

[0051] A switchable RF / pulse RF power amplifier circuit with linear output power, stable output frequency, strong anti-interference capability, and suitable for various requirements such as ICP and CCP, is disclosed. The power amplifier circuit includes: a crystal oscillator circuit, an RF signal amplification circuit, an RF / pulse RF switching control circuit, a Class E control signal amplification circuit, two parallel Class AB power amplifier circuits, and a power combining and filtering circuit.

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

[0053] The filtering network is a circuit used to smooth the output waveform of the crystal oscillator. 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 radio frequency signal amplification circuit is used to amplify the weak signal in the input circuit for subsequent circuit processing. Its key feature is the use of a common-emitter amplifier circuit composed of transistors. The common-emitter amplifier circuit has a relatively high voltage gain, which can amplify the radio frequency signal generated by the crystal oscillator several times.

[0055] The transistor used is a 2N3866A, which has a characteristic frequency of 800MHz, meeting the requirements for radio frequency output. Its amplification factor can reach up to 200 times, and the crystal oscillator signal can be stably amplified by using common-emitter amplification.

[0056] The radio frequency (RF) and pulse RF switching control circuit consists of a microcontroller, an analog switch chip, a toggle switch, buttons, and an LCD display. The microcontroller uses pulse output as the control signal to control the analog switch chip to output a pulse RF signal. The toggle switch allows switching between RF and pulse RF outputs, making it suitable for various RF output environments.

[0057] The pulse output can be implemented by microcontroller programming, using an external I / O interface to adjust the output pulse frequency and duty cycle, thereby changing the RF output energy.

[0058] Furthermore, the analog switch chip used is the DG202, which has a switching frequency of up to 1MHz, meeting the control requirements in most scenarios.

[0059] The Class E control signal amplification circuit consists of an RF power amplifier, a transmission line transformer, and a balun transformer. It divides the pre-stage sinusoidal RF signal into two control signals, which are then used as control signals for the subsequent Class AB power amplifier circuit.

[0060] The transmission line transformer consists of two hydroxyl iron powder magnetic rings wound with twisted-pair wires. Its secondary side splits the sine wave signal into two half-wave signals to drive the radio frequency power amplifier. The power amplifier operates in Class E mode, with low output power, low loss, and high efficiency.

[0061] The Class AB power amplifier circuit uses two parallel circuits, each consisting of four Class AB push-pull output modules. Each module consists of two RF MOSFETs forming the Class AB push-pull output. Compared to traditional power amplifiers which use a single power amplifier device for push-pull output, the parallel connection of multiple circuits greatly reduces the workload of individual devices and decreases the failure rate.

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

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

[0064] The power combining and filtering circuit consists of a balancing resistor and a power combining magnetic ring. The balancing resistor, designed to absorb half of the output power in an unbalanced output state, is an RF power resistor with a resistance twice the characteristic impedance, i.e., 100Ω. The power combining magnetic ring combines the two output powers, superimposing them to achieve the desired final output power.

[0065] In one embodiment, as shown in Figure 1, an overall structure for RF and pulse RF power output control is proposed. The system includes a crystal oscillator circuit, an RF signal amplification circuit, an RF / pulse RF switching control circuit, a Class E control signal amplification circuit, two parallel Class AB power amplifier circuits, and a power combining and filtering circuit. The system generates an RF signal from the crystal oscillator and outputs a pulse RF signal or RF signal by adjusting the frequency and duty cycle of the pulse control signal. The Class E power amplifier circuit amplifies the signal and then splits it into a set of Class AB power amplifier control signals with equal amplitude and a 180° phase difference by a transmission line transformer. The Class AB power amplifier circuit consists of two parallel circuits, each composed of four Class AB push-pull output modules, each consisting of two RF MOSFETs forming the Class AB push-pull output. Finally, a power combining magnet performs power combining and filtering for the output.

[0066] In one embodiment, as shown in Figure 2, a radio frequency signal amplification circuit, a radio frequency and pulse radio frequency switching control circuit, and a Class E control signal amplification circuit are described.

[0067] Specifically, as shown in Figure 2, the crystal oscillator signal is a filtered crystal oscillator signal after passing through a capacitor and resistor. The RF signal amplification circuit includes a common-emitter transistor amplifier circuit, which amplifies the crystal oscillator signal to reduce distortion during transmission and improve the circuit's driving capability. The amplified voltage's complex amplitude can be changed by adjusting the transistor's drain voltage to suit the input of subsequent amplification circuits. After signal amplification, the output can be switched between RF and pulse RF signals according to the load's requirements. The Class E amplifier circuit controls the output power when a DC power control signal is applied.

[0068] The RF / pulse RF switching control circuit, as shown in Figure 3, consists of a microcontroller, an analog switch chip, a toggle switch, buttons, and an LCD display. The microcontroller uses a pulse output as the control signal to control the analog switch chip to output a pulse RF signal. The toggle switch allows switching between RF and pulse RF outputs, making it suitable for various RF output environments.

[0069] The pulse output can be implemented by microcontroller programming, using an external I / O interface to adjust the output pulse frequency and duty cycle, thereby changing the RF output energy. This pulse is then used as a control signal for an analog switch chip, thus outputting an adjustable pulse RF signal.

[0070] According to one embodiment of the present invention, as shown in Figure 4, the pulse signal frequency and duty cycle can be set by a microcontroller or a host computer. In Figure 4(a), the output frequency is set to 100Hz and the duty cycle of a single cycle is 50%, i.e., 100 times per second, with a high-level output of 5ms. Through microcontroller control, high-precision, low-oscillation output can be achieved. Figure 4(b) shows the pulse radio frequency output signal. The pulse control signal controls the on / off state of the analog switch chip, modulating the continuously output radio frequency signal into a pulse radio frequency signal. Its 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 radio frequency signal.

[0071] The Class E control signal amplifier circuit, as a switching type amplifier circuit, is characterized by high efficiency and low output power, making it suitable as the first stage of signal amplification. Its drain is supplied with DC power through a choke coil, and the gate is supplied with the preceding stage RF signal. When the applied DC power control signal reaches the turn-on voltage, the power amplifier circuit outputs an amplified sine wave signal. The final output power depends on the amplitude of the sine wave signal, i.e., the power control signal voltage.

[0072] Furthermore, since the selected MOSFET is the SD2918, which achieves 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 split into two drive signals with equal amplitude and opposite phase via a transmission line transformer, providing drive voltage for the subsequent Class AB amplifier.

[0073] One of the AB class power amplifier circuits is shown in Figure 5. It consists of two channels, each with four sets of push-pull MOSFET power amplifiers. Its gate is connected to the power amplifier circuit output radio frequency signal or pulse radio frequency signal with a phase difference of 180°. When one side of the power amplifier circuit is turned on, the other side is turned off. Its output power is indirectly controlled by the power control DC signal.

[0074] According to one embodiment of the present invention, a 0-5V analog control signal is used to achieve linear control of the rated maximum output of the power supply, which is 2000W. If the output is 1000W, each device will output 1 / 16, or 62.5W, which greatly reduces the thermal effect of the device and extends its 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] For example, the power combining and filtering circuit consists of a balancing resistor and a power combining magnetic ring. It superimposes sinusoidal power signals with the same amplitude and phase from two Class AB power amplifier circuits to achieve a multi-channel combined output. The two output power lines are twisted into a twisted pair to reduce interference. Finally, after filtering, the required radio frequency or pulsed radio frequency power output is obtained.

[0076] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled 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 description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A switchable power amplifier circuit for radio frequency and pulse radio frequency, 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 a Class E control signal amplification circuit. The Class E control signal amplification circuit is connected in sequence with a Class AB power amplification circuit, a power combining and filtering circuit. The crystal oscillator circuit includes a 27.12MHz crystal oscillator signal source and its oscillation circuit; The radio frequency signal amplification circuit includes a transistor amplification circuit; The radio frequency and pulse radio frequency switching control circuit includes a pulse generation module, a soft switch, and a physical switch. The Class E control signal amplification circuit includes an RF MOSFET and a transmission line transformer; The Class AB power amplifier circuit consists of two parallel circuits, each of which includes four Class AB push-pull output modules. Each module consists of two radio frequency MOSFETs forming a Class AB push-pull output. The power combining and filtering circuit includes a power combining magnetic ring and a filtering circuit.

2. The radio frequency / pulse radio frequency switchable power amplifier circuit according to claim 1, characterized in that, The aforementioned radio frequency and pulse radio frequency switching control circuit switches the output mode via manual or automatic control: A pulse signal with adjustable frequency and duty cycle is generated by a microcontroller and used as a control signal for an analog switch chip to achieve pulse output of the front-end RF signal, thereby meeting the requirements of pulse RF output. The manual or automatic control output mode switching is changed by a switch to three modes: pulse radio frequency, radio frequency, and stop signal output. The frequency and duty cycle of the duty-cycle adjustable pulse signal are set externally by the button and displayed by the digital tube.

3. The radio frequency / pulse radio frequency switchable power amplifier circuit according to claim 2, characterized in that, The Class E control signal amplification circuit uses a transmission line transformer to divide the preceding control signal into a group of signals with equal amplitude and 180° phase difference, and drives a pair of RF MOSFETs to push-pull output the signal as the control signal for the subsequent Class AB power amplifier circuit. Using the principle of mutual inductance, the sinusoidal signal from the front stage is mutually induced on the secondary side by a 1:1 transmission line transformer to generate a set of signals with equal amplitude and 180° phase difference; The transmission line transformer is composed of a hydroxyl magnetic ring and a 17Ω coaxial cable wound together, as shown by the formula: The required number of turns is calculated; In the formula: Indicates the inductance coefficient. This indicates the corresponding inductance. Indicates the number of turns in the coil.

4. The RF / pulse RF switchable power amplifier circuit according to claim 3, characterized in that, The total power of the AB class power amplifier circuit is combined and output by 16 power transistors.

5. The RF / pulse RF switchable power amplifier circuit according to claim 4, characterized in that, The power combining and filtering circuit uses a balancing resistor and a power combining magnetic ring to combine two parallel AB class power amplifier circuits, and uses a T-type filter circuit to standardize the waveform.

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