Broadband high-voltage radio frequency power supply

Abstract

The invention relates to the field of high-voltage radio-frequency power supplies, and provides a broadband high-voltage radio-frequency power supply, which comprises a signal source S1, a power amplifier A, a coaxial line balun transformer T, a resistor R, a selective switch S2, a plurality of adjustable inductors and a load capacitor C1, the signal source S1 is connected with the input end of the selection switch S2 through the power amplifier A, the coaxial line balun transformer T and the resistor R in sequence; each output end of the selection switch S2 is connected with one end of a load capacitor C1 through an adjustable inductor L1, and the other end of the load capacitor is grounded. According to the broadband high-voltage radio frequency power supply, the wide working bandwidth is realized through the coaxial line balun transformer, the adjustable frequency is realized through the resonant circuit formed by the adjustable inductor and the load capacitor, and the key problems of low frequency upper limit and narrow working bandwidth of the broadband high-voltage radio frequency power supply can be solved.

Description

Technical Field

[0001] This invention relates to the field of high-voltage radio frequency power supplies, and more specifically, to a broadband high-voltage radio frequency power supply. Background Technology

[0002] High-voltage radio frequency power supplies, operating in the frequency range of several hundred kHz to 300 MHz, are widely used in semiconductor chip etching, synchronous scanning fringe cameras, spacecraft ion accelerators, and mass spectrometers. Among these, synchronous scanning fringe cameras, with their ultrafast light source technology and precise ultrafast measurement techniques, play a crucial role in the study of microscopic ultrafast phenomena. They can rapidly record the instantaneous light intensity distribution of the measured object and possess extremely high temporal and spatial resolution. This contributes to a deeper understanding of the mechanisms in physics, chemistry, and biomedicine at the microscopic level, providing a theoretical foundation for technological advancement and development.

[0003] High-voltage radio frequency (RF) power supplies are a crucial component of synchronous scanning streak cameras. They are RF power supplies capable of generating high-frequency, high-power sinusoidal signals. The core requirements of streak cameras for RF power supplies include providing high voltage to ensure sufficient deflection energy for electrons and a wide operating bandwidth. Since the load of a RF power supply is capacitive, current research primarily uses a power amplifier followed by a spiral resonator. This resonator acts as a transformer cavity structure, employing a loosely coupled dual-coil configuration to form a series resonant circuit with the capacitive load, enabling high output voltage and a high quality factor. However, it suffers from narrow bandwidth. Another approach involves switching different inductors after a Class E power amplifier to adjust the resonant frequency of the series resonant circuit formed with the capacitor, facilitating resonant point switching and thus widening the bandwidth of the Class E RF power supply. The drawback is the limited bandwidth extension of Class E power amplifiers, typically within a few MHz, making this method unsuitable for frequencies in the hundreds of MHz range. A further approach involves adding two adjustable inductors to the L-type, Π-type, and T-type circuits, enabling precise matching when switching between capacitive and inductive loads, thereby increasing the range of matched loads. The disadvantage is that it can match loads with a real part of 1Ω to 1000Ω and an imaginary part of -500Ω to +500Ω, but it is not suitable for capacitive loads with a few pF at frequencies of several hundred MHz.

[0004] To achieve higher temporal resolution, streak cameras require a larger scanning slope from the high-voltage radio frequency (RF) power supply. Since the RF power supply uses a high-frequency sine wave as the scanning signal, the scanning slope can be increased by raising the peak-to-peak value of the sine wave while keeping the scanning time constant.

[0005] Therefore, a design method is needed that can both increase the operating frequency of high-voltage RF power supplies and widen their operating bandwidth. Summary of the Invention

[0006] The present invention aims to provide a broadband high-voltage radio frequency power supply, in order to design a high-voltage radio frequency power supply that can both increase the frequency and widen the operating bandwidth.

[0007] The present invention provides a broadband high-voltage radio frequency power supply, comprising a signal source S1, a power amplifier A, a coaxial balun transformer T, a resistor R, a selection switch S2, several adjustable inductors and a load capacitor C1; Signal source S1 is connected to the input terminal of selector switch S2 via power amplifier A, coaxial balun transformer T and resistor R in sequence; each output terminal of selector switch S2 is connected to one end of load capacitor C1 via an adjustable inductor L1, and the other end of load capacitor is grounded.

[0008] In a preferred embodiment, the coaxial balun transformer is implemented by simultaneously installing magnetic rings on two coaxial cables.

[0009] In a preferred embodiment, the coaxial balun transformer includes coaxial lines TL1 and TL2 of the same length, both wound on a magnetic ring Fer1. The core and shell of each coaxial line constitute a 1:1 transmission line transformer. The input terminal P1 of the coaxial balun transformer is connected to the output terminal P2 of the coaxial balun transformer via the core of coaxial line TL1. One end of the shell of coaxial line TL1 is grounded, and the other end is connected to the output terminal P2 of the coaxial balun transformer via the core of coaxial line TL2. One end of the shell of coaxial line TL2 is grounded, and the other end is connected to the output terminal P2 of the coaxial balun transformer.

[0010] In a preferred embodiment, each adjustable inductor has a different range of inductance values, and the range of frequencies corresponding to the broadband high-voltage RF power supply to be implemented is covered.

[0011] In a preferred embodiment, the selection switch S2 is a single-pole double-throw switch, and the adjustable inductor includes adjustable inductor L1 and adjustable inductor L2.

[0012] In a preferred embodiment, when the frequency range of the broadband high-voltage radio frequency power supply is 30MHz~200MHz: The inductance value of the adjustable inductor L1 ranges from 840nH to 9500nH, corresponding to a frequency range of 30MHz to 100MHz. The adjustable inductor L2 has an inductance range of 205nH to 840nH, corresponding to a frequency range of 100MHz to 200MHz.

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This invention achieves a wide operating bandwidth through a coaxial balun transformer and frequency tunability through a resonant circuit composed of an adjustable inductor and a load capacitor, thus solving the key problems of low upper frequency limit and narrow operating bandwidth of broadband high-voltage RF power supplies. Attached Figure Description

[0014] Figure 1 This is a circuit diagram of a broadband high-voltage radio frequency power supply proposed in an embodiment of the present invention.

[0015] Figure 2 This is a circuit diagram of a coaxial balun transformer in an embodiment of the present invention.

[0016] Figure 3 This is a simulation diagram of the voltage ratio of the coaxial balun transformer in an embodiment of the present invention. Figure 3 The horizontal axis represents time, and the vertical axis represents voltage magnitude (Vc3 represents the input voltage, and Vc4 represents the output voltage).

[0017] Figure 4 This is a circuit diagram of a broadband high-voltage radio frequency power supply with a coaxial balun transformer connected to an inductor in an embodiment of the present invention.

[0018] Figure 5 This is a time-domain result diagram of the output voltage Vc of the broadband high-voltage radio frequency power supply in an embodiment of the present invention. Figure 5 The horizontal axis represents time (time), and the vertical axis represents the voltage magnitude (ts(Vc)).

[0019] Figure 6 This is a frequency domain result diagram of the output voltage Vc of the broadband high-voltage radio frequency power supply in an embodiment of the present invention. Figure 6 The horizontal axis represents the frequency freq, and the vertical axis represents the magnitude of the output voltage Vc, mag(Vc).

[0020] Figure 7 This is a circuit diagram of a broadband high-voltage radio frequency power supply with a coaxial balun transformer, as described in an embodiment of the present invention.

[0021] Figure 8 This is a diagram showing the output results of the broadband high-voltage radio frequency power supply from 30MHz to 100MHz in an embodiment of the present invention. Figure 8 The horizontal axis represents the frequency freq, and the vertical axis represents the magnitude of the output voltage Vc, mag(Vc).

[0022] Figure 9 This is a diagram showing the output results of the broadband high-voltage radio frequency power supply from 100MHz to 200MHz in an embodiment of the present invention. Figure 9 The horizontal axis represents the frequency freq, and the vertical axis represents the magnitude of the output voltage Vc, mag(Vc). Detailed Implementation

[0023] 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, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] Example In a streak camera, the deflection plate is not only the device that directly applies scanning voltage to the photoelectrons, but also the final matched load of the high-voltage RF power supply, which is a capacitive load. However, the output of the power amplifier and the final capacitive load are mismatched, resulting in significant signal loss during transmission. Therefore, this invention proposes a broadband high-voltage RF power supply. Combining current cutting-edge transmission line transformer technology, an impedance matching network is designed between the power amplifier and the load capacitor in the broadband high-voltage RF power supply. Frequency tunability is achieved through a resonant circuit composed of an adjustable inductor and the load capacitor, and a wide operating bandwidth is achieved through a coaxial balun transformer, thereby solving the key problems of low upper frequency limit and narrow operating bandwidth of high-voltage RF power supplies.

[0026] For a frequency range of 30MHz to 200MHz, the capacitive load of the deflection plate in the streak camera is taken as 3pF as an example. Figure 1 As shown in the figure, a broadband high-voltage radio frequency power supply proposed in this embodiment of the invention includes a signal source S1, a power amplifier A, a coaxial balun transformer T, a resistor R, a selection switch S2, several adjustable inductors and a load capacitor C1. Signal source S1 is connected to the input terminal of selector switch S2 via power amplifier A, coaxial balun transformer T and resistor R in sequence; each output terminal of selector switch S2 is connected to one end of load capacitor C1 via an adjustable inductor L1, and the other end of load capacitor is grounded.

[0027] In this embodiment, the coaxial balun transformer T, resistor R, selector switch S2, and adjustable inductor L1 constitute an impedance matching network. Taking the selector switch S2 as a single-pole double-throw switch and the adjustable inductors including adjustable inductors L1 and L2 as an example, the signal source S1 outputs a radio frequency (RF) signal. The RF signal is amplified by power amplifier A1 to output a higher power voltage. The high impedance of 50Ω is then transformed to a low impedance (the impedance of resistor R) by the coaxial balun transformer T. The selector switch S2 switches between adjustable inductors L1 and L2 to connect different inductor values ​​in the link. The adjustable inductor L1 or L2 connected to the link forms a series resonance with the load capacitor C1, ensuring smooth signal transmission.

[0028] A coaxial balun transformer is an unbalanced-to-unbalanced converter built on coaxial cable. It utilizes the transmission line principle, employing a ferrite core to provide a high-impedance path for common-mode current, effectively suppressing its radiation and ensuring signal transmission in balanced mode. This design not only handles high power but also offers a wide operating bandwidth. Without the ferrite core, current would leak directly from the coaxial cable sheath to ground at low frequencies, failing to form an effective transmission line coupling current pair. Therefore, a large inductance is required at low frequencies to suppress leakage current on the sheath. However, increasing the inductance introduces additional parasitic capacitance, and the large inductance can resonate with the coaxial cable's parasitic capacitance at high frequencies, limiting its use in the high-frequency range.

[0029] Therefore, the coaxial balun transformer of this invention is achieved by simultaneously adding magnetic rings to two coaxial cables. This avoids the problems associated with not adding magnetic rings at low frequencies. The problem of excessively large physical structures for wavelength is addressed by improving impedance transformation accuracy through suppression of common-mode current. The specific structure is as follows: Figure 2 As shown, the coaxial balun transformer includes coaxial cables TL1 and TL2 of the same length, both wound on a magnetic ring Fer1. The core and shell of each coaxial cable constitute a 1:1 transmission line transformer; the input terminal P1 of the coaxial balun transformer is connected to the core of coaxial cable TL1 (… Figure 2 The 1st and 2nd ports of the coaxial cable TL1 are connected to the output terminal P2 of the coaxial cable balun transformer; one end of the shell of the coaxial cable TL1 ( Figure 2 The four ports of the TL1 coaxial cable are grounded, and the other end ( Figure 2 The 3-port of coaxial cable TL1 passes through the core of coaxial cable TL2 ( Figure 2 The 1st and 2nd ports of the coaxial cable TL2 are connected to the output terminal P2 of the coaxial cable balun transformer; one end of the shell of the coaxial cable TL2 ( Figure 2 The 4-port terminal of the TL2 coaxial cable is grounded, and the other end ( Figure 2 The 3-port of the coaxial cable TL2 is connected to the output terminal P2 of the coaxial cable balun transformer.

[0030] The impedance path of the coaxial balun transformer is as follows: the input signal enters from port 1 of coaxial line TL1 and flows directly out through port 2 of coaxial line TL1; simultaneously, the casing of coaxial line TL1 generates an induced current that flows out from port 3 of coaxial line TL1, enters port 1 of coaxial line TL2, and flows out from port 2 of coaxial line TL2; similarly, the casing of coaxial line TL2 also generates an induced current that flows out from port 3 of coaxial line TL2, merging with ports 2 of coaxial line TL1 and coaxial line TL2 at the output terminal P2, thereby changing the input impedance from 50Ω to 5.5Ω. The simulation results of this coaxial balun transformer are as follows. Figure 3 As shown.

[0031] The deflection plate in the streak camera is the final matched load of the high-voltage RF power supply, and is a parallel-plate capacitor. To achieve the peak-to-peak voltage required by the streak camera, this invention uses a series inductor and load capacitor to form a series resonance, thus achieving impedance matching and resonant coupling of the load capacitor. Taking a frequency of 90MHz as an example, the high-voltage RF power supply... Figure 4 As shown (with adjustable inductor L1 connected). The output voltage Vc of the high-voltage RF power supply is as follows. Figure 5 , Figure 6 As shown. By Figure 5 It can be seen that at a frequency of 90MHz and a load capacitance of 3pF, the maximum output voltage of the high-voltage RF power supply reaches over 1.8kV. From... Figure 6 It can be seen that when the load capacitance is 3pF and the output voltage of the high-voltage RF power supply reaches more than 1kV, the frequency bandwidth is 88MHz~92MHz.

[0032] Each adjustable inductor has a different inductance value range, corresponding to the frequency range of the broadband high-voltage RF power supply to be implemented. To achieve a broadband high-voltage RF power supply frequency range of 30MHz~200MHz, a selector switch S1 is used to switch between adjustable inductors L1 and L2 with different inductance value ranges. Adjusting the resonant frequency of adjustable inductor L1 or L2 with the load capacitor C1 expands the operating bandwidth. The specific link is as follows... Figure 7 As shown.

[0033] In this embodiment of the invention, the frequency range of the broadband high-voltage radio frequency power supply, 30MHz~200MHz, is divided into two segments, one segment being 30MHz~100MHz, according to the formula:

[0034] in, For frequency, L For inductance, C Assuming it is a capacitor, the calculated inductance value of the corresponding adjustable inductor L1 ranges from 840nH to 9500nH.

[0035] Another frequency range is 100MHz~200MHz. Similarly, the inductance range of the adjustable inductor L2 is calculated to be 205nH~840nH.

[0036] from Figure 8 , Figure 9 The results show that, across the entire bandwidth of 30MHz to 200MHz, the peak voltage supplied to the 3pF load capacitor is ≥1kV. This demonstrates that the present invention achieves a wide operating bandwidth through a coaxial balun transformer and frequency tunability through a resonant circuit composed of an adjustable inductor and a load capacitor, thus solving the key problems of low upper frequency limits and narrow operating bandwidth in broadband high-voltage RF power supplies.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A broadband high-voltage radio frequency power supply, characterized in that, Includes signal source S1, power amplifier A, coaxial balun transformer T, resistor R, selector switch S2, several adjustable inductors and load capacitor C1; Signal source S1 is connected to the input terminal of selector switch S2 via power amplifier A, coaxial balun transformer T and resistor R in sequence; each output terminal of selector switch S2 is connected to one end of load capacitor C1 via an adjustable inductor L1, and the other end of load capacitor is grounded.

2. The broadband high-voltage radio frequency power supply according to claim 1, characterized in that, The coaxial balun transformer is achieved by simultaneously installing magnetic rings on two coaxial cables.

3. The broadband high-voltage radio frequency power supply according to claim 2, characterized in that, The coaxial balun transformer includes coaxial lines TL1 and TL2 of the same length, both wound on a magnetic ring Fer1. The core and shell of each coaxial line constitute a 1:1 transmission line transformer. The input terminal P1 of the coaxial balun transformer is connected to the output terminal P2 of the coaxial balun transformer via the core of coaxial line TL1. One end of the shell of coaxial line TL1 is grounded, and the other end is connected to the output terminal P2 of the coaxial balun transformer via the core of coaxial line TL2. One end of the shell of coaxial line TL2 is grounded, and the other end is connected to the output terminal P2 of the coaxial balun transformer.

4. The broadband high-voltage radio frequency power supply according to claim 1, characterized in that, Each adjustable inductor has a different range of inductance values, and these ranges cover the frequency range of the broadband high-voltage RF power supply to be implemented.

5. The broadband high-voltage radio frequency power supply according to claim 4, characterized in that, The selection switch S2 is a single-pole double-throw switch, and the adjustable inductor includes adjustable inductor L1 and adjustable inductor L2.

6. The broadband high-voltage radio frequency power supply according to claim 5, characterized in that, When the frequency range of the broadband high-voltage radio frequency power supply is 30MHz~200MHz: The inductance value of the adjustable inductor L1 ranges from 840nH to 9500nH, corresponding to a frequency range of 30MHz to 100MHz. The adjustable inductor L2 has an inductance range of 205nH to 840nH, corresponding to a frequency range of 100MHz to 200MHz.

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