High-voltage Gaussian pulse generation circuit based on avalanche transistor

Abstract

A high-voltage Gaussian pulse generation circuit based on avalanche transistors comprises N Marx circuits which are connected in parallel, and each Marx circuit comprises an avalanche transistor, an energy storage capacitor and a charging resistor which are alternately connected in series; the waveform adjusting inductor L is connected between the output end of the parallel Marx circuit and the load resistor RL and is used for adjusting the waveform; the gate driving chip is connected to the collector electrode and the base electrode of the first-stage avalanche transistor of the Marx circuit and used for triggering synchronous conduction of the avalanche transistor; a 300V power supply VDC charges the four Marx circuits through a charging resistor, after charging, pulses generated by a gate driving chip enter the four Marx circuits, first-stage avalanche transistors of the four Marx circuits are made to be simultaneously subjected to avalanche conduction, and the avalanche transistors of all stages are conducted stage by stage due to the fact that the voltage borne by the avalanche transistors is increased; after the avalanche of each transistor is conducted, the four marx circuits are connected in parallel to release energy to a load through a waveform adjusting inductor, and a required waveform is formed on the load; the device has the characteristics of convenient design, simple structure, stability and reliability.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage Gaussian pulse technology, specifically relating to a high-voltage Gaussian pulse generation circuit based on avalanche transistors, which is suitable for generating pulse signals with pulse widths of several nanoseconds to tens of nanoseconds and voltages of several kilovolts. Background Technology

[0002] Sub-nanosecond pulse sources based on avalanche transistors and microsecond-level pulse sources based on MOSFETs are relatively mature technologies, and pulse sources ranging from hundreds to thousands of volts have been widely used.

[0003] However, methods for generating high-power pulses with pulse widths ranging from several nanoseconds to tens of nanoseconds are not yet mature. Currently, existing high-voltage pulse generation technologies have the following limitations: I. Pulse Sources Based on MOSFETs: Due to the limitation of the junction capacitance of the switching transistor on and off speeds, nanosecond-level pulses cannot be generated.

[0004] Second, pulse sources based on avalanche transistors operate in an avalanche state, with extremely fast and uncontrollable conduction speeds. They can only generate sub-nanosecond fast leading-edge pulses, thus introducing high-frequency components when analyzing low-frequency pulse effects and affecting the effect analysis.

[0005] III. Most pulse sources based on avalanche transistors currently adopt a single-channel Marx series structure. While increasing the Marx capacitor can extend the pulse width to the nanosecond level, it is difficult to generate high-voltage pulses due to the limited switching power capacity (although increasing the capacitor in a single-channel Marx circuit can widen the pulse width, it is limited by the switching power and has poor high-voltage stability).

[0006] Fourth, although there are pulse generation methods based on parallel avalanche transistors, which utilize the parallel connection of avalanche transistors to increase power capacity and can work normally with a large Marx capacitor to form nanosecond-level high-voltage pulses, the parameter differences of avalanche transistors make it difficult to ensure synchronous conduction of parallel transistors (i.e., when avalanche transistors are connected in parallel, the parameter differences can easily lead to asynchronous conduction). The actual capacity is much smaller than the sum of the power capacities of each transistor, resulting in increased cost and insufficient system stability. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a high-voltage Gaussian pulse generation circuit based on avalanche transistors. By using multiple Marx circuits in parallel and a waveform adjustment inductor design, this invention solves the technical problem of the shortcomings of existing high-power pulse generation methods with pulse widths of several nanoseconds to tens of nanoseconds. It features convenient design, simple structure, and stable and reliable operation.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a high-voltage Gaussian pulse generation circuit based on an avalanche transistor, comprising: N parallel Marx circuits (N≥2), each Marx circuit contains alternating series avalanche transistors, energy storage capacitors and charging resistors; The waveform adjustment inductor L is connected between the output terminal of the parallel Marx circuit and the load resistor RL, and is used to adjust the waveform. The gate driver chip is connected to the collector and base of the first-stage avalanche transistor in the Marx circuit and is used to trigger the synchronous conduction of the avalanche transistor. The parallel Marx circuits are isolated from each other by charging resistors before the avalanche transistors are turned on, and the current sharing discharge is achieved by waveform adjustment inductor L after the transistors are turned on.

[0009] The avalanche transistor is an FMMT417 with a breakdown voltage range of 320V~340V and a single-transistor peak current ≥60A.

[0010] The waveform adjustment inductor L has a value range of 1nH to 300nH and is used to adjust the pulse width of the output pulse to be 0.5ns to 20ns.

[0011] The rise time of the output pulse of the gate driver chip is ≤ 1ns Drive current ≥ 5A This ensures the synchronous triggering of multiple avalanche transistors.

[0012] Each Marx circuit contains 20 series-connected units, each consisting of an avalanche transistor, a storage capacitor, and a charging resistor connected in series.

[0013] The voltage range of the output pulse of the circuit is 1kV~10kV, the pulse width is 3ns~20ns, and the leading edge time is ≥2ns.

[0014] The value of N is 4.

[0015] The beneficial effects of this invention are: 1) Current sharing design: Marx circuits are isolated before conduction, and automatic current sharing is achieved through inductor L after conduction; To increase power capacity, multiple Marx circuits are connected in parallel in the pulse generation section. Unlike pulse generation methods based on parallel avalanche transistors, this circuit does not simply use parallel avalanche transistors to improve current carrying capacity. Instead, it uses multiple Marx circuits connected in parallel, with each Marx circuit isolated from the others before the avalanche transistor is turned on. After the avalanche transistor is turned on, all Marx circuits discharge together, achieving excellent current sharing and thus increasing power capacity.

[0016] 2) Pulse width adjustment: Parallel Marx circuits effectively increase the capacitance of the main circuit, and the pulse is widened by combining the LC effect of inductor L; The design of multiple Marx circuits in parallel can also increase the pulse width. When multiple Marx circuits discharge in parallel, it is equivalent to multiple capacitors discharging in parallel. From the circuit perspective, it is equivalent to a large capacitor discharging, thereby increasing the LC of the main circuit and increasing the width of the output pulse.

[0017] To broaden the pulse leading edge, an inductor of tens to hundreds of nanohenries was added after multiple Marx circuits were connected in parallel. This inductor can effectively isolate the fast leading edge pulse generated by each Marx circuit in the preceding stage when the avalanche transistor is turned on, and increase the LC of the main circuit, thus effectively broadening the pulse leading edge.

[0018] 3) Stable triggering: A high-current gate drive chip is used to ensure that multiple avalanche transistors are turned on synchronously.

[0019] To improve the stability of the output pulse, a gate driver chip is used instead of the traditional fast leading edge comparator to trigger the avalanche transistor. The gate driver chip can provide a large transient current and can stably trigger multiple avalanche transistors. Attached Figure Description

[0020] Figure 1 This is a circuit board diagram of a high-voltage Gaussian pulse generation circuit based on an avalanche transistor.

[0021] Figure 2 This is a schematic diagram of a high-voltage Gaussian pulse generation circuit based on an avalanche transistor according to the present invention.

[0022] Figure 3 This is a schematic diagram of one of the Marx circuit structures of the present invention. Detailed Implementation

[0023] The structural and working principles of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] See Figure 1-3 A high-voltage Gaussian pulse generation circuit based on avalanche transistors, comprising: N parallel Marx circuits (N≥2), each Marx circuit contains alternating series avalanche transistors, energy storage capacitors and parallel charging resistors; The waveform adjustment inductor L is connected between the output terminal of the parallel Marx circuit and the load resistor RL, and is used to adjust the waveform. The gate driver chip is connected to the collector and base of the first-stage avalanche transistor in the Marx circuit and is used to trigger the synchronous conduction of the avalanche transistor. The parallel Marx circuits are isolated from each other by a charging resistor before the avalanche transistor is turned on, and the current sharing discharge is achieved through inductor L after the transistor is turned on.

[0025] The avalanche transistor is an FMMT417 with a breakdown voltage range of 320V~340V and a single-transistor peak current ≥60A.

[0026] The waveform adjustment inductor L has a value range of *1nH~300nH*, and is used to adjust the pulse width of the output pulse to be 0.5ns~20ns.

[0027] The rise time of the output pulse of the gate driver chip is ≤ 1ns Drive current ≥ 5A This ensures the synchronous triggering of multiple avalanche transistors.

[0028] Each Marx circuit contains 20 series-connected units, each consisting of an avalanche transistor, a storage capacitor (100pF~1000pF), and a charging resistor (1kΩ~100kΩ) connected in series.

[0029] The voltage range of the output pulse of the circuit is 1kV~10kV, the pulse width is 3ns~20ns, and the leading edge time is ≥2ns.

[0030] Before implementing the circuit of this invention, appropriate circuit parameters need to be selected based on the target voltage and target pulse width. Taking a target voltage of 2kV and a pulse width of 15ns as an example, the specific implementation method of this circuit is introduced.

[0031] Combination Figure 2 The high-voltage Gaussian pulse generation circuit based on avalanche transistors of the present invention includes four Marx circuits composed of capacitors, avalanche transistors, and charging resistors, as well as waveform adjustment inductor L; resistor RL is the load resistor.

[0032] Before the output pulse, the 300V power supply VDC charges the four Marx circuits through charging resistors, where the charging resistor is 20kΩ, C is 500pF, and the charging time is about 10us.

[0033] After the Marx circuit is fully charged, the pulse generated by the gate driver chip enters through the IN port, causing the first-stage avalanche transistor in the Marx circuit to conduct, and subsequently, the avalanche transistors conduct one after another. This circuit uses a separate design of 4 Marx circuits, making... Figure 2 The four Marx circuits are isolated from each other, preventing the phenomenon where a single Marx circuit conducts first, causing current to converge and burn out the transistor.

[0034] The waveform adjustment inductor L is used to adjust the waveform. In this embodiment, L is 100nH. Combined with four Marx circuits, a high-voltage Gaussian pulse with a voltage of 2kV and a pulse width of 15ns can be obtained.

[0035] The circuit parameters can be adjusted according to different needs to obtain the target pulse. Increasing the number of parallel Marx circuits increases the main circuit capacitance, thereby increasing the pulse width and output amplitude. Increasing the number of Marx circuit stages decreases the main circuit capacitance and increases stray resistance, thereby reducing the pulse width and pulse tail. Increasing the waveform adjustment inductor L increases the pulse width and decreases the output amplitude, while decreasing the waveform adjustment inductor L decreases the pulse width and increases the output amplitude.

[0036] See Figure 2-3 As shown, the high-voltage Gaussian pulse generation circuit based on avalanche transistors includes four Marx circuits (each Marx circuit contains alternating series avalanche transistors (Q1, Q2, Q3, Q4, ..., Q20, Q21), energy storage capacitors (C1, C2, C3, ..., C19, C20), and parallel charging resistors (R1, R1', R2, R2', ..., R20, R20')), a waveform adjustment inductor, and a gate driver chip.

[0037] The first Marx circuit consists of alternating series-connected avalanche transistors, energy storage capacitors, and parallel-connected charging resistors. One end of each energy storage capacitor is connected to the power supply VDC terminal through a charging resistor, and the other end is connected to ground through a charging resistor. Each energy storage capacitor is alternately connected in series with an avalanche transistor. The input terminal of the Marx circuit is connected to the gate driver chip, and the output terminal is connected to a waveform adjustment inductor. The second Marx circuit also consists of alternating series-connected avalanche transistors, energy storage capacitors, and parallel-connected charging resistors. One end of each energy storage capacitor is connected to the power supply VDC terminal through a charging resistor, and the other end is connected to ground through a charging resistor. Each energy storage capacitor is alternately connected in series with an avalanche transistor. The input terminal of the Marx circuit is connected to the gate driver chip, and the output terminal is connected to a waveform adjustment inductor. The third Marx circuit consists of alternating series-connected avalanche transistors, energy storage capacitors, and parallel-connected charging resistors. One end of each energy storage capacitor is connected to the power supply VDC terminal through a charging resistor, and the other end is connected to ground through a charging resistor. The energy storage capacitors and avalanche transistors are alternately connected in series. The input terminal of the Marx circuit is connected to the gate driver chip, and the output terminal is connected to the waveform adjustment inductor. The fourth Marx circuit consists of alternating series-connected avalanche transistors, energy storage capacitors, and parallel-connected charging resistors. One end of each energy storage capacitor is connected to the power supply VDC terminal through a charging resistor, and the other end is connected to ground through a charging resistor. The energy storage capacitors and avalanche transistors are alternately connected in series. The input terminal of the Marx circuit is connected to the gate driver chip, and the output terminal is connected to the waveform adjustment inductor.

[0038] One end of the waveform adjustment inductor is connected to the tail of the four Marx circuits, and the other end is connected to the output port of the overall circuit and outputs to the load.

[0039] One end of the gate driver chip is connected to the head of four Marx circuits, and the other end is connected to the input port of the overall circuit and is controlled by logic levels.

[0040] The working principle of this invention is as follows: Before the output pulse, a 300V power supply (VDC) charges four Marx circuits respectively through charging resistors, where the charging resistor is 20kΩ, C is 500pF, and the charging time is approximately 10µs. After the Marx circuits are fully charged, the pulse generated by the gate driver chip enters the four Marx circuits through the IN port, causing the first-stage avalanche transistors of the four Marx circuits to conduct simultaneously. Subsequently, each stage of the avalanche transistors conducts sequentially due to the increased voltage. After each transistor conducts avalanche, the four Marx circuits, connected in parallel, release energy to the load through a waveform adjustment inductor, forming the desired waveform on the load.

Claims

1. A high-voltage Gaussian pulse generation circuit based on an avalanche transistor, characterized in that, include: N parallel Marx circuits, N≥2, each Marx circuit contains alternating series avalanche transistors, energy storage capacitors and charging resistors; The waveform adjustment inductor L is connected between the output terminal of the parallel Marx circuit and the load resistor RL, and is used to adjust the waveform. The gate driver chip is connected to the collector and base of the first-stage avalanche transistor in the Marx circuit and is used to trigger the synchronous conduction of the avalanche transistor. The parallel Marx circuits are isolated from each other by charging resistors before the avalanche transistors are turned on, and the current sharing discharge is achieved by waveform adjustment inductor L after the transistors are turned on.

2. The high-voltage Gaussian pulse generation circuit based on an avalanche transistor according to claim 1, characterized in that, The avalanche transistor is an FMMT417 with a breakdown voltage range of 320V~340V and a single-transistor peak current ≥60A.

3. The high-voltage Gaussian pulse generation circuit based on an avalanche transistor according to claim 1, characterized in that, The waveform adjustment inductor L has a value range of 1nH to 300nH and is used to adjust the pulse width of the output pulse to be 0.5ns to 20ns.

4. The high-voltage Gaussian pulse generation circuit based on an avalanche transistor according to claim 1, characterized in that, The rise time of the output pulse of the gate driver chip is ≤ 1ns Drive current ≥ 5A This ensures the synchronous triggering of multiple avalanche transistors.

5. The high-voltage Gaussian pulse generation circuit based on an avalanche transistor according to claim 1, characterized in that, Each Marx circuit contains 20 series-connected units, each consisting of an avalanche transistor, a storage capacitor, and a charging resistor connected in series.

6. A high-voltage Gaussian pulse generation circuit based on an avalanche transistor according to any one of claims 1-5, characterized in that, The voltage range of the output pulse of the circuit is 1kV~10kV, the pulse width is 3ns~20ns, and the leading edge time is ≥2ns.

7. The high-voltage Gaussian pulse generation circuit based on an avalanche transistor according to claim 1, characterized in that, The value of N is 4.

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