Breakdown of transistors in Marx bank circuit
TL;DR: In this article, the authors consider the mode of operation of a Marx bank circuit and analyze the secondary breakdown of transistors with shorted emitter-base and propose a new explanation for the working of the circuit consistent with the experimental observations.
Abstract: We reconsider the mode of operation of a Marx bank circuit and analyze the secondary breakdown of transistors with shorted emitter-base. The mechanism of breakdown of the transistor when a fast rising voltage pulse is applied across is investigated. The device exhibits chaotic behavior at the breakdown point where it can go into two possible modes of breakdown. A new explanation for the working of the circuit consistent with the experimental observations is proposed.
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TL;DR: In this article, the authors proposed an auxiliary triggering topology (ATT) for improving the reliability of high-power MBCs based on avalanche transistors, where the auxiliary triggering pulse is generated between the base and emitter of the transistor, and the switching mode is changed from “overvoltage switching-on ” to “triggering switching on.
Abstract: Marx bank circuits (MBCs) based on avalanche transistors are widely used to generate nanosecond pulses with high power, high repetition rate, and low jitter. However, it was observed that avalanche transistors in the first and second stages of traditional M × N -stage MBCs have high failure rates. This paper proposes an auxiliary triggering topology (ATT) for improving the reliability of high-power MBCs based on avalanche transistors. The operation principles of ATT and failure mechanisms of traditional MBCs are analyzed. By adopting ATT, the auxiliary triggering pulse is generated between the base and emitter of the transistor, and the switching mode is changed from “overvoltage switching- on ” to “triggering switching- on . ” The combined effect of overvoltage ramp and auxiliary triggering pulse significantly reduces the failure rate and prolongs the lifetime of easily damaged transistors. Two high-power nanosecond pulse generators, 3 × 12-stage and 6 × 10-stage MBCs adopting ATT, are developed to verify the feasibility of the proposed configuration. The output amplitude and the rising time are 8.5 kV/6 ns and 17 kV/6 ns at the open end of coaxial cable with 75-Ω impedance, respectively. Both generators are tested continuously at the repetition rate of 2 kHz for 60 min and no failure occurs, which shows much better performance in repetition rate and reliability than traditional M × N -stage MBCs.
27 citations
Cites background from "Breakdown of transistors in Marx ba..."
...The operation principle of ATT and the failure mechanisms of traditional M×N-stage MBCs are analyzed in detail....
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...It can greatly enhance the reliability of M×N-stage MBCs. 2) The auxiliary triggering resistors R12–R1M and R21–R2M are introduced, by which the amplitude of auxiliary triggering pulse voltage and the current can be easily adjusted....
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...In this paper, a novel ATT is proposed to improve the reliability of M×N-stage MBCs based on avalanche transistors....
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...Such displacement current plays an important role in the switching-ON process of transistors in M×N-stage MBCs [14]....
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...In fact, before adopting the ATT for M×N-stage MBCs, we used another method to reduce the failure rate of transistors....
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TL;DR: A repetitive nanosecond pulse generator is developed based on the optimized parameters, which can produce pulses with an amplitude of 9.04 kV, a rise time of 3.4 ns, a pulse width of 18.8 ns, and a maximum repetition rate of 1 kHz.
Abstract: Avalanche transistor-based Marx bank circuit (MBC) is widely used to generate nanosecond pulses with high amplitude, high repetition rate, fast rise time, and low jitter. Recently, the problem that avalanche transistors in the first several stages of $M \times N$ -stage MBC fail frequently has been alleviated by adopting auxiliary triggering topology (ATT). However, the reasons for improvement and the optimal design method have not been fully understood. In this article, a flexible $4\,\,\times10$ -stage MBC is developed to further investigate the output characteristics under different modified stages, capacitors, and loads through both experiments and simulations. The results show that on the one hand, adopting ATT will cause energy loss of the main capacitors to auxiliary triggering capacitors, which can decrease the output voltage; and on the other hand, transistors operating in the auxiliary triggering switching-ON mode have lower residual voltage than in the lower overvoltage switching-ON mode, which can increase the output voltage. This implies that there exists an optimal value of modified stages, which is 5 for the $4\,\,\times10$ -stage MBC. Besides, by adopting ATT, the waveform of output pulse changes, and the rising edge becomes faster. Finally, a repetitive nanosecond pulse generator is developed based on the optimized parameters, which can produce pulses with an amplitude of 9.04 kV, a rise time of 3.4 ns, a pulse width of 18.8 ns, and a maximum repetition rate of 1 kHz at the 75- $\Omega $ open-ended cable. Also, the feasibility of this modified MBC is validated by the preliminary experiments of driving atmospheric pressure plasma jet (APPJ).
21 citations
Cites background from "Breakdown of transistors in Marx ba..."
...Thus, all the subsequent transistors operate in the similar pattern [29], and the larger the number of stages, the higher the overvoltage....
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TL;DR: In this article, it is shown by detailed comparison of experiments with physical modeling that picosecond switching determined by double avalanche injection in the collector-base diode gives way to formation and shrinkage of the collector field domain typical of avalanche transistors under the second breakdown.
Abstract: Although Marx-bank connection of avalanche transistors is widely used in applications requiring high-voltage nanosecond and subnanosecond pulses, the physical mechanisms responsible for the voltage-ramp-initiated switching of a single transistor in the Marx chain remain unclear. It is shown here by detailed comparison of experiments with physical modeling that picosecond switching determined by double avalanche injection in the collector–base diode gives way to formation and shrinkage of the collector field domain typical of avalanche transistors under the second breakdown. The latter regime, characterized by a lower residual voltage, becomes possible despite a short-connected emitter and base, thanks to the 2-D effects.
18 citations
Cites background or methods or result from "Breakdown of transistors in Marx ba..."
...already been formulated, and attempts to resolve it have been undertaken earlier [5], [6], while in our opinion, the question...
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...from the emitter, and that this injection is possible also for shortened emitter and base, but 1-D approach used in [6] is unable to interpret this regime)....
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...Our experimental and simulation results contradict the interpretation suggested in [5] and [6], which assumes a TRAPATT-like zone at the beginning of the transient similar to that reported for the SAS regime in an n0 layer (see [17]–[19] and references therein) and a diodelike breakdown with double avalanche injection at the end of the transient [with an electric field profile similar to that shown by curve 3 in Fig....
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TL;DR: In this article, an improved version of the auxiliary triggering topology (ATT) is proposed to solve the problem of high failure probability of transistors in M × N -stage Marx bank circuits.
Abstract: The avalanche transistor-based Marx circuit has great advantages in generating high-voltage nanosecond pulses. The introduction of auxiliary triggering topology (ATT) can reduce the damage probability of transistors in M × N -stage Marx bank circuits (MBCs). However, as the number of modified stages increases, the output voltage drops significantly, which makes it not achievable to adopt ATT at each stage. The transistors in nonmodified stages still have a certain failure rate when operating at a high repetition rate. Moreover, the previous ATT is only applicable in the negative polarity MBC. In this article, an improved ATT is proposed to solve the above problems. First, its operating principle is analyzed, and the feasibility of its application in both negative and positive MBCs is verified by simulations. Then, the effects of the improved ATT on M × N -stage MBCs are experimentally studied, and the results show that the improved ATT can be used in all stages of MBC without reducing the output voltage. It can also reduce the minimum operating voltage of transistors and widen the regulating range of output voltage. In addition, it can improve the synchronous conduction of parallel-connected transistors. Finally, two nanosecond pulse generators with positive and negative polarity, respectively, are developed and used to drive the atmospheric pressure plasma jet. The amplitude of output voltage can be adjusted in the range of 5–10 kV, measuring at the open end of a coaxial cable with 75 Ω impedance, and the maximum repetition rate is up to 7 kHz.
13 citations
TL;DR: In this article, two different modes of breakdown in the reverse-biased I-V characteristics observed generically in bipolar junction transistors (BJTs) with the base emitter shorted, showing an erratic behavior, in the presence of large displacement currents.
Abstract: This paper discusses two different modes of breakdown in the reverse-biased I–V characteristics observed generically in bipolar junction transistors (BJTs) with the base emitter shorted, showing an erratic behavior, in the presence of large displacement currents. Experimental observations related to reverse-biased collector junctions of BJTs, that exhibit two different states of breakdown when a fast voltage ramp is applied are presented. Numerical simulations of the transient behavior of avalanche injection in p∕n−∕n+ structures show that two very close breakdown states coexist. The mechanisms leading to the erratic behavior of the second breakdown are discussed. The jittery nature of the breakdown is attributed to the delay associated with the buildup of the electric field across the n−∕n+ junction.
8 citations
References
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TL;DR: In this paper, it was shown that transistors having thin, lightly doped collector regions are particularly susceptible to avalanche injection, which suggests that some compromise may be necessary in the design of high-frequency power transistors.
Abstract: A rapid type of second breakdown observed in silicon n+-p-n-n+transistors is shown to be due to avalanche injection at the collector n-n+junction. Localized thermal effects, which are usually associated With second breakdown, are shown to play a minor role in the initiation of the transition to the low voltage state. A useful tool in the analysis of avalanche injection is the n+-n-n+diode, which exhibits negative resistance at a critical voltage and current. A close correspondence between the behavior of the diode and the transistor (open base) is established both theoretically and experimentally. Qualitative agreement with the proposed model is obtained for both directions of base current flow. It is shown that transistors having thin, lightly doped collector regions are particularly susceptible to avalanche injection, which suggests that some compromise may be necessary in the design of high-frequency power transistors.
214 citations
TL;DR: In this paper, a simplified physical model was used to describe TRAPATT (TRApped Plasma Avalanche Triggered Transit) operation, and a complete high-efficiency device design was generated and the dependence of operation on physical parameters was elucidated.
Abstract: This paper utilizes a simplified physical model to describe TRAPATT (TRApped Plasma Avalanche Triggered Transit) operation. By yielding on computational accuracy, a complete high-efficiency device design is generated and the dependence of operation on physical parameters is elucidated. The extreme complexity of the precise differential equations describing TRAPATT operation has made the calculation of a single diode-circuit configuration a tour de force. However, by observing the important features of such a solution, a simplified approach giving realistic answers has been evolved. A theoretical device design has been evolved. This design provides device width and impurity density as a function of TRAPATT frequency, and indicates a decreasing degree of "reach through" with increasing frequency. In addition, the explicit dependence of width and impurity density on the diode's reverse saturation current has been obtained. The launching of the avalanche zone through the diode, and, in particular, the limitations implicit in the recovery to a swept-out state, are of broad significance in other types of diodes, particularly p-i-n switches and "snap" diodes.
109 citations
TL;DR: In this article, the authors studied the second breakdown in silicon-on-sapphire (SOS) thin-film diodes using the stroboscopic technique of Sunshine.
Abstract: Second breakdown has been studied in silicon-on-sapphire (SOS) thin-film diodes using the stroboscopic technique of Sunshine. Nucleation of current filaments, filament growth, and damage through the formation of melt channels are observed and related to the voltage waveforms, geometry, and base layer resistivity. The delay time and the minimum energy for the onset of second breakdown are related to heating of the high-resistivity side of the junction. Theoretical models are presented to describe nucleation of current channels in the junction and the melt transition. A junction channel forms when the sum of minority carrier and thermally generated current densities becomes equal to the local applied current density. The voltage across the junction then goes close to zero locally, but the internal field is not "washed out." The channel is ballasted by the spreading resistance of the high-resistance region. The melt transition is described in terms of a single heat-transfer coefficient characteristic of the device type. As the melt filament grows, the voltage across the filament (and the device) falls. The threshold current for filamentation varies as (ρ-3/4), where ρ is the resistivity of the high-resistance region. Data on transistors are presented in support of the theoretical models.
67 citations
TL;DR: In this article, the characteristics of a bipolar junction transistor operating in the avalanche region and then triggered into current mode second breakdown are formulated, and several methods of fast pulse generation, electrical and optical, using this mode of operation are discussed.
Abstract: The characteristics of a bipolar junction transistor operating in the avalanche region and then triggered into current mode second breakdown are formulated If the time the BJT is subjected to secondary breakdown is limited the BJT may be used as a nanosecond, high voltage switch without sustaining damage Several methods of fast pulse generation, electrical and optical, using this mode of operation are discussed A 2000 V pulse generator, into 50 Ω, with a risetime of approximately 1 ns, jitter <100 ps, is then designed using these results
57 citations