JPH0119472Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a high-speed high-voltage pulse generation circuit that lowers the output impedance without impairing the high-speed performance of the switching element used as a high-speed switch in the high-speed high-voltage pulse generation circuit, and protects the switching element from destruction. .

Conventionally, as a circuit for generating high-speed high-voltage pulses, a circuit has been used that connects a series circuit of a resistor _R1 and a switch SW to a high-voltage power supply HV, as shown in Figure 1, and takes out the output from an intermediate output point OUT. ing. That is, when the switch SW is in the off state, a high voltage from the high voltage power supply HV appears at the output point OUT via the high resistance _R1 . When the switch SW is turned on, the high voltage is shorted to earth, and the output point OUT is also at the same potential as earth. If a high-speed, high-voltage switch such as an avalanche transistor array is used as the switch SW in this circuit, a high-speed voltage step (pulse) can be obtained at high voltage.

However, when the high speed switch SW is in the off state, the impedance is determined by the resistor _R1 and is therefore very high, making the voltage unstable. Therefore, in order to lower the impedance, a capacitor C must be connected in parallel as shown in Figure 2, but in this circuit, when the high-speed switch SW is on, the discharge current of the capacitor C is equal to that of the high-speed switch SW.
It will flow to SW. The higher the speed of the high-speed switch SW, the larger this discharge current becomes.If a high-speed switching element is used as the switch SW in the conventional circuit shown in Fig. 2,
The life of this high-speed switching element is significantly shortened. Experiments revealed that this phenomenon was caused by the peak value of the discharge current becoming too large, but as shown in Figure 3, the resistor R was simply used to limit the current flowing through the switch SW. If you just connect ₂ in series, the output point
Since the voltage appearing at OUT has a time constant determined by capacitor C and resistor _R2 , the high speed performance of the switch SW will be significantly impaired.

In view of the above points, this invention provides a high-speed, high-voltage pulse generation circuit that lowers the output impedance and allows high-speed switches to be used stably and with a long life.

Figure 4 shows the principle of this invention, in which capacitor C and resistor R ₃ are inserted and connected in series in a circuit in which resistor R ₁ and switch SW are connected in series, and capacitor C is connected in parallel. It is. If you configure it like this and choose the value of resistor R ₃ to an appropriate value,
The impedance seen from the output point OUT is the switch
Even when SW is off, it can be made much smaller than when only one resistor _R is used. When the switch is on, the voltage drop due to the discharge current of capacitor C flowing through resistor _R3 is at the output point OUT.
does not appear on the switch, and the voltage at the output point OUT does not appear on the switch.
If the internal resistance of SW is ignored, it immediately becomes zero. Moreover, since the current that flows when the switch SW is turned on is limited by the resistor _R3 , the high-speed switching element used in the switch SW will not be destroyed by the peak current.

Next, one embodiment of this invention will be described.
FIG. 5 is a circuit diagram in which a load L is actually connected to the principle diagram of FIG. 4, and FIG. 6 is a characteristic diagram of voltage change at the output point OUT. Since the load L is affected by disturbances from other sources in addition to high-voltage pulses, if the impedance of the pulse source is high, a very large fluctuation will appear at the output point OUT. As is clear from the characteristic diagram, there is an external disturbance at time A, but its magnitude is so small that it poses no practical problem, and furthermore, just before time B, when the switch SW starts operating, there is an external disturbance. It can be seen that the voltage has recovered to its original level.

As described above, this idea has great practical effects because it is possible to maintain the high-speed performance of the high-speed voltage pulse generation circuit by simply changing the connection points of the resistors, and it also prevents the switching elements used as switches from being destroyed. .

[Brief explanation of drawings]

Figure 1 is a diagram of a conventional high-speed pulse generation circuit, Figures 2 and 3 are improved diagrams thereof, Figure 4 is a principle circuit diagram of this invention, Figure 5 is a circuit diagram of an embodiment of this invention, and Figure 5 is a circuit diagram of an embodiment of this invention. FIG. 6 is a characteristic diagram of FIG. In the figure, HV is a high voltage power supply, SW is a switch,
C is a capacitor, R ₁ , R ₂ , R ₃ are resistors, and L is a load.

Claims (1)

[Scope of utility model registration request] A high-voltage power supply, a resistor, and a self-recovery high-speed switch that turns off the high voltage from the high-voltage power supply as the current decreases are connected in series, and a high-speed high-voltage pulse is generated between the resistor and the high-speed switch. In high-speed high-voltage pulse generation circuits, voltage stabilization capacitors and
A high-speed, high-voltage pulse generation circuit characterized in that a series circuit with a current-limiting resistor is connected in parallel to the above-mentioned high-speed switch.