JPH0548645B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a circuit using a transistor,
In particular, the present invention relates to a bipolar transistor base drive circuit that enables high-speed switching operations.

[Prior art]

Transistors are used in various electronic circuits, but there are many cases where high-speed operation is required, and various studies are being conducted on them. For example, in order to improve the pulse response characteristics of a transistor switch circuit using bipolar transistors,
Usually, a capacitor is placed in parallel with the base resistor. In addition, in order to quickly turn off the transistor, it is necessary to apply external force to suck out the charge accumulated inside the transistor. That is, a reverse current is passed between the base and emitter, and the larger the reverse current, the shorter the time required to suck out the charge, that is, the storage time. In this way, by shortening the turn-off time of the transistor, high-speed operation of the transistor is enabled. However, care must be taken when the reverse current flowing between the base and the emitter, that is, the base reverse current, is too large, as it tends to cause secondary precipitation breakdown of the transistor. Now, in conventional base drive circuits, a constant reverse voltage is applied between the base and emitter to cause a base reverse current to flow. However, when a constant reverse current is used in this way, the base reverse current is limited by the increase in internal resistance due to the accumulation of charge inside the transistor when the transistor is turned off, so it is difficult to allow an excessively large base reverse current to flow. Therefore, high-speed switching operations are limited.

[Summary of the invention]

The present invention comprises a trigger signal generation circuit, a forward and reverse bias voltage circuit, an off-time voltage circuit, and a base control circuit connected to the forward and reverse bias voltage circuits and the off-time voltage circuit, and includes an internal resistance of a transistor. When the voltage increases, the reverse voltage between the base and emitter is increased to allow a constant base reverse current to flow.

[Embodiments of the invention]

Now, embodiments of the present invention will be described with reference to the drawings. In addition, the same reference numerals are given to items common to each drawing.

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. 1 is a trigger signal generation circuit, 2 is a forward bias voltage circuit, 3 is a first stage reverse bias voltage circuit, 4 is a second stage reverse bias voltage circuit, and 5 is an OFF voltage circuit, which generates a trigger signal. A forward bias voltage circuit 2 is connected to the circuit 1, a first stage reverse bias voltage circuit 3 is connected to the forward bias voltage circuit 2 in parallel with a base control circuit 6, and a first stage reverse bias voltage circuit 3 is connected in parallel to the base control circuit 6. 3, a second-stage reverse bias circuit 4 and an off-state voltage circuit 5 are connected in parallel with a base control circuit 6, and a second-stage reverse bias voltage circuit 4 and an off-state voltage circuit 5 are connected in parallel with a base control circuit 6. Circuit 6 is connected.

FIG. 2 is a circuit diagram showing more specifically this schematic configuration diagram. 11 is a timer circuit that constitutes a sequence and serves as a base drive signal source; 12;
is a comparator that raises the output signal of the timer circuit 11 to a certain level, and constitutes the trigger signal generation circuit 1. 13 is a monostable multivibrator that generates a forward bias voltage signal, and 14 is a comparator that raises the output signal of this multivibrator 13 to a certain voltage level, forming the forward bias voltage circuit 2. 15 is the first
A monostable multivibrator that generates a reverse bias voltage signal in the first stage, 16 is a comparator that amplifies the output signal of this multivibrator to a constant voltage, and the first stage reverse bias voltage circuit 3
Configure. 17 is a monostable multivibrator that generates the second stage reverse bias voltage signal; 18 is a comparator that amplifies the output signal of this multivibrator 17 to a constant voltage; Configure. 19 is a monostable multivibrator that generates a reverse bias voltage signal when it is off, and 20 is this multivibrator 1.
This is a comparator that amplifies the output signal of 9 to a constant voltage, and constitutes the off-state voltage circuit 5. Note that 21 is a summing amplifier that converts four types of signals, ie, the forward bias voltage circuit 2, the first and second stage reverse bias voltage circuits 3 and 4, and the off-time voltage circuit 5, into one signal.

FIG. 3 is a time chart showing the signal waveforms of each part of this circuit diagram. 1 is the output signal A of the timer 11, 2 is the output signal B of the comparator 12, 3 is the output signal C of the multivibrator 13, and 4 is the comparator 14 is the output signal D, 5 is the output signal E of the multivibrator 15, 6 is the output signal F of the comparator 16, 7 is the output signal G of the multivibrator 17, 8 is the output signal H of the comparator 18, and 9 is the output signal of the multivibrator 19. Output signal I, 10 indicates output signal J of comparator 20, and 11 indicates output signal K of summing amplifier 21.

The operation of one embodiment configured in this way will be explained with reference to each figure. A basic signal for driving the base of the transistor is generated as an output signal A by a timer 11, and further amplified by a comparator 12 to become an output signal B. Output signal B becomes output signals C and D by multivibrator 13 and comparator 14, respectively. Output signal D becomes output signals E and F by multivibrator 15 and comparator 16, respectively. The output signal F is multivibrator 17, 19 and comparator 18,
20 respectively output signals G, H and I, J.
becomes. Note that the output signals D, F, H, and J are input to the summing amplifier 21 and become the output signal K. Therefore, this output signal K becomes a signal for driving the base of the transistor.

That is, as shown in FIG. 3, the reverse bias voltage has a signal waveform in which the absolute value increases in two stages.

〔Effect of the invention〕

The present invention processes the output signal of a trigger signal generation circuit including a timer etc. in a sequence consisting of a combination of a monostable multivibrator and a comparator, a reverse bias voltage circuit and an off-state voltage circuit, and then leads it to an adder circuit to create a base. It is used as a drive signal, and instead of the conventional constant reverse voltage, a two-step waveform reverse bias voltage whose absolute value increases in the rear part is applied to the base, and the point at which the internal resistance of the transistor increases. By increasing the reverse voltage between the base and emitter, a constant base reverse current can flow, and the transistor can be turned off quickly, which has the effect of ensuring high-speed switching operation.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 2 is a circuit diagram specifically showing this embodiment, and FIG. 3 is a time chart showing signal waveforms at various parts of this circuit diagram. 1...Trigger signal generation circuit, 2...Forward bias voltage circuit, 3, 4...Reverse bias voltage circuit, 5...
...Off voltage circuit, 11...Timer, 12, 1
4, 16, 18, 20... comparator, 13,
15, 17, 19...monostable multivibrator, 21...summing amplifier.

Claims (1)

[Scope of Claims] 1. A trigger signal generation circuit that generates a trigger signal that is a basic signal for driving the base of a transistor, and a forward bias voltage circuit that generates a forward bias voltage of the base based on this trigger signal. , a first stage reverse bias voltage circuit that generates a first reverse bias voltage of the base at the end of this forward bias voltage, and a first stage reverse bias voltage circuit that is generated at the rear part of this first reverse bias voltage and is connected until its end. At the same time, a second stage reverse bias generates a second reverse bias voltage for forming a two-stage waveform whose absolute value is larger than the first reverse bias voltage when added to the first reverse bias voltage. a voltage circuit; an OFF voltage circuit that generates an OFF voltage of the base at the end of the first reverse bias voltage; and a voltage circuit that generates an OFF voltage of the base at the end of the first reverse bias voltage; A base drive circuit for a transistor, comprising: a base control circuit for adding voltages; 2 The trigger signal generation circuit includes a timer and a comparator connected to the timer, and the forward bias voltage circuit, first stage and second stage reverse bias voltage circuits, and off-state voltage circuit are each monostable multivibrators. 2. The transistor base drive circuit according to claim 1, further comprising a comparator connected to the vibrator, and the base control circuit comprising an adder.