SU957417A1 - Pulse shaper - Google Patents

Description

(5) PULSE FORMER

one

The invention relates to a pulse technique and can be used as a source of pulses for driving injection semiconductor lasers, high power LEDs, generator lamps, etc.

A pulse shaper is known that contains an avalanche transistor with a load in the emitter circuit, a charging resistor and a storage capacitor l.

This device can not generate short pulses (and me - it is not) of increased amplitude (50, 100 or more volts). This is explained by the fact that in the relaxator on the avalanche transistor increased amplitude, pulses can be obtained only with a large value of the storage capacitor S.ts. However, an increase in capacitance leads to an increase in the width of the pulse, since the duration of its cutoff is determined by the time constant CcS, where R is the load resistance. Therefore, in order to obtain short pulses, the capacitance value needs to be reduced, which automatically leads to a decrease in amplitude.

A pulse shaper is also known that contains two series-connected avalanche transistors with a load in the emitter circuit of the first avalanche transistor, a charging resistor and a storage capacitor in the collector circuit of the second avalanche transistor, between the base and the emitter of the pulse transformer 2.

It allows you to get short pulses (ft 10-20 no). However, the load voltage amplitude is helpful.

Claims (2)

20 is approximately halved. To increase the amplitude of the pulses, a storage capacitor can be used instead of the discharge line. The disadvantages of the famous shaper. reliability and performance are also low. The purpose of the invention is to increase speed and reliability. The goal is achieved by the fact that a pulse generator containing two series-connected avalanche transistors with a load in the emitter circuit of the first avalanche transistor, an accumulator and a charging resistor in the collector circuit of the second avalanche transistor The base and emitter of which includes the secondary winding of the pulse transformer, a diode is inserted, the anode of which is connected to the base of the first avalanche transistor, and the cathode is connected to the common busbar e. The drawing shows a device, the device contains a master generator 1, a pulse transformer 2, an avalanche transistor 3, a storage capacitor k, a charging resistor 5, a power source 6, a avalanche granulator 7, a diode 8 and a load 9. The device operates as follows. In the initial state, the avalanche transistors 3 and 7 are closed. The storage capacitor is charged up to a voltage UCQ, the value of which is chosen to be slightly smaller than the sum of the avalanche transistors 3 and 7. The value (i is set by the resistance of the resistor 5 and the voltage of the power source 6. Transition of the transistors 3 and 7 from closed state the open occurs when a trigger pulse arrives from the master oscillator 1, the inclusion of avalanche transistors 3 and 7 is regenerative in nature. In the process of turning them on, instantaneous currents in the emitter and base circuit The razistor is growing like an avalanche in time. Since the direct impulse resistance of diode 8 is large at the first moment, the main part of the collector current of transistor 7 is branched into the circuit, emitter and, consequently, into the load 9. The resistance of diode 8 decreases in magnitude, as a result of which the base current of transistor 7 increases, the latter increases the effect of shunting the emitter junction and decreases the load current. After reaching a direct pulse impedance of a steady-state value, the emitter junction of the transistor 7 becomes almost completely shunted. The current in load 9 drops to zero. This completes the formation of a pulse in the load 9. The charge accumulated in the base of the transistor 7 is quickly absorbed by the current of the diode 8, the direction of which is opposite to the unlocking base current. This leads to the locking of the avalanche transistor 7 and, accordingly, of the transistor 3. High-frequency dot diodes have the time to establish the impulse direct resistance equal to, Q20 HC. Therefore, the connection of the diode 8 to the base of the transistor 7 makes it possible to form a pulse cutoff, starting from the moment of time corresponding to the current reaching the peak value, i.e. much faster. It should be noted that for normal operation of the circuit, the inclusion of avalanche transistors 3 and 7 is possible if the unlocking signal arrives at the base of transistor 3. This is explained by the fact that the pulse of the master oscillator 1 applied to the base of transistor 7 affects the value charge accumulated in the base of the diode 8, and, therefore, at the time of establishing its direct impulse resistance. Thus, the amplitude of the voltage pulse in the load of the driver is determined by the capacitance of the storage capacitor, while the duration of its cut-off is determined by the establishment time of the direct pulse impedance of the diode connected to the avalanche transistor base circuit. Due to this, the pulse duration in the proposed device with the same amplitude is noticeably less than in the known one. The invention The pulse shaper containing two series-connected avalanche transistors with a load in the emitter circuit of the first avalanche transistor, a charging resistor and a storage capacitor in the collector circuit pa of the second avalanche transistor, between which the secondary winding of the pulse transformer is connected, and that, in order to increase speed and reliability, a diode is inserted into it, the anode of which is connected to the base of the first avalanche transistor, and the cathode is connected to the common bus e. 957 5 76 Sources of information taken into account during the examination 1.Agahan, N.N., Gavri ov L.E., Mishchenko 5.G. Basics of nanosecond technology. Atomizdat, 1976, p. 208. 2.Frequenz 1970, 2k, K 1, S U, V. 16.