JP2007042731A - Pulse power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse power supply device capable of generating a repetitive pulse at a high frequency. <P>SOLUTION: A collector electrode of a transistor Q having avalanche breakdown characteristics is connected with a bias voltage source Vb which generates a bias voltage higher than a breakdown voltage of the transistor Q via a bias resistor R, and also, connected with a capacitor C charged by the bias voltage source Vb and discharging electrical charges to the transistor Q by the avalanche breakdown of the transistor Q. A semiconductor laser LD is operated as a pulse optical source by a current flowing in the transistor Q with the electric discharge of the capacitor C after applying a pulse trigger signal to a base electrode of the transistor Q. It is controlled so that the bias voltage source Vb is turned off simultaneously with the pulse trigger signal, and the bias voltage source Vb is turned on at the finish timing of the pulse trigger signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pulse power supply device that generates a pulse output.

  2. Description of the Related Art Conventionally, as a pulse power supply device that emits a short pulse of a semiconductor laser or a light emitting diode, one using a transistor having an avalanche breakdown characteristic (avalanche transistor) or one using a step recovery diode is known.

  Among these, in a pulse power supply device using an avalanche transistor, a bias voltage higher than the breakdown voltage of the avalanche breakdown characteristic is applied, and a pulse trigger signal is applied to the base electrode. -A steep pulse current flowing between the emitter electrodes is used.

  As a pulse power source using such an avalanche transistor, for example, one disclosed in Non-Patent Document 1 is known. FIG. 4 shows a basic circuit of the pulse power source disclosed in Non-Patent Document 1. In the avalanche transistor Q, a control circuit 101 that provides a pulse trigger signal is connected to a base electrode. The collector electrode is grounded via a capacitor C, connected to a bias voltage source Vb via a bias resistor R, and the emitter electrode is grounded via a semiconductor laser LD.

In such a configuration, when a pulse trigger signal as shown in FIG. 5 (a) is applied to the base electrode of the avalanche transistor Q, the charge charged in the capacitor C is discharged as shown in FIG. 5 (b). Then, a large pulse current (avalanche current) flows between the collector and the emitter electrode, and a short pulse output current from the emitter electrode is applied to the semiconductor laser LD as shown in FIG. At the same time, the potential of the collector electrode becomes approximately 0V. Thereafter, the capacitor C is charged according to a time constant determined by the values of the bias resistor R and the capacitor C, and the collector potential is restored to the state before the input of the pulse trigger signal. After charging the capacitor C, an output current can be generated again from the emitter electrode by applying a pulse trigger signal to the base electrode.
Zetex 杜 (UK) Application Note 8 Issue 2 January 1996

  However, in the pulse power supply configured as described above, the pulse repetition frequency is limited by the time until the collector potential is recovered. That is, the repetition frequency of the pulse is determined by the time until the capacitor C is discharged and recharged by the time constant with the bias resistor R. For this reason, it is conceivable to generate pulses at a high frequency by reducing the time constant determined by the capacitor C and the bias resistor R as much as possible and shortening the recovery time of the collector potential. However, if the capacitance of the capacitor C is reduced in order to reduce the time constant, the output current of the emitter electrode obtained when the avalanche transistor Q is turned on decreases. If the bias resistance R is reduced, the current flowing between the emitter and collector electrodes becomes a problem when the avalanche transistor Q is off, and the bias resistance R cannot be reduced much. 6A, 6B, and 6C show waveforms of the trigger pulse signal, the collector potential, and the output current from the emitter electrode when the bias resistor R is reduced and the time constant of charging is reduced. As shown in FIG. 5B, the collector potential is rapidly recovered, but the output current from the emitter electrode shown in FIG. 6C includes an unnecessary component other than the pulse. It becomes difficult to use as a pulse power source.

  Therefore, in practice, a bias resistor R of about 10 kΩ and a capacitor C of about 100 pF are used, and the recovery of the collector potential takes about several microseconds. Therefore, the pulse generation frequency is from 10 kHz to the maximum. However, there was a problem that it was suppressed to about 100 kHz.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pulse power supply device capable of generating high-frequency repetitive pulses.

  The invention according to claim 1 is a transistor having an avalanche breakdown characteristic, a bias voltage source connected to a collector electrode of the transistor via a resistance means and generating a bias voltage higher than the breakdown voltage of the transistor, Capacitor means connected to the collector electrode of the transistor, charged through the resistance means by the bias voltage source, and discharging the charge to the transistor due to avalanche breakdown of the transistor, and the transistor by discharging of the capacitor means Pulse output generating means for generating a pulse output by a current flowing through the transistor, and generating a pulse trigger signal for the base electrode of the transistor, and turning off the bias voltage source in synchronization with the generation of the pulse trigger signal, End of trigger signal In is characterized by comprising a control means for turning on said bias voltage source.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control unit includes a switching unit, and the switching unit controls on / off of the bias voltage source.

  According to a third aspect of the present invention, in the second aspect of the present invention, the switching means comprises a field effect transistor.

  ADVANTAGE OF THE INVENTION According to this invention, the pulse power supply device which can generate | occur | produce the repetition pulse of a high frequency can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of a pulse power supply device according to a first embodiment of the present invention. In FIG. 1, Q is a transistor having an avalanche breakdown characteristic, that is, an avalanche transistor, and the avalanche transistor Q has a base electrode connected to a base drive circuit 1 for driving a pulse trigger signal. The collector electrode is grounded via a capacitor C and connected to a bias voltage source Vb via a bias resistor R and a field effect transistor FET. Further, the emitter electrode is grounded via a semiconductor laser LD such as a pulse laser diode as a pulse output generating means. Here, the capacitor C is charged via a bias resistor R by a bias voltage source Vb, and an avalanche transistor. This is a capacitive means for discharging electric charges between the collector and emitter electrodes of the avalanche transistor Q by Q avalanche breakdown. The bias resistor R is a resistance means for connecting the bias voltage source Vb and the collector electrode of the avalanche transistor Q through the field effect transistor FET. The field effect transistor FET is a switching means for turning on and off the bias voltage of the bias voltage source Vb, and a gate drive circuit 2 for driving a gate signal is connected to the gate electrode. The bias voltage source Vb generates a bias voltage slightly higher than the voltage obtained by adding the breakdown voltage of the avalanche transistor Q and the voltage drop due to the resistance value when the field effect transistor FET is turned on.

  A control circuit 3 is connected to the base drive circuit 1 and the gate drive circuit 2. This control circuit 3 constitutes a control means together with the base drive circuit 1, field effect transistor FET and gate drive circuit 2 of the avalanche transistor Q described above, and controls the base drive circuit 1 and the gate drive circuit 2 separately. I am doing so.

  In such a configuration, first, before a pulse is generated, a gate signal for turning on the field effect transistor FET is output from the gate drive circuit 2 as shown in FIG. Further, a signal for turning off the avalanche transistor Q is output from the base drive circuit 1 as shown in FIG. In this case, when the field effect transistor FET is turned on, the capacitor C is charged by the bias voltage source Vb (FIG. 2C), and the potential Vc of the collector electrode of the avalanche transistor Q becomes substantially the same as the bias voltage source Vb. Yes.

  In this state, when a pulse trigger signal as shown in FIG. 2A is output from the base drive circuit 1 to the base electrode of the avalanche transistor Q in accordance with an instruction from the control circuit 3, the collector electrode of the avalanche transistor Q is applied to the collector electrode. Since a voltage higher than the breakdown voltage is applied by the bias voltage source Vb, avalanche breakdown occurs. As a result, the electric charge charged in the capacitor C is discharged (FIG. 2C), and a steep pulse current flows between the collector and emitter electrodes of the avalanche transistor Q (FIG. 2D). The semiconductor laser LD emits light by this pulse current and operates as a pulse light source that generates a pulse output.

  On the other hand, simultaneously with the generation of the pulse trigger signal from the base drive circuit 1, a gate signal for turning off the field effect transistor FET is output from the gate drive circuit 2 (FIG. 2B). As a result, the field effect transistor FET is immediately turned off, and the current supply source to the collector electrode of the avalanche transistor Q is only the charge charged in the capacitor C, and the pulse current to the semiconductor laser LD is stopped when the capacitor C is discharged. To do.

  Then, after the pulse current is stopped, at the timing of the end of the pulse trigger signal from the base drive circuit 1, the field effect transistor FET is turned on again from the gate drive circuit 2 as shown in FIG. A gate signal for turning on is output. At this time, the collector potential Vc of the avalanche transistor Q is in a state lower than the potential of the bias voltage source Vb due to the discharge of the capacitor C. Accordingly, when the field effect transistor FET is turned on, a charging current flows from the bias voltage source Vb to the capacitor C via the bias resistor R. Since the base signal of the avalanche transistor Q is off, all the current from the bias resistor R to the capacitor C flows to the capacitor C without flowing to the avalanche transistor Q side.

  Thereafter, when the charging of the capacitor C is completed, the control circuit 3 repeats the above-described procedure, so that a pulse current is continuously generated, and the semiconductor laser LD can be operated as a pulse light source.

  Therefore, according to such a pulse power supply device, a pulse trigger signal is output to the base electrode of the avalanche transistor Q to start avalanche breakdown, and at the same time, the field effect transistor FET is turned off to turn off the bias voltage source Vb. By turning off, the electric charge charged in the capacitor C flows between the collector and emitter electrodes of the avalanche transistor Q as a steep pulse current, and the semiconductor laser LD can be operated as a pulse light source. When the field effect transistor FET is turned on and the bias voltage source Vb is turned on after the output of the pulse current, that is, at the end timing of the pulse trigger signal, the avalanche breakdown is completed at this time. The current from the source Vb does not flow into the collector electrode but all flows to the capacitor C, and the capacitor C can be charged quickly. Further, when the avalanche breakdown occurs, the field effect transistor FET is off and the current from the bias voltage source Vb is cut off, so that the bias resistor R connected between the bias voltage source Vb and the collector electrode is used. Even if the value of is reduced, no current flows from the bias voltage source Vb to the collector electrode, and it is possible to quickly recover from the avalanche breakdown after the capacitor C is discharged. In other words, by doing this, even if the bias resistor R is made smaller than the conventional value, unnecessary current is not generated between the emitter and collector electrodes, and the capacitor C can be charged at high speed. Pulses can be generated at a higher repetition frequency.

  Incidentally, conventionally, in order to keep the current flowing between the collector and the emitter electrode as low as possible when the avalanche transistor Q is turned off as described above, the bias resistor R having a value of about 10 kΩ is used, and the pulse generation frequency is used. However, in the present invention, it is possible to use a bias resistor R having a value of about several hundreds Ω, and the pulse generation frequency can be repeated from several tens of MHz to 100 MHz. became.

  In the first embodiment described above, the field effect transistor FET is used as a switch for turning on and off the bias voltage source Vb. However, it is replaced with another element that can be used as a switching element, such as a semiconductor switch or a semiconductor relay. It is possible.

(Second embodiment)
Next, a second embodiment of the present invention will be described.

  FIG. 3 shows a schematic configuration of the pulse power supply device according to the second embodiment of the present invention. The same parts as those in FIG.

  In the first embodiment, a field effect transistor FET is disposed between the avalanche transistor Q and the bias voltage source Vb, and the bias voltage applied to the avalanche transistor Q is turned on and off using the field effect transistor FET. However, in the second embodiment, the bias voltage source 4 is connected to the collector electrode of the avalanche transistor Q via the bias resistor R. The bias voltage source 4 generates a bias voltage to be applied to the avalanche transistor Q and allows the control circuit 3 to directly control the on / off of the bias voltage, and has the same effect as the switching function by the field effect transistor FET described above. It was made to let you.

  Even in this case, the same effect as in the first embodiment can be obtained, and in addition, since a switching element such as a field effect transistor FET, a gate driving circuit thereof, and the like can be omitted, the size can be further reduced. A simple configuration can be realized.

  In addition, this invention is not limited to the said embodiment, In the implementation stage, it can change variously in the range which does not change the summary.

  Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and is described in the column of the effect of the invention. If the above effect is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.

The figure which shows schematic structure of the pulse power supply device concerning the 1st Embodiment of this invention. FIG. 5 is a signal waveform diagram for explaining the operation of the first embodiment. The figure which shows schematic structure of the pulse power supply device concerning the 2nd Embodiment of this invention. The figure which shows schematic structure of the conventional pulse power supply device. The signal waveform diagram for demonstrating operation | movement of the conventional pulse power supply device. The signal waveform diagram for demonstrating operation | movement of the conventional pulse power supply device.

Explanation of symbols

Q ... Avalanche transistor C ... Capacitor R ... Bias resistor Vb ... Bias voltage source LD ... Semiconductor laser FET ... Field effect transistor Vc ... Collector potential 1 ... Base drive circuit 2 ... Gate drive circuit 3 ... Control circuit 4 ... Bias voltage source

Claims (3)

A transistor having avalanche breakdown characteristics;
A bias voltage source connected to the collector electrode of the transistor via a resistance means and generating a bias voltage higher than a breakdown voltage of the transistor;
Capacitance means connected to the collector electrode of the transistor, charged through the resistance means by the bias voltage source, and discharging the charge to the transistor by avalanche breakdown of the transistor;
Pulse output generating means for generating a pulse output by a current flowing through the transistor by discharging of the capacity means;
Control means for generating a pulse trigger signal for the base electrode of the transistor, turning off the bias voltage source in synchronization with the generation of the pulse trigger signal, and turning on the bias voltage source at the end timing of the pulse trigger signal A pulse power supply device comprising:   2. The pulse power supply device according to claim 1, wherein the control means includes switching means, and the switching means controls on / off of the bias voltage source.   3. The pulse power supply device according to claim 2, wherein the switching means comprises a field effect transistor.

Images