JPH10285929A - Electric circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectifier circuit which can efficiently rectify an AC voltage. SOLUTION: A voltage to be rectified from a power source is applied across an emitter E of an NPN transistor 11, and a load 17 is connected to a collector C of the transistor 11. When the voltage at the emitter E is higher than that at the collector C, an operational amplifier 21 turns on the transistor 11 in a saturated area by applying a positive voltage across the base of the transistor 11. In the saturated area, the voltages at the emitter E and the collector C become nearly equal to each other, and the voltage from the power source 15 is applied across the load 17 by causing little loss in the transistor 11. When the voltage at the emitter E is lower than that at the collector C, the amplifier 21 turns off the transistor 11 by applying a negative voltage across the base of the transistor 11. Therefore, the power supply voltage to the transistor 11 is applied across the emitter E and the collector C, and a grounding voltage is applied across the load 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric circuit for rectifying an alternating current, and more particularly to an electric circuit for rectifying an alternating current with low loss.

[0002]

2. Description of the Related Art A rectifier circuit is used as a circuit for converting an AC voltage into a DC voltage. Conventional rectifier circuits are configured using silicon diodes, Schottky barrier diodes, and the like.

[0003]

However, in the conventional rectifier circuit, the relationship between the voltage Vf and the current If is indicated by a broken line in FIG.
１．０1.0 V, and there is a problem that the voltage drop in the diode constituting the rectifier circuit, that is, the loss is large, and the rectification efficiency is low.

[0004] The present invention has been made in view of the above circumstances, and has as its object to provide an electric circuit capable of rectifying alternating current with low loss.

[0005]

In order to achieve the above object, an electric circuit according to a first aspect of the present invention comprises a transistor and a control circuit connected to the transistor, wherein the transistor has a current Road and control end,
A rectification target voltage is received at one end of the current path, and the rectified voltage is output to the other end of the current path by being turned on or off under the control of the control circuit. Connected to at least one end of the current path and the control end, to turn on the transistor when a reverse voltage is applied to the current path, and to turn off the transistor when a forward voltage is applied to the current path, By turning on or off the transistor by controlling a signal applied to an end, the transistor rectifies the rectification target voltage.

According to the electric circuit according to the first aspect of the present invention, the transistor is turned on when the voltage applied to the current path of the transistor is the reverse voltage, and is turned off when the voltage is the forward voltage. Therefore, only a voltage of one polarity is applied to the load connected to the transistor. Further, when the transistor is turned off, a forward voltage is applied to the current path, so that a large withstand voltage can be obtained.

Further, an electric circuit according to a second aspect of the present invention comprises a transistor and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, and one end of the current path. And outputs a rectified voltage to the other end of the current path by turning on and off according to the control of the control circuit, and the control circuit is connected to both ends of the current path and the control end. Detecting a potential difference between both ends of the current path, turning on the transistor when a reverse voltage of the transistor is applied to the current path of the transistor, and a forward voltage of the transistor is applied to the current path. By controlling a signal applied to the control terminal to turn on or off the transistor so that the transistor is turned off when the transistor is applied, the transistor is turned off. The cause of the rectified target voltage is rectified to register, characterized in that.

Further, an electric circuit according to a third aspect of the present invention comprises a transistor and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, and one end of the current path. Receiving a rectification target voltage to be rectified, and outputting a rectified voltage to the other end of the current path by turning on or off in accordance with the control of the control circuit. Connected to an end of the transistor, detects the polarity of a potential difference between both ends of the current path, turns on the transistor when a reverse voltage is applied to the current path of the transistor, and applies a forward voltage to the current path. By turning on or off the transistor by controlling a signal applied to the control terminal so that the transistor is turned off when the rectification is performed, To rectify the voltage, and wherein the.

According to the electric circuit according to the second and third aspects of the present invention, the voltage applied across the current path of the transistor or the polarity thereof is detected, and the transistor is turned on when the voltage is in the reverse direction. Then, the transistor is turned off at the time of the forward voltage. Therefore, only a voltage of one polarity is applied to the load connected to the other end of the current path of the transistor, and a rectified voltage can be applied to the load. Further, when the transistor is turned off, a forward voltage is applied to the current path, so that a large withstand voltage can be obtained. In the case of such an electric circuit, it is conceivable to turn on / off the transistor based on the value of the supplied rectification target voltage and its polarity. However, with this method, if the load is of a type that has a voltage, such as a capacitor or a battery,
When the transistor is turned on, the power supply voltage becomes lower than the load voltage, and the current may flow backward. In these inventions, since the voltage applied to the current path of the transistor is detected, such a problem does not occur, and the voltage to be rectified can be rectified.

[0010] The transistor is, for example, a bipolar transistor. In this case, both ends of the current path are composed of an emitter and a collector of the bipolar transistor, the control terminal is composed of a base of the bipolar transistor, and the control circuit is configured to control a voltage and / or a voltage between the emitter and the collector. It comprises means for detecting the polarity and supplying a voltage and a current to the base.

When the bipolar transistor is of the NPN type, one end of the current path is constituted by the emitter of the NPN bipolar transistor, the other end of the current path is constituted by the collector, and the control end is constituted by the base. When a positive potential higher than the collector is applied to the base, a voltage and current for turning on the NPN transistor are supplied to the base, and when a positive polarity voltage lower than the collector is applied to the emitter, the NPN transistor is turned on. A voltage and a current for turning off the transistor are supplied to the base.

Further, the bipolar transistor is PN
In the case of a P-type, one end of the current path is an emitter of the PNP bipolar transistor, the other end of the current path is a collector,
The control terminal includes a base, and the control circuit supplies a voltage and a current for turning on the PNP transistor to the base when a positive potential higher than the emitter is applied to the collector, and supplies the collector with the collector. When a positive voltage lower than the emitter is applied, the PNP
A voltage and a current for turning off the transistor are supplied to the base.

[0013] The bipolar transistor comprises an emitter and a collector composed of semiconductor layers having substantially the same thickness. According to such a configuration, there is substantially no distinction between the emitter and the collector, so that a large current amplification factor can be ensured when turned on, and a high breakdown voltage can be obtained when turned off.

[0014] The transistor may be a field effect transistor. In this case, both ends of the current path are composed of a source and a drain of the field effect transistor, the control terminal is composed of a gate of the field effect transistor, and the control circuit is configured to control a voltage between the source and the drain. And / or a means for detecting the polarity thereof and applying a control voltage to the gate according to the detected voltage.

When the field effect transistor is an N-channel type, one end of the current path is constituted by a source, the other end of the current path is constituted by a drain, the control end is constituted by a gate, and the control circuit is Applying an ON voltage to the gate when a positive voltage higher than the drain is applied to the source, and supplying an OFF voltage to the gate when a positive voltage lower than the drain is applied to the source It consists of means.

When the field-effect transistor is a P-channel type, the control circuit applies a voltage to the gate to turn on the P-channel field-effect transistor when a positive voltage lower than the drain is applied to the source. Means for applying a voltage to the gate to turn off the P-channel field effect transistor when a positive voltage higher than the drain is applied to the source.

In the control circuit, for example, one input terminal is connected to one end of the current path of the transistor, the other input terminal is connected to the other end of the current path of the transistor, and the output terminal is connected to the transistor. It comprises an amplifier circuit such as an operational amplifier connected to the control terminal. in this case,
A diode connected in reverse direction between the one input terminal and the other input terminal of the amplifier circuit, and a diode connected between the one input terminal and one end of the current path or the other input terminal and the other of the current path. And a constant current source inserted between the ends. The operational amplifier is not only a pure amplification operation,
It may function as a comparator. That is, the output voltage may be saturated according to the input voltage.

Further, an electric circuit according to a fourth aspect of the present invention includes a transistor and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, and one end of the current path. Receiving a rectification target voltage and turning on and off according to the control of the control circuit to output a rectified voltage to the other end of the current path.The control circuit outputs the rectified voltage to the current path and the control end of the transistor. Connected, according to the direction of the current flowing to one end of the current path and the node of the external circuit, by controlling the signal applied to the control end to turn on or off the transistor, the rectification target voltage to the transistor Rectification.

According to the electric circuit of the fourth aspect of the present invention, the transistor is turned on / off according to the direction of the current flowing through the current path of the transistor and the connection node (connection point) of the external circuit. When the transistor is turned on, the current flows through the current of the transistor and is supplied to the load circuit. Therefore, the rectified current can be applied to the load. When the transistor is off,
Since a forward voltage is applied to the current path, a large withstand voltage can be obtained.

The transistor is, for example, a bipolar transistor. In this case, both ends of the current path are constituted by an emitter and a collector of the bipolar transistor, and the control end is constituted by a base.
The control circuit supplies a voltage and a current to the base,
The bipolar transistor is turned on.

When the bipolar transistor is of NPN type, one end of the current path is constituted by an emitter, the other end is constituted by a collector, and the control end is constituted by a base. The control circuit is connected to a node between the emitter and the external circuit. When the direction of the flowing current is detected and the current in the predetermined direction is detected,
A voltage and a current for turning on the NPN transistor are supplied to the base.

In this case, a diode is connected between the emitter and the collector or between the emitter and the base so that the current in the predetermined direction flows through the node even when the NPN bipolar transistor is off. May be.

When the bipolar transistor is a PNP type, one end of the current path is an emitter, the other end is a collector,
The control terminal includes a base, and the control circuit detects a direction of a current flowing to a node between the emitter and the external circuit, and when detecting a current in a predetermined direction, the PN
A voltage and a current for turning on the P transistor are supplied to the base.

In these cases, a diode is connected between the emitter and the collector or between the emitter and the base so that the current in the predetermined direction flows through the node even when the NPN bipolar transistor is off. You may comprise.

The transistor comprises, for example, a field effect transistor, both ends of the current path are constituted by a source and a drain of the field effect transistor, and the control terminal is constituted by a gate of the field effect transistor. The circuit includes means for applying a gate voltage to the gate to turn on the field effect transistor in a region.

In the case where the field effect transistor is an N-channel type, for example, one end of the current path is constituted by a source, the other end is constituted by a drain, and the control end is constituted by a gate. Means for applying a voltage to the gate to turn on the N-channel field effect transistor when a current flowing through the node is in a predetermined direction.

When the field-effect transistor is an N-channel type, the control circuit detects a current flowing from the source to the drain through a parasitic diode of the N-channel field-effect transistor, for example. N
It comprises means for turning on the channel field effect transistor.

[0028] A diode may be connected between the source and the drain, or a constant voltage diode may be connected between the gate and the source.

When the field effect transistor is a P-channel type, for example, one end of the current path is constituted by a source, the other end is constituted by a drain, and the control end is constituted by a gate. The control circuit includes means for applying, to the gate, a voltage for turning on the P-channel field-effect transistor when a current flowing in a node between the source and the external circuit is in a predetermined direction.

The control circuit is configured to detect a current flowing from the drain to the source via the parasitic diode of the P-channel field-effect transistor and turn on the P-channel field-effect transistor. Is also good. In these cases, a diode may be connected between the source and the drain, or a constant voltage diode may be connected between the gate and the source.

The control circuit may include, for example, a transformer having a primary winding connected to one end of the current path of the transistor, and a secondary winding magnetically coupled to the primary winding; And a bias circuit connected to the secondary winding of the transformer and controlling a signal supplied to the control terminal of the transistor in accordance with a current generated in the secondary winding.

[0032] The control circuit may include, for example, means for converting an induced current of the secondary winding into a voltage signal and applying the voltage signal to the control terminal. In this case, for example, the control circuit converts the induced current of the secondary winding into a voltage signal, and amplifies the voltage signal converted by the conversion circuit and applies the voltage signal to the control terminal of the transistor. And means.

The control circuit includes, for example, an active element that requires power supply, and the rectified voltage is supplied to the active element as a power supply.

An electric circuit according to a fifth aspect of the present invention comprises a transistor and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, and a power supply is provided at one end of the current path. Receiving a voltage to be rectified from, a resistive load is connected to the other end of the current path, and outputs a rectified voltage to the other end of the current path by turning on and off under the control of the control circuit, A predetermined reference potential is applied to the control terminal.

Although this configuration is a very simple configuration, a rectified voltage can be applied to a resistive load.

For example, the control terminal of the transistor, the power supply and the load are connected to a substantially common ground point.

It is preferable that the control circuit turns on the transistor in its saturation region. In the saturation region,
The emitter and the collector of the bipolar transistor have substantially the same potential. Therefore, when the bipolar transistor is turned on, that is, when a rectified voltage is applied to the load, a voltage drop in the transistor hardly occurs. Therefore, rectification can be performed efficiently with little loss.

In the first to fifth inventions, the voltage to be rectified may be an AC signal, an AC signal to which a DC component is added (pulsating current), or the like, and its waveform may be any of a sine wave, a triangular wave, a rectangular wave, and the like. .

The term "connection" includes not only the connection but also the case where the connection is made physically and electrically by magnetism, electric field, light or the like. For example, when the transistor is of a type that is turned on / off by the amount of light applied to the control terminal, the control circuit and the control terminal are connected by light. When the transistor responds to a magnetic field such as a Hall element, the control terminal and the control circuit are connected by a magnetic field.

Further, an electric circuit according to a sixth aspect of the present invention comprises a semiconductor switching element and a control circuit for controlling the semiconductor switching element, one end of the semiconductor switching element being connected to a power supply side, The other end has a current path connected to the load side, and turns on and off according to the control of the control circuit. The control circuit is connected to both ends of the current path of the semiconductor switching element and is applied to the current path. It is characterized in that a voltage is detected, a signal is supplied to the semiconductor switching element according to the detection result, and the signal is turned on or off.

As the semiconductor switching element, for example, a bipolar transistor, a field effect transistor, a phototransistor, a Hall element, a thyristor, or the like can be used. The control circuit applies a control signal to the semiconductor switching element according to the characteristics of the semiconductor switching element. For example, when the semiconductor switching element is a bipolar transistor, the voltage and current supplied to the base are controlled to turn on and off. When the semiconductor switching element is a field-effect transistor, the electric field applied to the gate is controlled and turned on / off. When there is a gate electrode, the voltage applied to the gate electrode is controlled. When the semiconductor switching element is a phototransistor, the amount of light (or intensity) of light applied to the base is controlled and turned on / off. When the semiconductor switching element is a Hall element, the applied magnetic field (magnetic flux) is controlled and turned on / off.

[0042]

Embodiments of the present invention will be described below with reference to the drawings. (Rectifier Circuit Using NPN Bipolar Transistor) FIG. 1 is a circuit diagram of a rectifier circuit according to an embodiment of the present invention. This rectifier circuit includes an NPN bipolar transistor 11 and a control circuit 13 connected to the base of the bipolar transistor 11. The emitter E of the bipolar transistor 11 is connected to an AC power supply 15,
Collector C of bipolar transistor 11 is connected to load 17.

The control circuit 13 is connected to an AC power supply 15 and supplies a bias voltage (a voltage sufficiently higher than the emitter voltage) and a current sufficient to turn on the bipolar transistor 11 in a saturated state when the power supply voltage has a positive polarity. Base B
Is applied. On the other hand, when the output voltage of the AC power supply 15 has a negative polarity, a sufficiently low (negative with respect to the emitter voltage) voltage is applied to the base B, and the bipolar transistor 11
Turn off.

In the case where the load 17 has a voltage such as a secondary battery, the control circuit 13 operates when the emitter voltage is higher than the collector voltage (when the positive voltage is higher).
A bias voltage (a voltage sufficiently higher than the emitter voltage) and a current sufficient to turn on the bipolar transistor 11 in a saturated state are applied to the base B. On the other hand, when the emitter voltage is lower than the collector voltage, a sufficiently low (negative to the emitter voltage) voltage is applied to the base B,
The bipolar transistor 11 is turned off.

Next, the operation of the rectifier circuit shown in FIG.
This will be described with reference to timing charts (A) to (E). 2A shows the waveform of the power supply voltage output from the AC power supply 15, FIG. 2B shows the waveform of the voltage (control voltage) of the control signal output from the control circuit 13, and FIG. OFF, (D) shows the waveform of the voltage applied between the emitter and collector of the bipolar transistor 11, and (E) shows the waveform of the voltage applied to the load 17.

First, when the power supply voltage shown in FIG. 2A has a positive polarity (more precisely, when the emitter voltage becomes higher than the collector voltage), the control circuit 13 applies a voltage to the base B of the bipolar transistor 11. A positive control signal shown in FIG. 2 (B) is applied. With this control signal, the bipolar transistor 11 is turned on as shown in FIG.

At this time, unlike the normal use state (the voltage of the collector C is higher than the voltage of the emitter E), the bipolar transistor 11 has the collector C connected to the emitter E.
Voltage higher than that of the bipolar transistor 1
1 functions as a so-called inverse transistor.
However, a sufficiently large current amplification factor (hfe) can be secured,
A sufficiently large current with respect to the bias current (base current) can flow in the current path between the emitter E and the collector C.

Since the driving capability of control circuit 13 is sufficiently large, sufficient minority carriers are injected into base B of bipolar transistor 11, and bipolar transistor 11 operates in a saturation region. As shown in the characteristic diagram of FIG. 3, in the saturation region, the bipolar transistor 11
The voltage between the emitter E and the collector C is almost 0 (short-circuit state), and the voltage between the emitter E and the collector C is substantially equal. Furthermore, this voltage is much lower than the diode forward voltage shown by the dashed line. For this reason, the voltage drop in the bipolar transistor 11 is substantially zero as shown in FIG. 2D, and a voltage substantially equal to the power supply voltage is applied to the load 17 as shown in FIG.

On the other hand, when the power supply voltage shown in FIG. 2A becomes negative, the control circuit 13 supplies a control signal of negative polarity to the base B of the bipolar transistor 11 as shown in FIG. As a result, as shown in FIG.
The bipolar transistor 11 is turned off, and the ground voltage is applied to the load 17 as shown in FIG.
2, a power supply voltage is applied between the emitter E and the collector C (FIG. 2D shows the voltage of the collector C based on the voltage of the emitter E). At this time, the bipolar transistor 11 is connected in the forward direction, and mainly the collector C
Withstand voltage determined by the withstand voltage of the PN junction between the semiconductor device and the base B.

As a result of repeating such processing, the load 17
, A half-wave rectified voltage is applied as shown in FIG.

According to the configuration shown in FIG. 1, when the bipolar transistor 11 is turned on, the voltage drop between the emitter E and the collector C becomes almost 0 (for example, about 5 mV to 40 mV). Therefore, the AC voltage can be rectified with low loss. Further, when the bipolar transistor 11 is turned off, a high breakdown voltage substantially determined by the breakdown voltage between the collector C and the base B can be obtained. The timing at which the bipolar transistor 11 is turned on or off is determined when the voltage to be rectified is substantially zero.
Therefore, no overshoot or undershoot occurs in the rectified voltage.

It is desirable to use a single bipolar transistor as the bipolar transistor 11, and a so-called Darlington transistor is
Because the bias current (base current) does not flow when turned on,
Not desirable.

The voltage to be rectified is not limited to a sine wave as shown in FIG. 2A, but may be a triangular wave, a rectangular wave, or the like. Further, a voltage whose average value does not become 0, in other words, a voltage obtained by adding a DC component to an AC component may be used.

Next, a specific configuration example of the control circuit 13 will be described with reference to FIG. In this example, the control circuit 13 is configured using an operational amplifier (operational amplifier) 21.
In FIG. 4, an output terminal of an operational amplifier 21 is connected to an NPN bipolar transistor 11 via a current limiting resistor 23.
The positive input terminal is connected to the emitter E of the bipolar transistor, and the negative input terminal is connected to the collector C of the bipolar transistor via the constant current source 25. Further, between the positive input terminal and the negative input terminal, a diode 27a and a diode 27b are connected in parallel so that the directions are opposite to each other.

The operational amplifier 21 has a capability of driving a sufficiently large current (about twice or more) as compared with the bias current of the bipolar transistor, and the ground (reference) potential of the power supply supplied to the operational amplifier 21. Is adapted to be equal to the emitter potential of the bipolar transistor 11 (in the case of a single power supply, the ground power supplied to the operational amplifier 21 may be supplied to the emitter E).

The portion surrounded by the broken line 14 in FIG. 4, that is, the bipolar transistor 11, the operational amplifier 21, the resistor 2
3. The constant current circuit 25 and the diodes 27a and 27b are integrated circuits (ICs). The IC 14 has a power supply terminal to which a voltage to be rectified is applied, an output terminal to which a rectified voltage is applied, Power supply terminals VDD and VSS of operational amplifier 21
Terminals.

In this configuration, when the voltage of the emitter E of the bipolar transistor 11 becomes higher than the voltage of the collector C to a positive polarity, a forward voltage is applied to the diode 27a and a reverse voltage is applied to the diode 27b. You. As a result, a voltage drop occurs between both input terminals of the operational amplifier 21 due to a forward current flowing through the diode 27a. The operational amplifier 21 amplifies this voltage,
A control signal having a positive polarity is applied to the base B of the bipolar transistor 11. As a result, the bipolar transistor 11 is turned on and operates in the saturation region, a conduction state is established between the emitter E and the collector C, and the emitter E and the collector C
And the power supply voltage is applied to the load 17 almost as it is. Note that the forward current flowing through the diode 27a is limited to a constant value by the constant current source 25, and the operational amplifier 21 and the diode 27a are protected from destruction.

When the power supply voltage becomes negative and the voltage at the emitter E of the bipolar transistor 11 becomes positively lower than the voltage at the collector C, a reverse voltage is applied to the diode 27a and a forward voltage is applied to the diode 27b. Is applied. As a result, a voltage drop occurs between the two input terminals of the operational amplifier 21 due to the forward current flowing through the diode 27b. This voltage is amplified by the operational amplifier 21, and a negative control signal is applied to the base of the bipolar transistor 11. With this control signal, the bipolar transistor 11 is turned off, and a non-conductive state is established between the emitter E and the collector C. The power supply voltage is substantially applied between the emitter E and the collector C of the bipolar transistor 11. A ground voltage is applied. In addition,
The forward current flowing through the diode 27b is
, And the operational amplifier 21 and the diode 27b are protected from destruction.

In this manner, the rectifier circuit shown in FIG. 4 can efficiently rectify the AC power supply voltage as shown in FIGS. 2A to 2E. Moreover, there is no need to supply any control signal from outside the IC 14. In this embodiment, the bipolar transistor 11 is turned on and off in accordance with the polarity of the voltage between the emitter E and the collector C. Therefore, even when the load 17 has a voltage, the backflow of the current can be prevented. For example, when the load 17 is a secondary battery of a constant voltage, simply turning on and off the bipolar transistor 11 according to the polarity of the output voltage of the AC power supply 15 makes the power supply voltage higher than the output voltage of the secondary battery. When the current is low, the current flows backward (the battery is discharged). However, such a problem does not occur in the configuration of FIG.

The constant current source 25 can be replaced with a current limiting resistor, a constant current diode, or the like. Further, not only the operational amplifier but also an arbitrary amplifier can be used. Further, the set of diodes 27a and 27b may be replaced with a Zener diode or a resistor.

FIGS. 5A and 5B show another specific example of the rectifier circuit. This rectifier circuit includes a control circuit 13 which is a transformer (hereinafter, a current transformer (CT)).
An example composed of an operational amplifier 31 and an operational amplifier 33 is shown. Power supply 15
The primary winding of the current transformer 31 is interposed in a current path from the current path to the emitter E of the bipolar transistor 11.

In FIG. 5A, a diode 11b is connected between the emitter E and the collector C of the bipolar transistor 11 so as to be in a forward direction from the emitter E to the collector C. Note that a Schottky barrier diode, a fast recovery diode, or the like may be connected instead of the diode 11b. FIG.
4B, the emitter E of the bipolar transistor 11 is shown.
A diode 11b is connected between the base E and the base B so as to be forward from the emitter E toward the base B.

The secondary winding of the current transformer 31 is magnetically coupled to the primary winding, and one end is connected to the power supply 15. The primary winding and the secondary winding generate electromotive forces in opposite directions (indicating polarities).

A voltage limiting diode 35 connected in the opposite direction is connected between one end and the other end of the secondary winding. Further, the voltage at one end of the secondary winding is directly applied to the negative input terminal of the operational amplifier 33, and the voltage at the other end of the secondary winding is applied to the positive input terminal of the operational amplifier 33 via the resistor 37. The operational amplifier 33 has a slightly negative offset. As a result, when there is no significant input to the operational amplifier 33, the output of the operational amplifier 33 exhibits a negative polarity, thereby preventing the bipolar transistor 11 from being turned on due to noise or the like. Instead of the resistor 37, a DC power supply such as a battery may be connected in a direction in which the positive input terminal and the negative side of the DC power supply are connected.

The output terminal of the operational amplifier 33 is connected to the base B of the bipolar transistor 11 via a current limiting resistor 39.
It is connected to the. In addition, the bipolar transistor 11
Is connected to the ground voltage terminal GND of the operational amplifier 33.

The portion surrounded by the broken line 14 in FIG. 5A, that is, the bipolar transistor 11, the transformer 31, the operational amplifier 33, the diode 35, and the resistors 37 and 39 are formed as a hybrid IC. It has two terminals: a power supply terminal to which a voltage to be rectified is applied, an output terminal to which the rectified voltage is applied, and power supply terminals VDD and VSS of the operational amplifier 21.

The operation of the rectifier circuit shown in FIGS. 5A and 5B will be described with reference to the timing chart of FIG. First, when the power supply voltage shown in FIG. 6A becomes positive, a current flows from the emitter E side to the collector C side in the circuit of FIG. 5A due to the forward conduction characteristic of the diode 11b. At this time, the voltage between the emitter E and the collector C is about 0.6 V (about 0.4 V when a Schottky barrier diode is connected) as shown in FIG. 6B.

In the circuit of FIG. 5B, the emitter E
Current flows from the side to the base B side. Due to this current, a voltage is also generated in the secondary winding of the current transformer 31. The operational amplifier 33 amplifies this voltage and applies a positive control signal to the base B of the bipolar transistor 11. As a result, the bipolar transistor 11 is turned on, the voltage between the emitter E and the collector C drops to almost 0 V, and the power supply voltage is almost applied to the load 17.

When the power supply voltage decreases and the current approaches 0 A, the induced voltage on the secondary side also decreases, and the operational amplifier 33 is biased to the negative polarity.
Applies a bias signal of negative polarity to the base B and turns off the bipolar transistor 11. However, a current flows through the diode 11b, and a forward voltage of the diode 11b is applied between the emitter E and the collector C of the bipolar transistor 11.

When the power supply voltage becomes negative, bipolar transistor 11 and diode 11b are turned off. Therefore, no current flows through the primary winding of the current transformer 31, and no current is generated through the secondary winding.
However, since the operational amplifier 33 is biased on the negative side, the control signal of the negative polarity is supplied to the bipolar transistor 11.
To the base B. As a result, the bipolar transistor 11 is completely turned off, the entire power supply voltage is applied between the emitter E and the collector C, and the ground voltage is applied to the load 17.

As described above, the AC voltage can be rectified also by the configurations shown in FIGS. 5 (A) and 5 (B). Moreover,
Since the bipolar transistor 11 is turned on in the saturation region, the voltage between the emitter E and the collector C is almost 0 V, and rectification with almost no loss is possible.

FIG. 7 shows another specific example of the rectifier circuit. This rectifier circuit controls the control circuit 13 by using the current transformer 3
1 shows an example composed of 1 and a protection diode 41. In a current path from the power supply 15 to the emitter E of the bipolar transistor 11, a primary winding of the current transformer 31 is interposed.

One end of the secondary winding of the current transformer 31 is connected to the power supply 15 so as to show additional polarity, and the other end of the secondary winding is connected to the base B of the bipolar transistor 11. Further, the emitter E of the bipolar transistor 11
And the base B, the anode and the cathode of the diode 41 are respectively connected.

The operation of the rectifier circuit shown in FIG. 7 will be described. When the power supply voltage rises and becomes positive, a current flows from the emitter E side to the base B side due to the forward conduction characteristic of the diode 41. At this time, the potential difference between the emitter E and the base B is about 0.6 V (about 0.4 V when a Schottky barrier diode is connected).

With this current, a secondary current corresponding to the turn ratio between the primary winding and the secondary winding of the current transformer 31 is generated and supplied to the base B. Further, the voltage of the base B becomes higher than that of the emitter E due to the secondary current, the diode 41 becomes a reverse voltage, and no current flows through the diode 41. As a result, the bipolar transistor 11 is turned on, the potential difference between the emitter E and the collector C is reduced to almost 0 V, and the power supply voltage is almost applied to the load 17.

When the power supply voltage decreases and the current approaches 0 A, the voltage on the secondary side of the current transformer 31 also decreases. Further, a back electromotive force is generated by self-induction action, and a forward current flows through the diode 41. A reverse bias voltage of about 0.6 V (about 0.4 V when a Schottky barrier diode is connected) is applied between the base B and the emitter E.

Therefore, the AC voltage can be rectified also by the configuration of FIG. Moreover, since the current driving capability of the current transformer 31 is large, the bipolar transistor 1
A sufficient bias current is supplied to one base B, and the bipolar transistor 11 is turned on in the saturation region. Therefore, the voltage between the emitter E and the collector C can be reduced to almost 0 V, and rectification with almost no loss is possible.

As shown by a broken line in FIG. 7, a diode 11b may be connected between the emitter E and the collector C of the bipolar transistor 11 so as to be in a forward direction from the emitter E to the collector C. In this case, when the power supply voltage rises and becomes positive, a current flows through the diode 11b, and the current transformer 31
, A secondary current is generated in the secondary winding and supplied to the base B,
The bipolar transistor 11 turns on.

(Rectifier Circuit Using PNP Bipolar Transistor) In the above embodiment, an NPN bipolar transistor is used as a rectifying switching element. However, a PNP bipolar transistor can be used.

An example of a rectifier circuit using a PNP bipolar transistor 51 is shown in FIGS. 8, 9A and 9B, FIG.
0 is shown. The basic configuration of these rectifier circuits is shown in FIGS.
(A), (B), which is the same as the basic configuration of the rectifier circuit of FIG. 7, the emitter E of the PNP bipolar transistor 51 is connected to the power supply 15, the collector C is connected to the load 17, and the base B is the control circuit. It is connected to the.

In FIG. 9A, the diode 11b or the Schottky barrier diode is connected between the emitter E and the collector C of the bipolar transistor 51 so as to be in the forward direction from the collector C to the emitter E. . Also, in FIG.
1b is connected between the emitter E and the base B of the bipolar transistor 51 so as to be in the forward direction from the base B to the emitter E.

In the example shown in FIGS. 9A and 9B, the bipolar transistor 51 is turned off when a positive control signal is applied to the base B, so that the negative input terminal of the operational amplifier 33 has two inputs. The voltage at one end of the secondary winding is applied as it is, and the voltage at the other end of the secondary winding is applied to the positive input terminal of the operational amplifier 33 via the resistor 37 (the offset voltage of the operational amplifier 33 is slightly increased to the positive voltage side). May be set).

In the rectifier circuit shown in FIG. 10, when the power supply voltage becomes negative, a current flows through the collector C, the base B, the diode 41, and the transformer 31. Due to this current, a secondary current is generated in the secondary winding of the current transformer 31,
The bipolar transistor 51 is turned on, and the potential difference between the emitter E and the collector C is substantially zero.
V, and the power supply voltage is almost applied to the load 17.

When the power supply voltage decreases and the current approaches 0 A, the voltage on the secondary side of the current transformer 31 also decreases. Further, a back electromotive force is generated by the self-induction effect, and a forward current flows through the diode 41. Flow, a reverse bias voltage is applied between the base B and the emitter E, and the bipolar transistor 51 is turned off.

As shown by the broken line in FIG. 10, a diode 11b may be connected between the emitter E and the collector C of the bipolar transistor 51 so as to be in the forward direction from the collector C to the emitter E. In this case, when the power supply voltage becomes negative, a current flows through the diode 11b, and this current generates a secondary current in the secondary winding of the current transformer 31 and is supplied to the base B, so that the bipolar transistor 51 Turn on.

Each control circuit turns on the PNP bipolar transistor 51 in the saturation region when the power supply voltage is negative (more precisely, when the emitter voltage is lower than the collector voltage), and when the power supply voltage is positive. (When the emitter voltage is higher than the collector voltage), the PNP bipolar transistor 51 is turned off.

According to these rectifier circuits, as shown in FIG. 11, when the power supply voltage is negative (when the emitter voltage is lower than the collector voltage), the bipolar transistor 51 is turned on, and the emitter E of the bipolar transistor 51 is turned on. The voltage between the power supply and the collector C is reduced to almost 0 V, and the load 17
Is supplied with a power supply voltage. On the other hand, when the power supply voltage has a positive polarity (when the emitter voltage is higher than the collector voltage), the bipolar transistor 51 is turned off, and the power supply voltage is applied between the emitter E and the collector C of the bipolar transistor 51, so that the load 17 Is applied with a ground voltage.

(Rectifier Circuit Using N-Channel FET)
It is also possible to use a field effect transistor (FET) as a switching element for rectification. FIG. 1 shows a configuration example of a rectifier circuit using an N-channel type FET 61.
2, and shown in FIGS.

The basic configuration of these rectifier circuits is the same as the basic configuration of the rectifier circuit shown in FIGS.
One source S is connected to the power supply 15, the drain D is connected to the load 17, and the gate G is connected to the control circuit. Each control circuit applies a positive voltage to the gate G to turn on the FET 61 in the saturation region when the power supply voltage is positive (when the source voltage is higher than the drain voltage), and when the power supply voltage is negative. (When the source voltage is lower than the drain voltage), a negative voltage is applied to the gate G to turn off the FET 61.

According to these rectifier circuits, when the power supply voltage is positive (when the source voltage is higher than the drain voltage)
Since the FET 61 is turned on in the saturation region,
The voltage between the source S and the drain D is reduced to about 0 V, and the power supply voltage is applied to the load 17. On the other hand, when the power supply voltage is negative, the FET 61 is turned off and the source S
A power supply voltage is applied between the load 17 and the drain D, and a ground voltage is applied to the load 17. Thus, the load 17
A rectified positive voltage is applied. In the rectifier circuits shown in FIGS. 13 and 14, it is possible to use a parasitic diode of the FET 61 as the diode 11b.

(Rectifier circuit using P-channel type FET)
P-channel FE is used as the switching FET 61.
It is also possible to use a T-channel FET 6
15, 16, and 17 show examples of the configuration of a rectifier circuit using the circuit 1 of FIG.
Shown in Further, as a switching FET, a junction FET (J-FET) and a MOS (Metal-Oxide-Semico) are used.
nductor) type FET, static induction type transistor (SI
Any configuration such as T) can be used.

The voltage of the control signal output from the control circuit can be arbitrarily selected according to the characteristics of the transistor (bipolar transistor or FET) used. For example, when a normally-on type element such as a junction type FET or a depletion type MOS is used as a transistor, an arbitrary voltage (for example, the same as the source potential and the same as the source potential) is maintained at the gate G at the time of ON. Potential), and an off-state voltage may be applied at the time of off-state.

In addition, the numerical values shown in the above embodiment,
The voltage value and the like are examples, and can be arbitrarily changed. Also,
If the bias voltage, the pinch-off voltage, and the like cannot be obtained with a single diode, zener diode, resistor, or the like, a plurality of them may be directly connected. Also, MOS
In the case of an element such as an FET, in which the input impedance of the control terminal is sufficiently high and a current that cannot destroy the element can flow,
The current limiting resistors 23 and 39 are unnecessary.

FIGS. 5, 7, 9, 10, 13, 14, 16,
17, a transformer having a primary winding and a secondary winding is used as the transformer 31. For example, as shown in FIG. 18 as a modified example of the rectifier circuit shown in FIG. As shown in FIG. 19, an autotransformer 81 or the like can be used as a modification of the first embodiment. If a transformer 31 having primary and secondary windings is used, the autotransformer 81
Is used, the primary terminal is connected to one end of the current path of the transistor, and the secondary terminal is connected to the control terminal.

(Rectifier Circuit with Collector Connected to Power Supply Side) FIGS. 4, 5 (A) and 5 (B), FIGS. 7, 8 and 9
(A), (B), the emitter of the bipolar transistor 11 or 51 is connected to the power supply side and the collector is connected to the load side in the rectifier circuit shown in FIG. 10, but the collector of the bipolar transistor 11 or 51 is connected to the power supply side. And a rectifier circuit in which the emitter is connected to the load side is also possible.

For example, the rectifier circuit shown in FIG. 4 can be modified as shown in FIG. 20, and the rectifier circuit shown in FIG. 8 can be modified as shown in FIG. 20 and 21, the emitter E of the bipolar transistor 51 or 11 is connected to the load 17, and the collector C is connected to the power supply 1
5 is connected. The output terminal of the operational amplifier 21 is connected to the bipolar transistor 51 via the current limiting resistor 23.
The positive input terminal is connected to the emitter E of the bipolar transistors 51 and 11, and the negative input terminal is connected to the collector C of the bipolar transistors 51 and 11 via the constant current source 25. . The diodes 27a and 27b connected in anti-parallel are connected between the positive input terminal and the negative input terminal. In addition, operational amplifier 2
One ground terminal is connected to the emitters of the bipolar transistors 51 and 11. Further, in these circuits, the power supply of the operational amplifier 21 is obtained from the rectified current. According to this configuration, the operating voltage of the operational amplifier 21 can be set to a relatively low value, and the power supply voltage can be reduced.

Similarly, as shown in FIGS. 22A and 22B, the rectifier circuit shown in FIGS.
The rectifier circuit shown in (B) can be modified as shown in FIGS. 23 (A) and (B).

In FIGS. 22A and 22B, the power supply 15 is connected to the collector of a PNP bipolar transistor 51, and the emitter E is connected to the load 17 via the primary winding of the current transformer 31. I have.

One end of the secondary winding of the current transformer 31 is connected to the load 17. A diode 35 for voltage limitation is connected between one end and the other end of the secondary winding. Further, the voltage at one end of the secondary winding is directly applied to the negative input terminal of the operational amplifier 33, and the voltage at the other end of the secondary winding is applied to the positive input terminal of the operational amplifier 33 via the resistor 37. The output terminal of the operational amplifier 33 is a current limiting resistor 39.
Is connected to the base B of the bipolar transistor 11. The operational amplifier 33 is biased on the positive polarity side. The emitter E of the bipolar transistor 11 is connected to the ground voltage terminal GND of the operational amplifier 33. Also in these circuits, the rectified voltage is used as the operating voltage of the operational amplifier 33. Even in such a configuration,
The operating voltage of the operational amplifier can be set to a relatively low value, and the power supply voltage can be kept low.

In the configuration of FIG. 22A, a diode 11b is connected between the emitter and the collector of bipolar transistor 51. In the configuration of FIG. 22B, a diode is connected between the emitter and the base of bipolar transistor 51. 11b is connected. When the voltage of the power supply 15 becomes negative, a current flows through the diode 11b, the primary winding of the current transformer 31, and the load 17, and a voltage is generated in the secondary winding. The operational amplifier 33 amplifies this voltage and sends a negative control signal to the base B of the bipolar transistor 51.
Is applied. Thereby, the bipolar transistor 51
Is turned on, the voltage between the emitter E and the collector C drops to almost 0 V, and the power supply voltage is almost applied to the load 17.

When the power supply voltage rises and the current approaches 0 A, the induced voltage on the secondary side also decreases, and the operational amplifier 33 is biased to the positive polarity.
Applies a bias signal of positive polarity to the base B and turns off the bipolar transistor 51.

When the power supply voltage becomes positive, bipolar transistor 11 and diode 11b are turned off. Therefore, no current flows through the primary winding of the current transformer 31, and no current is generated through the secondary winding.
However, since the operational amplifier 33 is biased to the positive side, the control signal of the positive polarity is supplied to the bipolar transistor 11.
To the base B. As a result, the bipolar transistor 11 is completely turned off, the entire power supply voltage is applied between the emitter E and the collector C, and the ground voltage is applied to the load 17.

The configuration of FIGS. 23A and 23B is similar to that of FIG.
As compared with the configurations of (A) and (B), the difference is that the PNP bipolar transistor 51 is replaced with the NPN bipolar transistor 11 and the operational amplifier 33 is biased to the negative polarity side. When the voltage of the power supply 15 becomes positive, a current flows through the diode 11b, the primary winding of the current transformer 31, and the load 71, and a voltage is generated in the secondary winding. The operational amplifier 33 amplifies this voltage and applies a positive control signal to the base B of the bipolar transistor 51. As a result, the bipolar transistor 51 is turned on, and the voltage between the emitter E and the collector C becomes almost 0V.
And the power supply voltage is almost applied to the load 17.

When the power supply voltage rises and the current approaches 0 A, the induced voltage on the secondary side also decreases, and the operational amplifier 33 is biased to the negative polarity.
Applies a negative bias signal to the base B and turns off the bipolar transistor 51. When the power supply voltage becomes negative, the bipolar transistor 11 and the diode 11b are turned off. Therefore, no current flows through the primary winding of the current transformer 31, and no current is generated through the secondary winding. However, since the operational amplifier 33 is biased to the negative polarity side, it applies a negative control signal to the base B of the bipolar transistor 11. Thereby, the bipolar transistor 11 is completely turned off,
The entire power supply voltage is applied between the emitter E and the collector C, and the ground voltage is applied to the load 17.

As described above, FIGS. 22A and 22B and FIG.
The AC voltage can also be rectified by the configurations 3 (A) and (B). Moreover, the bipolar transistor 11
Is turned on in the saturation region, the voltage between the emitter E and the collector C is almost 0 V, and rectification with almost no loss is possible.

Similarly, the rectifier circuit shown in FIG. 7 can be modified as shown in FIG. 24, and the rectifier circuit shown in FIG. 10 can be modified as shown in FIG.

The rectifier circuit shown in FIG. 12 can be modified as shown in FIG. 26, and the rectifier circuit shown in FIG. 15 can be modified as shown in FIG. Also, the rectifier circuit shown in FIG. 13 can be modified as shown in FIG. 28, and the rectifier circuit shown in FIG. 16 can be modified as shown in FIG. In these rectifier circuits, since a control unit for turning on / off the transistor is arranged on the ground side (load side), a voltage is not applied to the control unit at the time of reverse voltage, so that it is safe. Further, the power supply voltage can be kept low. Also,
Since the operating voltages of the operational amplifiers 21 and 33 are obtained from the rectified voltages, the operation is efficient. The diode 1
It is also possible to remove 1b.

The rectifier circuit shown in FIG. 14 can be modified as shown in FIG. 30, and the rectifier circuit shown in FIG. 17 can be modified as shown in FIG. In these rectifier circuits, since a control unit for turning on / off the transistor is arranged on the ground side (load side), a voltage is not applied to the control unit at the time of reverse voltage, so that it is safe. The diode 1
It is also possible to remove 1b.

FIG. 32 shows another example of the rectifier circuit of the present invention. In the rectifier circuit 100 of FIG. 32, the field effect transistor 110 is, for example, an N-channel type MOS-F
The source is connected to the secondary coil of the transformer 112, and the drain terminal D is connected to the load 113.

A branch line from the source terminal S and a zero-potential power supply line of the FET 110 are connected to the positive input terminal of the operational amplifier 111 constituting the control circuit, and a branch line from the drain terminal D is connected to the negative input terminal. The lines are connected via a resistor Ra. A diode Dr is provided between each input terminal.
Is connected to prevent the current from flowing around. A voltage dividing resistor Rc is connected between the power supply line of the positive bias potential (Vcc) and the negative input terminal (−) of the operational amplifier 11. The output of the operational amplifier 11 is connected to F
Input to the gate G of the ET110. The resistance Ra is, for example, 10 kΩ, the resistance Rb is 2 MΩ, and the resistance Rc is 180 Ω.
The degree is a gift. The resistor Rb is used for adjusting the potential, but may be removed in the case of an FET. In actual use, for example, a capacitor having a predetermined capacity is connected in parallel with the load 113.

In the circuit of FIG. 32 as well, when there is no AC power input to the FET 110, the balance between the positive and negative input terminals of the operational amplifier 11 is maintained. Therefore, the operational amplifier 11
The output Sb of 1 becomes zero potential. In this state, FIG.
It is assumed that a sinusoidal AC voltage Sa is input from the transformer 112 to the FET 110 as shown in FIG. FET1
Reference numeral 10 denotes a source terminal S when the AC voltage Sa has a positive polarity.
Is slightly higher than the potential of the drain terminal D.
At this moment, the operational amplifier 111 detects the occurrence of the potential difference based on the potential difference between the positive and negative input terminals, and sets the output potential Sb to the positive bias potential (Vcc). Conversely, the AC voltage Sa
When the potential of the source terminal S changes from the positive polarity to the negative polarity, the potential of the source terminal S becomes lower than the potential of the drain terminal D. Therefore, the operational amplifier 111 detects this and immediately changes the output voltage Sb to the negative bias potential (−Vcc). And The waveform in FIG. 33B shows the potential change of the output power Sb of the operational amplifier 111.

When the output voltage Sb of the operational amplifier 111 has a positive polarity, the FET 110 is turned on and the source terminal S
, A current flows in the direction of the drain terminal D. On the other hand, when the output voltage Sb of the operational amplifier 111 is at the negative bias potential, the FET 110 is turned off, and the current is cut off. As a result, the voltage (rectified voltage) Sc applied to the load 113
Is a pulsating voltage in which only the negative polarity portion of the sine wave is cut as shown in FIG.

Such a power supply mode for the source terminal S and the drain terminal D of the FET 110 is opposite to the original power supply mode for the FET. However, in the present invention,
The reverse withstand voltage, that is, the potential difference between the gate and the drain at the time of current blocking can be considerably increased because the potential difference is inherently distributed from the viewpoint of the FET, and the resistance component in the forward direction is extremely low and stable. In order to positively use the point where the reverse recovery time is short, the point where the leakage current is small, and the like, the power supply mode is set as described above. According to experiments, even a general-purpose FET can ensure a reverse breakdown voltage of about 1000 [V].

It should be noted that instead of the N-channel type FET, P
It is also possible to use a channel type FET. In this case, the same operation is performed only by changing the direction of the current. Also, when a coupling-type FET (J-FET) or a bipolar transistor is used, almost the same operation is performed with only a slight difference in the voltage drop between the input and output terminals.

As described above, by using the rectifier circuit of the present invention, the forward voltage drop can be significantly reduced as compared with the conventional device. This means that power loss at the time of rectification and accompanying heat generation inside the element are significantly reduced. In addition, since no cooling means is required, the configuration of the apparatus can be simplified and downsized.

As described above, the rectified voltage can be used as the power supply of the operational amplifier. For example, FIG.
When the load 17 of the rectifier circuit includes a battery as shown in FIG. 34, the operational amplifier 21 can be driven by supplying a positive voltage after rectification to a power supply terminal of the operational amplifier 21.

Similarly, when the load 17 of the rectifier circuit in FIG. 4 includes a capacitor, the rectified positive voltage is supplied to the power terminal of the operational amplifier 21 to drive the operational amplifier 21 as shown in FIG. It is also possible. In this rectifier circuit, at first, the external diode 11b (FE
A rectified current flows due to a parasitic diode at the time of T, and a voltage is generated at the load 17. With this voltage, the operational amplifier 21 operates, and the transistor 51 operates as a diode.

Even when the load 17 is a resistor having no voltage, the rectified voltage can be used as the operating voltage of the operational amplifier as shown in FIG. Also in this case, a rectified current first flows through the external diode 11b, and the load 17
Voltage is generated. With this voltage, the operational amplifier 21 operates, and the transistor 51 operates as a diode.

Further, when the load 17 is a resistor having no voltage or the like, the rectifier circuit can be constituted by a simple circuit as shown in FIGS. 37 and 38.

In the configuration of FIG. 37, the collector C of the PNP bipolar transistor 51 is connected to the output of the power supply 15, the base B is grounded via the current limiting resistor 31, and the emitter E is connected to the load 17. .

In this configuration, when the output of the power supply 15 has a positive polarity, the collector C of the PNP bipolar transistor 51
A base current flows through a path from the base B to the resistor 31. By this base current, the collector C → the emitter E → the load 17
, A load current flows. On the other hand, when the output of the power supply 15 has a negative polarity, a reverse bias voltage is applied between the collector C and the base B of the PNP bipolar transistor 51, so that no base current flows, and therefore no current flows from the emitter E to the collector C.

A diode having a forward direction from the base B to the emitter E may be connected between the base B and the emitter E. In this case, the base current flows through this diode until the base current flows through the resistor 31.

In the configuration of FIG. 38, the P-channel FET 71
Is connected to the output of the power supply 15, the gate G is grounded via a current limiting resistor 31, and the source S is connected to the load 17. Further, the gate G and the source S
Between them, a Zener diode 41 for gate protection having a forward direction from the gate G to the source S is connected.

In this configuration, when the output of the power supply 15 has a positive polarity, a current flows through the drain D → source S → load 17 path of the FET 71 by the parasitic diode, and a positive voltage is applied to the load 17. When the voltage of the load 17 becomes positive, the voltage of the gate G becomes relatively negative,
71 turns on. On the other hand, when the output of the power supply 15 has a negative polarity,
No current flows through the parasitic diode, and no bias voltage is applied to the gate G. Therefore, the FET 71 is turned off.

(Switching Power Supply) Next, an embodiment in which the rectifier circuit of the present invention is applied to a switching (SW) power supply will be described. FIG. 39 is a configuration diagram of the SW power supply according to this embodiment.

As shown in FIG. 39, the SW power supply 102 includes a transformer 215 for outputting a rectangular wave alternating voltage, and a semiconductor active element for rectifying the alternating voltage obtained from the transformer 215, for example, a MOS-FET 220 And The secondary coil of the transformer 215 is provided with two taps for outputting voltages having the same alternating period and different amplitude values. The first tap for power output having a small amplitude value is connected to the source terminal S of the FET 220, and the second tap for power output having a large amplitude value is connected to the gate terminal G of the FET 220. FET220
Of the load 2 via a smoothing coil L
17 and a capacitor, for example, an electrolytic capacitor C, are connected in parallel.

In the SW power supply 202 having such a configuration, as shown in FIG.
z], the amplitude value is ± 5 [V], and the current value is 1
An alternating signal Sd of a rectangular wave of 0 [A] is applied to the source terminal S of the FET 220 from the first tap of the transformer 212,
From the second tap, the alternating voltage having an amplitude value of ± 12 [V] is F
It is assumed that the voltage is applied to the gate terminal G of ET20. In this case, in the FET 220, when the alternating voltage Sd has a positive polarity, the power amplitude value (12 [V]) at the gate terminal G is relatively larger than the power amplitude value (5 [V]) at the source terminal S. As a result, the ON state, that is, the conduction state between the source terminal S and the drain terminal D is established, and a current flows from the source terminal S to the drain terminal D.

On the other hand, when the alternating voltage Sd has a negative polarity, FE
T220 is the power amplitude value at the gate terminal G (−1
2 [V]) is the amplitude value of the power at the source terminal S (−5).
[V]), it is turned off, and the current is interrupted. Therefore, from the FET 220, FIG.
As shown in (B), the positive polarity component Se of the alternating voltage Sd is output, and rectification is performed. The forward voltage drop at this time is almost 0 as in the case described above, and the leakage current in the reverse direction is negligibly small, so that power loss is reduced and efficient rectification is performed. In fact, it has been confirmed by the present inventors that the FET 220 does not generate heat even when the rectifying operation is continuously performed for several hours, and a heat radiating plate or the like is unnecessary. Further, since the alternating voltage Sd is a rectangular wave and the change time from the positive polarity to the negative polarity and from the negative polarity to the positive polarity are short, a control circuit is not required. In addition, the voltage distribution in the reverse direction is, for the FET 220, the original voltage distribution during normal use, that is, the drain-source voltage Vds.
, It is possible to increase the breakdown voltage.

It is to be noted that substantially the same operation is obtained by using a bipolar transistor or a J-FET instead of the MOSFET. However, in this case, a current limiting element, for example, a resistance element is inserted between the gate terminal and the second tap of the transformer 12.

In the above embodiment, a half-wave rectifier circuit is mainly shown. However, a full-wave rectifier circuit can be formed by combining the half-wave rectifier circuits. That is, as shown in FIG. 41 (A), these half-wave rectifier circuits (FIG.
1 (A) and 1 (B) are represented by diodes) to form a full-wave rectifier circuit by bridging, and as shown in FIG. 41 (B), a secondary winding It is also possible to configure a full-wave rectifier circuit using a transformer having a middle point and two half-wave rectifier circuits.

In the full-wave rectifier circuits shown in FIGS. 41A and 41B, each of the half-wave rectifier circuits D1 to D6 is turned on when the voltage applied thereto has a positive polarity, and the load is full-wave rectified. The applied voltage is applied.

In the above embodiment, the half-wave rectifier circuit using a single transistor has been described, but a plurality of transistors may be used. For example, FIG. 42A shows an example in which a plurality of NPN bipolar transistors are connected in parallel, and ON / OFF control is performed by a control circuit. FIG. 42B shows an example in which a plurality of junction FETs are connected in parallel and on / off control is performed by a control circuit. FIG. 42 (C) shows N-
Connect multiple channel junction FETs in parallel,
An example in which on / off control is performed by a control circuit will be described. With such a configuration, the amount of current that can be turned on and off can be increased to a plurality when a single transistor is used.

FIG. 43 shows an example in which a plurality of transistors are cascaded. According to this configuration, a plurality of cascaded transistors are turned on almost simultaneously.
It is turned off and the breakdown voltage can be increased.

When a large number of transistors are connected in cascade, for example, a phototransistor which is turned on / off in response to light is used as a transistor to synchronize the on / off of the transistors.
May be provided with a light emitting element that emits light for on / off control. Further, a Hall element can be used as the transistor. In this case, connect the Hall element between the power supply and the load, detect the voltage applied to the Hall element or its polarity, apply a magnetic field to the Hall element according to the detection result, and turn on or off the Hall element. Turn off. In addition, it is possible to use any semiconductor switching element that is turned on / off according to external control.

It is desirable that the transistor which is a switching element has low on-resistance and high withstand voltage when off. As the bipolar transistor having such a configuration, for example, as shown in FIG. 44, a transistor having substantially the same thickness te of the emitter layer and the thickness tc of the collector layer can be used.

Further, as a field effect transistor,
As shown in FIG. 45, the source and the drain having the same structure can be used.

[0137]

【Example】

Example 1 A half-wave rectifier circuit having the structure shown in FIG. 12 was constructed, and its characteristics were compared with those of a normal silicon diode and a Schottky barrier diode. FIG. 46 shows the comparison result. This result indicates that the voltage to be rectified is a commercial power supply, the load 17 is a 10 A load, the product number 2SK905 manufactured by Fuji Electric Co., Ltd.
3 is 100Ω, and the operational amplifier 21 is a product number LM455 commercially available from National Semiconductor.
It was obtained when it was set to 8.

As is clear from FIG. 46, in the half-wave rectifier circuit of FIG. 4, the voltage drop at the time of ON (the voltage between the emitter E and the collector C) is about 0.01 V, while the voltage drop of the Schottky barrier diode is about 0.01 V. It is 0.4 V and about 0.9 V for the silicon diode, and it is understood that the AC voltage can be rectified with low loss by the half-wave rectifier circuit of FIG.

Example 2 A half-wave rectifier circuit having the configuration shown in FIG. 14 was constructed, and its characteristics were compared with those of a normal silicon diode and a Schottky barrier diode. FIG. 46 shows the comparison result. This result indicates that the voltage to be rectified is a commercial power supply, the load 17 is
Obtained by using a product number 2SK905 manufactured by Fuji Electric Co., Ltd. and setting the turns ratio of the current transformer 31 to 1: 100.

As is apparent from FIG. 47, in the 14 half-wave rectifier circuit, the voltage drop at the time of ON (the voltage between the emitter E and the collector C) is immediately after the power supply voltage becomes positive, and The voltage is about 0.6 V immediately before the voltage becomes 0 V, but is almost 0 during most of the period in which the power supply voltage is positive.
V. On the other hand, the voltage is about 0.4 V for the Schottky barrier diode and about 0.9 V for the silicon diode, and it can be seen that the AC voltage can be rectified with low loss by the half-wave rectifier circuit of FIG.

Examples 1 and 2 also prove that the rectifier circuit of the present invention can rectify an AC voltage efficiently with low loss.

[0142]

As described above, according to the present invention, an AC voltage can be rectified with low loss.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram schematically showing a configuration of a rectifier circuit according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the rectifier circuit of FIG.

FIG. 3 is a graph showing a common emitter characteristic of an NPN bipolar transistor and a current / voltage characteristic of a diode.

FIG. 4 is a circuit diagram showing a specific configuration example of the rectifier circuit of FIG. 1;

FIGS. 5A and 5B are circuit diagrams showing specific examples of the configuration of the rectifier circuit of FIG. 1;

FIG. 6 is a timing chart showing an operation of the rectifier circuit shown in FIG.

FIG. 7 is a circuit diagram showing a specific configuration example of the rectifier circuit of FIG. 1;

FIG. 8 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIGS. 9A and 9B are circuit diagrams showing modified examples of the rectifier circuit shown in FIGS. 5A and 5B.

FIG. 10 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 11 is a timing chart for explaining a basic operation of the rectifier circuit shown in FIGS. 8 to 10;

FIG. 12 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 13 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 14 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 15 is a circuit diagram showing a modified example of the rectifier circuit shown in FIG.

FIG. 16 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 17 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 18 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 19 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

20 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 21 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 22 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 23 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 24 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 25 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 26 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 27 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 28 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 29 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 30 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 31 is a circuit diagram showing a modification of the rectifier circuit shown in FIG.

FIG. 32 is a circuit diagram showing another embodiment of the rectifier circuit of the present invention.

FIG. 33 is a timing chart illustrating the operation of the rectifier circuit shown in FIG. 32;

FIG. 34 is a circuit diagram showing an example of a rectifier circuit using a rectified voltage as a power supply of an operational amplifier.

FIG. 35 is a circuit diagram showing an example of a rectifier circuit using a rectified voltage as a power supply of an operational amplifier.

FIG. 36 is a circuit diagram showing an example of a rectifier circuit for a resistance load.

FIG. 37 is a circuit diagram showing an example of a rectifier circuit for a resistance load.

FIG. 38 is a circuit diagram showing an example of a rectifier circuit for a resistance load.

FIG. 39 is a diagram illustrating an example of a configuration of a rectifier circuit that rectifies an alternating current by turning on / off a transistor by an output of a secondary winding of a transformer.

40 is a timing chart for explaining the operation of the rectifier circuit shown in FIG. 39.

FIG. 41A is a circuit diagram showing a configuration example of a full-wave rectifier circuit in which rectifier circuits are combined in a bridge type;
(B) is a circuit diagram illustrating a configuration example of a full-wave rectifier circuit including a transformer having a middle point in a secondary winding and two rectifier circuits.

FIG. 42 is a circuit diagram showing a configuration example of a rectifier circuit configured by connecting a plurality of transistors in parallel.

FIG. 43 is a circuit diagram illustrating a configuration example of a rectifier circuit including a plurality of transistors connected in cascade.

FIG. 44 is a diagram illustrating a configuration example of a bipolar transistor.

FIG. 45 is a diagram illustrating a configuration example of a field-effect transistor.

FIG. 46 is a diagram showing characteristics of the embodiment of the rectifier circuit shown in FIG. 12;

FIG. 47 is a diagram showing characteristics of the embodiment of the rectifier circuit shown in FIG. 14;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 NPN bipolar transistor 11b Diode 13 Control circuit 15 AC power supply 17 Load 21 Operational amplifier 23 Current limiting resistor 25 Constant current source 27a, 27b Diode 31 Current transformer 41 Diode or Zener diode 51 PNP type bipolar transistor 61 N channel type FET 71 P channel Type FET 81 autotransformer

Claims (38)

[Claims] 1. A transistor comprising: a transistor; and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, receives a rectification target voltage at one end of the current path, and operates under control of the control circuit. Outputting a rectified voltage to the other end of the current path by turning on or off, the control circuit is connected to at least one end of the current path and the control end of the transistor, and a reverse voltage is applied to the current path. When the transistor is turned on when a forward voltage is applied to the current path, the transistor is turned off, and a signal applied to the control terminal is controlled to turn the transistor on or off. And rectifying the voltage to be rectified by the transistor. 2. A transistor comprising: a transistor; and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, receives a voltage to be rectified at one end of the current path, and operates under control of the control circuit. By turning on and off, the rectified voltage is output to the other end of the current path. The control circuit is connected to both ends of the current path and the control end, and detects a potential difference between both ends of the current path. The transistor is turned on when a reverse voltage of the transistor is applied to the current path of the transistor, and the transistor is turned off when a forward voltage of the transistor is applied to the current path. Controlling the signal applied to the control terminal to turn on or off the transistor, thereby causing the transistor to rectify the rectification target voltage; Electrical circuit which is characterized. 3. The control circuit, comprising: a transistor; and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, and one end of the current path receives a rectification target voltage to be rectified. A rectified voltage is output to the other end of the current path by being turned on or off according to the control of the control circuit, and the control circuit is connected to both ends of the current path and the control end, and between the both ends of the current path. Detect the polarity of the potential difference,
A signal applied to the control terminal is controlled such that the transistor is turned on when a reverse voltage is applied to the current path of the transistor, and the transistor is turned off when a forward voltage is applied to the current path. Turning on or off the transistor to rectify the voltage to be rectified by the transistor. 4. The transistor comprises a bipolar transistor, both ends of the current path comprise an emitter and a collector of the bipolar transistor, the control terminal comprises a base of the bipolar transistor, and the control circuit comprises: A circuit configured to detect a voltage between an emitter and the collector and supply a base current for turning on or off the bipolar transistor to the base according to the detected voltage, 4. The electric circuit according to 2 or 3. 5. The bipolar transistor according to claim 1, wherein both ends of said current path are formed by an emitter and a collector of said bipolar transistor, said control end is formed by a base of said bipolar transistor, and said control circuit comprises: A circuit for detecting a polarity of a voltage between an emitter and the collector, and supplying a base current for turning on or off the bipolar transistor to the base in accordance with the detected polarity. 4. The electric circuit according to 1, 2, or 3. 6. The bipolar transistor is constituted by an NPN bipolar transistor, one end of the current path is constituted by an emitter of the NPN bipolar transistor, and the other end of the current path is constituted by a collector of the NPN bipolar transistor. The control terminal includes a base of the NPN bipolar transistor. The control circuit supplies a voltage and a current for turning on the NPN transistor to the base when a positive potential higher than the collector is applied to the emitter. And a circuit for supplying a voltage and a current for turning off the NPN transistor to the base when a positive polarity voltage lower than the collector is applied to the emitter. Electrical circuit as described. 7. The bipolar transistor is constituted by a PNP bipolar transistor, one end of the current path is constituted by an emitter of the PNP bipolar transistor, and the other end of the current path is constituted by a collector of the PNP bipolar transistor. The control terminal includes a base of the PNP bipolar transistor. The control circuit supplies a voltage and a current for turning on the PNP transistor to the base when a positive potential higher than the emitter is applied to the collector. And a circuit for supplying a voltage and a current for turning off the PNP transistor to the base when a positive polarity voltage lower than that of the emitter is applied to the collector. Electrical circuit as described. 8. The control circuit according to claim 8, wherein the transistor comprises a field effect transistor, both ends of the current path comprise a source and a drain of the field effect transistor, and the control terminal comprises a gate of the field effect transistor. Comprises a means for detecting a voltage between the source and the drain, and applying a gate voltage for turning on or off the field-effect transistor to the gate according to the detected voltage. The electric circuit according to claim 1, 2 or 3. 9. The control circuit according to claim 9, wherein the transistor comprises a field-effect transistor, both ends of the current path comprise a source and a drain of the field-effect transistor, and the control terminal comprises a gate of the field-effect transistor. Comprises means for detecting the polarity of the voltage between the source and the drain, and applying a gate voltage for turning on or off the field effect transistor to the gate according to the detected polarity. The electric circuit according to claim 1, 2, or 3. 10. The field effect transistor comprises an N-channel field effect transistor, one end of the current path comprises the source of the N channel field effect transistor, and the other end of the current path comprises the N channel field effect transistor. And the control terminal is constituted by the gate of the N-channel field-effect transistor. The control circuit is configured to control the N-channel field-effect transistor when a positive voltage higher than that of the drain is applied to the source. Applying a voltage to turn on the transistor to the gate,
10. A means for applying a voltage to the gate to turn off the N-channel field effect transistor when a positive voltage lower than the drain is applied to the source. An electric circuit according to claim 1. 11. The field-effect transistor comprises a P-channel field-effect transistor, one end of the current path comprises the source of the P-channel field-effect transistor, and the other end of the current path comprises the P-channel field-effect transistor. And the control terminal is constituted by the gate of the P-channel field-effect transistor. The control circuit is configured to control the P-channel field-effect transistor when a positive voltage lower than the drain is applied to the source. Applying a voltage to turn on the transistor to the gate,
10. A means for applying a voltage to said gate to turn off said P-channel field effect transistor when a positive voltage higher than said drain is applied to said source. An electric circuit according to claim 1. 12. The control circuit includes a two-input amplifier circuit, one input terminal of the amplifier circuit is connected to one end of the current path of the transistor, and the other input terminal of the amplifier circuit is connected to the transistor. The electric circuit according to any one of claims 1 to 11, wherein the electric circuit is connected to the other end of the current path, and an output terminal of the amplifier circuit is connected to the control terminal of the transistor. . 13. The control circuit includes a two-input comparison circuit, one input terminal of the comparison circuit is connected to one end of the current path of the transistor, and the other input terminal of the comparison circuit is connected to the transistor The electric circuit according to claim 1, wherein an output terminal of the comparison circuit is connected to the other end of the current path, and an output terminal of the comparison circuit is connected to the control terminal of the transistor. . 14. A control circuit comprising: a transistor; and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, and receives the rectification target voltage at one end of the current path, and controls the control circuit. The rectified voltage is output to the other end of the current path by turning on and off according to the control of the control circuit. The control circuit is connected to the current path and the control end of the transistor, and one end of the current path is connected to the outside. An electric circuit that rectifies the voltage to be rectified by the transistor by controlling a signal applied to the control terminal to turn on or off the transistor in accordance with a direction of a current flowing to a node with a circuit. . 15. The transistor comprises a bipolar transistor, both ends of the current path comprise an emitter and a collector of the bipolar transistor, the control terminal comprises a base of the bipolar transistor, and the control circuit comprises: Supply voltage and current to the base,
15. The electric circuit according to claim 1, comprising means for turning on the bipolar transistor. 16. The bipolar transistor is constituted by an NPN bipolar transistor, one end of the current path is constituted by an emitter of the NPN bipolar transistor, and the other end of the current path is constituted by a collector of the NPN bipolar transistor. The control terminal includes a base of the NPN bipolar transistor. The control circuit detects a direction of a current flowing to a node between the emitter and the external circuit, and when detecting a current in a predetermined direction, turns the NPN transistor on. The electric circuit according to claim 15, further comprising a unit that supplies a voltage and a current to be turned on to the base. 17. A diode is connected between the emitter and the collector of the NPN bipolar transistor with the collector being in a forward direction from the emitter,
17. The electric circuit according to claim 16, wherein the current in the predetermined direction is allowed to flow through the node even when the NPN bipolar transistor is off. 18. A diode is connected between said emitter and said base of said NPN bipolar transistor, said diode having a forward direction from said emitter and said base being connected to said node even when said NPN bipolar transistor is off. The electric circuit according to claim 16, wherein the electric current is allowed to flow. 19. The bipolar transistor is constituted by a PNP bipolar transistor, one end of the current path is constituted by an emitter of the PNP bipolar transistor, and the other end of the current path is constituted by a collector of the PNP bipolar transistor. The control terminal includes a base of the PNP bipolar transistor. The control circuit detects a direction of a current flowing to a node between the emitter and the external circuit, and detects a current in a predetermined direction. The electric circuit according to claim 15, further comprising a unit that supplies a voltage and a current to be turned on to the base. 20. A diode is connected between the emitter and the collector of the PNP bipolar transistor, with the emitter being in a forward direction from the collector,
20. The electric circuit according to claim 19, wherein the current in the predetermined direction is allowed to flow through the node even when the PNP bipolar transistor is off. 21. A diode is connected between said emitter and said base of said PNP bipolar transistor with said emitter being in a forward direction from said base, and said diode is connected to said node in said predetermined direction even when said NPN bipolar transistor is off. 20. The electric circuit according to claim 19, wherein the electric current is allowed to flow. 22. The control circuit according to claim 22, wherein the transistor comprises a field effect transistor, both ends of the current path comprise a source and a drain of the field effect transistor, and the control terminal comprises a gate of the field effect transistor. 15. The electric circuit according to claim 1, further comprising means for applying a gate voltage to the gate to turn on the field effect transistor in a region. 23. The field effect transistor comprises an N-channel field effect transistor, one end of the current path comprises the source of the N channel field effect transistor, and the other end of the current path comprises the N channel field effect transistor. And the control terminal is constituted by a gate of the N-channel field effect transistor. The control circuit is configured to control the N-channel electric field when a current flowing to a node between the source and the external circuit is in a predetermined direction. 23. The device according to claim 22, further comprising means for applying a voltage to turn on the effect transistor to said gate.
An electric circuit according to claim 1. 24. The control circuit comprises means for detecting a current flowing from the source to the drain through a parasitic diode of the N-channel field-effect transistor and turning on the N-channel field-effect transistor. 24. The electric circuit according to claim 23, wherein: 25. The electric circuit according to claim 23, wherein a diode having a forward direction from said source to said drain is connected between said source and said drain. 26. The device according to claim 23, further comprising a constant voltage diode, wherein the gate is connected to the cathode of the constant voltage diode, and the source is connected to the anode of the low voltage diode. Electrical circuit. 27. The field effect transistor comprises a P-channel field effect transistor, one end of the current path comprises the source of the P channel field effect transistor, and the other end of the current path comprises the P channel field effect transistor. And the control terminal is constituted by the gate of the P-channel field effect transistor. The control circuit is configured to control the P-channel electric field when a current flowing through a node between the source and the external circuit is in a predetermined direction. 23. The device according to claim 22, further comprising means for applying a voltage to turn on the effect transistor to said gate.
An electric circuit according to claim 1. 28. The control circuit comprises means for detecting a current flowing from the drain to the source via the parasitic diode of the P-channel field-effect transistor and turning on the P-channel field-effect transistor. 28. The electrical circuit of claim 27, wherein: 29. The electric circuit according to claim 27, wherein a diode having a forward direction from said drain to said source is connected between said source and said drain. 30. The device according to claim 27, further comprising a constant voltage diode, wherein the gate is connected to the anode of the constant voltage diode, and the source is connected to the cathode of the low voltage diode. Electrical circuit. 31. A transformer comprising: a primary winding connected to one end of the current path of the transistor; and a secondary winding magnetically coupled to the primary winding; A circuit that is connected to the secondary winding of the transformer and controls a signal supplied to the control terminal of the transistor in accordance with a current generated in the secondary winding. The electric circuit according to any one of claims 14 to 30, wherein 32. The electric circuit according to claim 31, wherein the control circuit includes means for converting an induced current of the secondary winding into a voltage signal and applying the voltage signal to the control terminal. 33. The control circuit, wherein the control circuit converts an induced current of the secondary winding into a voltage signal, and amplifies the voltage signal converted by the conversion circuit and applies the amplified voltage signal to the control terminal of the transistor. The electric circuit according to claim 31, comprising means. 34. The control circuit according to claim 1, wherein the control circuit includes an active element that requires power supply, and the rectified voltage is supplied to the active element as a power supply. An electric circuit according to any one of the preceding claims. 35. A transistor, comprising: a transistor; and a control circuit connected to the transistor, wherein the transistor has a current path and a control terminal, one end of the current path receives a voltage to be rectified from a power supply, A resistive load is connected to the other end, and a rectified voltage is output to the other end of the current path by turning on and off under the control of the control circuit, and a predetermined reference potential is applied to the control end. An electric circuit, characterized by: 36. The electric circuit according to claim 35, wherein said control terminal of said transistor, said power supply and said load are connected to a substantially common ground point. 37. The electric circuit according to claim 1, wherein the control circuit turns on the transistor in a saturation region of the transistor. 38. A semiconductor switching device, comprising: a semiconductor switching device; and a control circuit for controlling the semiconductor switching device. The semiconductor switching device includes a current path having one end connected to a power supply side and the other end connected to a load side. Turning on and off according to the control of the control circuit, the control circuit is connected to both ends of a current path of the semiconductor switching element, detects a voltage applied to the current path, and according to a detection result, An electric circuit, which turns a switching element on or off.