JPH07273622A - Switch circuit - Google Patents

Abstract

PURPOSE:To obtain a switch circuit employing a semiconductor switch to intermit the supply of a constant voltage source or a constant current source to a load line where its response speed against a change in a circuit/current setting value or a load fluctuation of the load line is improved by reducing an inter- terminal capacitance when the switch circuit is open and the effect of a waveform onto the load line is avoided by decreasing a series resistive component when the switch circuit is closed. CONSTITUTION:A series circuit comprising a semiconductor switch SW 1.5 and a diode D1.10 and a series circuit comprising a semiconductor switch SW 2.6 and a diode D2.11 whose connection polarity is opposite to the diode D2.10 are connected in parallel and when the parallel circuit is connected, the switches 1.5 and 2.6 are closed. When the parallel circuit is disconnected, the switches 1.5 and 2.6 are open and the diode D1.10 and the diode D2.11 are open simultaneously by closing semiconductor switches SW 3.8 and 4.9 connecting between other power supply and connecting points of the semiconductor switches and the diodes of the series circuits so as to apply reverse bias to the diodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit for connecting or disconnecting a constant voltage source or a constant current source to a load line.

[0002]

2. Description of the Related Art FIG. 4 shows a switch circuit for connecting and disconnecting a constant voltage source or a constant current source to a load line 7 by using semiconductor switches. The semiconductor switches SW1 and SW2 and SW2.
6 is a method of a constituent circuit according to the related art using 6. However, the characteristics of the load line 7 must be kept severe. However, when connecting or disconnecting a circuit network including the operational amplifiers A0 and 2 to the load line 7, the semiconductor
It is required that the inter-terminal capacitance of SW1.5 and SW2.6 and the series resistance component of SW1.5 be small.

However, according to the prior art, for example, as shown in FIG. 4, when the semiconductor switches SW1 and SW5 and SW2 and 6 are used to connect and disconnect the constant voltage source to and from the load line 7, the following description will be made. It has been difficult to simultaneously achieve the two characteristics described above. That is, (1) To reduce the influence on the load line 7 of the constant voltage source when disconnecting with SW1.5 and SW2.6, that is, when the switch is off, SW
Reduce the capacitance between terminals 1.5 and SW2.6. (2) When connecting with SW1.5 and SW2.6, that is, in order to prevent the constant voltage source from slowing down in response to changes in the voltage to be supplied to the load line 7 when it is on, the series resistance of SW1.5 That is to reduce the components.

[0004]

A semiconductor switch is used to connect or disconnect a set voltage of a constant voltage source or a set current of a constant current source to a load line through a force line and a sense line. In this case, when connecting, it is necessary to have a small series resistance component in order to speed up the response to changes in the load line, and when disconnecting, reduce the capacitance between terminals to reduce the effect on the load line. It needs to be small. However, in a semiconductor switch, there is no one that satisfies both characteristics that the series resistance component is small and the capacitance between terminals is small at the same time, and there is only one that satisfies only one of the characteristics. It was not possible to construct a more sophisticated switch circuit using switches.

Therefore, in the present invention, even if the characteristics of the existing semiconductor switch are used, a switch circuit for connecting and disconnecting the constant voltage power supply or the constant current source to the load line is constructed by using them. 1) At the time of disconnection, reduce the inter-terminal capacitance for the load line, which is the connected line, and reduce the influence on the waveform of the load line. (2) At the time of connection, reduce the series resistance component and increase the response speed to load fluctuations. Another object of the present invention is to realize a switch circuit using a semiconductor switch capable of increasing the response speed corresponding to changes in voltage and current set values.

[0006]

In order to achieve the above object, a feedback loop formed by an operational amplifier is provided, that is, a constant voltage source for sensing a voltage and returning it to an input, or a constant current source is intermittently connected to a load line. It was decided to connect the switch circuits in parallel. At this time, the two diodes are set in opposite directions to each other to form a force line intermittent switch that functions in the entire switch circuit.

(1) When connecting a constant voltage source or a constant current source to the load line, turn on the semiconductor switch. The sense line is also turned on by a separate semiconductor switch. (2) When disconnecting the constant voltage source or the constant current source from the load line, turn off the semiconductor switch. At the same time, the semiconductor switch provided separately causes the above-mentioned 2
Turn off the diodes. That is, the semiconductor switches connected in parallel as a series circuit are connected to another power source so that the diode has a reverse bias.

[0008]

Each element constituting the intermittent switch circuit of the present invention has its own required characteristics and circuit conditions. (1) First, none of the existing semiconductor switches simultaneously satisfy both characteristics of small inter-terminal capacitance and small series resistance component. Since it is possible if either one of them is satisfied, in configuring the switch circuit, an element for a part requiring a characteristic with a small series resistance component and an element for a part requiring a characteristic with a small inter-terminal capacitance are required. , Selected, applied, combined, and made to function as a switch circuit. (2) Further, as the diode, one having a small inter-terminal capacitance is selected. (3) For the voltage from the semiconductor switch connected to the series and the separate power source connected to the middle point of the diode, add one higher than the load line voltage and the other lower voltage.

[0009]

1 is a block diagram showing the concept of a switch circuit for connecting or disconnecting a set voltage V1.1 of a constant voltage source to a load line 7 in an embodiment according to the present invention. (1) When connecting the set voltage V1.1 to the load line 7,
Each switch is in the state shown in FIG. Semiconductor switch
SW1.5 and SW2.6 are configured with a small series resistance component, and the set voltage V1.1 is turned on to the load line 7 through the force line 3. At this time, operational amplifier A0
The potential difference between the two outputs and the load line 7 is the diode D
Since it is the forward voltage of 1 · 10 and D2 · 11, the response to the change in the load line 7 can be made sufficiently fast. The sense line 4 is also turned on at the same time.
The semiconductor switches SW5, 12 are configured with small inter-terminal capacitance, but since no current flows, there is no adverse effect due to the large series resistance component.

(2) Further, the set voltage V1.1 is applied to the load line 7
When separated from each switch, each switch is in the state shown in parentheses in FIG. That is, semiconductor switch SW3 ・ 8
Also, the switches SW4 and SW9 are turned on, and the other semiconductor switches are turned off. By turning on SW3.8 and SW4.9, which have small inter-terminal capacitance, reverse bias is applied to the diodes D1.10 and D2.11, and they are turned off. Since the switches 5 and 12 of the sense line 4 are turned off by the one having a small inter-terminal capacitance and are disconnected from the load line 7, the waveform of the load line 7 is not adversely affected.

(3) FIG. 2 shows an embodiment according to the present invention, in which the set current 13 of the constant current source is output from the operational amplifiers A1 and 14 and the operational amplifier A2 and 15 and connected to the load line 7 through the force line 3. FIG. 3 is a block diagram showing the concept of a switch circuit in the case of disconnection. As shown in FIG. 2, there is no sense line 4, but a force line 3
The switch circuit for connecting and disconnecting the switch has exactly the same configuration as in the case of the constant voltage source, and the operation principle at the time of turning on and off does not change.

(4) FIG. 3 shows the configuration of a switch circuit showing the concept of another embodiment according to the present invention. In order to prevent the impedance of the diodes D1 · 10 and D2 · 11 from rising when the current of the force line 3 is small when the switch circuit of the present invention is on, as shown in FIG.
Semiconductor switches SW6 and 16 are added in parallel in the switch circuit of force line 3. SW6, 16 are turned on when connecting the constant voltage source and the constant current source to the load line 7.
SW6 16 has a small terminal capacitance, for example, about 1PF,
The series resistance component is large, for example, about 100Ω, but is sufficiently smaller than the rising impedances of D1 · 10 and D2 · 11, and since the current is small, the purpose can be sufficiently achieved.

[0013]

Since the present invention is constructed as described above, it has the following effects. (1) When connecting a constant voltage source or a constant current source to the load line, that is, when switching on,
Since it operates as a switching circuit with a small series resistance component, the response speed can be increased in response to load fluctuations in the load line, and the response speed can be increased in response to changes in the set voltage / current value. (2) In addition, when disconnecting, that is, when the switch is turned off, it operates as a switching circuit with a small inter-terminal capacitance, so the influence on the waveform of the load line can be reduced.

(3) The present invention has the advantage that the existing semiconductor switch use defect that only one of the series resistance component is small and the inter-terminal capacitance is small is not visible. Since it can be realized by a method that combines only the small size and high speed of the semiconductor switch,
We have obtained an intermittent switch circuit with excellent characteristics such as high functionality, high reliability and long life.

[Brief description of drawings]

FIG. 1 is a block diagram showing a concept of an intermittent switch circuit corresponding to a constant voltage source according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a concept of an intermittent switch circuit corresponding to a constant current source according to an embodiment of the present invention.

FIG. 3 is a block diagram showing the concept of an intermittent switch circuit that can be used when the current of a force line is small according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a concept of an intermittent switch circuit according to a conventional technique.

[Explanation of symbols]

 1 set voltage V1 2 operational amplifier A0 3 force line 4 sense line 5 SW1 6 SW2 7 load line 8 SW3 9 SW4 10 D1 11 D2 12 SW5 13 set current 14 operational amplifier A1 15 operational amplifier A2 16 SW6

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H03K 17/74 Z

Claims (2)

[Claims] 1. A switch circuit for connecting and disconnecting a constant voltage source or a constant current source to a load line (7), wherein (A) series is provided between a force line output (3) of an operational amplifier and a load line (7). SW1 (5), which is a connected semiconductor switch
And a diode D1 (10) are provided, and (B) a semiconductor switch SW2 (6) connected in series.
And a diode D2 (11) having a polarity opposite to that of the diode D1 (10) are provided, and (C) a reverse bias power source is connected to the midpoint between the SW1 (5) and the diode D1 (10). SW3 (8) which is a semiconductor switch is provided, and (D) A SW4 (9) which is a semiconductor switch connected to a reverse bias power source is provided at the midpoint between the SW2 (6) and the diode D2 (11). A switch circuit having the above configuration. 2. A force line output (3) of an operational amplifier.
And the load line (7) between the semiconductor switch SW6
The switch circuit according to claim 1, further comprising (16).