JPH0661823A - Switch circuit - Google Patents

Abstract

PURPOSE:To reduce the switching time by implementing switching without saturation of transistors(TRs). CONSTITUTION:When a switch changeover signal is inputted to a switch changeover signal input terminal 8, a current of a current mirror circuit comprising TRs 9, 11 and resistors 10, 12 is switched on/off and its on/off levels are given to a resistor 13. When a current flows to the resistor 13, an upper limit is produced by a TR 24 and when no current flows through the resistor 13, a lower limit is produced by a TR 23 based on a potential at a common connecting point of resistors 19, 20. A high or a low level of switch signals at switch signal output terminals 21, 22 are selected depending on the upper limit and the lower limit potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit.

[0002]

2. Description of the Related Art An example of a conventional switch circuit will be described with reference to FIG. In this switch circuit, as shown in FIG. 2, one end of the resistor 2 is connected to the power supply terminal 1, one end of the resistor 3 is connected to the other end of the resistor 2, the other end of the resistor 3 is grounded, and the resistor 2, The base of the transistor 4 is connected to the common connection point of the transistors 3, one end of the current source 6 is connected to the emitter of the transistor 4, and the other end of the current source 6 is grounded.

The collector of the transistor 5 is connected to the power supply terminal 1, the emitter of the transistor 4 is connected to the emitter of the transistor 5, one end of the resistor 7 is connected to the base of the transistor 5, and the other end of the resistor 7 is switched. It is connected to the switching signal input terminal 8. Also, one end of the resistor 10 is connected to the power supply terminal 1, the collector of the transistor 4 is connected to the collector and base of the transistor 9, the other end of the resistor 10 is connected to the emitter of the transistor 9, and one end of the resistor 12 is connected to the power supply terminal. 1, the collector and the base of the transistor 9 are connected to the base of the transistor 11, the other end of the resistor 12 is connected to the emitter of the transistor 11, and the transistor 9 and the transistor 11 form a current mirror circuit. ing.

Further, one end of the resistor 13 is connected to the collector of the transistor 11, the other end of the resistor 13 is grounded, the base of the transistor 25 is connected to the connection point between the collector of the transistor 11 and the resistor 13, and the collector of the transistor 25 is connected. Is connected to one end of the resistor 26, and the emitter of the transistor 25 is grounded. Further, one end of the resistor 27 is connected to the power supply terminal 1
And one end of the resistor 28 is connected to the other end of the resistor 27,
The other end of the resistor 28 is grounded, and the other end of the resistor 26 is connected to the connection point of the resistors 27 and 28.

The base of the transistor 15 is connected to the connection point of the resistors 27 and 28, one end of the current source 14 is connected to the power supply terminal 1, and the emitter of the transistor 15 is connected to the current source 1.
The other end of the transistor 4 is connected, and the emitter of the transistor 16 is connected to the emitter of the transistor 15. Also, the resistance 1
One end of the resistor 9 is connected to the power supply terminal 1, the other end of the resistor 19 is connected to the base of the transistor 16, one end of the resistor 20 is connected to the base of the transistor 16, and the other end of the resistor 20 is grounded.

Further, one end of the load 17 is connected to the transistor 15
Switch signal output terminal 2 as well as connecting to the collector of
1, the other end of the load 17 is grounded, one end of the load 18 is connected to the collector of the transistor 16 and the switch signal output terminal 22, and the other end of the load 18 is grounded. Here, the operation of the switch circuit of FIG. 2 will be described.

First, when a high level signal is input to the switch switching signal input terminal 8, the base potential of the transistor 5 becomes higher than the base potential of the transistor 4, which is the divided voltage of the resistors 2 and 3, and the transistor 4 is turned off. 5 is turned on, and the current of the current source 6 is the transistor 5
Flow to. As a result, the transistors 9 and 11 are turned off, no current flows through the current mirror circuit, and the transistor 25 is turned off.

Therefore, the base potential of the transistor 16 is a voltage divided by the resistors 19 and 20, whereas the base potential of the transistor 15 is the resistors 27 and 2.
Since the base potential of the transistor 15 is higher than the base potential of the transistor 16, the transistor 15 is turned off and the transistor 16 is turned on. Therefore, the current of the current source 14 is
Since it flows into the load 18 through the load 18 and does not flow into the load 17, the switch signal at the switch signal output terminal 22 becomes high level, and the switch signal at the switch signal output terminal 21 becomes low level.

The switch signal of the switch signal output terminal 21 and the switch signal of the switch signal output terminal 22 are exactly 180 ° out of phase with each other. That is, they are mutually inverted signals. Next, the switch switching signal input terminal 8
When a low level signal is input to the transistor 4, the base potential of the transistor 5 is the divided voltage of the resistors 2 and 3
Becomes lower than the base potential of the transistor 4, the transistor 4 is turned on and the transistor 5 is turned off, the current of the current source 6 flows to the transistor 4, the current of the current source 6 flows to the transistor 9, and the same current flows to the transistor 11 by the current mirror circuit. Flows. As a result, a part of the current flowing through the transistor 11 flows into the base of the transistor 25, and the transistor 25 is turned on (saturated).

Therefore, the base potential of the transistor 16 is a voltage divided by the resistors 19 and 20, whereas the base potential of the transistor 15 is the resistors 27 and 2.
The voltage is divided by the parallel circuit of 6 and 28, and the base potential of the transistor 15 becomes lower than the base potential of the transistor 16. Therefore, the transistor 15 is turned on and the transistor 16 is turned off. Therefore, the current of the current source 14 flows into the load 17 through the transistor 15 and does not flow into the load 18, so that the switch signal output terminal 2
The switch signal of 1 becomes high level, and the switch signal of the switch signal output terminal 22 becomes low level.

[0011]

As described above, in the switch circuit of FIG. 2, the switch signal output terminal 2
Switching between high and low of the switch signals output from 1 and 22 is performed by switching the base potential of the transistor 15 by turning on / off the transistor 25, and the transistor 25 is saturated due to the switching.

As described above, in the conventional configuration, the switching signal is switched between high and low by saturating the transistor 25, so that there is a problem that a long switching time is required. Therefore, an object of the present invention is to provide a switch circuit that can shorten the switch switching time.

[0013]

According to the switch circuit of the present invention, one end of a first resistor is connected to a power supply potential point, one end of a second resistor is connected to the other end of the first resistor, and a second resistor is connected to the second resistor. Ground the other end of the resistor and connect the first and second resistors to the common connection point.
The base of the second transistor is connected, the emitter of the first transistor is connected to one end of the first current source, the other end of the first current source is grounded, and the collector of the second transistor is connected to the power supply potential point. Then, the emitter of the first transistor is connected to the emitter of the second transistor, the base of the second transistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the switch switching signal input terminal. Connected.

Further, one end of the fourth resistor is connected to the power supply potential point, the collector and base of the third transistor are connected to the collector of the first transistor, and the third transistor is connected to the other end of the fourth resistor. Connected to the emitter of, the one end of the fifth resistor is connected to the power supply potential point, the base of the fourth transistor is connected to the connection point of the collector and base of the third transistor, and the other end of the fifth resistor is connected. The emitter of the fourth transistor is connected, and the third transistor and the fourth transistor form a current mirror circuit.

Further, the collector of the fifth transistor is connected to the power supply potential point, the collector of the fourth transistor is connected to the emitter of the fifth transistor, and the collector of the fourth transistor and the emitter of the fifth transistor are connected. The emitter of the sixth transistor is connected to the connection point, the base of the sixth transistor is connected to the base of the fifth transistor, and the collector of the sixth transistor is grounded.

Further, one end of the sixth resistor is connected to the collector of the fourth transistor and the other end of the sixth resistor is grounded,
The base of the seventh transistor is connected to the collector of the fourth transistor, one end of the second current source is connected to the power supply potential point, and the other end of the second current source is connected to the emitter of the seventh transistor. , The emitter of the eighth transistor is connected to the emitter of the seventh transistor, and the base of the eighth transistor is connected to the commonly connected bases of the fifth and sixth transistors.

Also, one end of the seventh resistor is connected to the power supply potential point, the other end of the seventh resistor is connected to the base of the eighth transistor, and one end of the eighth resistor is connected to the base of the eighth transistor. And the other end of the eighth resistor is grounded. Also, one end of the first load is connected to the collector of the seventh transistor and is also connected to the first switch signal output terminal, the other end of the first load is grounded, and one end of the second load is connected to the eighth switch. Is connected to the collector of the transistor and the second switch signal output terminal, and the other end of the second load is grounded.

[0018]

According to the structure of the present invention, by switching the signal applied to the switch switching signal input terminal, the current flowing through the sixth resistor via the current mirror circuit is interrupted. When no current flows from the current mirror circuit to the sixth resistor with reference to the potential at the connection point of the seventh and eighth resistors, the fifth transistor operates to flow current into the sixth resistor, The base potential of the transistor 7 is set to a predetermined lower limit potential.

Since this lower limit potential is lower than the base potential of the eighth transistor, which is the potential at the connection point of the seventh and eighth resistors, the seventh transistor turns on and the eighth transistor turns off. , The switch signal of the first switch signal output terminal becomes low, and the switch signal of the second switch signal output terminal becomes high. Also,
When a current flows from the current mirror circuit to the sixth resistor, the sixth transistor operates and a part of the current flowing into the sixth resistor is extracted to set the base potential of the seventh transistor to a predetermined upper limit potential. To do.

Since this upper limit potential is higher than the base potential of the eighth transistor, which is the potential at the connection point of the seventh and eighth resistors, the seventh transistor is turned off and the eighth transistor is turned on. , The switch signal of the first switch signal output terminal becomes high, and the switch signal of the second switch signal output terminal becomes low.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In this switch circuit, as shown in FIG. 1, one end of a first resistor 2 is connected to a power supply terminal 1, the other end of the first resistor 2 is connected to one end of a second resistor 3, and a second resistor 3 is connected. The other end of the resistor 3 is grounded, the base of the first transistor 4 is connected to the common connection point of the first and second resistors 2 and 3, and the emitter of the first transistor 4 is connected to the emitter of the first current source 6. One end is connected and the other end of the first current source 6 is grounded.

The second transistor 5 is connected to the power supply terminal 1.
The collector of the second transistor 5 is connected to the emitter of the first transistor 4 and the emitter of the second transistor 5 is connected to the base of the second transistor 5.
The other end of the third resistor 7 is connected to the switch switching signal input terminal 8. In addition, one end of the fourth resistor 10 is connected to the power supply terminal 1
To the collector of the first transistor 4, the collector and the base of the third transistor 9 are connected, the other end of the fourth resistor 10 is connected to the emitter of the third transistor 9, and the fifth resistor 12 is connected. Is connected to the power supply terminal 1, the collector and base of the third transistor 9 are connected to the base of the fourth transistor 11, and the other end of the fifth resistor 12 is connected to the emitter of the fourth transistor 11. And the third transistor 9 and the fourth transistor 11 form a current mirror circuit.

The collector of the fifth transistor 23 is connected to the power supply terminal 1, the collector of the fourth transistor 11 is connected to the emitter of the fifth transistor 23, and the collector of the fourth transistor 11 and the fifth transistor 23 are connected to each other. The emitter of the sixth transistor 24 is connected to the connection point of the emitter of the transistor 23, the base of the sixth transistor 24 is connected to the base of the fifth transistor 23, and the collector of the sixth transistor 24 is grounded. .

Further, one end of the sixth resistor 13 is connected to the collector of the fourth transistor 11, the other end of the sixth resistor 13 is grounded, and the collector of the fourth transistor 11 is connected to the seventh resistor 13.
Of the second current source 1 by connecting the base of the transistor 15 of
4 has one end connected to the power supply terminal 1 and the seventh transistor 1
The other end of the second current source 14 is connected to the emitter of
The eighth transistor 1 at the emitter of the transistor 15 of
6 is connected, and the base of the eighth transistor 16 is connected to the commonly connected bases of the fifth and sixth transistors 23 and 24.

Further, one end of the seventh resistor 19 is connected to the power supply terminal 1
, The other end of the seventh resistor 19 is connected to the base of the eighth transistor 16, one end of the eighth resistor 20 is connected to the base of the eighth transistor 16, and the other end of the eighth resistor 20 is connected. The end is grounded. In addition, one end of the first load 17 is connected to the collector of the seventh transistor 15 and is also connected to the first switch signal output terminal 21.
7 is grounded, one end of the second load 18 is connected to the collector of the eighth transistor 16 and the second switch signal output terminal 22, and the other end of the second load 18 is grounded. ing.

That is, the switch circuit of this embodiment is different from the conventional example of FIG. 2 in that the resistors 26, 27 and 28 and the transistor 25 are removed and the fourth transistor 1 is used.
The connection point between the collector of 1 and the sixth resistor 13 is connected to the base of the seventh transistor 15, and the fifth and sixth transistors 23 and 24 are provided as upper and lower limit potential limiters.

As a result, the switching of the switch signals of the first and second switch signal output terminals 21 and 22 is switched to the sixth from the current mirror circuit composed of the third transistor 9 and the fourth transistor 11. It is performed depending on whether or not a current flows into the resistor 13, and without saturating the fifth and sixth transistors 23 and 24,
The switch signals of the first and second switch signal output terminals 21 and 22 can be switched, and the switch switching time can be shortened.

The operation of the switch circuit of the embodiment shown in FIG. 1 will be described. First, when a high-level signal is input to the switch switching signal input terminal 8, the base potential of the second transistor 5 becomes lower than the base potential of the first transistor 4 which is the divided voltage of the first and second resistors 2 and 3. The voltage rises, the first transistor 4 is turned off, the second transistor 5 is turned on, and the current of the first current source 6 flows through the second transistor 5. As a result, the third and fourth transistors 9 and 11 are turned off, no current flows in the current mirror circuit, and no current flows in the sixth resistor 13.

When no current flows into the sixth resistor 13 on the basis of the potential of the connection point of the seventh and eighth resistors 19 and 20, the lower limit is applied by the fifth transistor 23 (fifth transistor). 23 is an unsaturated state). That is, a current flows into the sixth resistor 13 through the fifth transistor 23, and the base potential of the seventh transistor 15 becomes a predetermined lower limit potential.

Therefore, while the base potential of the eighth transistor 16 is a voltage divided by the seventh resistor 19 and the eighth resistor 20, the base potential of the seventh transistor 15 is a predetermined lower limit potential. , 7th transistor 1
Since the base potential of 5 becomes lower than the base potential of the eighth transistor 16, the seventh transistor 15 is turned on and the eighth transistor 16 is turned off. Therefore, the current of the second current source 14 flows into the first load 17 through the seventh transistor 15 and does not flow into the second load 18, so that the switch signal at the first switch signal output terminal 21 becomes high. Then, the switch signal at the second switch signal output terminal 22 becomes low level.

Next, when a low-level signal is input to the switch switching signal input terminal 8, the base potential of the second transistor 5 is the divided voltage of the first and second resistors 2 and 3, and the first transistor 4 is divided. Lower than the base potential of
The first transistor 4 is turned on and the second transistor 5 is turned off, so that the current of the first current source 6 flows through the first transistor 4. As a result, the current flowing through the first transistor 4 flows through the third transistor 9, the current mirror circuit causes the same current as the third transistor 9 to flow through the fourth transistor 11, and the current flows through the sixth resistor 13. Pour in.

When a current flows into the sixth resistor 13 with reference to the potential at the connection point of the seventh and eighth resistors 19 and 20, an upper limit is applied by the sixth transistor 24 (sixth transistor). 24 is an unsaturated state). That is, the current that should flow into the sixth resistor 13 is extracted through the sixth transistor 24,
The base potential of the transistor 15 has a predetermined upper limit potential.

Therefore, while the base potential of the eighth transistor 16 is a voltage divided by the seventh resistor 19 and the eighth resistor 20, the base potential of the seventh transistor 15 becomes a predetermined upper limit potential. , 7th transistor 1
Since the base potential of 5 becomes higher than the base potential of the eighth transistor 16, the seventh transistor 15 is turned off and the eighth transistor 16 is turned on. Therefore, the current of the second current source 14 flows into the second load 18 through the eighth transistor 16 and does not flow into the first load 17, so that the switch signal of the first switch signal output terminal 21 becomes low. And the switch signal of the second switch signal output terminal 22 becomes high level.

[0034]

According to the switch circuit of the present invention, the fourth
The connection point between the transistor and the sixth resistor is connected to the base of the fifth transistor, and the series circuit of the fifth and sixth transistors is connected between the power supply potential point and the ground potential point,
The common emitters of the fifth and sixth transistors are connected to the base of the seventh transistor, and the common bases of the fifth and sixth transistors are connected to the base of the eighth transistor, that is, the connection point of the seventh and eighth resistors. Because I did, the fifth
Also, the switch can be switched without saturating the sixth transistor, and the switch switching time can be shortened.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing a configuration of an example of a conventional switch circuit.

[Explanation of symbols]

 1 Power Supply Terminal 2 First Resistor 3 Second Resistor 4 First Transistor 5 Second Transistor 6 First Current Source 7 Third Resistor 8 Switch Switching Signal Input Terminal 9 Third Transistor 10 Fourth Resistor 11 4th transistor 12 5th resistance 13 6th resistance 14 2nd current source 15 7th transistor 16 8th transistor 17 1st load 18 2nd load 19 7th resistance 20 8th Resistance 21 1st switch signal output terminal 22 2nd switch signal output terminal 23 5th transistor 24 6th transistor

Claims (1)

[Claims] 1. A first terminal having one end connected to a power supply potential point (1)
A second resistor (3) having one end connected to the other end of the first resistor (2) and the other end grounded, and the first and second resistors (2, 3) A first transistor (4) having a base connected to a common connection point of, a first current source (6) having one end connected to the emitter of the first transistor (4) and the other end grounded, and a collector A second transistor connected to the power supply potential point (1) and having an emitter connected to the emitter of the first transistor (4)
Transistor (5), a third resistor (7) having one end connected to the base of the second transistor (5) and the other end connected to the switch switching signal input terminal (8), and one end connected to the power supply potential point ( Fourth resistor (10) connected to 1)
And a collector and a base connected to the first transistor (4)
And the emitter is connected to the collector of the fourth resistor (10)
A third transistor (9) connected to the other end of the and a fifth resistor (12) having one end connected to the power supply potential point (1)
And a base connected to a connection point between the collector and the base of the third transistor (9) and an emitter connected to the other end of the fifth resistor (12).
And a fourth transistor (11) forming a current mirror circuit, and a fifth transistor (23) having a collector connected to the power supply potential point (1) and an emitter connected to the collector of the fourth transistor (11). ), And an emitter connected to a connection point between the collector of the fourth transistor (11) and an emitter of the fifth transistor (23), a base connected to the base of the fifth transistor (23), and a collector grounded. A sixth transistor (24), a fifth resistor (13) having one end connected to the collector of the fourth transistor (11) and the other end grounded, and a base connected to the fourth transistor (11). A seventh transistor (15) connected to the collector, one end of which is connected to the power supply potential point (1) and the other end of which is connected to the emitter of the seventh transistor (15) A second current source (14), and an eighth whose emitter is connected to the emitter of the seventh transistor (15) and whose base is connected to the commonly connected bases of the fifth and sixth transistors (23, 24) Transistor (16) and a seventh resistor (1) having one end connected to the power supply potential point (1) and the other end connected to the base of the eighth transistor (16).
9), an eighth resistor (20) having one end connected to the base of the eighth transistor (16) and the other end grounded, and one end connected to the collector of the seventh transistor (15) and A first load (17) connected to the first switch signal output terminal 21 and the other end grounded; and a second switch signal output terminal (22) connected to the collector of the eighth transistor (16) at one end A switch circuit having a second load (18) connected to and having the other end grounded.