JPH04270511A - Electronic switch circuit - Google Patents

Abstract

PURPOSE:To realize the circuit having a wide dynamic range with less leakage of a signal between input/output terminals by employing two NPN bipolar transistors(TRs) and three NPN bipolar TRs for the circuit. CONSTITUTION:The circuit is provided with two NPN bipolar TRs Q3, Q4 whose emitters are connected in common and with two PNP bipolar TRs Q5, Q6 whose collectors are connected to collectors of the bipolar TRs Q3, Q4, whose bases are connected to a 1st control terminal 3 and whose emitters are connected to a power supply voltage application terminal 1, and also with an NPN bipolar TR Q2 whose emitter connects to a reference voltage application terminal 2 and whose base is connected to a 2nd control terminal 4. Thus, the NPN bipolar TR Q3 is completely turned on/off.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic switch circuit, and particularly to a circuit configuration of an electronic switch circuit that improves the dynamic range and eliminates signal leakage between input and output.

[Conventional technology]

A conventional electronic switch circuit will be described using an electronic switch circuit using a diode bridge as an example.

FIG. 4 is a diagram showing the circuit configuration of an electronic switch circuit using a diode bridge.

As shown in FIG. 4, this electronic switch circuit includes a diode bridge consisting of diodes D1, D2, D3, and D4, and a PNP bipolar transistor Q1 connected to a common anode of this diode bridge and a power supply voltage supply terminal 1. and an NPN bipolar transistor Q2 connected to the common cathode of the diode bridge mentioned above and the reference voltage supply terminal 2.

Here, the bases of the two bipolar transistors mentioned above are connected to the first control terminal 3 and the second control terminal 4, respectively.

The operation of this electronic switch circuit will be described below.

In FIG. 4, when the first control terminal 3 and the second control terminal 4 are controlled so that the PNP bipolar transistor Q1 and the NPN bipolar transistor Q2 are turned off, that is, no collector current flows, no current is supplied to the diode bridge circuit. , the signal input to the input terminal 5 is not output to the output terminal 6.

That is, this electronic switch circuit is turned off.

Next, the PNP bipolar transistor Q1 and the NPN bipolar transistor Q2 are turned on, that is, the first control terminal 3 and the second control terminal 4 are turned on so that the collector current flows.
When the diode bridge circuit is controlled, a current is supplied to the diode bridge circuit, so that the signal input to the input terminal 5 is output to the output terminal 6.

That is, this electronic switch circuit is turned on.

At this time, if the potential of the input signal is higher than , the diode D1 turns off, so the output terminal 6
There is no output signal.

On the other hand, if the potential of the input signal is lower than , the diode D3 is turned off, so there is no output signal at the output terminal 6.

Therefore, the input/output dynamic range VD (=VIH-VIL) of this electronic switch circuit is as follows.

However, VCC; power supply voltage VCSAT; PNP bipolar transistors Q1 and N
Collector-emitter saturation voltage VBE of PN bipolar transistor Q2; forward voltage of diodes D1, D2, D3, D4.

In FIG. 4, diode connections of bipolar transistors are generally used as diodes constituting the diode bridge.

[Problem to be solved by the invention]

BACKGROUND ART Currently, as electronic devices become smaller, consume less power, and have higher performance, the power supply voltage of electronic circuits, typically integrated circuits, used in these devices is becoming lower.

On the other hand, in the electronic circuits mentioned above, the signal amplitude is large in order to prevent malfunctions due to noise and leakage between signals.
It is important that the input and output signals are strictly separated.

However, the conventional electronic switch circuit described above has the characteristic that as the power supply voltage decreases, the dynamic range of the input/output signal also decreases, as expressed by equation (2). is required to improve this dynamic range.

Furthermore, since each diode constituting the diode bridge of this electronic switch circuit does not have a control terminal for controlling current-voltage characteristics, it is impossible to completely prevent the reverse current of diode D1 from flowing into diode D2. This cannot be prevented and the input signal leaks into the output signal.

An object of the present invention is to provide an electronic switch circuit that has a wider dynamic range than conventional electronic switch circuits and has less signal leakage between input and output terminals.

[Means to solve the problem]

The electronic switch circuit of the present invention includes a first NPN bipolar transistor whose base is connected to an input terminal, whose base and collector are connected to an output terminal, and whose emitter is connected to the emitter of the first NPN bipolar transistor. a second NPN bipolar transistor; a first P transistor having a collector connected to the collector of the first NPN bipolar transistor, an emitter connected to the power supply voltage supply terminal, and a base connected to the first control terminal;
a second PNP bipolar transistor having a collector connected to the collector of the second NPN bipolar transistor, an emitter connected to the power supply voltage supply terminal, and a base connected to the first control terminal; , a collector is connected to the emitters of the first NPN bipolar transistor and the second NPN bipolar transistor, and the emitter is connected to a reference voltage supply terminal,
and a third NPN bipolar transistor whose base is connected to the second control terminal.

Furthermore, the electronic switch circuit according to the invention according to claim 2 is the electronic switch circuit according to the invention according to claim 1, wherein the first
The collector and base of the NPN bipolar transistor are short-circuited.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

In this embodiment, as shown in FIG. 1, two NPN bipolar transistors Q3 and Q4 have a common emitter, the collectors are connected to the collectors of the respective bipolar transistors, and the bases are connected to the first control terminal. Two PNP bipolar transistors Q5 and Q6 whose emitters are connected to the power supply voltage supply terminal 1, whose collectors are connected to the emitters of the aforementioned two NPN bipolar transistors Q3 and Q4, whose emitters are connected to the reference voltage supply terminal 4, It is composed of an NPN bipolar transistor Q2 whose base is connected to the second control terminal 4.

In this electronic switch circuit, when the first control terminal 3 and the second control terminal 4 are controlled so that the PNP bipolar transistors Q5, Q6 and the NPN bipolar transistor Q2 are turned off, that is, the collector current does not flow, the NPN
Since no current is supplied to the N transistors Q3 and Q4, the input signal input to the input terminal is not output to the output terminal 6.

That is, this electronic switch circuit is turned off.

Next, PNP bipolar transistors Q5, Q6 and N
When the first control terminal 3 and the second control terminal 4 are controlled so that the PN bipolar transistor Q2 is turned on, that is, the collector current flows, current is supplied to the NPN bipolar transistors Q3 and Q4, so that the input terminal 5 The input signal input to is output to the output terminal 6.

That is, this electronic switch circuit is turned on.

At this time, the input/output dynamic range VD of this electronic switch circuit is defined by the power supply voltage being VCC, the collector-emitter saturation voltage of the PNP bipolar transistors Q5, Q6, and the NPN bipolar transistor Q2 being VCSAT, N
If the base-emitter voltage of the PN bipolar transistors Q3 and Q4 is VBE, then the dynamic range of the conventional electronic switch circuit expressed by equation 1 is wider by VBE.

Furthermore, in this electronic switch circuit, since the control PNP bipolar transistor Q5 is connected to the collector of the NPN bipolar transistor Q3, the NPN bipolar transistor Q3 can be completely turned on and off.
No input signal leaks from the input terminal 5 to the output terminal 6.

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

FIG. 2 is a circuit diagram showing a second embodiment of the invention.

In this second embodiment, the collector and base of the NPN bipolar transistor Q3 are short-circuited, whereas in the first embodiment shown in FIG. 1, the collector and base of the NPN bipolar transistor Q3 are open.

The operation of this embodiment is basically the same as that of the first embodiment, and its dynamic range is expressed by the equation (2).

This second embodiment includes the effects of the first embodiment, and furthermore, since the collector and base of the NPN bipolar transistor Q3 are short-circuited, matching with the NPN bipolar transistor Q4 is achieved, and the input-output connection is improved. This has the advantage that the offset voltage becomes zero.

In addition, in the above explanation, conduction type bipolar transistors as shown in FIGS. 1 and 2 are used as the conduction type of each bipolar transistor constituting the electronic switch circuit, but the present invention is not limited to this. Instead, the same effect can be obtained by replacing each bipolar transistor with a bipolar transistor of the opposite conduction type, and further replacing the power supply voltage supply terminal with a reference voltage supply terminal and the reference voltage supply terminal with a power supply voltage supply terminal. It is clear that it can be done.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a circuit diagram showing the circuit configuration of a third embodiment of the present invention.

This embodiment is an electronic switch circuit for signal selection using the electronic switch circuit of the first embodiment shown in FIG.
Therefore, the above two equations hold true as well.

In Figure 3, five bipolar transistors Q7~
The first electronic switch circuit 7 consisting of Q11 and the first electronic switch circuit 7 consisting of Q11 and
The second electronic switch circuit 8, consisting of two bipolar transistors Q12-Q16, is identical to the first embodiment of the invention.

A first output of a comparator 10 consisting of four bipolar transistors Q17 to Q20 and a constant current source 9 is connected to a first output consisting of bipolar transistors Q17 and Q21.
is applied to the control terminal 11 of the first electronic switch circuit 7 via a current mirror circuit.

Similarly, the second output of the comparator 10 is passed through a second current mirror circuit composed of bipolar transistors Q20 and Q22 to a second electronic switch circuit 8.
is applied to the control terminal 12 of.

Here, in this embodiment with the circuit configuration as described above, if the potential of the constant voltage source 13 is VR and the potential of the control terminal 14 is VC, (1) When VC<VR, the first current mirror circuit and the 1 electronic switch circuit 7
Both are turned on, and the signal input to the first input terminal 15 is output from the output terminal 16.

(2) When VC>VR, second current mirror circuit and second electronic switch circuit 8
Both are turned on, and the signal input to the second input terminal 17 is output from the output terminal 16.

That is, in this embodiment, by changing the potential of the control terminal 14, the signal output to the output terminal 16 can be selected.

In other words, according to this embodiment, it is possible to realize an electronic switch circuit for signal selection that selects and switches one signal from two input signals.

It is clear that the electronic switch circuit for signal selection according to this embodiment also has a wide dynamic range and no signal leakage between input and output.

〔Effect of the invention〕

As explained above, the present invention has the effect of making the dynamic range wider by VBE than in the conventional electronic switch circuit.

Furthermore, since a bipolar transistor for control is connected to the collector of the bipolar transistor on the input side, the bipolar transistor on the input side can be completely turned on and off, preventing leakage of input signals from the input terminal to the output terminal. It has the effect that it can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the invention, FIG. 2 is a circuit diagram showing a second embodiment of the invention, and FIG. 3 is a circuit diagram showing a third embodiment of the invention. The circuit diagram shown in FIG. 4 is a circuit diagram showing a conventional electronic switch circuit. DESCRIPTION OF SYMBOLS 1... Power supply voltage supply terminal, 2... Reference voltage supply terminal, 3... First control terminal, 4... Second control terminal, 5... Input terminal, 6... Output terminal, 7... First electronic switch circuit, 8... Third 2 electronic switch circuit, 9... constant current source, 10... comparator, 1
1, 12, 14...control terminal, 13...constant voltage source, 15...first input terminal, 16...output terminal, 17...second input terminal. Agent: Susumu Uchihara, patent attorney

Claims (6)

[Claims] Claim 1: A first NP whose base is connected to an input terminal.
a second NPN bipolar transistor whose base and collector are connected to the output terminal and whose emitter is connected to the emitter of the first NPN bipolar transistor; and whose collector is connected to the collector of the first NPN bipolar transistor. a first P, whose emitter is connected to the power supply voltage supply terminal and whose base is connected to the first control terminal;
a second PNP bipolar transistor having a collector connected to the collector of the second NPN bipolar transistor, an emitter connected to the power supply voltage supply terminal, and a base connected to the first control terminal; , a collector is connected to the emitters of the first NPN bipolar transistor and the second NPN bipolar transistor, and the emitter is connected to a reference voltage supply terminal,
a third NPN bipolar transistor whose base is connected to the second control terminal. 2. The electronic switch circuit according to claim 1, wherein the collector and base of the first NPN bipolar transistor are short-circuited. 3. In the electronic switch circuit according to claims 1 and 2, the NPN bipolar transistor is replaced with a PNP bipolar transistor, the PNP bipolar transistor is replaced with an NPN bipolar transistor, and the power supply voltage supply terminal is replaced with a reference voltage supply terminal. An electronic switch circuit in which the reference voltage supply terminal is replaced with a power supply voltage supply terminal. 4. A first electronic switch circuit, a second electronic switch circuit, and a differential comparator, wherein a first output signal of the differential comparator is input to a control terminal of the first electronic switch circuit. , a second output signal of the differential comparator is input to a control terminal of the second electronic switch circuit, and an output signal of the first electronic switch circuit and an output signal of the second electronic switch circuit are input to the output terminal. An electronic switch circuit connected so as to output an output to the electronic switch circuit, wherein the first electronic switch circuit and the second electronic switch circuit are the electronic switch circuit according to claim 1. . 5. The electronic switch circuit according to claim 4, wherein the first electronic switch circuit and the second electric switch circuit are the electronic switch circuit according to claim 2. . 6. The electronic switch circuit according to claim 4, wherein the first electronic switch circuit and the second electronic switch circuit are the electronic switch circuit according to claim 3. .