JP2797694B2 - Electronic switch circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic switch circuit, and more particularly to a circuit configuration of an electronic switch circuit that has improved dynamic range and has no 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 a circuit configuration of an electronic switch circuit using a diode bridge.

As shown in FIG. 4, the electronic switch circuit is connected to a diode bridge composed of diodes D ₁ , D ₂ , D ₃ and D ₄ , a common anode of the diode bridge, and a power supply terminal 1. a PNP bipolar transistor Q _1, which is an NPN bipolar transistor Q ₂ Metropolitan connected to the second common cathode and a reference voltage supply terminal of the aforementioned diode bridge.

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

Hereinafter, the operation of the electronic switch circuit will be described.

In FIG. 4, PNP bipolar transistors Q ₁ and N
PN bipolar transistor Q ₂ is turned off, i.e., by controlling the first control terminal 3 and the second control terminal 4 as the collector current does not flow, since no current is supplied to the diode bridge circuit, is input to the input terminal 5 signals Is not output to the output terminal 6.

 That is, the electronic switch circuit is turned off.

Next, PNP bipolar transistor Q ₁ and NPN bipolar transistor Q ₂ is turned on, i.e., by controlling the first control terminal 3 and the second control terminal 4 as the collector current flows, the current is supplied to the diode bridge circuit The signal input to the input terminal 5 is output to the output terminal 6.

 That is, the electronic switch circuit is turned on.

At this time, the potential of the input signal V _iH = V _CC higher than -V _CSAT -V _BE diode D ₁ is no output signal at the output terminal 6 because off.

On the other hand, the output since the potential of the input signal is less than _{V iL = V CSAT + V BE} , the diode D ₃ is turned off the terminal 6
Has no output signal.

Therefore, the input / output dynamic range V _D (= V _iH −V _iL ) of the electronic switch circuit is as follows: V _D = V _CC −2V _CSAT −2V _BE .

Where, V _CC ; power supply voltage V _CSAT ; collector-emitter saturation voltage V _{BE of} PNP bipolar transistor Q ₁ and NPN bipolar transistor Q ₂ ; forward voltage of diodes D ₁ , D ₂ , D ₃ , D ₄ is there.

In FIG. 4, it is general that a diode connection of a bipolar transistor is generally used as a diode constituting a diode bridge.

[Problems to be solved by the invention]

2. Description of the Related Art At present, with the miniaturization, low power consumption, and high performance of electronic devices, the power supply voltage of electronic circuits, such as integrated circuits, used in the electronic devices has been reduced.

On the other hand, in the above electronic circuit, it is important that the signal amplitude is large and the input signal and the output signal are strictly separated in order to prevent malfunction due to noise or signal leakage.

However, in the conventional electronic switch circuit described above,
As represented by the formula, since the dynamic range of the input / output signal decreases as the power supply voltage decreases, it is required to improve the dynamic range for stable operation of the circuit. You.

Also, each diode constituting the diode bridge of the electronic switching circuit, because it does not have a control terminal for controlling a current-voltage characteristic, the complete a reverse current of the diode D ₁ flows into the diode D ₂ However, the input signal leaks into the output signal.

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

[Means for solving the problem]

An electronic switch circuit according to the present invention includes a first NPN bipolar transistor having a base connected to an input terminal, a base and a collector connected to an output terminal, and an emitter connected to an emitter of the first NPN bipolar transistor. A second NPN bipolar transistor, a first PN having a collector connected to the collector of the first NPN bipolar transistor, an emitter connected to the power 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 third NPN bipolar transistor having a collector connected to emitters of the first NPN bipolar transistor and the second NPN bipolar transistor, an emitter connected to a reference voltage supply terminal, and a base connected to a second control terminal; And a transistor.

Further, an electronic switch circuit according to a second aspect of the present invention is the electronic switch circuit according to the first aspect, wherein a collector and a base of the first NPN bipolar transistor are short-circuited.

〔Example〕

 Next, the present invention will be described 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 Q ₃ and Q ₄ having a common emitter, a collector is connected to the collector of each of the bipolar transistors, and a base is connected to the first control terminal. The two PNP bipolar transistors Q ₅ and Q ₆ whose emitters are connected to the power supply voltage supply terminal 1 and the collectors are connected to the emitters of the two NPN bipolar transistors Q ₃ and Q ₄ described above, and the emitters supply the reference voltage Connected to terminal 4 and base is second
NPN bipolar transistor Q ₂ connected to control terminal 4
It is composed of

In this electronic switch circuit, when the PNP bipolar transistors Q ₅ and Q ₆ and the NPN bipolar transistor Q ₂ are turned off, that is, the first control terminal 3 and the second control terminal 4 are controlled so that the collector current does not flow, the NPN transistor since the current in Q ₃ and Q ₄ is not supplied, the input signal inputted to the input terminal, the output terminal 6 is not output.

 That is, the electronic switch circuit is turned off.

Next, when the first control terminal 3 and the second control terminal 4 are controlled so that the PNP bipolar transistors Q ₅ and Q ₆ and the NPN bipolar transistor Q ₂ are turned on, that is, the collector current flows, the NPN bipolar transistor Q 5 _Since current is supplied to ₃ and Q ₄ , the input signal input to the input terminal 5 is output to the output terminal 6.

 That is, the electronic switch circuit is turned on.

At this time, the output dynamic range V _D of the electronic switch circuit, a power supply voltage V _CC, PNP bipolar transistor Q _5, Q ₆ and NPN bipolar transistor Q ₂ collector-emitter saturation voltage V _CSAT, NPN bipolar transistor Assuming that the base-emitter voltage of Q ₃ and Q ₄ is V _BE , V _D = V _CC −2V _CSAT −V _BE ..., And the dynamic range of the conventional electronic switch circuit represented by the equation is obtained. Only V _{BE is} wider.

Moreover, in this electronic switch circuits, so connecting the PNP bipolar transistor Q ₅ for controlling the collector of the NPN bipolar transistor Q _3, it can be completely turned-off NPN bipolar transistor Q _3, an input terminal 5
No input signal leaks from the output terminal 6 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 present invention.

In this second embodiment, in the first embodiment shown in FIG. 1, between the collector and base of the NPN bipolar transistor Q ₃ Whereas was opened, it is short-circuited.

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

The second embodiment includes the effects of the first embodiment, further, since the short-circuiting the collector and base of the NPN bipolar transistor Q _3, NPN bipolar transistor Q ₄
Has the advantage that the offset voltage between the input and output becomes zero.

In the above description, the conduction type of each bipolar transistor constituting the electronic switch circuit is a conduction type bipolar transistor as shown in FIGS. 1 and 2, but the present invention is not limited to this. Instead, the same effect can be obtained by replacing each bipolar transistor with a reverse conducting bipolar transistor, further replacing the power supply voltage supply terminal with a reference voltage supply terminal, and replacing the reference voltage supply terminal with a power supply voltage supply terminal. Obviously you can.

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

FIG. 3 is a circuit diagram showing a 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. 1, and therefore, the above-mentioned equation is similarly established.

In FIG. 3, five bipolar transistors Q ₇ ~
A first electronic switching circuit 7 consisting of Q _11, also of five bipolar transistors consisting of Q ₁₂ to Q ₁₆ second electronic switch circuit 8 is the same as the first embodiment of the present invention.

The first output of the comparator 10 consisting of four bipolar transistors Q ₁₇ to Q ₂₀ and the constant current source 9 via a first current mirror circuit composed of bipolar transistors Q ₁₇ and Q _21, a first It is applied to the control terminal 11 of the electronic switch circuit 7.

Similarly, the second output of the comparator 10 via the second current mirror circuit composed of bipolar transistors Q ₂₀ and Q _22, applied to the control terminal 12 of the second electronic switch circuits 8.

Here, in this embodiment having the above-described circuit configuration,
When the potential of the constant voltage source 13 is V _R and the potential of the control terminal 14 is V _C , (1) When V _C <V _{R Both} the first current mirror circuit and the first electronic switch circuit 7 are on. And the signal input to the first input terminal 15 is output from the output terminal 16.

(2) When V _C > V _{R Both} the second current mirror circuit and the second electronic switch circuit 8 are turned on, and the signal input to the second input terminal 17 is output from the output terminal 16. .

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

In other words, according to the present embodiment, it is possible to realize a signal-selecting electronic switch circuit that selects and switches one signal from two input signals.

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

〔The invention's effect〕

As described above, the present invention has an effect that the dynamic range can be made wider by V _BE 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 / off, and there is an effect that leakage of an input signal from an input terminal to an output terminal can be eliminated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a second embodiment of the present invention, and FIG. 3 is a circuit diagram showing a third embodiment of the present invention. FIG. 4 is a circuit diagram showing a conventional electronic switch circuit. 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 ... second electronic switch circuit, 9 ... constant current source, 10 ...
... comparators, 11, 12, 14 ... control terminals, 13 ... constant voltage sources, 15 ... first input terminals, 16 ... output terminals, 17 ... second input terminals.

Claims (6)

(57) [Claims] 1. A first NPN having a base connected to an input terminal.
A bipolar transistor, a second NPN bipolar transistor having a base and a collector connected to an output terminal, and an emitter connected to the emitter of the first NPN bipolar transistor; and a collector connected to a collector of the first NPN bipolar transistor. And the emitter is connected to a power supply terminal, the base is connected to a first control terminal, and the first
PNP controlled to one of a cutoff state and a conduction state according to a first binary control signal applied to a control terminal of the first PNP
A bipolar transistor, a collector connected to the collector of the second NPN bipolar transistor, an emitter connected to the power supply terminal, and a base connected to the first control terminal;
A second PNP bipolar transistor that is controlled in either a cut-off state or a conduction state together with the first PNP bipolar transistor in response to the first control signal; and a collector having the first NPN bipolar transistor and the second PNP bipolar transistor. A second NPN bipolar transistor is connected to an emitter, the emitter is connected to a reference voltage supply terminal, the base is connected to a second control terminal, and the second NPN bipolar transistor is responsive to a second control signal applied to the second control terminal. An electronic switch circuit comprising, together with the first PNP bipolar transistor and the second bipolar transistor, a third NPN bipolar transistor which is controlled to be in a cutoff state or a conduction state. 2. The electronic switch circuit according to claim 1, wherein a collector and a base of the first NPN bipolar transistor are short-circuited. 3. The electronic switch circuit according to claim 1, wherein the NPN bipolar transistor is replaced with a PNP bipolar transistor, the PNP bipolar transistor is replaced with an NPN bipolar transistor, and a power supply voltage supply terminal is 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 comprising the electronic switch circuit according to claim 1, wherein the first and second switches are connected to a first control terminal of the first electronic switch circuit. A first electronic switch circuit controlled by turning on or off a second PNP bipolar transistor and a third NPN bipolar transistor connected to a second control terminal; and a second electronic switch circuit comprising the electronic switch circuit according to claim 1. An electronic switch circuit, wherein first and second PNPs whose opening and closing are connected to a first control terminal of the second electronic switch circuit.
A second electronic switch circuit which is controlled by conduction or cutoff of a bipolar transistor and a third NPN bipolar transistor connected to a second control terminal; a constant voltage applied to one input point and a second electronic switch circuit applied to the other input point. A differential comparator for comparing the binary control signal with the binary control signal and outputting complementary first and second output signals, wherein the first output signal is the first and second output signals of the first electronic switch circuit. A second control terminal controls conduction and cutoff of the first and second PNP bipolar transistors and the third NPN bipolar transistor of the first electronic switch circuit, and the second output signal outputs Via the first and second control terminals of the second electronic switch circuit, the first and second PNP bipolar transistors and the third NPN bipolar transistor of the second electronic switch circuit A differential comparator for controlling conduction and interruption of the transistor, wherein a signal output point of the first electronic switch circuit and a signal output point of the second electronic switch circuit are commonly connected to one output terminal; An electronic switch, wherein the first electronic switch circuit and the second electronic switch circuit open and close complementarily in response to a binary control signal applied to the other input point of the differential comparator. circuit. 5. The electronic switch circuit according to claim 4, wherein said first electronic switch circuit and said second electronic switch circuit are the electronic switch circuits according to claim 2. . 6. The electronic switch circuit according to claim 4, wherein said first electronic switch circuit and said second electronic switch circuit are the electronic switch circuits according to claim 3. .