JP2001313552A - Electronic switch and ultrasonic wave image pickup device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a reverse block recovery time that requires an AC electronic switch with a small forward current. SOLUTION: The electronic switch is provided with an ON control circuit (Vc, FET1, R3) where the emitter and base of a bipolar transistor(TR) Q1 are electrically connected, the collector and base of the bipolar TR are inserted to an AC signal transmission circuit and a forward bias Vc is applied between the collector and the base of the TR in response to a command Vcnt for passing the AC signal and an OFF control circuit (Vp, FET1) that applies a reverse bias (Vp-Vc) between the collector and the base of the TR in response to a command Vcnt for interrupting the AC signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic switch for controlling on / off of a high-frequency AC signal, and more particularly to an ultrasonic imaging device, a fish finder, a sonar, an electronic exchange, an antenna device, a transceiver, an electronic device, or an ultrasonic applied measurement. The present invention relates to an electronic switch suitable for a signal transmission circuit such as a device.

[0002]

2. Description of the Related Art An ultrasonic imaging apparatus (also referred to as an ultrasonic diagnostic apparatus) transmits an ultrasonic signal from a probe to a subject, and responds to this by transmitting an ultrasonic signal from the subject to the probe. It receives a sound wave signal and performs ultrasonic imaging of the subject based on the received signal. Then, since it is necessary to control the timing and the period of transmitting the ultrasonic signal to the probe, an electronic switch for controlling on / off of the transmission signal is provided in the ultrasonic signal transmission circuit. Similarly, since it is necessary to control the timing and period for receiving the ultrasonic signal from the probe, an electronic switch for controlling the ON / OFF of the received signal is provided in the ultrasonic signal transmission circuit. In the case of an ultrasonic imaging apparatus,
Since the transmission signal and the reception signal pass through the same signal transmission circuit, the electronic switch is shared. Here, the voltage of the signal transmitted to the probe is, for example, 1 to 300 V, and the voltage of the signal received from the probe is approximately several μV to 300 mV. Therefore, the electronic switch is required to have an ability to pass and block an AC signal of several μV to 300 V and several tens of kHz or more with crosstalk of 50 to 60 dB or less.

Conventionally, at a high frequency of 1 to 10 MHz, about 100 V
As an electronic switch for turning on / off (pass-cut) a voltage signal of pp (full amplitude), a switching element having a high withstand voltage that can pass a signal of both polarities is known. However, this has a problem that the circuit configuration is complicated and expensive.
On the other hand, as a method for realizing switching of an AC signal with a simple configuration, a method using a diode having a long reverse blocking recovery time (Japanese Patent No. 1252076) is known. This method requires a fixed reverse blocking recovery time until the diode recovers the cut-off state even if a reverse polarity voltage is applied to the conducting diode. This is in view of the fact that an AC signal having a frequency having a wave cycle can be passed. That is, the diode is instantaneously used as a bipolar switching element. As such a diode, for example, a diode of type HSK122 is known.

[0004]

In the conventional technology using a diode as an AC switch, for example, in order to pass a signal having a frequency of 50 kHz, a reverse blocking recovery time of 10 μs is required. The reverse blocking recovery time generally varies depending on the magnitude of the forward current. For example, model HSK122
In the case of the diode described above, 30 mA of forward direct current is required to obtain a reverse blocking recovery time of 10 μs according to experiments. Therefore, in order to pass an AC signal having a frequency of 50 kHz or less, for example, a longer reverse blocking recovery time is required, so that a forward current of 30 mA or more is required.

[0005] For this reason, there is a problem that, when an attempt is made to realize a multi-channel switch, power consumption is increased, which is against the demand for energy saving. For example, in an ultrasonic diagnostic apparatus, the number of probes connected to one device and the number of ultrasonic transducers mounted on one probe are increasing, and these numbers are Increasing the forward current of the diode is problematic as the number of AC electronic switches is required accordingly.

An object of the present invention is to secure a required reverse blocking recovery time with a small forward current in an electronic switch that allows an AC signal to pass through using the reverse blocking recovery time.

[0007]

The above objects can be attained by the following means.

The electronic switch of the present invention electrically connects the emitter and the base of the bipolar transistor, inserts the collector and the base of the bipolar transistor into an AC signal transmission circuit, and issues a command to cut off the AC signal. An off control circuit for applying a reverse bias between the collector and the base of the transistor in response is provided.

That is, the present invention is characterized in that the collector-base PN junction of a bipolar transistor is used as a switch circuit for an AC signal. The reason for electrically connecting the emitter and the base is based on the knowledge that the withstand voltage protection of the emitter is taken into consideration and that the reverse blocking recovery time is lengthened.

Here, when electrically connecting between the emitter and the base, it is most preferable to connect with a capacitor. In particular, as the capacitance of the capacitor is increased, the reverse blocking recovery time can be increased for the same forward current. However, the present invention is not limited to the capacitor, and a short-circuit line, a diode, a resistor, or a combination thereof can be used instead of the capacitor. In any case, the reverse blocking recovery time can be made longer than that of the conventional diode.

In the electronic switch of the present invention, when the voltage of the AC signal is equal to or higher than the level for turning on the collector and the base and when it is not necessary to control the passage timing of the AC signal, the collector and the collector of the bipolar transistor may be used. There is no need for an ON control circuit for applying a forward bias between the bases. However, if it is necessary to control the passage timing of the AC signal, or if the voltage of the AC signal is lower than the level for turning on the collector and the base, the collector and base of the bipolar transistor are responded to the command to pass the AC signal. It is necessary to provide an ON control circuit for applying a forward bias therebetween.

The bipolar transistor according to the electronic switch of the present invention can be applied to either an NPN type or a PNP type. However, when the ON control circuit is not provided, a bipolar transistor in which the polarity of the first half wave of the transmitted AC signal is in the forward direction is selected.

Further, one electronic switch can be configured by inserting a plurality of bipolar transistors in a transmission circuit in parallel or in series. In this case, the plurality of bipolar transistors may have the same forward direction between the collector and the base or may have the same reverse direction. When the forward direction is matched and parallel, the on-resistance of the electronic switch can be reduced. When the forward direction and the reverse direction are mixed in parallel, the on-resistance of the electronic switch can be reduced, and even if the on-control circuit is not provided and the first half wave is negative, bidirectional electronic Switch can be realized. on the other hand,
When a plurality of bipolar transistors are connected in series, leakage current at the time of off can be reduced, and so-called off isolation is improved. When a plurality of bipolar transistors are arranged in parallel, NPN and PNP may be mixed. According to this, spike noise due to switching is reduced to NPN.
And a PNP switching circuit.

An ultrasonic imaging apparatus according to the present invention includes an electronic switch for controlling transmission and reception of an ultrasonic signal on and off in a signal transmission circuit connected to an ultrasonic probe, and controls the electronic switch to control the ultrasonic. An ultrasonic imaging apparatus that transmits an ultrasonic signal to an ultrasonic probe, receives an ultrasonic signal output from the ultrasonic probe, and performs ultrasonic imaging of a subject based on the received signal. The electronic switch includes a bipolar transistor having a collector and a base connected to a pair of terminals, a capacitor connected between an emitter and a base of the transistor, and a collector of the transistor in response to a command to cut off the ultrasonic signal.・
An off-control circuit for applying a reverse bias between the bases, and an on-control circuit for applying a forward bias between the collector and the base of the bipolar transistor in response to a command to pass the ultrasonic signal are formed. It is a feature. Thus, the power consumption of the electronic switch can be reduced, so that the number of ultrasonic probes and ultrasonic transducers can be easily increased.

Further, the application of the electronic switch according to the present invention is not limited to a signal transmission circuit of an ultrasonic imaging apparatus, and it is needless to say that the electronic switch can be applied to various apparatuses that require switching of an AC signal. Examples of such a device include a fish finder, a sonar, an electronic exchange, a transceiver, an antenna device, an electronic device, and an ultrasonic applied measuring device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments.

(First Embodiment) FIG. 1 shows an electronic switch according to an embodiment of the present invention. As shown in the figure, the electronic switch includes a capacitor C1 connected in series between a pair of terminals IN and OUT, and an NPN-type bipolar transistor Q1.
(Hereinafter simply referred to as Q1), field-effect transistor FE
It is configured to include T1 (hereinafter, simply referred to as FET1) and a capacitor C2, and is used by inserting and connecting a pair of terminals IN and OUT into an AC signal transmission circuit. A capacitor C3 is connected between the emitter and the base of Q1, and the collector and the base of Q1 are inserted into an AC signal transmission circuit. The base of Q1 is connected to a power supply Vc via a resistor R1, and the collector is connected to one main circuit electrode of FET1 and a power supply Vp via a resistor R2. The connection point between the other main circuit electrode of the FET1 and the capacitor C2 is grounded via a resistor R3. An on / off command Vcnt of the electronic switch is input to the control electrode of the FET1 via the resistor R4. The relationship between the power supply voltages is V
c≪Vp (for example, Vc = 5V, Vp = 100V).

The operation of the electronic switch thus configured will be described with reference to a timing chart shown in FIG. The passing or blocking of the AC signal (FIG. 2 (b)) input from the terminal IN is switched by Q1 and transmitted to the terminal OUT. The switching control of Q1 is performed by FET1. That is, the FET 1 is turned on and off in accordance with an on / off command Vcnt (FIG. 2A) given from a control device (not shown). When FET1 is turned on, Q1
, The main electrode circuit of FET1, the resistor R3, and the ground circuit, the forward current If flows through Q1, and Q1 turns on. As a result, the AC signal (Fig.
2 (b)). Here, since the reverse blocking recovery time of Q1 is set to be longer than the time width of the negative half wave of the input AC signal, the input AC signal passes through Q1 and
The output AC signal shown in FIG. 2 (c) is transmitted from the terminal OUT through the terminal C and the capacitor C2. On the other hand, when the FET 1 is turned off, a reverse bias (Vp-Vc) is applied between the base and the collector of the transistor Q1 due to the relationship of Vp≫Vc, and the transistor Q1 is turned off to block the passage of the AC signal.

Here, with respect to the reverse blocking recovery time of Q1,
This will be described using the measurement example shown in FIG. FIG. 3 (a)
It shows an example of a measurement circuit, in which components having the same functional configuration as in FIG. However, the electrical constants of the circuit elements are changed as appropriate. As shown in the figure, in a state where a forward current is applied to Q1 and turned on, an input waveform that changes from 0V to -10V in a step-like manner is input from the terminal IN, and the output waveform output from the terminal OUT is output by an oscilloscope. Observed. As shown, a reverse current flows for some time until the reverse blocking recovery of Q1 is established. The time required for the reverse current to decrease to 0.1 × Ir with respect to the maximum value Ir was measured as a reverse blocking recovery time Trr. As a result, in the case of the high-withstand-voltage bipolar transistor of model 2SC4702, Trr was 1.2 μs when a forward current of 10 mA was passed, as shown by line 1 in FIG. 3B. In addition,
The capacitor C3 used was 33000 pF. On the other hand, in the case of the diode of the conventional type HSK122, the characteristic shown by the line 2 in FIG.
r was 0.4 μs. Also, according to the catalog value of the diode, to make Trr 10 μs, it is necessary to supply a forward current of 30 mA. On the other hand, according to the bipolar transistor of the example of FIG. That is, the reverse blocking recovery time of the bipolar transistor is about three times as long as that of the diode. Therefore,
When a bipolar transistor is used as a switch,
It is possible to pass an AC signal having a lower frequency than a diode with a constant forward current. Conversely, when a bipolar transistor is used, a fixed reverse blocking recovery time can be realized with a forward current smaller than that of a diode.

In the embodiment shown in FIG. 1, the power supply Vc and the FET 1
An ON control circuit of Q1 is formed by a circuit including the resistor R3, and an OFF control circuit of Q1 is formed by a circuit including the power supply Vp and the FET1. Therefore, the present invention can be applied to a case where the voltage level of the input AC signal is lower than the ON voltage of Q1 (for example, 0.6 V). For example, the reception signal from the ultrasonic probe is often lower than the ON voltage of Q1,
In this case, it can also be applied as an electronic switch.

When the voltage level of the input AC signal is Q
When the ON voltage is higher than 1, the ON control circuit can be omitted. In this case, the AC signal is passed at the input timing. The Q1 off control circuit is shown in FIG.
However, the invention is not limited to this example, and any circuit may be used as long as it applies a reverse bias between the collector and base of Q1. For example, when Q1 is turned off, the voltage of the power supply Vp may be switched from low to high.

Further, instead of the capacitor C3 connected between the emitter and the base of Q1, a short-circuit line, a resistor, a diode, a combination thereof, or a combination thereof with a capacitor may be used. The point is that the reverse blocking recovery time of Q1 can be extended to a desired time,
What is necessary is just to select the circuit element which can reduce the ON resistance of 1.
Here, FIG. 4 shows a measurement example of the on-resistance of Q1 when a capacitor, a short-circuit line, a resistor, and a diode are individually connected between the emitter and base of Q1. FIG. 4A shows a measurement circuit, and FIG. 4B shows a measurement result. The AC signal used for the measurement is a burst wave (three waves) of 3.5 kHz and 10 Vpp. The forward current If of Q1 was 2 mA. Other circuit constants and the like are as shown in FIG. As is clear from these results, it is understood that the circuit element connected between the emitter and the base of Q1 is preferably a capacitor in that the on-resistance can be reduced, and it is preferable to increase the capacitance of the capacitor.

In FIG. 1, capacitors C1, C
Numeral 2 is inserted to prevent the DC component of Vc or Vp from flowing out to an external circuit, and can be omitted if there is no such fear. Further, the electronic switch of the present invention includes:
FIG. 1 is not limited to the embodiment, but the point is that a bipolar transistor is used as a switch element, and the following modes can be appropriately adopted corresponding to various conditions.

(Other Embodiments) FIGS. 5 to 18 show other embodiments of the electronic switch of the present invention. In the embodiment shown in FIG. 5, the NPN type of Q1 in FIG. 1 is replaced with a PNP type. Accordingly, the base voltage of Q1 is applied from the negative power supply -Vc, and the collector voltage is applied from the negative power supply Vn.

In the embodiment shown in FIG. 6, one main switch of the electronic switch shown in FIG. 1 is connected in anti-parallel to form one electronic switch. In particular, this is an example in which an ON control circuit for forcibly passing a forward current to the bipolar transistors Q1 and Q2 is not provided. Therefore, according to the present example, the electronic switch is turned on by the first half-wave of the input AC signal. Since Q1 and Q2 are connected in anti-parallel, they are turned on regardless of whether the first half-wave is positive or negative. According to this, the on-resistance of the electronic switch can be reduced. As a result, for example, in the THI method or the pulse inversion method known in the ultrasonic diagnostic apparatus, in order to enhance the clinical effect, there is a demand to reduce the waveform distortion generated in the apparatus. According to the present embodiment, distortion of a transmission waveform can be minimized as one switch.

The embodiment shown in FIG. 7 is an example in which two NPN-type bipolar transistors Q1 and Q2 are connected in series to a signal so as to face a transmission direction to form one electronic switch. Further, an off-control FET 1 is inserted into the circuit of the power supply Vp. According to this, when the FET 1 is turned on, a reverse voltage Vp is applied between the collectors and the bases of the two transistors Q1 and Q2, and the input / output terminals IN and OUT are cut off (off). The ON state is based on the voltage of the input AC signal. According to this embodiment, since the two transistors Q1 and Q2 are connected in series, it is excellent in off-isolation.

The embodiment shown in FIG. 8 is a modification of FIG. 6, in which Q1 and Q2 are of PNP type. In the embodiment shown in FIG. 9, one electronic switch is formed by connecting a PNP type and a PNP type in parallel. In the example of FIG. 8, since the same components are connected in parallel, an inexpensive electronic switch with excellent performance can be obtained. On the other hand, in the example of FIG. 9, since different types of bipolar transistors are used, both Vp and Vn power supplies are required, and the control becomes complicated.However, since the switching spike noise can be canceled by positive and negative, the advantage is that it can be reduced. You.

The embodiment shown in FIG. 10 is an example in which Q2 is simply connected in parallel to Q1 in FIG. According to this,
ON resistance can be reduced. The embodiment of FIG. 11 is an example in which Q1 and Q2 of FIG. 10 are replaced with PNP type.

In the embodiment shown in FIG. 12, NPN type Q1 and Q2 are connected in series in the same direction, and two power supplies Vp and V'p (for example, Vp = 100V, V ') are used as power supplies for turning off. p = 200
V) is required. The embodiment of FIG. 13 corresponds to Q1 of FIG.
This is an example in which Q2 is replaced with a PNP type, and the power source is set to Vn and V'n accordingly.

In the embodiment shown in FIG. 14, the positions of the base and the collector of Q1 and Q2 in the embodiment of FIG. 7 are interchanged. Further, the embodiment shown in FIG. 15 is an example in which Q1 and Q2 of the embodiment of FIG. 7 are replaced with PNP type. The embodiment of FIG. 16 is an example in which Q1 and Q2 of the embodiment of FIG. 14 are replaced with a PNP type. The embodiment shown in FIG. 17 is an example in which Q1 of the embodiment of FIG. 16 is an NPN type. The embodiment shown in FIG. 18 is an example in which the relationship of the series connection of Q1 and Q2 of the embodiment of FIG. 17 is changed. Although various embodiments have been described above, it goes without saying that Darlington-connected transistors may be used as the bipolar transistors.

(Embodiment of Ultrasonic Imaging Apparatus) FIG.
1 shows a conceptual diagram of the overall configuration of an ultrasonic imaging apparatus to which the electronic switch of the present invention is applied. As shown, a probe 10 using ultrasonic waves is connected to a transmission / reception separation circuit 12 via a changeover switch 11. The transmission / reception separation circuit 12 has a function of transmitting an ultrasonic transmission wave output from the transmission pulse generator 13 to the probe 10 via the changeover switch 11 based on a command given from the control unit 14. ing. On the other hand, the ultrasonic wave received by the probe passes through the same transmission circuit as the transmission wave and is input to the transmission / reception separation circuit 12 via the changeover switch 11. Transmission / reception separation circuit 1
The reception wave input to 2 is input to reception amplifier 15 and amplified. The amplified received wave is input to a phasing circuit 18 including a delay circuit 16 and an adder 17 for processing.
The phasing-processed received wave is detected by the detector 19,
The data is input to the display device 20. The probe 10 is composed of a plurality (n) of vibrators 10 ₁ to 10 n.
The reception waves output from the plurality of transducers 10 ₁ to 10 n are switched by a changeover switch 11 and input to a predetermined transmission / reception separation circuit 12. This switching control is performed based on a command given from the control unit 14. The transmission / reception separation circuit 12 includes the transmission pulse generator 1
This is to separate the transmission wave output from the probe 3 to the probe 10 or the reception wave output from the probe 10 to the reception amplifier 15. The ultrasonic imaging apparatus configured as described above forms and displays an image by the image processing means provided in the display device 20 based on the reception wave including the acoustic information of the subject output from the probe 10. It is designed to be displayed on the screen.

The electronic switch according to the present invention is applied to the changeover switch 11 described above. That is, recently, not only the number n of ultrasonic transducers mounted on one probe 10 increases, but also the number of probes 10 tends to increase rapidly. To cope with this, the number of electronic switches constituting the changeover switch 11 becomes enormous. Therefore, there is a strong demand for an electronic switch having a simple circuit configuration and low power consumption. The electronic switch of the present invention is most suitable for this application.

The application of the electronic switch of the present invention is not limited to a changeover switch of an ultrasonic imaging apparatus, and it is needless to say that the electronic switch can be applied to various apparatuses which require switching of an AC signal. Examples of such a device include a fish finder, a sonar, an electronic exchange, a transceiver, an antenna device, an electronic device, and an ultrasonic applied measuring device.

[0034]

As described above, according to the electronic switch of the present invention, the required reverse blocking recovery time can be secured with a small forward current with a simple structure.
In other words, the lower limit of the applicable frequency can be extended.

According to the ultrasonic imaging apparatus of the present invention,
Even if the number of probes increases, an increase in power consumption can be suppressed.

[Brief description of the drawings]

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

FIG. 2 is a timing chart illustrating the operation of the electronic switch of FIG.

3A and 3B are diagrams for explaining the effect of the present invention. FIG. 3A shows a circuit for measuring a reverse blocking recovery time, and FIG. 3B shows a relationship between a forward current and a reverse blocking recovery time. FIG.

FIG. 4 is a diagram showing experimental values of on-resistance of a bipolar transistor depending on a difference in a circuit element connected between an emitter and a base.

FIG. 5 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 6 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 8 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 9 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 10 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 11 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 12 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 13 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 14 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 15 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 16 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 17 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 18 is a circuit configuration diagram of an electronic switch according to another embodiment of the present invention.

FIG. 19 is a conceptual configuration diagram of an embodiment of an ultrasonic imaging apparatus to which the electronic switch of the present invention is applied.

[Explanation of symbols]

 Q1, Q2 Bipolar transistor FET1 Field effect transistor C1, C2, C3 Capacitor R1, R2, R3, R4 Resistance Vc, Vp, Vn Power supply Vcnt On / off control command If Forward current

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C301 HH01 JA20 5J055 AX04 AX56 AX66 BX17 CX24 DX03 DX12 DX55 DX65 EX06 EX07 EY01 EY10 EY17 EY21 FX12 FX17 FX35 GX00 GX01 5J083 AA02 AB01 AB17 AC18 AC40 CA01 CC10

Claims (9)

[Claims] An electrical connection is made between an emitter and a base of a bipolar transistor, and a collector and a base of the bipolar transistor are inserted into an AC signal transmission circuit.
An electronic switch comprising an off control circuit for applying a reverse bias between a collector and a base of the transistor in response to a command to cut off the AC signal. 2. The electronic device according to claim 1, further comprising an on-control circuit for applying a forward bias between a collector and a base of the bipolar transistor in response to a command to pass the AC signal. switch. 3. The transmission circuit according to claim 1, wherein a plurality of the bipolar transistors are inserted in parallel, and the plurality of bipolar transistors are arranged in parallel with a forward direction between a collector and a base. Or 2
An electronic switch according to claim 1. 4. The transmission circuit, wherein a plurality of the bipolar transistors are inserted in parallel, and the plurality of bipolar transistors are arranged in parallel with a mixture of a forward direction and a reverse direction between a collector and a base. Item 3. The electronic switch according to item 1 or 2. 5. The transmission circuit according to claim 1, wherein a plurality of the bipolar transistors are inserted in series, and the plurality of bipolar transistors are connected in series with a forward direction between a collector and a base. Or 2
An electronic switch according to claim 1. 6. The transmission circuit, wherein a plurality of the bipolar transistors are inserted in series, and the plurality of bipolar transistors are connected in series by mixing a forward direction and a reverse direction between a collector and a base. Item 3. The electronic switch according to item 1 or 2. 7. The electronic switch according to claim 1, wherein a capacitor is connected between an emitter and a base of said bipolar transistor. 8. A signal transmission circuit connected to an ultrasonic probe is provided with an electronic switch for controlling transmission and reception of an ultrasonic signal on and off, and controls the electronic switch to transmit an ultrasonic signal to the ultrasonic probe. And an ultrasonic imaging apparatus that receives an ultrasonic signal output from the ultrasonic probe and performs ultrasonic imaging of a subject based on the received signal. A bipolar transistor having a collector and a base connected thereto, a capacitor connected between the emitter and the base of the transistor, and applying a reverse bias between the collector and the base of the transistor in response to a command to cut off the ultrasonic signal. And a forward via between the collector and the base of the bipolar transistor in response to a command to pass the ultrasonic signal. And an on-control circuit for applying a pulse. 9. A fish finder, a sonar, an electronic exchange, a transceiver, an antenna device, an electronic device or an ultrasonic applied measuring device comprising the electronic switch according to claim 1 in a transmission circuit for an alternating current signal. .