JP2008188321A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus using a pulse wave generation circuit or a continuous wave generation circuit capable of reducing higher harmonics in the entire region of a frequency band to be used and the ultrasonic diagnostic apparatus capable of being miniaturized by enabling the pulse wave generation circuit to serve also as the continuous wave generation circuit, both circuit capable of reducing the higher harmonics to be used in common. <P>SOLUTION: The pulse wave generation circuit or the continuous wave generation circuit includes: a first amplifier 2a by an operational amplifier 2a1; a second amplifier 2b operated by the DC power source ±HV of a positive polarity and a negative polarity to the center level of an output voltage for amplifying the output of the first amplifier 2a; and an AC negative feedback means 2c by a resistor 2c2 for negative feedback for performing the AC negative feedback of the output voltage of the second amplifier 2b to the first amplifier 2a and a capacitor 2c3 for the negative feedback. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus mainly used for medical purposes, and in particular, reduces harmonic components of pulse waves and / or continuous waves that drive ultrasonic transducers, and generates the pulse waves and continuous waves. TECHNICAL FIELD OF THE INVENTION

  A medical ultrasonic diagnostic apparatus irradiates a subject with ultrasonic waves from an ultrasonic probe and reconstructs a tomographic image of the subject based on an echo signal received through the ultrasonic probe The reconstructed tomographic image is displayed on a display device for diagnosis.

  The ultrasonic probe is configured to include a large number of ultrasonic transducers arranged in parallel, and each of these ultrasonic transducers inputs a drive signal from a transmission circuit arranged in an ultrasonic diagnostic apparatus. A pulse wave (PW) and a continuous wave (CW) are used as the voltage applied from the transmission circuit to the piezoelectric element of the ultrasonic probe depending on the purpose of diagnosis. .

The pulse wave is used in the B mode, the M mode, and the pulse Doppler mode, the number of transmitted pulses per one is about several waves, and the amplitude of the transmitted pulse is a high voltage pulse of about 120 Vpp.
On the other hand, the continuous wave is used in a continuous wave Doppler mode, and the amplitude of the continuous wave is a relatively low voltage of about 10 to 20 Vpp.

  In this way, a pulse wave (PW) and a continuous wave (CW) are necessary.However, if a circuit for generating these voltages is provided separately, the circuit configuration becomes large-scale and the installation space increases. The good portability due to the small size and light weight, which is one of the features of the ultrasonic diagnostic apparatus, is impaired.

  Therefore, in order to solve this problem, Patent Document 1 discloses a common use of the pulse wave generation circuit and the continuous wave generation circuit.

  On the other hand, when a harmonic component is included in the pulse wave and continuous wave, a new ultrasonic wave utilizing the problem of thermal action on the living body due to the harmonic component and the nonlinearity of ultrasonic propagation in the microbubble or the subject. The problem of image quality deterioration in the imaging method occurs.

  That is, the generation of the heat of the living body by the irradiation of the ultrasonic wave includes a lot of harmonic components other than the pulse wave and the fundamental wave of the continuous wave, and a waveform in which unnecessary harmonic components are suppressed during transmission. It is necessary to transmit the voltage.

  In recent years, attention has been drawn to an ultrasonic imaging method called harmonic imaging that utilizes the nonlinearity of microbubbles or the nonlinear effect of ultrasonic propagation within a subject. In this ultrasonic imaging method, if a harmonic component is included in the transmitted ultrasonic wave from the beginning, it becomes difficult to distinguish the echo signal from microbubbles or echoes due to the nonlinear effect of the subject, and a good image is obtained. I can't get it.

  As described above, since the above-described problem occurs when the transmitted pulse wave and continuous wave contain harmonic components, a technique for reducing the harmonic components is disclosed in Patent Document 2.

JP 2002-306476 A Japanese Patent Laid-Open No. 11-347030

  However, although the above Patent Document 1 can generate a pulse wave and a continuous wave having different voltage levels by a common oscillation circuit, since a rectangular wave pulse is used as a driving pulse for an ultrasonic probe, The pulse waveform includes many harmonic components. Therefore, there remains a problem of the thermal action on the living body due to this harmonic component and a problem of image quality deterioration in the new ultrasonic imaging method using the nonlinearity of the ultrasonic propagation in the microbubble or the subject.

  On the other hand, Patent Document 2 proposes a circuit in which LC filters including inductors and capacitors are combined in multiple stages as means for reducing harmonics of a transmission pulse. However, the frequencies of the pulse wave and the continuous wave to be transmitted differ depending on the purpose of diagnosis and the site to be diagnosed, and the frequency of the driving pulse of the ultrasonic probe covers a wide range from 2 MHz to 15 MHz.

  Therefore, the inductor and capacitor values of the LC filter must also correspond to the frequency, so a plurality of LC filters must be prepared according to the frequency to be used, and these must be switched according to the frequency. .

  For this reason, the number of circuit components becomes so large that the circuit becomes complicated, and it is difficult to make the LC filter match all the frequencies used. The wave reduction effect cannot be obtained.

  From the above, even when Patent Document 1 and Patent Document 2 are combined, not only the apparatus is increased in size but also the harmonics cannot be sufficiently reduced.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus that can be miniaturized by using a pulse wave generation circuit or a continuous wave generation circuit that can reduce harmonics in the entire frequency band to be used.

  In order to achieve the above object, an ultrasonic diagnostic apparatus of the present invention includes a pulse wave generation circuit or a continuous wave generation circuit that generates a pulse wave or a continuous wave for driving a transducer of an ultrasonic probe. In the ultrasonic diagnostic apparatus, the pulse wave generation circuit or the continuous wave generation circuit is positive with respect to a first amplifier by an operational amplifier and a center level of an output voltage for amplifying the output of the first amplifier. A second amplifier that operates with a DC power source having a negative polarity and a negative polarity, and an AC negative feedback means that AC negatively feeds back the output voltage of the second amplifier to the first amplifier. .

  The second amplifier includes a complementary source grounded amplifier composed of two sets of P-channel and N-channel MOSFETs, and between each source of the two sets of MOSFETs and the positive polarity and negative polarity DC power supplies. The amplifier is configured by connecting a parallel connection body of a first resistor and a capacitor.

  Further, a second resistor is connected in series to the second amplifier between the DC power source and the parallel connection body, and the first resistor and the voltage across the second resistor are equal to or higher than a predetermined threshold. A configuration in which switch means for short-circuiting the second resistor may be added.

  Furthermore, between the output end of the second amplifier and the circuit configuration provided with means for varying the gain of the pulse wave generation circuit or the continuous wave generation circuit and the ground, the DC signal has a low impedance, the AC signal On the other hand, it includes a circuit configuration in which a high impedance is connected.

  The ultrasonic diagnostic apparatus of the present invention is an ultrasonic diagnostic apparatus including a pulse wave generation circuit that generates a pulse wave and a continuous wave for driving a transducer of an ultrasonic probe, and a continuous wave generation circuit. The pulse wave generation circuit and the continuous wave generation circuit include a first amplifier based on an operational amplifier, a second amplifier that amplifies the output of the first amplifier, and an output voltage of the second amplifier. AC negative feedback means for AC negative feedback to the first amplifier, a first DC power source having a positive polarity and a negative polarity with respect to the center level of the output voltage of the second amplifier, and the first DC power source A second DC power source having a positive polarity and a negative polarity lower than the first voltage, a power source switching means for switching between the first DC power source and the second DC power source, and a pulse of the power source of the second amplifier When the wave is generated, the first DC power source is used.When the continuous wave is generated, the second DC power source is used. Characterized by comprising a power switching control means for switching the flow power.

  The second amplifier includes a complementary source grounded amplifier composed of two sets of P-channel and N-channel MOSFETs, and a first resistor is provided between each source of the two sets of MOSFETs and the power source switching unit. It is an amplifier of the structure which connected the parallel connection body of a capacitor | condenser.

Furthermore, the following (1) or (2) may be added to the second amplifier.
(1) A second resistor is connected in series between the power supply switching unit and the parallel connection body, and the voltage across the second resistor is equal to or higher than a predetermined threshold value, and the first resistor and the second resistor are connected. A switch means for short-circuiting is provided.
(2) A third resistor and diode series connection is connected between the sources of the two sets of MOSFETs and the parallel connection to the second DC power supply so as to be in the forward direction of the diode.

  Furthermore, between the output end of the second amplifier and the ground, a circuit configuration provided with means for varying the gain of the pulse generation circuit and the continuous wave generation circuit, and a low impedance with respect to the DC signal, This includes a circuit configuration in which an impedance that is a high impedance is connected.

  According to the present invention, it is possible to transmit a pulse wave and a continuous wave by configuring a low distortion circuit that hardly generates harmonic components. Therefore, it is possible to prevent the generation of heat in the living body, and the safety is enhanced, and the image quality in the new ultrasonic imaging method such as the harmonic imaging method using the nonlinearity of the ultrasonic propagation in the microbubble or the subject is improved. It will contribute to improvement. In addition, since the pulse wave with reduced harmonics and the transmission of continuous wave are performed using the same circuit, the circuit scale is reduced, and an ultrasonic diagnostic apparatus that is small, lightweight and excellent in portability is provided. Can be provided.

Hereinafter, preferred embodiments of an ultrasonic diagnostic apparatus of the present invention will be described in detail with reference to the accompanying drawings.
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment of the present invention, and the repetitive description thereof will be omitted.

First Embodiment
FIG. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus including a pulse wave generation circuit that reduces harmonics in the first embodiment of the present invention.
This ultrasonic diagnostic apparatus includes a control unit 1 that controls the entire apparatus, an operation unit 2 that operates by inputting various operation signals, a pulse wave generation circuit 3 that is a main part of the present invention, and the pulse wave An input signal generation circuit 4 for generating an input pulse wave signal to be input to the generation circuit 3, a transmission unit 5 for transmitting the pulse signal generated by the pulse wave generation circuit 3, and an echo based on the pulse transmitted from the transmission unit 5 A receiving unit 6 for receiving a signal, an ultrasonic probe 7 composed of the transmitting unit 5 and the receiving unit 6 and an ultrasonic transducer (not shown), a power supply unit 8 for supplying operating power of the apparatus, A signal processing and image generation unit 9 that processes an echo signal received by the reception unit 6 to generate an ultrasonic image, and a display that displays an ultrasonic image, a diagnosis result, and the like generated by the signal processing and image generation unit 9 Unit 10 and a recording device 11 for recording the ultrasonic image, diagnosis result, and the like Configured to include a.

  As shown in FIG. 2, the pulse wave generation circuit 3 includes a low-voltage power supply + LV and −LV supplied from the power supply unit 8 and a high gain / wideband first amplifier 2a. A complementary source grounded amplifier 2b, which is a second amplifier that combines a P-channel and N-channel MOSFET (Metal-Oxide Semiconductor Field Effect Transistor) that operates on the high-voltage power supply + HV and -HV supplied from, and a feedback circuit And 2c.

  The first amplifier 2a includes an operational amplifier 2a1 that uses a low voltage power supply + LV and −LV supplied from the power supply unit 8 as a power supply, and a resistor 2a2 connected between the − input terminal of the operational amplifier 2a1 and the ground. The resistor 2a3 is connected between the output terminal of the operational amplifier 2a1 and the negative input terminal of the operational amplifier 2a1, and the resistor 2a2 and 2a3 provide a wide band by applying local negative feedback to the operational amplifier 2a1. .

The second amplifier 2b connects the drains D of the P-channel PMOSFET (first MOSFET) 2b1 and the N-channel NMOSFET (second MOSFET) 2b2 in series, and is parallel to the source S of the PMOSFET 2b1. Connect one end of the capacitor 2b3 connected to the resistor 2b4 and the other end of the parallel connection body to the high voltage power source + HV supplied from the power supply unit 8, and in parallel to the source S of the NMOSFET 2b2 The capacitor 2b5 and one end of the resistor 2b6 are connected, and the other end of the parallel connection body is connected to the high voltage power supply -HV supplied from the power supply unit 8.
Then, one end of decoupling capacitors 2b7 and 2b8 for cutting a DC voltage component is connected to the output terminal of the first amplifier 2a, and the other ends of these decoupling capacitors are connected to the gates G of the PMOSFET 2b1 and the NMOSFET 2b2, respectively. Connect to.

  The resistors 2b4 and 2b6 are for suppressing idling current flowing in the PMOSFET 2b1 and NMOSFET 2b2 due to bias voltages Vb1 and Vb2 described later, and the capacitors 2b3 and 2b5 are AC signals to the gate G of the PMOSFET 2b1 and NMOSFET 2b2. The second amplifier 2b is provided as a high gain amplifier by grounding the sources S of the PMOSFET 2b1 and the NMOSFET 2b2 at a high frequency at the time of input.

  The Vb1 and Vb2 are for applying a bias voltage to the respective gates G of the PMOSFET 2b1 and the NMOSFET 2b2, and are applied to the gate G via the high resistances 2b9 and 2b10.

  In general, the threshold voltage, which is the minimum conduction voltage of the PMOSFET 2b1 and the NMOSFET 2b2, is different, and this causes a difference in the idling current of both MOSFETs. Therefore, this difference current is passed through the resistor 2b11, and the output DC voltage level is 0V. So that it does not deviate greatly.

  Further, a resistor 2c1 is connected between the + input terminal of the operational amplifier 2a1 and the output terminal of the input signal generating circuit 4 shown in FIG. 1, and the output terminal of the second amplifier 2b and the + input of the operational amplifier 2a1. An amplifier having a configuration in which a resistor 2c2 and a capacitor 2c3 connected in series are connected between the terminals and the output voltage of the second amplifier 2b is negatively fed back to the operational amplifier 2a1 by the resistor 2c2 and the capacitor 2c3. And

  Since the pulse wave output from the pulse wave generation circuit 3 generally requires a high amplitude pulse voltage, the high voltage power supply + HV supplied from the power supply unit 8 is a DC high voltage power supply of about + 100V, for example. As for -HV, for example, a DC high voltage power supply of about -100V is used.

  Further, as described above, the output voltage of the output terminal connected to both drain terminals of the PMOSFET 2b1 and the NMOSFET 2b2 is negatively fed back to the first amplifier 2a via the resistor 2c2 and the capacitor 2c3 connected in series, and the output voltage is In addition to reducing distortion, a high DC voltage is not applied to the operational amplifier 2a1 by the capacitor 2c3, so that the operational amplifier 2a1 can be protected from the high voltage.

  Note that the total gain of the circuit according to the present embodiment shown in FIG. 2 is mainly determined by the ratio of the resistor 2c1 and the feedback resistor 2c2 provided in the feedback circuit 2c.

The pulse wave generation circuit 3 according to the first embodiment of the present invention configured as described above can operate as follows to obtain a distortion-free output pulse waveform with reduced harmonic components.
(1) From the input signal generation circuit 4 (FIG. 1), for example, the sine wave input signal <1> shown in FIG. When input to 2a, the first amplifier 2a performs an AC negative feedback operation so as to correct distortion of the voltage waveform output from the second amplifier 2b, and is an output voltage of the first amplifier 2a. An AC voltage such as <2> is output from the amplifier 2a1.
(2) When the alternating voltage <2> is applied to the gates G of the PMOSFET 2b1 and the NMOSFET 2b2, the PMOSFET 2b1 and the NMOSFET 2b2 perform conduction and non-conduction.
(3) That is, during the positive half-cycle period of the AC voltage of <2>, the PMOSFET 2b1 is non-conductive and the NMOSFET 2b2 is conductive and current flows.
(4) During the period of the negative half cycle of the alternating voltage <2>, the PMOSFET 2b1 is conductive and current flows, and the NMOSFET 2b2 is non-conductive and no current flows.
(5) The second amplifier 2b operates as described in (3) and (4) above, and the drain currents of PMOSFET 2b1 and NMOSFET 2b2 are <3> and <4>, respectively, and are output by these currents. The voltage is proportional to the input voltage as shown in <5>.

  In this way, the pulse wave generation circuit 3 combines the first amplifier 2a with a wide band and high gain that operates with a low-voltage power supply and the second amplifier 2b that operates with a high-voltage power supply, and the second amplifier 2b The output ground voltage of the second amplifier is configured to be negatively fed back to the first amplifier 2a via the feedback circuit 2c, so that the source-grounded amplifier circuit, which is the second amplifier that is likely to generate distortion, does not generate distortion. Compensation can be performed by the first wideband / high gain amplifier, and a low distortion amplifier can be configured as a whole, and harmonic components can be suppressed.

  By using the pulse wave with less harmonic components in the B mode, M mode, and pulse Doppler mode, the problem of thermal action on the living body is solved, and the nonlinear propagation of ultrasonic waves in the microbubble or subject This contributes to the improvement of image quality in a new ultrasonic imaging method using the property.

<< Modification of First Embodiment >>
FIG. 3 is a modification of the first embodiment of the present invention that generates a low-gain pulse wave and a high-gain pulse wave from the same pulse wave generation circuit. The first amplifier 2a in the circuit of FIG. The resistor 2c4 and the changeover switch 2c5 are added, and one end of the resistor 2c4 is connected to the illustrated input terminal, and the other end of the resistor 2c4 is connected to one changeover terminal of the changeover switch 2c5. One end of the resistor 2c1 is connected to the other switching terminal of the switch 2c5.
The common switch terminal of the switch 2c5 is connected to the + input terminal of the operational amplifier 2a1.

  In the pulse wave generation circuit of this configuration, the total gain is determined by the size of the resistors 2c1 and 2c4 and the feedback resistor 2c2 on the input side of the operational amplifier 2a1, and the pulse wave generation circuit is set by appropriately setting the values of these resistors. Can be set to a desired gain.

That is, the total gain when the changeover switch 2c5 is connected to the resistor 2c1 side is −2c2 / 2c1, and the total gain when the changeover switch 2c5 is connected to the resistor 2c4 side is −2c2 / 2c4.
In this way, a desired total gain can be obtained by arbitrarily setting the magnitudes of the resistors 2c1 and 2c4 on the + input side of the operational amplifier 2a1 and the feedback resistor 2c2.

<< Second Embodiment >>
In order to share the pulse wave generation circuit of FIG. 2 in the first embodiment with the continuous wave generation circuit, it is necessary to consider the following points, and therefore the NMOSFET 2b2 side will be described as an example.

  In FIG. 2, the AC signal flows between the source S and the drain D of the NMOSFET 2b2 during a period in which the input signal has a positive half cycle, and charges are accumulated in the capacitor 2b5 during this period. On the other hand, during the negative half cycle of the input signal, the accumulated charge is discharged through the resistor 2b6, but the resistor 2b6 must be increased in order to suppress the idling current. The constant becomes longer, and the charge remains without being discharged in a half cycle. The same phenomenon also occurs on the PMOSFET 2b2 side.As a result, the voltage VGS between the gate and the source decreases with time in transmission over a long time such as a continuous wave, and the PMOSFET 2b1 and the NMOSFET 2b2 are unlikely to be in a conductive state. A droop phenomenon occurs in which the output amplitude is attenuated.

  Therefore, in order to eliminate the droop phenomenon and output a continuous wave, it is necessary to have a circuit configuration in which the voltage VGS between the gate and the source does not decrease with time.

In general, a pulse wave has about several transmission pulses per time, and the amplitude of the transmission pulse requires a high voltage pulse of around 100 Vpp. Must be a high voltage power supply of about 100V.
On the other hand, since the continuous wave needs to continuously generate pulses of relatively low voltage of about 10 to 20 Vpp, the high voltage power supply of about ± 100 V in the first embodiment should be used. I can't.
That is, when a continuous wave is generated, a relatively low voltage of about several tens of volts must be used as a power source.

  FIG. 4 shows the droop phenomenon and the second embodiment of the present invention that can be applied to a continuous wave by clearing the problem of lowering the power supply voltage of the second amplifier 2b when the continuous wave is generated. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus including a pulse wave and a continuous wave generation circuit that share a pulse wave generation circuit and a continuous wave generation circuit. FIG.

  The ultrasonic diagnostic apparatus shown in FIG. 4 includes the newly added power supply control unit 12, the power supply unit 8 ′, and the pulse wave and continuous wave generation circuit 3 ′ in the first embodiment shown in FIG. Since only the difference is the same as FIG. 1, the description of this part is omitted.

  In FIG. 4, a power supply unit 8 ′ includes + LV ′ and −LV ′, which will be described later, in addition to the power supplies + LV, −LV, + HV, and −HV in FIG. The + LV ′ and −LV ′ power supplies are switched, and these power supply voltages are used as the DC power sources for the pulse wave generation circuit and the continuous wave generation circuit 3 ′ when the pulse wave and the continuous wave are generated.

  As shown in FIG. 5, the pulse wave generation circuit and the continuous wave generation circuit 3 ′ include a high-gain and wide-band first amplifier 2a that operates with low-voltage power supplies + LV and −LV supplied from the power supply unit 8 ′. And a second amplifier in which a P-channel PMOSFET 2b1 and an N-channel NMOSFET 2b2 operating on the high-voltage power supply + HV and −HV or the low-voltage power supply + LV ′ and −LV ′ supplied from the power supply unit 8 ′ are combined. A complementary type grounded-source amplifier 2b ′ and a feedback circuit 2c are provided.

  Since the first amplifier 2a is the same as the first amplifier shown in FIG. 2, description of the circuit configuration and operation of the first amplifier 2a is omitted, and here the second amplifier 2b ′ is described. explain.

  The second amplifier 2b ′ includes the changeover switches 2b16 and 2b17 for switching the power supply voltage of the second amplifier 2b shown in FIG. 2 between the generation of a pulse wave and the generation of a continuous wave, and the power supply control of FIG. When the pulse wave is generated, the selector switch 2b16 is connected to the + HV power source and the changeover switch 2b17 is connected to the -HV power source to supply a high voltage. When the continuous wave is generated, the selector switch 2b16 is set to the + LV 'power source. Further, the changeover switch 2b17 is connected to the −LV ′ power source to supply a low voltage.

  The drains D of the P-channel PMOSFET 2b1 and the N-channel NMOSFET 2b2 are connected in series, one end of a parallel connection body of a capacitor 2b3 and a resistor 2b4 connected in parallel is connected to the source of the PMOSFET 2b1, and the parallel connection body The other end of the diode 2b16 is connected to the changeover switch 2b16, and the anode of the diode 2b15 of the series connection body having a resistance value sufficiently smaller than the resistance 2b4 and the diode 2b15 is connected to the low voltage power supply + LV ′. A resistor 2b14 is connected to the source of the PMOSFET 2b1.

  Similarly, one end of a parallel connection body of a capacitor 2b5 and a resistor 2b6 connected in parallel is connected to the source of the NMOSFET 2b2, the other end of the parallel connection body is connected to the changeover switch 2b17, and more fully than the resistance 2b6. The node of the diode 2b13 of the series connection body composed of the resistor 2b12 and the diode 2b13 connected in series having a small resistance value is connected to the low voltage power supply -LV ', and the resistor 2b12 is connected to the source of the NMOSFET 2b2.

Furthermore, the unnecessary DC voltage level that appears in the output voltage generated when the current of the idling current difference due to the characteristic difference between the PMOSFET 2b1 and the NMOSFET 2b2 flows in the resistor 2b11 (shown in FIG. 2) is a circuit configuration in which a large idling current flows. In order to prevent this from occurring, the inductor voltage 2b18 may be provided in place of the resistor 2b11 between the output terminal and the ground, as shown in FIG. desirable.
Since the inductor 2b18 has a small impedance with respect to a DC signal, an unnecessary DC voltage is hardly generated for an idling difference current which is a DC component. On the other hand, for the AC signal, the inductor 2b18 has a sufficiently large impedance, so the impedance of the ultrasonic probe connected as a load becomes dominant, and a transmission signal with sufficient amplitude can be output. It becomes possible.

  In addition, since the gate circuit and bias circuit of the PMOSFET 2b1 and the NMOSFET 2b2 are the same as those in the first embodiment of FIG. 2, description of these circuit configurations and operations is omitted.

  The pulse wave generation circuit and the continuous wave generation circuit 3 ′ configured as described above according to the second embodiment of the present invention operate as follows to obtain a distortion-free output waveform with reduced harmonic components. be able to.

(1) In the case of pulse wave generation In response to an operation command from the operation unit 2, the power supply control unit 12 configures a pulse wave generation circuit by connecting the switch 2b16 to the + HV power supply and 2b17 to the -HV power supply.
The pulse wave generation circuit configured as described above has the same circuit configuration as that of FIG. 2 of the first embodiment, and the operation thereof is also the same, so description thereof will be omitted.

(2) In the case of continuous wave generation In response to an operation command from the operation unit 2, the power supply control unit 12 connects the switch 2b16 to the + LV ′ power supply and 2b17 to the −LV ′ power supply and is lower than the pulse wave generation circuit. A continuous wave generating circuit operating with voltage is configured.

  In the continuous wave generating circuit configured as described above, the first wideband / high gain amplifier 2a has the same circuit configuration as that at the time of generating the pulse wave, and the bias circuit of the second amplifier 2b 'is also at the time of generating the pulse wave. The only difference is the output side of the PMOSFET 2b1 and NMOSFET 2b2, and the PMOSFET 2b1 side and the NMOSFET 2b2 side operate symmetrically, so the NMOSFET 2b2 side will be described here.

In this NMOSFET 2b2 side circuit, a newly provided resistor 2b12 and a high voltage diode 2b13 are connected in series, the cathode of the diode 2b13 is connected to the -LV 'power source, and the other end of the resistor is connected to the source of the NMOSFET 2b2. It consists of
That is, as described above, when the changeover switch 2b17 is connected to the −LV ′ power source, the resistor 2b6 and the resistor 2b12 are connected in parallel.
Here, by setting the resistance value of the resistor 2b12 to a sufficiently small value, that is, a time constant sufficient to discharge the charge accumulated in the capacitor 2b5 during the half cycle of the input AC signal, the resistance value is accumulated in the capacitor 2b5. The generated charge is discharged mainly through the resistor 2b12, and the droop phenomenon can be eliminated.

  In other words, when transmitting a continuous wave, the discharge time constant is reduced by switching the resistance connected to the source of the NMOSFET 2b2 to a low resistance, and accumulated in the capacitor 2b5 during the half cycle of the input AC signal. By discharging the generated charge, it becomes possible to eliminate the droop phenomenon that occurs when the voltage VGS between the gate G and the source S of the NMOSFET 2b2 decreases with time, and this causes the problem that the amplitude of the output voltage attenuates. Can be resolved.

As described above, by sharing the pulse wave generation circuit and the continuous wave generation circuit, the circuit becomes smaller and the portability, which is one of the features of the ultrasonic diagnostic apparatus, is improved.
In addition, the harmonic components contained in the pulse wave and continuous wave are reduced, improving the image quality in the new ultrasonic imaging method using the problem of thermal action on the living body and the nonlinearity of ultrasonic propagation inside the microbubble or subject. It can be set as the ultrasonic diagnostic apparatus which contributes.

<< Modification of Second Embodiment >>
FIG. 6 shows a modification of the second embodiment that can output a continuous wave without a droop phenomenon when a continuous wave is generated.
In the modified example of FIG. 6, the polarity of the power supply is different between the PMOSFET 2b1 side and the NMOSFET 2b2 side, but the other configurations are the same, so the NMOSFET 2b2 side will be described here.

  In this NMOSFET 2b2 side circuit, the newly provided resistor 2b20 is connected in series to the resistor 2b6, and the base of the newly provided bipolar transistor 2b22 is connected to these connection points, and the series-connected resistors 2b6 and 2b20 The collector and emitter of the bipolar transistor 2b22 are connected to both ends, the collector of the transistor 2b22 is connected to the source S of the NMOSFET 2b2, and the emitter of the transistor 2b22 is connected to the changeover switch 2b17 that switches between the -HV power supply and the -LV 'power supply.

The resistance values of the resistors 2b6 and 2b20 are set to values at which the DC voltage applied across the resistor 2b20 is equal to or lower than the threshold voltage between the base and the emitter of the bipolar transistor 2b22. As a result, when no AC signal is input to the gate of the NMOS FET 2b2, the bipolar transistor 2b22 is non-conductive, and the DC idling current is limited by the resistor 2b6 and the resistor 2b20.
When an AC signal is input to the gate of the NMOS FET 2b2, the base current of the NMOSFET 2b2 flows through the capacitor 2b5 in the positive half cycle of the AC input signal, and the bipolar transistor 2b22 becomes conductive and has a low resistance. The second amplifier 2b ″ is a common source amplifier.

  In this way, since only the base current flows in the capacitor 2b5, there is almost no charge accumulation, and the voltage VGS between the gate and the source does not decrease with time, so the problem of the droop phenomenon can be solved. .

  The PMOSFET 2b1 side also constitutes the same source grounded amplifier as the NMOSFET 2b2 side, and switches to the PMOSFET 2b1 side circuit and the NMOSFET 2b2 side switch 2b16 and 2b17, the high voltage power supply ± HV and the low voltage power supply ± LV ′. The first amplifier 2a is provided in the previous stage of the circuit configured in this way, and the pulse wave generation circuit and the continuous wave generation circuit can be shared, and the pulse wave generation circuit of FIG. The same effect as the continuous wave generation circuit can be obtained.

<< Other Modifications of Second Embodiment >>
FIG. 7 shows another modification of the second embodiment of the present invention in which the total gain is changed between the generation of a pulse wave and the generation of a continuous wave. The first amplifier 2a of the circuit of FIG. And one end of the resistor 2c4 is connected to the illustrated input terminal, the other end of the resistor 2c4 is connected to one switching terminal of the changeover switch 2c5, and the changeover switch 2c5 is connected. One end of the resistor 2c1 is connected to the other switching terminal.
The common switch terminal of the switch 2c5 is connected to the + input terminal of the operational amplifier 2a1.

  In the pulse wave and continuous wave generation circuit of this configuration, the total gain is determined by the size of the resistors 2c1 and 2c4 and the feedback resistor 2c2 on the input side of the operational amplifier 2a1, and the pulse is set by appropriately setting the values of these resistors. The gain at the time of wave generation and continuous wave generation can be set to a desired gain.

That is, the total gain when the changeover switch 2c5 is connected to the resistor 2c1 side is −2c2 / 2c1, and the total gain when the changeover switch 2c5 is connected to the resistor 2c4 side is −2c2 / 2c4.
Thus, by setting the magnitudes of the resistances 2c1 and 2c4 on the + input side of the operational amplifier 2a1 and the feedback resistance 2c2 as desired, a desired total gain can be obtained when a pulse wave is generated and when a continuous wave is generated.

As mentioned above, although various embodiment was described about this invention, this invention is not limited to these embodiment, In the range which does not deviate from the summary of this invention, it can change variously as follows.
(1) The circuit of FIG. 2 of the first embodiment can also be used for a continuous wave generation circuit when it is used within a range where the droop phenomenon and the heat generation of the circuit accompanying the use of a high voltage power source do not become a problem. In this case, the power loss of the circuit can be reduced by reducing the power supply voltage of the second amplifier 2b.

(2) Further, the resistor 2b12 and resistor 2b14 of the circuit of FIG. 5 and the high voltage diodes 2b13 and 2b15 are added to (1), or the resistor 2b19 and resistor 2b20 of the circuit of FIG. 6 are added to (1). By adding the circuits of the transistors 2b21 and 2b22, a pulse wave generation circuit or a continuous wave generation circuit in which no droop phenomenon occurs can be obtained.

(3) Further, by adding the gain variable means shown in FIG. 3 to (2), a pulse wave generation circuit or a continuous wave generation circuit with a total gain corresponding to the application can be obtained.

(4) Furthermore, the impedance of the DC signal is low between the output terminal of the circuit of FIGS. 2 and 3 of the first embodiment and the circuit of (1), (2) and (3) and the ground. By connecting a high impedance to the AC signal, it is possible to eliminate the limitation of the output voltage due to the unnecessary DC voltage level appearing in the output voltage caused by the difference in idling current due to the characteristic difference between PMOSFET 2b1 and NMOSFET 2b2. .

(5) By adding the gain varying means shown in FIG. 7 to the circuit shown in FIG. 6 of the modification of the second embodiment, the total gain can be changed between when a pulse wave is generated and when a continuous wave is generated. Furthermore, the same gain variable means can set the total gain corresponding to each application when the pulse wave is generated or when the continuous wave is generated.

Although an operational amplifier is used for the first amplifier, any amplifier may be used as long as it is a wideband and high gain amplifier capable of negative feedback, and the second amplifier is not limited to a source grounded MOSFET. Alternatively, a complementary amplifier using a transistor or another semiconductor may be used.
Furthermore, the DC power supplies + HV and -HV and + LV 'and -LV' of the above embodiment do not have to have the same positive and negative voltages, and the DC power supplies + HV and -HV are at the center level of the output voltage of the second amplifier. In contrast, a DC power supply having a positive polarity and a negative polarity may be used, and the DC power supplies + LV ′ and −LV ′ are lower than the DC power supplies + HV and −HV, and are the center of the output voltage of the second amplifier. A DC power supply having a positive polarity and a negative polarity with respect to the level may be used.

1 is an overall configuration diagram of an ultrasonic diagnostic apparatus including a pulse wave generation circuit that reduces harmonics in the first embodiment of the present invention. FIG. FIG. 2 is a pulse wave generation circuit diagram according to the first embodiment of the present invention. 6 shows a modification of the pulse wave generation circuit according to the first embodiment of the present invention. FIG. 6 is an overall configuration diagram of an ultrasonic diagnostic apparatus in which a pulse wave generation circuit for reducing harmonics and a continuous wave generation circuit are shared in a second embodiment of the present invention. FIG. 6 is a circuit diagram in which a pulse wave generation circuit and a continuous wave generation circuit are shared in a second embodiment of the present invention. 6 is a circuit modification example in which the pulse wave generation circuit and the continuous wave generation circuit are shared in the second embodiment of the present invention. 10 is another modification of the circuit in which the pulse wave generation circuit and the continuous wave generation circuit are shared in the second embodiment of the present invention.

Explanation of symbols

  1 control unit, 2 operation unit, 2a 1st amplifier, 2a1 operational amplifier, 2c feedback circuit, 2c2 negative feedback resistor, 2c3 negative feedback capacitor, 2c5 gain selector switch, 2b, 2b ', 2b ”2nd amplifier , 2b1 P-channel MOSFET, 2b2 N-channel MOSFET, 2b4, 2b6 Idling current suppression resistor, 2b3, 2b5 High frequency grounding capacitor, 2b7, 2b8 Decoupling capacitor, 2b13, 2b15 High voltage diode, 2b16, 2b17 Power switch, 2b18 Inductor , 2b21, 2b22 Bipolar transistor, 3 pulse wave generator, 3 'pulse wave and continuous wave generator, 4 input signal generator, 5 transmitter, 6 receiver, 7 ultrasonic probe, 8, 8' power supply , 9 Signal processing and image generation unit, 10 Display unit, 11 Recording device, 12 Power supply control unit, ± LV Low voltage DC power supply for the first amplifier, ± LV 'Low voltage DC power supply for the second amplifier, ± HV 2 increase High-voltage direct-current power supply vessel

Claims (11)

  An ultrasonic diagnostic apparatus comprising a pulse wave generation circuit or a continuous wave generation circuit for generating a pulse wave or a continuous wave for driving a transducer of an ultrasonic probe, the pulse wave generation circuit or the continuous wave generation The circuit includes a first amplifier based on an operational amplifier, and a second amplifier that operates with a DC power source having a positive polarity and a negative polarity with respect to a center level of an output voltage for amplifying the output of the first amplifier. And an AC negative feedback means for negatively feeding back the output voltage of the second amplifier to the first amplifier.   The second amplifier includes a complementary grounded-source amplifier composed of two sets of P-channel and N-channel MOSFETs, and is connected between the sources of the two sets of MOSFETs and the positive polarity and negative polarity DC power supplies. The ultrasonic diagnostic apparatus according to claim 1, further comprising a parallel connection body of a first resistor and a capacitor.   Further, a second resistor is connected in series between the DC power source and the parallel connection body, and the first resistor and the second resistor are short-circuited when a voltage across the second resistor is equal to or higher than a predetermined threshold. The ultrasonic diagnostic apparatus according to claim 2, further comprising switch means.   The ultrasonic diagnostic apparatus according to claim 1, further comprising means for varying a gain of the pulse generation circuit or the continuous wave generation circuit.   Furthermore, between the output terminal of said 2nd amplifier and the earth | ground, the impedance which becomes a low impedance with respect to a DC signal and becomes a high impedance with respect to an AC signal is connected, The ultrasonic diagnostic apparatus according to any one of 3 and 4.   A pulse wave generation circuit for generating a pulse wave and a continuous wave for driving a transducer of an ultrasonic probe, and an ultrasonic diagnostic apparatus including the continuous wave generation circuit, the pulse wave generation circuit and the continuous wave generation The circuit includes a first amplifier by an operational amplifier, a second amplifier for amplifying the output of the first amplifier, and an AC negative feedback for AC negative feedback of the output voltage of the second amplifier to the first amplifier. Means, a first DC power supply having a positive polarity and a negative polarity with respect to the center level of the output voltage of the second amplifier, and a positive polarity of a voltage lower than the voltage of the first DC power supply. A second DC power source having a negative polarity, power source switching means for switching between the first DC power source and the second DC power source, and the first DC power source when the pulse wave is generated as the power source of the second amplifier. To the power supply, when the continuous wave occurs, to the second DC power supply An ultrasonic diagnostic apparatus comprising power switching control means for switching.   The second amplifier includes a complementary source grounded amplifier composed of two sets of MOSFETs of a P channel and an N channel, and a first resistor is provided between each source of the two sets of MOSFETs and the power source switching unit. The ultrasonic diagnostic apparatus according to claim 6, wherein a parallel connection body of a capacitor and a capacitor is connected.   Further, a second resistor is connected in series between the power supply switching means and the parallel connection body, and the first resistor and the second resistor are short-circuited when a voltage across the second resistor is equal to or higher than a predetermined threshold. The ultrasonic diagnostic apparatus according to claim 7, further comprising a switch unit configured to perform switching.   Further, a series connection body of a third resistor and a diode is connected between the sources of the two sets of MOSFETs and the parallel connection body to the second DC power source so as to be in the forward direction of the diode. The ultrasonic diagnostic apparatus according to claim 7.   The ultrasonic diagnostic apparatus according to claim 6, further comprising means for varying gains of the pulse generation circuit and the continuous wave generation circuit.   Furthermore, between the output terminal of said 2nd amplifier and the earth | ground, the impedance which becomes a low impedance with respect to a DC signal and becomes a high impedance with respect to an AC signal is connected, The ultrasonic diagnostic apparatus according to any one of 8, 9 and 10.

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