JP2004073883A - Transmission circuit of ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of heat generation and to amplify an optional waveform with a low distortion factor even when the level of a transmission signal is varied. <P>SOLUTION: An ultrasonic diagnostic apparatus is constituted so as to generate a pair of pedestal clamp pulses (bias pulses) Vb1 and Vb2 each having a pulse width corresponding to an original transmission signal and having a bipolar symmetric property by a pedestal clamp circuit (a bias setting circuit) 30. A pseudo-linear amplifier 32 sets a bias point according to levels of the pulses Vb1 and Vb2, and linearly amplifies the original transmission signal only in the period of the pulse. Also, a drive power source variably sets electrical potentials HV1 and HV2 of the drive power source, and the level of the transmission signal outputted from the pseudo-linear amplifier 32 is variably set. Furthermore, an operating point is kept at a prescribed value by the levels of the pedestal clamp pulses Vb1 and Vb2. <P>COPYRIGHT: (C)2004,JPO

Description

{Circle over (1)} The present invention relates to a transmission circuit of an ultrasonic diagnostic apparatus, and particularly to setting of a bias.

超 An ultrasonic diagnostic apparatus that displays a tomographic image or a Doppler image by transmitting and receiving ultrasonic waves is known. In these ultrasonic diagnostic apparatuses, a technique of electronic focusing for converging an ultrasonic beam is widely used in order to obtain high image quality.

However, since there are some side lobes in the directional characteristics of the focused ultrasonic beam, artifacts are displayed on the screen, which causes deterioration in image quality. As a method of reducing side lobes that cause artifacts, an apodization technique for weighting a transmission wave is applied to an ultrasonic diagnostic apparatus.

Conventional ultrasonic diagnostic apparatuses generally include a plurality of displays such as a B mode, a continuous wave Doppler mode (CW), a CFM (color flow mapping) mode, and a harmonic imaging mode using a second harmonic component in an echo. Mode.

In the ultrasonic diagnostic apparatus having such a plurality of display modes, from the viewpoint of the relationship between the ultrasonic energy and the signal-to-noise ratio (SNR) in the living body, the waveform of the transmission wave applied to the transducer according to each display mode and It is necessary to change the peak value.

For example, in the CW mode, it is required that the transmission wave be a sine wave from the viewpoint of SNR and the content of harmonics be kept low. On the other hand, in the case of harmonic imaging by the second harmonic of the reflected wave in the living body, It is necessary to keep the second harmonic of the wave sufficiently lower than the second harmonic of the reflected wave in the living body.

Therefore, in such an ultrasonic diagnostic apparatus, a transmission circuit capable of driving the vibrator with an arbitrary waveform, for example, a pulse wave, a sine wave, a Gaussian wave, or the like is required.

FIG. 6 is an example of a transmission circuit that performs transmission apodization in a conventional ultrasonic diagnostic apparatus. This transmission circuit includes a power supply unit 10, a transmission voltage control unit 12, pulsar units C1 to C4, and voltage limiters D1 to D4. The power supply unit 10 supplies a constant voltage Vdc to the pulsar units C1 to C4.

The pulsar units C1 to C4 output constant voltage pulses β1 to β4 of the output voltage Vdc based on the drive pulses α1 to α4 corresponding to each channel. The transmission voltage control unit 12 supplies the transmission voltage control signals φ1 to φ4 to the voltage limiters D1 to D4, and the voltage limiters D1 to D4 clip the voltages of the constant voltage pulses β1 to β4, and generate pulses of different peak values. The transducers td1 to td4 of the ultrasonic probe 14 are driven by γ1 to γ4. The apodization of transmission is executed in the above procedure.

However, since the power supply voltage of the pulser section is constant at Vdc, β1 to β4 are always output at the maximum output voltage, and the output voltage of the difference is consumed in the voltage limiters D1 to D4 at the time of the minimum drive pulse due to apodization. Therefore, the power loss is large, and the problem of heat generation in the entire circuit increases.

On the other hand, since the transmission wave is a pulse wave, a filter for holding down the second harmonic of the transmission wave sufficiently lower than the second harmonic of the in-vivo reflected wave in the harmonic imaging mode is separately provided for each channel, or It is necessary to provide a dedicated transmission circuit separately.

Also, since the pulsar units C1 to C4 and the voltage limiters D1 to D4 are constituted by non-linear circuits, it goes without saying that the oscillator cannot be driven by a sine wave, a Gaussian wave or any other arbitrary waveform.

Therefore, in order to provide a high-performance, multifunctional ultrasonic diagnostic apparatus, it is necessary to provide a dedicated transmission circuit for each type of transmission wave, which causes heat generation and cost problems.

FIG. 7 shows another example of a transmission circuit for performing apodization in a conventional ultrasonic diagnostic apparatus. This transmission circuit includes a clamp unit 20, a voltage comparison unit 22, a voltage-current conversion unit 24, a high-voltage current control unit 26, and a transformer 28 with a tap, and is provided corresponding to each transducer TD (not shown). A constant high voltage HV (for example, 100 V) is connected to each tap of the transformer 28, and each circuit is off when there is no signal.

(4) The clamp unit 20 fixes the transmission pulse Pulse 1 and the transmission control signal Vpc cont.1 to predetermined values based on the power supply −Vee, and supplies them to the voltage comparison unit 22. The voltage comparison unit 22 clips the transmission pulse Pulse 1 having the fixed potential at the Vpc1 potential based on the transmission control signal Vpc cont.1, and supplies a voltage pulse having a peak value α1 to the voltage-current conversion unit 24. The voltage-to-current converter 24 generates a current pulse β1 based on a current value flowing into R1 by a voltage pulse having a peak value α1 generated by the voltage comparator 22 and outputs the current pulse β1 to the high-voltage current controller 26 configured by an FET switch. Supply. The high-voltage current controller 26 constituted by an FET switch is turned on by a voltage generated by a current flowing through R2 and R3 with the power supply Vcc as a reference voltage by the current pulse β1, supplies the current pulse β1 to the transformer 28, and Converts the current pulse β1 into a high-voltage pulse and drives a vibrator TD (not shown). The apodization of transmission is executed in the above procedure.

送信 This transmission circuit has stopped its operation when there is no signal, because the FET switch constituting the high voltage current control unit 26 is in the off state. Accordingly, power consumption when there is no signal is zero (0), which is advantageous in terms of heat generation.

However, since the transmission wave is a pulse wave, in the harmonic imaging mode, a filter for suppressing the second harmonic of the transmission wave sufficiently lower than the second harmonic of the in-vivo reflected wave is separately provided for each channel, Alternatively, it is necessary to separately provide a dedicated transmission circuit. Also, since a transformer is used, it is difficult to reduce the size of the circuit, reduce the cost, and integrate the circuit into an integrated circuit.

{Circle around (4)} In the transmission circuit, since the clamp unit 20 and the voltage comparison unit 22 are constituted by non-linear circuits, it goes without saying that the vibrator cannot be driven by a sine wave, a Gaussian wave or any other arbitrary waveform.

JP-A-7-231247 JP-A-62-117533 JP-A-10-57373 JP-A-3-162838 Toshi Kubota, Easy-to-Make Super Amplifier FET Amplifier Collection (4th print), Seibundo Shinkosha, December 15, 1988 Toshio Kubota, Semiconductor Amplifier Manufacturing Technique, Seibundo Shinkosha, February 25, 1995

As described above, in the above-described conventional transmission circuit, the transmission wave is a pulse wave because the circuit is configured by the non-linear circuit method. For example, the second harmonic of the transmission wave is in vivo in the harmonic imaging mode. A filter for holding down sufficiently lower than the second harmonic of the reflected wave had to be separately provided for each channel.

た め Also, since low-voltage output transmission is performed during Doppler (CW), a dedicated low-voltage linear amplifier for transmitting a sine wave, a so-called linear circuit transmission circuit, is separately provided from the viewpoint of SNR.

Accordingly, it was not possible to drive the vibrator with an arbitrary waveform from low voltage to high voltage, for example, a pulse wave, a sine wave, a Gaussian wave, or the like, with one transmission circuit.

In addition, JP-A-5-344970, JP-A-8-252251, JP-A-10-57373, JP-A-11-56839, and U.S. Pat. No. 4,821,706 disclose related techniques. I have.

An object of the present invention is to provide a transmission circuit of an ultrasonic diagnostic apparatus that can perform linear amplification and reduce heat generation under each transmission condition.

Another object of the present invention is to make it possible to drive a vibrator with an arbitrary waveform from a low voltage to a high voltage, for example, a pulse wave, a sine wave, a Gaussian wave, or the like, with one transmission circuit.

(1) Preferably, a bias setting circuit that outputs a pair of bias pulses having a bipolar width and a pulse width corresponding to the original transmission signal, and an operation period and an operation point are determined by the pair of bias pulses. And a drive circuit for amplifying the original transmission signal.

According to the above configuration, the pair of bias pulses is generated by the bias setting circuit, and the drive circuit amplifies the original transmission signal according to the pair of bias pulses. That is, the operation period of the drive circuit is defined by the pulse width of the pair of bias pulses, and the operating point of the drive circuit is defined by the level of each of the pair of bias pulses. Therefore, a bias is formed only during a period in which the operation is necessary, that is, an operable state is set, so that the problem of heat generation can be dealt with. If the drive circuit is operated linearly by appropriately setting the level of the bias pulse, amplification can be performed under desired operating conditions.

Preferably, the drive circuit has a circuit for flowing a bias current for a period corresponding to a pulse width of the pair of bias pulses. That is, in other periods, the supply of the bias current is stopped, whereby the operation of the circuit is effectively stopped, and unnecessary power consumption is suppressed.

Preferably, the pair of bias pulses rise before the start point of the original transmission signal by a standby time. According to this configuration, the circuit can be stabilized prior to the amplification of the original transmission signal.

Preferably, the drive circuit has a circuit for fixedly setting an operating point in a linear amplification region according to the level of the pair of bias pulses. According to this configuration, it is possible to achieve linear amplification of an arbitrary waveform by operating the drive circuit linearly.

Preferably, the drive circuit has a complementary symmetrical circuit configuration in which all stages from input to output are DC-coupled. According to this configuration, responsiveness can be improved. Since it is a complementary type, amplification is performed independently for each polarity component, and finally components of both polarities are integrated.

Preferably, the drive circuit is a high-speed negative feedback amplifier. According to this configuration, the operating point is stabilized, and a higher frequency, a higher speed response, a lower distortion rate of the waveform, and the like are achieved.

Preferably, the bias setting circuit variably sets the level of the pair of bias pulses according to transmission conditions, whereby the operating point of the drive circuit is variably set. According to this configuration, amplification can be performed under desired operating conditions.

Preferably, the power supply includes a drive power supply connected to the drive circuit, wherein the drive power supply variably sets a voltage of the drive power supply according to a transmission condition, and thereby a transmission signal output from the drive circuit. Is variably set.

(2) Preferably, a bias setting circuit for outputting a pair of bias pulses having a bipolar width and having a pulse width corresponding to a plurality of original transmission signals, and an operation period and an operation by the pair of bias pulses And a plurality of drive circuits for amplifying the original transmission signal are provided, and the bias setting circuit is shared by the plurality of drive circuits.

According to this configuration, a circuit configuration can be simplified by providing one bias circuit for a plurality of drive circuits. Preferably, the bias setting circuit has a pulse width that includes all of the plurality of original transmission signals.

(3) Incidentally, the above-mentioned bias pulse can also be referred to as a pedestal clamp pulse. In this case, the bias setting circuit corresponds to a pedestal clamp circuit. Since the operating point of the drive circuit is fixed in the linear operation region only during the period of the pulse, it can be called a pseudo linear amplifier.

Therefore, according to the above configuration, the problem of heat generation in the transmission circuit can be solved, the transmission circuit can be mounted with high density, and the device can be downsized. By operating the drive circuit as a high-speed negative feedback amplifier, an arbitrary waveform such as a pulse wave, a sine wave, and a Gaussian wave can be amplified at a low distortion rate.

(4) According to the present invention, the operating point of the circuit can be kept at a predetermined value by the set level of the pedestal clamp pulse even if the high-voltage power supply supplied to the drive circuit is varied. That is, in each mode such as the B mode, the Doppler (CW) mode, and the CFM (color flow mapping) mode, even if the voltage of the high voltage power supply is set to an appropriate value and the level of the transmission signal is changed, the operating point of the drive circuit is changed. A predetermined value is maintained, amplification is performed with a low distortion rate, and the power consumption of the transmission circuit can be minimized.

(5) That is, the present invention has a bias setting circuit that outputs a pair of bias pulses having a pulse width corresponding to an original transmission signal and having a positive / negative symmetry, and a complementary circuit configuration with a positive / negative symmetry, A drive circuit that defines a positive and negative operation period and an operation point by the pair of bias pulses, and linearly amplifies the original transmission signal; and a drive power supply connected to the drive circuit. Sets the voltage of the drive power supply variably according to the transmission conditions, thereby variably setting the level of the transmission signal output from the drive circuit, and the drive circuit varies the drive power supply voltage In this case, the operating point of the drive circuit is maintained at a predetermined value by the pair of bias pulses.

As described above, according to the present invention, the power consumption of the drive circuit when there is no signal can be reduced to zero, so that the problem of heat generation can be solved and an arbitrary waveform can be amplified with a low distortion rate. You get the benefits.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a transmission circuit used for an ultrasonic diagnostic apparatus. 1, in this embodiment, a pair of pedestal clamp circuits 30 and a pseudo linear amplifier 32 are provided for each transducer (or transmission signal).

The pedestal clamp circuit 30 receives, from a control unit (not shown), a transmission control signal PD in consideration of transmission focusing and a standby time for converging an ultrasonic beam, and generates positive and negative symmetric pedestal clamp pulses Vb1 and Vb2 based thereon. Each is sent to the pseudo linear amplifier 32. FIGS. 5A to 5C illustrate the waveforms of the transmission control signal PD and the pedestal clamp pulses Vb1 and Vb2. Here, the transmission control signal PD and the pedestal clamp pulses Vb1 and Vb2 associated therewith have a longer period before and after the entire period 100 of the original transmission waveform shown in FIG. It is set so that it rises before the start point by the period 102 and falls later by the period 104 than the end point of the original transmission waveform.

The pseudo-linear amplifier 32 is a drive circuit having a complementary symmetrical circuit configuration with no input and direct-current coupling and direct-current coupling, and has no power consumption when there is no signal. The quasi-linear amplifier 32 operates as a high-speed negative feedback amplifier with the operating point of the circuit fixed in the linear operation region only during the generation period of the pedestal clamp pulse by the pedestal clamp pulses Vb1 and Vb2 sent from the pedestal clamp circuit 30. , Linearly amplifies the ultrasonic probe driving arbitrary waveform signal (original transmission signal) Tx in inputted in synchronization with the transmission control signal PD, and sends out Tx out to a vibrator (not shown). FIG. 5 (D) shows the original transmission waveform as described above, and FIG. 5 (E) shows the waveform of the output signal Tx out.

Tx in is an arbitrary waveform such as a pulse wave, a sine wave, and a Gaussian wave in consideration of transmission focusing, transmission level and transmission weighting (apodization) transmitted from a control unit (not shown), and is generated in synchronization with the transmission control signal PD. It was done.

Tx out is an output signal after the pseudo linear amplifier 32 linearly amplifies Tx in during the generation period of the pedestal clamp pulses Vb1 and Vb2, and is output to a vibrator (not shown).

In FIG. 1, Vcc and Vee are power supplies for the pedestal clamp circuit 30. For example, a predetermined voltage value within ± 5 to ± 15V of positive / negative symmetry is used. HV1 and HV2 are high-voltage power supplies of the quasi-linear amplifier 32, have positive and negative symmetric voltage values, and can be variably set within a range of ± 10 V to ± 100 V automatically, for example, by a display mode or the like.

Therefore, when the drive circuit is constituted by the pseudo linear amplifier 32, the power consumption of the drive circuit when there is no signal can be reduced to zero (0), so that the problem of heat generation of the transmission circuit is solved, and the generation period of the pedestal clamp pulse is reduced. It can be operated as a high-speed negative feedback amplifier only in the middle, so that high frequency, high-speed response, low waveform distortion rate and circuit stabilization can be achieved. The operating point is maintained at a predetermined value according to the set pedestal clamp pulse level, and the high-voltage power supply in each mode such as B mode, Doppler (CW) mode, CFM (color flow mapping) mode is adjusted to an appropriate value. By doing so, the power consumption of the drive circuit and high-voltage power supply is minimized, and arbitrary waveforms such as pulse waves, sine waves, and Gaussian waves The input wave is linearly amplified to a predetermined value at a low strain rate, it can be driven (not shown) oscillator.

FIG. 2 is a schematic configuration diagram showing a transmission circuit according to another embodiment. In FIG. 2, a pedestal clamp circuit 34 is commonly connected to a plurality of pseudo linear amplifiers B1 to B48.

The pedestal clamp circuit 34 generates positive and negative symmetric pedestal clamp pulses Vb1 and Vb2 based on the transmission control signal PD1 in consideration of the transmission focusing and the standby time for converging the ultrasonic beam from the control unit (not shown), as described above. To the pseudo linear amplifiers B1 to B48.

The pseudo linear amplifiers B1 to B48 are, similarly to the above, drive circuits each composed of a non-biased complementary symmetric circuit with input / output all-stage DC coupling, and the power consumption when there is no signal is zero (0). The quasi-linear amplifiers B1 to B48 use the pedestal clamp pulses Vb1 and Vb2 sent from the pedestal clamp circuit 34 to fix the operating point of the circuit to the linear operation area only during the period of generation of the pedestal clamp pulse, and to perform high-speed negative feedback amplification. And linearly amplifies the ultrasonic probe driving arbitrary waveform signals Tx in1 to Tx in48 input in synchronization with the transmission control signal PD1, and sends out Tx out1 to Tx out48 to a vibrator (not shown). Here, Vcc, Vee, HV1, and HV2 are the same as those in the above-described embodiment, and thus description thereof will be omitted.

Therefore, the pedestal clamp circuit can be grouped for each transmission focusing group, so that the cost of the transmission circuit can be reduced.

FIGS. 3 and 4 show specific circuit configuration examples of the pseudo linear amplifier shown in FIGS. 1 and 2. FIG.

First, in FIG. 3, Q1 to Q14 are transistors, R1 to R24 are resistors, and C1 to C3 are capacitors. This circuit includes a complementary symmetric current mirror circuit including resistors R1 to R14 and transistors Q1 to Q8, a floating shunt regulator circuit including resistors R15 to R17 and transistors Q9 and Q9, resistors R18 to R22, and capacitors C2 and C3. And a complementary symmetric single-ended push-pull circuit composed of transistors Q11 to Q14, and a feedback circuit having resistors R23 and R24 and a capacitor C1. In this circuit, the power consumption when there is no signal is zero (0) due to the zero bias in the input / output all-stage DC coupling. Hereinafter, the operation will be described in detail.

(4) The pedestal clamp pulses Vb1 and Vb2 are generated based on the transmission control signal, and are respectively sent to both ends of the transmission control signal input terminals R2 and R3 of the pseudo linear amplifier. Then, the operating point of the positive / negative symmetric complementary symmetric current mirror circuit including the resistors R1 to R14 and the transistors Q1 to Q8 is fixed to the class AB1.

When the operating point of the positive-negative symmetric complementary symmetric current mirror circuit composed of the transistors Q1 to Q8 is fixed to class AB1, the collector of the transistor Q10 is determined based on the voltage generated at the resistors R15 and R16 by the collector current of the transistors Q7 and Q8. Further, a voltage for fixing the operating point of the complementary symmetric single-ended push-pull circuit including the transistors Q11 to Q14 at the next stage to the class AB1 is sent to the emitter.

に よ り By this voltage, the operating point of the complementary symmetric single-ended push-pull circuit composed of the transistors Q11 to Q14 is fixed to the class AB1. Here, the capacitors C2 and C3 are used for phase correction, and values of several pF to several tens pF are used.

With the above procedure, the operating point of the drive circuit with no bias is fixed by DC coupling in all stages of input and output, and at that time, the feedback circuit composed of the resistors R23 and R24 and the capacitor C1 applies negative feedback to It becomes an in-phase high-speed negative feedback amplifier. Here, the capacitor C1 is used for phase correction, and a value of several pF is used.

増 幅 The amplification factor Av of the circuit is expressed by the following equation.

Av = R24 / R23

The pedestal clamp pulse is set to Vb1 and Vb2 with positive and negative symmetry, and the input / output all-stage DC-coupled bias-free drive circuit is a complementary circuit with the above-mentioned positive and negative symmetry for all stages. Spike noise during response can be suppressed. The effect of suppressing the spike noise at the time of the transient response also operates when the high-voltage power supplies HV1 and HV2 are varied when there is no input signal.

で は In a general linear amplifier, the drive circuit consisting of Q1 to Q8 is composed of a differential amplifier circuit, the operating point when there is no signal is class A, and the bias current when there is no signal is several hundred mA. Since tens to hundreds of drive circuits are used, heat generation is a problem.

Although not shown, at the time of reception for amplifying the in-vivo reflected wave, since the linear amplifier is operating, noise generated from the linear amplifier becomes a problem from the viewpoint of SNR.

In the circuit of the present embodiment, since the drive circuit has a circuit configuration of no input / output DC coupling and no bias, the power consumption when there is no signal is zero (0). Absent. Further, in this embodiment, the drive circuits Q1 to Q8 are composed of positive-negative symmetric complementary symmetric current mirror circuits, and the operating point is fixed to class AB1 by the pedestal clamp pulse. Since it is several tenths when there is no class bias signal, it also has a thermal advantage during transmission for driving a vibrator (not shown).

Next, an example of the circuit configuration of FIG. 4 will be described. In FIG. 4, Q1 to Q12 are transistors, R1 to R19 are resistors, and C1 to C3 are capacitors. This circuit includes a complementary symmetric current mirror circuit including resistors R1 to R10 and transistors Q1 to Q6, a floating shunt regulator circuit including resistors R11 to R13 and transistors Q7 and Q8, resistors R14 to R18, and capacitors C2 and C3. And a complementary symmetric single-ended push-pull circuit consisting of transistors Q9 to Q12, and a feedback circuit consisting of a resistor R19 and a capacitor C1. ). Hereinafter, the operation will be described in detail.

When pedestal clamp pulses Vb1 and Vb2 are generated based on the transmission control signal and are sent to both ends of the transmission control signal input terminals R2 and R3 of the pseudo linear amplifier, respectively, the resistors R1 to R10 and the transistors Q1 to Q6 The operating point of the positive-negative symmetric complementary symmetric current mirror circuit is fixed to the AB1 class. When the operating point of the positive-negative symmetric complementary symmetric current mirror circuit composed of the transistors Q1 to Q6 is fixed to class AB1, the collector of the transistor Q8 is determined based on the voltage generated at the resistors R11 and R12 by the collector current of the transistors Q5 and Q6. Further, a voltage for fixing the operating point of the complementary symmetric single-ended push-pull circuit including the transistors Q9 to Q12 of the next stage to the class AB1 is sent to the emitter.

に よ り By this voltage, the operating point of the complementary symmetric single-ended push-pull circuit including the transistors Q9 to Q12 is fixed to the class AB1. Here, the capacitors C2 and C3 are used for phase correction, and are several pF to several tens pF.

By the above procedure, when the operating point of the input / output DC-coupled bias-free drive circuit is fixed, negative feedback is applied to the input / output by the feedback circuit composed of the resistors R1 and R19 and the capacitor C1. The result is a high-speed negative feedback amplifier of opposite phase. Here, the capacitor C1 is for phase correction, and is of the order of several pF. The amplification factor Av of the circuit is expressed by the following equation.

Av = − (R19 / R1)

Transient response of rising and falling of the pedestal clamp pulse by setting the pedestal clamp pulse to Vb1 and Vb2 with positive / negative symmetry, and using the above-mentioned complementary circuit of all stage positive / negative symmetry with the input / output all-stage DC coupling no-bias drive Spike noise at the time can be suppressed. Other operations are the same as those in FIG.

As described above, according to the above configuration, the drive circuit is configured by a pseudo linear amplifier, and the power consumption when there is no signal is reduced to zero (0), thereby eliminating the problem of heat generation and generating a pedestal clamp pulse. By operating the amplifier as a high-speed negative feedback amplifier only during the period, an input waveform such as an arbitrary waveform such as a pulse wave, a sine wave, and a Gaussian wave can be linearly amplified to a predetermined value, and a vibrator (not shown) can be driven. .

In addition, since a coupling capacitor is not used for the bias of the drive circuit, the recovery time for transient response is very fast, and the spike noise due to the pedestal clamp pulse is reduced by using a complementary circuit with positive and negative symmetry for all stages of input and output. It can be suppressed effectively. Further, since a transformer is not used, downsizing by high-density mounting of circuits, integration of circuits into an integrated circuit, and the like are easy and cost can be reduced.

FIG. 3 is a block diagram of a transmission circuit according to the present invention. FIG. 11 is a block diagram of a transmission circuit according to another embodiment. FIG. 3 is a circuit diagram illustrating a configuration example of a drive circuit. FIG. 9 is a circuit diagram illustrating another configuration example of the drive circuit. FIG. 3 is a diagram illustrating waveforms of respective signals in the circuit. FIG. 11 is a diagram illustrating a conventional circuit configuration example. FIG. 11 is a diagram illustrating another conventional circuit configuration example.

Explanation of reference numerals

{30} pedestal clamp circuit (bias setting circuit), 32} pseudo linear amplifier (drive circuit).

Claims (8)

A bias setting circuit that outputs a pair of bias pulses having positive / negative symmetry having a pulse width corresponding to the original transmission signal,
A drive circuit having a positive-negative symmetric complementary circuit configuration, positive and negative operation periods and operating points are determined by the pair of bias pulses, and a linear amplification of the original transmission signal;
Including
Including a drive power supply connected to the drive circuit,
The drive power supply variably sets a voltage of the drive power supply according to a transmission condition, whereby a level of a transmission signal output from the drive circuit is variably set,
The drive circuit has a circuit configuration in which the operating point of the drive circuit is maintained at a predetermined value by the pair of bias pulses even when the voltage of the drive power supply is varied. The transmission circuit of the device. The transmission circuit according to claim 1,
The transmission circuit of an ultrasonic diagnostic apparatus, wherein the drive circuit includes a circuit that supplies a bias current only for a period corresponding to a pulse width of the pair of bias pulses. The transmission circuit according to claim 1,
The transmission circuit of the ultrasonic diagnostic apparatus, wherein the pair of bias pulses rise before a start point of the original transmission signal by a standby time. The transmission circuit according to claim 1,
The transmission circuit of an ultrasonic diagnostic apparatus, wherein the drive circuit has a circuit for fixedly setting an operating point in a linear amplification region according to a level of the pair of bias pulses. The transmission circuit according to claim 1,
A transmission circuit for an ultrasonic diagnostic apparatus, wherein the drive circuit has a complementary symmetrical circuit configuration in which all stages from an input to an output are DC-coupled. The transmission circuit according to claim 1,
The transmission circuit of the ultrasonic diagnostic apparatus, wherein the drive circuit is a negative feedback amplifier. The transmission circuit according to claim 1,
The bias setting circuit variably sets the level of the pair of bias pulses according to a transmission condition, whereby the operating point of the drive circuit is variably set. . The transmission circuit according to claim 1,
The transmission circuit of the ultrasonic diagnostic apparatus, wherein the voltage of the drive power supply is configured as a voltage value having positive / negative symmetry.

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