阅读说明：本技术 一种功率放大电路、方法及装置 (Power amplification circuit, method and device ) 是由 刘士敏 毛晟竹 马韩平 于 2019-10-08 设计创作，主要内容包括：一种功率放大电路,其用于低压驱动的聚焦超声治疗装置,包括：功率驱动模块,所述功率驱动模块又包括第一放大单元和第二放大单元,所述第一放大单元和第二放大单元具有一共同输出端；主控模块,用于控制正周期信号在所述第一放大单元的开通时间、关断时间,以及控制负周期信号在所述第二放大单元的开通时间、关断时间,使得所述共同输出端的输出信号无交越失真。此外,还通过超声监控模块的反馈,消除了内部存在的器件固有误差以及因为压电陶瓷自身工艺、后期二次打磨等造成的各种实际大规模生产时存在的误差,同时消除了高频信号回波叠加时产生的波形干扰,并直接补偿因为左右超声通道和设备电源干扰带来的幅值影响,确保输出的功率和频率的高精度及输出波形的平衡对称及稳定。(A power amplification circuit for a low voltage driven focused ultrasound therapy device, comprising: the power driving module comprises a first amplifying unit and a second amplifying unit, and the first amplifying unit and the second amplifying unit have a common output end; and the main control module is used for controlling the turn-on time and the turn-off time of the positive periodic signal in the first amplification unit and controlling the turn-on time and the turn-off time of the negative periodic signal in the second amplification unit, so that the output signal of the common output end has no cross-over distortion. In addition, the inherent errors of devices in the ultrasonic monitoring module and the errors in various actual large-scale production caused by the piezoelectric ceramic self process, the secondary polishing in the later period and the like are eliminated through the feedback of the ultrasonic monitoring module, the waveform interference generated when high-frequency signal echoes are superposed is eliminated, the amplitude influence caused by the interference of a left ultrasonic channel, a right ultrasonic channel and an equipment power supply is directly compensated, and the high precision of the output power and the frequency and the balance, symmetry and stability of the output waveform are ensured.)

1. A power amplification circuit comprising:

the power driving module comprises a first amplifying unit and a second amplifying unit, and the first amplifying unit and the second amplifying unit have a common output end;

the main control module is used for controlling the turn-on time and the turn-off time of the positive periodic waveform in the first amplification unit and controlling the turn-on time and the turn-off time of the negative periodic waveform in the second amplification unit so as to adjust the time sequence of the positive periodic waveform and the negative periodic waveform;

the first ultrasonic monitoring module (A) is connected with the first amplifying unit and the second amplifying unit to obtain amplified signals, pre-corrected preceding stage error data of the first amplifying unit and the second amplifying unit are obtained by comparing actual waveforms of a previous period with reserved reference data in the main control module, and the main control module adds corresponding preceding stage error compensation in advance;

and the second ultrasonic monitoring module (B) is arranged at the rear stage of the ultrasonic transducer to obtain an actual output signal of the ultrasonic transducer, and the output of the second ultrasonic monitoring module is connected with the main control module, and the main control module is used for correcting the error of the actual output signal of the ultrasonic transducer.

2. The power amplification circuit of claim 1, wherein: also included is a signal generation unit for generating an ultrasonic reference signal comprising a positive periodic signal and a negative periodic signal.

3. A power amplifying circuit according to claim 1 or 2, wherein: the first ultrasonic monitoring module (A) samples and obtains the start-stop time of the actual negative periodic waveform, and the main control module moves forward the opening time of the negative periodic waveform according to the turn-off time of the positive periodic waveform, so that gapless connection between the positive periodic waveform and the negative periodic waveform is realized.

4. A power amplification circuit according to claim 3, wherein: the main control module carries out phase shift and amplitude compensation by quickly and finely adjusting the frequency of the output signal in real time, so that the balance symmetry and stability of the output waveform are ensured.

5. A power amplification method for amplification of a drive signal in a low voltage driven focused ultrasound therapy device, comprising the steps of:

ultrasonic reference signals comprising positive periodic signals and negative periodic signals are subjected to frequency division synthesis and then input into a power driving module, and the signals subjected to frequency division synthesis are amplified by a first amplifying unit and a second amplifying unit of the power driving module respectively and then output amplified signals through a common output end;

acquiring an amplified signal through a first ultrasonic monitoring module (A), and comparing an actual waveform of a previous period with reserved reference data in a main control module to obtain preceding stage error data needing to be subjected to pre-correction by a first amplification unit and a second amplification unit;

the preceding stage error data is input into the main control module, the main control module adds the corresponding preceding stage error compensation into the subsequent ultrasonic reference signal in advance, and simultaneously, the negative period phase is advanced according to the actual turn-off time of the positive and negative period waveforms of the previous period; the method specifically comprises the following steps: and controlling the on-time and off-time of the positive periodic waveform in the first amplification unit and controlling the on-time and off-time of the negative periodic waveform in the second amplification unit by the main control module.

6. The power amplification method of claim 5, wherein: the process of obtaining the preceding-stage error data specifically includes: the first ultrasonic monitoring module (A) samples and obtains the start-stop time of the actual negative periodic waveform, and the main control module moves forward the opening time of the negative periodic waveform according to the turn-off time of the positive periodic waveform, so that phase shift is carried out, and gapless connection between the positive periodic waveform and the negative periodic waveform is realized.

7. The power amplification method of claim 6, wherein: the amplification process comprises: the first amplification unit and the second amplification unit are mirror image amplification units with the same or different amplification factors, and the positive periodic signals and the negative periodic signals are amplified by the same or different amplification factors.

8. The power amplification method of claim 5, wherein: further comprising the steps of: the second ultrasonic monitoring module (B) is arranged at the rear stage of the ultrasonic transducer to obtain the actual output signal of the ultrasonic transducer, the output end of the second ultrasonic monitoring module (B) is connected with the main control module, and the main control module is used for correcting the error of the actual output signal of the ultrasonic transducer.

9. The power amplification method of claim 8, wherein: the correction process of the main control module specifically comprises the following steps: the main control module carries out phase shift by quickly fine-tuning the frequency of the output signal in real time, so that the error correction of the actual output signal of the ultrasonic transducer is realized; in addition, the fine adjustment and correction of the signal amplitude are carried out to ensure the balance symmetry and stability of the output waveform.

10. A portable ultrasonic therapy apparatus comprising the power amplification circuit of any one of claims 1 to 4 and an ultrasonic transducer.

Technical Field

The invention relates to the technical field of medical instruments, in particular to a power amplification circuit, a method and a device, and more particularly relates to a method and a circuit capable of being driven at low voltage and eliminating crossover distortion, and a portable focused ultrasound treatment device driven by the circuit.

Background

In an ultrasound system, the output waveform of the power amplification circuit can significantly affect the performance of the ultrasound transducer. In a push-pull amplifying circuit adopted in a conventional power amplifying circuit, due to the existence of a triode or a field effect transistor and junction voltage or conduction voltage, certain crossover distortion often occurs in an output waveform of the amplifying circuit, so that an ultrasonic transducer works in a distortion state, and the influence is serious in a high-frequency signal circuit, particularly the influence on a MHz-level signal is obvious, and even the output efficiency of the piezoelectric ceramic transducer is reduced, the quality of an ultrasonic signal is reduced and the like.

In order to avoid cross-over distortion, a fixed direct current bias is usually added to a base circuit or a gate circuit of a triode or a field effect transistor in the prior art, so that the base circuit or the gate circuit is in a micro-conduction state. However, as the temperature of the triode or the field effect transistor rises, the on-resistance changes, and the fixed dc bias directly affects the linear amplification region of the triode or the field effect transistor, thereby reducing the amplification performance of the push-pull amplification circuit. And because the existence of direct current bias in the circuit, no matter the triode or field effect transistor is in the conducting state or the cut-off state, the triode or field effect transistor is in the little conducting state for the consumption is high, and greatly reduced life.

In addition, in the actual production process, because of errors of capacitance and impedance, the 2 amplifying units (A, B) of the push-pull amplifying circuit cause the amplitude, the phase and the turn-off time of the 2 amplifying units to be different, and the difference causes the cross-over distortion to be asymmetric and have uncertainty.

In addition, in the actual production process of each circuit board, the piezoelectric ceramics have errors of all levels caused by self-process, secondary polishing in the later period and the like, and the inherent errors of devices such as capacitors and resistors in the circuit, errors caused by environmental changes such as temperature and humidity and external interference and the like, so that the output ultrasonic signals are different even if the same waveform is applied.

Moreover, due to the interference of the ultrasonic echo signal, when the ultrasonic echo signal is coincidently superposed and offset with the transmitted ultrasonic treatment signal, the waveform of the actually required ultrasonic treatment signal is seriously interfered, the intensity of the local ultrasonic treatment signal is reduced, and the treatment effect is influenced.

The fluctuation of the error/circuit can cause the multiplied fluctuation of the actual focusing point power of the ultrasonic signal, and the precision requirement of the focused ultrasound on parameters such as terminal power, waveform and the like is higher, so that the accurate adjustment must be quickly responded, the additional influence of the error on the treatment process of the patient is reduced, and the safety and the adaptability of the product are improved.

In general therapeutic ultrasound, such as planar ultrasound, this phenomenon is partially acceptable in low-power therapeutic equipment, but in high-power ultrasound therapy, especially focused ultrasound therapy, when the total output variation is about ± 15% due to the unstable state of the front end, the influence of the energy fluctuation of ultrasound focusing to a point on human tissues and cells is very serious, and even cannot be used. Therefore, a circuit with high stability is urgently needed to ensure the reliability and safety of the output.

Further, the piezoelectric ceramic wafer is difficult to compress and easy to expand, and a method for solving the asymmetry of contraction and expansion of the piezoelectric ceramic wafer is required to ensure the balance and symmetry of the output waveform.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The invention provides a power amplifying circuit, which is used for a low-voltage driven focused ultrasonic therapeutic device and comprises: the power driving module comprises a first amplifying unit and a second amplifying unit, and the first amplifying unit and the second amplifying unit have a common output end; and the main control module is used for controlling the turn-on time and the turn-off time of the positive periodic signal in the first amplification unit and controlling the turn-on time and the turn-off time of the negative periodic signal in the second amplification unit, so that the output signal of the common output end has no cross-over distortion.

As in the foregoing power amplification circuit, the first amplification unit and the second amplification unit are mirror amplification units with the same or different amplification factors.

The power amplifying circuit as aforementioned, further comprising a signal generating unit for generating an ultrasonic reference signal comprising a positive periodic signal and a negative periodic signal.

As in the foregoing power amplification circuit, the main control module adjusts the timing sequence of the positive and negative periodic waveforms by controlling the on-time and off-time of the first amplification unit and the second amplification unit.

The power amplifying circuit further comprises a first ultrasonic monitoring module (a), wherein the first ultrasonic monitoring module (a) is connected to the first amplifying unit and the second amplifying unit to obtain amplified signals, and pre-stage error data of the first amplifying unit and the second amplifying unit, which needs pre-correction, is obtained by comparing the actual waveform of the previous period with the reserved reference data in the main control module, so that corresponding pre-stage error compensation is added in advance.

As for the power amplification circuit, the first ultrasonic monitoring module a samples and acquires the actual start-stop time of the negative periodic signal of the previous period, and the main control module moves forward the on-time of the negative periodic signal according to the off-time of the previous positive periodic signal to realize gapless connection between the positive periodic signal and the negative periodic signal, thereby avoiding crossover distortion.

As mentioned above, the main control module performs phase shift and amplitude compensation by quickly and finely adjusting the frequency of the output signal in real time, so as to ensure the balance and stability of the output waveform.

As in the foregoing power amplifying circuit, the signal generating unit includes a programmable waveform generator U8, a first digital-to-analog conversion U2, a second digital-to-analog conversion U3, two first-stage operational amplifiers U4A, U5A, a resistor R7, and a resistor R9; the reference signal generated by the programmable waveform generator U8 enters the first amplification unit via the first digital-to-analog conversion U2, the first stage operational amplifier U4A and the resistor R7, and enters the second amplification unit via the second digital-to-analog conversion U3, the other first stage operational amplifier U5A and the resistor R9.

As for the power amplification circuit, the first amplification unit includes a second-stage operational amplifier U4B, a third-stage operational amplifier U6, a resistor R15, and a transistor Q1;

the second amplifying unit comprises another second-stage operational amplifier U5B, another third-stage operational amplifier U7, a resistor R16 and another triode Q2.

The power amplifying circuit is also provided with a second ultrasonic monitoring module B, the second ultrasonic monitoring module B is arranged at the rear stage of the ultrasonic transducer to obtain an actual output signal of the ultrasonic transducer, the output of the second ultrasonic monitoring module B is connected to the main control module, and the main control module obtains an error compensation parameter according to the comparison between the actual output waveform and a stored theoretical original waveform, so as to correct the error of the actual output signal of the ultrasonic transducer, thereby correcting the overall error caused by the individual difference of the whole circuit device during mass production.

As mentioned above, the main control module performs phase shift and amplitude compensation by quickly and finely adjusting the frequency of the output signal in real time, so as to ensure the balance and stability of the output waveform.

The invention also provides a portable ultrasonic therapy device which comprises the power amplifying circuit and the ultrasonic transducer.

Further, the present invention provides a power amplifying method for amplification of a driving signal in a low voltage driven focused ultrasound treatment apparatus, comprising the steps of:

(1) inputting an ultrasonic reference signal comprising a positive periodic signal and a negative periodic signal into a power driving module, wherein the positive periodic signal and the negative periodic signal are respectively amplified by a first amplifying unit and a second amplifying unit of the power driving module and then output amplified signals through a common output end;

(2) acquiring an amplified signal through a first ultrasonic monitoring module A, and comparing an actual waveform of a previous period with reserved reference data in a main control module to obtain preceding stage error data needing to be subjected to pre-correction by a first amplification unit and a second amplification unit;

(3) the front stage error data is input into the main control module, and the main control module calculates out front stage error compensation according to the front stage error data and adds the corresponding front stage error compensation in advance so as to eliminate crossover distortion of output signals; wherein the compensation addition specifically comprises: and the main control module is used for controlling the on-time and the off-time of the positive periodic signal in the first amplification unit and controlling the on-time and the off-time of the negative periodic signal in the second amplification unit.

In the power amplification method, in the step (3), the first ultrasonic monitoring module a samples and acquires the start-stop time of the actual negative periodic signal, and the main control module moves forward the turn-on time of the negative periodic signal according to the turn-off time of the positive periodic signal, so as to realize gapless connection between the positive periodic signal and the negative periodic signal, thereby avoiding crossover distortion.

As for the aforementioned power amplification method, in step (1), the first amplification unit and the second amplification unit are mirror amplification units with the same or different amplification factors, and amplification with the same or different amplification factors of the positive periodic signal and the negative periodic signal can be achieved.

The power amplification method further comprises a step (4), wherein the second ultrasonic monitoring module B is arranged at the rear stage of the ultrasonic transducer to obtain an actual output signal of the ultrasonic transducer, the output end of the second ultrasonic monitoring module B is connected to the main control module, and the main control module is used for calculating an error of the actual output signal according to the actual output signal and correcting the error so as to correct an overall error caused by individual difference of the whole circuit device during mass production.

As for the aforementioned power amplification method, in step (4), the main control module performs phase shift by quickly fine-tuning the frequency of the output signal in real time, so as to implement error correction on the actual output signal of the ultrasonic transducer.

As mentioned above, in the power amplifying method, in step (4), a fine adjustment correction on the signal amplitude is further included to ensure the balance and the stability of the output waveform.

Based on the technical scheme, the invention has the following advantages:

1. the problem of hardware crossover distortion is solved.

2. The errors of the whole circuit caused by the errors of capacitors and resistors at all levels in the whole circuit in mass production and the errors caused by the self process of the piezoelectric ceramics, the secondary polishing at the later stage and the like are eliminated, and the consistency of output signals is ensured.

3. The waveform interference generated during echo superposition is eliminated, the error influence caused by the interference is directly supplemented, and the high precision of the output power and frequency and the balance symmetry and stability of the output waveform are ensured.

Drawings

Fig. 1 is a flow chart of a power amplification method provided by the present invention.

Fig. 2 is a schematic structural diagram of a power amplifying device provided by the present invention.

Fig. 3 is a circuit diagram of a power amplifier circuit according to the present invention.

Detailed Description

The technical contents of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention.

As shown in fig. 1, the present invention provides a power amplification method for amplification of a driving signal in a low voltage driven focused ultrasound treatment apparatus, and includes the steps of:

(1) ultrasonic reference signals comprising positive periodic signals and negative periodic signals are subjected to frequency division synthesis and then input into a power driving module, and the signals subjected to frequency division synthesis are amplified by a first amplifying unit and a second amplifying unit of the power driving module respectively and then output amplified signals through a common output end; the first amplification unit and the second amplification unit are mirror image amplification units with the same or different amplification factors and are used for amplifying positive periodic signals and negative periodic signals with the same or different amplification factors so as to ensure that the final output ultrasonic signals have the same positive and negative amplitudes. In practical application, the expansion and contraction coefficients of the piezoelectric ceramic wafer are different, and in addition, the characteristic parameters of the wafer are changed along with the change of working power, so that the amplitude of the final output ultrasonic signal is equal in positive and negative through the adjustment of real-time amplification factor.

(2) The amplified signal is obtained by the first ultrasonic monitoring module A, and the preceding stage error data of the first amplifying unit and the second amplifying unit which need to be subjected to pre-correction is obtained by comparing the actual waveform of the previous period with the reserved reference data of the I2C in the main control module U1.

(3) The front error data is input into the main control module U1, the main control module U1 calculates the front error compensation according to the front error data, adds the corresponding front error compensation into the subsequent ultrasonic reference signal in advance, and simultaneously leads the phase of the negative period to advance according to the actual turn-off time of the positive and negative periodic waveforms of the previous period so as to eliminate the crossover distortion of the output signal; wherein the compensation addition specifically comprises: the on-time and the off-time of the positive periodic waveform in the first amplification unit and the on-time and the off-time of the negative periodic waveform in the second amplification unit are controlled through a main control module U1. The first ultrasonic monitoring module A samples and acquires the start-stop time of the actual negative periodic waveform, and the main control module U1 moves forward the opening time of the negative periodic waveform according to the turn-off time of the positive periodic waveform, so that gapless connection between the positive periodic waveform and the negative periodic waveform is realized, and thus crossover distortion is avoided.

And (4) arranging a second ultrasonic monitoring module B at the rear stage of the ultrasonic transducer to obtain an actual output signal of the ultrasonic transducer, connecting the output end of the second ultrasonic monitoring module B to the main control module U1, and calculating an error of the actual output signal and correcting the error by the main control module U1 so as to correct an overall error caused by individual differences of the whole circuit device during mass production. The main control module U1 performs phase shift by quickly and finely adjusting the frequency of the output signal in real time, so as to correct the error of the actual output signal of the ultrasonic transducer.

In addition, the signal amplitude is subjected to fine adjustment and correction so as to ensure the balance and the stability of the output waveform.

The invention also provides a focused ultrasound treatment device, as shown in fig. 2, comprising a power amplifying circuit and an ultrasound transducer; the power amplification circuit is used for a low-voltage driven focused ultrasound treatment device, and comprises: signal generation unit, power drive module, master control module U1, ultrasonic transducer etc..

The signal generating unit is used for generating an ultrasonic reference signal comprising a positive periodic signal and a negative periodic signal.

The power driving module also comprises a first amplifying unit and a second amplifying unit, and the first amplifying unit and the second amplifying unit are provided with a common output end; the first amplification unit and the second amplification unit are mirror image amplification units with different amplification factors, so that the positive and negative equality of the amplitude of the finally output ultrasonic signal is guaranteed in hardware.

The main control module U1 adjusts the timing sequence of the positive and negative periodic waveforms by controlling the on-time and off-time of the positive periodic waveform in the first amplification unit and the on-time and off-time of the negative periodic waveform in the second amplification unit, so that the output signal of the common output end has no cross distortion.

The ultrasonic transducer is used for converting the driving signal output by the power driving module into an ultrasonic therapy signal.

The focused ultrasound treatment device also comprises a first ultrasound monitoring module A which is connected with the first amplification unit and the second amplification unit to obtain amplified signals, and pre-stage error data of the first amplification unit and the second amplification unit which need pre-correction is obtained by comparing the actual waveform of the previous period with the reserved reference data of I2C in the main control module U1, so that the corresponding pre-stage error compensation is added in advance. The first ultrasonic monitoring module A is used for sampling to obtain the start-stop time of an actual negative periodic waveform, and the main control module U1 moves forward the opening time of the negative periodic waveform according to the turn-off time of the positive periodic waveform to realize gapless connection between the positive periodic waveform and the negative periodic waveform, so that crossover distortion is avoided.

As shown in fig. 3, the signal generating unit includes a programmable waveform generator U8, a first digital-to-analog conversion U2, a second digital-to-analog conversion U3, a first stage operational amplifier U4A, a first stage operational amplifier U5A, a resistor R7, and a resistor R9. The programmable waveform generator U8 generates a reference clock source, generates an ultrasonic reference signal, divides the frequency in the main control module U1, and then enters a first amplification unit through a first digital-to-analog conversion U2, a first-stage operational amplifier U4A and a resistor R7, and enters a second amplification unit through a second digital-to-analog conversion U3, a first-stage operational amplifier U5A and a resistor R9.

The power driving module comprises a second-stage operational amplifier U4B, a second-stage operational amplifier U5B, a third-stage operational amplifier U6, a third-stage operational amplifier U7, a resistor R15, a resistor R16, a triode Q1 and a triode Q2. The second-stage operational amplifier U4B, the third-stage operational amplifier U6, the resistor R15, the triode Q1 and the like form a first amplifying unit. The second-stage operational amplifier U5B, the third-stage operational amplifier U7, the resistor R16, the triode Q2 and the like form a second amplifying unit.

The first amplification unit and the second amplification unit are mirror image amplification units with identical amplification factors. At the moment, the asymmetry problem of contraction and expansion of the piezoelectric ceramic wafer is solved by means of software adjustment. Such as: amplitude compensation is performed by the master control module U1. Further, as described above, the amplification factors of the first amplification unit and the second amplification unit may be set to be different, so that the asymmetry problem of the contraction and expansion of the piezoelectric ceramic wafer is solved in hardware, and the balance symmetry of the output waveform is ensured.

The focused ultrasound treatment device also comprises a second ultrasound monitoring module B which is arranged at the rear stage of the ultrasound transducer to obtain the actual output signal of the ultrasound transducer and output the actual output signal to the main control module U1, and the main control module U1 is used for calculating the error of the actual output signal according to the actual output signal and correcting the error so as to correct the overall error caused by the individual difference of the whole circuit device during mass production.

In addition, the main control module U1 performs phase shift and amplitude compensation by quickly and finely adjusting the frequency of the output signal in real time, so as to ensure the balance and stability of the output waveform.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.