CN112003591A - High-frequency ultrasonic pulse generator and optimization method - Google Patents
High-frequency ultrasonic pulse generator and optimization method Download PDFInfo
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Abstract
The invention relates to a high-frequency ultrasonic pulse generator and an optimization method. The pulse generator includes: the high-speed driving circuit receives the TTL trigger signal and converts the TTL trigger signal into a driving signal; the Marx circuit based on BJT avalanche conduction receives a driving signal, drives the BJT avalanche conduction according to the driving signal and a power supply voltage, and outputs a high-voltage unipolar excitation pulse; the isolation circuit receives the high-voltage unipolar excitation pulse and isolates the ultrasonic echo signal; the transducer impedance matching circuit performs impedance matching on the high-frequency ultrasonic transducer. The optimization method comprises the following steps: establishing a triangular wave model of the high-voltage unipolar excitation pulse; establishing an impulse response model of the high-frequency ultrasonic transducer; traversing the high-voltage unipolar excitation pulses with a certain amplitude, and calculating the peak value and the peak frequency of the ultrasonic signal corresponding to each high-voltage unipolar excitation pulse to obtain a target unipolar excitation pulse; and optimizing the circuit parameters of the high-frequency ultrasonic pulse generator according to the target unipolar excitation pulse.
Description
Technical Field
The invention relates to the field of ultrasonic detection, in particular to a high-frequency ultrasonic pulse generator and an optimization method of the high-frequency ultrasonic pulse generator.
Background
In 1924, according to the principles of capacitor parallel charging and serial discharging, a Marx generator for generating high-voltage pulses through a low-voltage direct-current power supply is provided by e.marx, and the early Marx generator is mainly applied to high-energy physical tests. In the last 50 s, avalanche transistors began to enter the technical field of nanosecond pulses, in the 60 s, people such as Bell, Prince, Hansen and the like developed the research on Marx circuits of avalanche transistors, and Marx generators began to be widely applied to the fields of laser systems, ultra-wideband radars, nuclear physics and the like.
At present, the conventional ultrasonic excitation methods are mainly of two types: (1) a Bipolar Junction Transistor (BJT) or a Field Effect Transistor (FET) forms a high-speed switching circuit to generate high-voltage pulse to excite an ultrasonic transducer, and the excitation method is usually matched with a corresponding Transistor driving circuit; (2) the ultrasonic transducer is directly excited using a high voltage digital pulse generator chip. Due to the limitation of components, the rise time and the fall time of the excitation pulse output by the two conventional ultrasonic excitation methods are dozens of nanoseconds, and the high-frequency ultrasonic transducer cannot be excited well. To excite high frequency ultrasonic transducers, many studies have proposed methods to reduce the unipolar excitation pulse width and edge time, and efforts are being made to generate excitation pulses that are narrower in time domain and wider in frequency domain coverage. Considering that the BJT operates in an avalanche region, the switching speed of the BJT is faster due to the multiplication effect of carriers, Chengolin 1993 adopts a single avalanche transistor 3DB2I to generate a unipolar high-voltage pulse with the pulse width of 5-10ns to excite a high-frequency ultrasonic transducer, but the pulse amplitude and the pulse power of the single avalanche transistor are limited. Jermey A.Brown in 2002 proposes a low-cost and high-performance pulse generator applied to high-frequency ultrasonic imaging, which consists of a three-stage circuit and can output unipolar excitation pulses with the width of 10ns and the amplitude of 110V under the load of 50 ohms. A Jeremy A.Brown method is adopted by Weibao Qiu in 2012, so that a multifunctional reconfigurable pulse generator for high-frequency ultrasonic imaging is realized, and unipolar pulses output by the pulse generator have the 6dB bandwidth of 70MHz, the width of 11ns and the amplitude of 165V. The excitation pulse width output by the research is about 10ns, and in order to well excite the high-frequency ultrasonic transducer with 200MHz or even higher frequency, the pulse generator is required to be capable of outputting excitation pulses with narrower time domain and wider frequency domain coverage.
Disclosure of Invention
The invention aims to solve the defects in the prior art.
In order to achieve the above object, in a first aspect, an embodiment of the present invention describes a high-frequency ultrasonic pulse generator, including: the device comprises a direct current low voltage source, a high-speed driving circuit, a direct current high voltage source, a Marx circuit, an isolation circuit and a transducer impedance matching circuit.
The direct-current low-voltage source provides working voltage for the high-speed driving circuit; the high-speed driving circuit receives the TTL trigger signal and converts the TTL trigger signal into a driving signal; the direct-current high-voltage source provides a power supply voltage for the Marx circuit; the Marx circuit is conducted based on BJT avalanche and is used for receiving a driving signal, driving BIT avalanche conduction in the Marx circuit according to the driving signal and a power supply voltage and outputting a high-voltage unipolar excitation pulse; the isolation circuit receives the high-voltage unipolar excitation pulse, isolates the influence brought by the ultrasonic echo signal and outputs the high-voltage unipolar excitation pulse for eliminating the influence of the echo signal; the transducer impedance matching circuit receives the high-voltage unipolar excitation pulse and performs impedance matching on the high-frequency ultrasonic transducer, so that the output power of the pulse generator is converted into the transmitting power of the transducer as much as possible, and the transmitting efficiency is improved.
In one implementation, the supply voltage approaches the BJT avalanche breakdown voltage of the Marx circuit.
In one implementation, the high-speed driving circuit is composed of a series of multiple-way reverse Schmitt triggers.
In one implementable embodiment, the isolation circuit is comprised of two anti-parallel diodes.
In one implementable embodiment, the transducer impedance matching circuit is an L-type matching circuit.
In a second aspect, an embodiment of the present invention describes an optimization method based on the high-frequency ultrasonic pulse generator in the first aspect, including the following steps:
establishing a triangular wave model of a high-voltage unipolar excitation pulse output by a high-frequency ultrasonic pulse generator; establishing a model of impulse response of the high-frequency ultrasonic transducer by adopting a cosine signal of Gaussian envelope; traversing the high-voltage unipolar excitation pulses with a certain amplitude, and calculating the peak value and the peak frequency of the ultrasonic signal corresponding to each high-voltage unipolar excitation pulse to obtain a target unipolar excitation pulse; and optimizing the circuit parameters of the high-frequency ultrasonic pulse generator according to the target unipolar excitation pulse.
In an achievable embodiment, convolution calculation is carried out on each high-voltage unipolar excitation pulse and impulse response to obtain a peak value and a peak value frequency of a corresponding ultrasonic signal; and determining the target unipolar excitation pulse according to the peak value and the peak frequency of the ultrasonic signal.
In one practical embodiment, the pulse width d of the target unipolar excitation pulse is 0.766/f0Front edge width d1And a back edge width d2Are equal.
The embodiment of the invention has the beneficial effects that: the Marx generator is introduced into the field of high-frequency ultrasonic excitation, and is improved, and a high-frequency ultrasonic pulse generator based on a Marx structure is provided. Aiming at a specific high-frequency ultrasonic application scene, the width and the front and back edges of the unipolar excitation pulse have important influence on the peak value and the peak value frequency of an ultrasonic signal, in order to enable the unipolar excitation pulse output by the pulse generator to be matched with the unipolar excitation pulse and realize optimal excitation, a target unipolar excitation pulse is determined firstly, and then the circuit parameters of the pulse generator are optimized according to the excitation pulse.
Drawings
FIG. 1 is a schematic block diagram of a high frequency ultrasound pulse generator according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for optimizing the high frequency ultrasonic pulse generator according to an embodiment of the present invention;
FIG. 3 is a triangular wave model of a high voltage unipolar excitation pulse of an embodiment of the present invention;
FIG. 4 is a circuit diagram of a Marx circuit and an isolation circuit according to an embodiment of the invention;
FIG. 5 is a diagram of an equivalent circuit for discharging the storage capacitor according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a high speed driving circuit according to an embodiment of the present invention;
FIG. 7 is a waveform diagram of a high voltage unipolar excitation pulse in accordance with an embodiment of the present invention;
fig. 8 is a circuit diagram of a transducer impedance matching circuit according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without any creative effort, shall fall within the protection scope of the present invention.
In the following detailed description of the present invention, certain specific details are set forth in order to provide a better understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details.
Fig. 1 is a schematic block diagram of a high-frequency ultrasonic pulse generator according to an embodiment of the present invention. As shown in FIG. 1, the high-frequency ultrasonic pulse generator comprises a direct-current low-voltage source, a direct-current high-voltage source, a high-speed driving circuit, a Marx circuit, an isolation circuit and a transducer impedance matching circuit.
The DC low voltage source provides a working voltage V to the high-speed driving circuitDD. The direct current high voltage source provides a BJT avalanche breakdown voltage BV approaching to the Marx circuitCESSupply voltage VCC. And the high-speed driving circuit receives the TTL trigger signal, converts the TTL trigger signal into a driving signal and then sends the driving signal to the Marx circuit. The Marx circuit receives the driving signal, drives BIT avalanche conduction according to the driving signal and Vcc, and outputs high-voltage unipolar excitation pulse to the isolation circuit. The isolation circuit receives the high-voltage unipolar excitation pulse, isolates the influence brought by the ultrasonic echo signal and outputs the high-voltage unipolar excitation pulse for eliminating the influence of the echo signal. The transducer impedance matching circuit receives the high-voltage unipolar excitation pulse and performs impedance matching on the high-frequency ultrasonic transducer to generate the pulseThe output power of the transducer is converted into the transmitting power of the transducer as much as possible.
In one possible embodiment, the high-speed driving circuit is composed of multiple-way reverse Schmitt trigger series connection to improve the driving capability. Since the Marx circuit for receiving the driving signal is based on BJT avalanche conduction, triggering BJT avalanche conduction is divided into two processes of delay and rise, and in order to reduce delay and rise time, the driving signal provided by the high-speed driving circuit is required to be a trigger pulse with larger driving voltage, driving current and faster leading edge.
Fig. 2 is a flowchart of an optimization method of a high-frequency ultrasonic pulse generator according to an embodiment of the present invention. As shown in fig. 2, the method comprises the following steps:
step S211: and establishing a triangular wave model of the high-voltage unipolar excitation pulse output by the high-frequency ultrasonic pulse generator.
And establishing a triangular wave model of the high-voltage unipolar excitation pulse x (t) based on the resonance characteristic of the high-frequency ultrasonic transducer. As shown in fig. 3, the start point P of the leading edge of the pulse is determined1Trough P of the pulse2And the end point P of the pulse trailing edge3The pulse leading edge of the high-voltage unipolar excitation pulse is P1And P2The straight line between the two is approximately replaced, the pulse back edge of the high-voltage unipolar excitation pulse is P2And P3The straight line between them is replaced by an approximation, and the high-voltage unipolar excitation pulse is approximated as a triangular wave.
Step S212: and establishing a model of the impulse response of the high-frequency ultrasonic transducer by adopting a cosine signal of the Gaussian envelope.
The impulse response h (t) is expressed as:
wherein, ω is0＝2πf0，f0σ is a constant related to the relative bandwidth B of the high frequency ultrasonic transducer, σ is 3.32/B, and θ is the initial offset phase. For high frequency ultrasonic transducers, the center frequency f0Greater than 20MHz, with a relative bandwidth B of typically 0.3 to 1.0, depending on the center frequency f of the high frequency ultrasound transducer0And taking the initial offset phase theta as 0 to obtain the impulse response h (t) of the high-frequency ultrasonic transducer relative to the bandwidth B.
Step S220: and traversing the high-voltage unipolar excitation pulses with a certain amplitude, and calculating the peak value and the peak frequency of the ultrasonic signal corresponding to each high-voltage unipolar excitation pulse to obtain the target unipolar excitation pulse. Wherein the ultrasonic signal is a convolution of the high-voltage unipolar excitation pulse and the impulse response.
Under the condition of same amplitude, different pulse widths d and front edge widths d are traversed with certain precision1And a back edge width d2High voltage unipolar excitation pulses. And (3) carrying out convolution calculation on each high-voltage unipolar excitation pulse x (t) and the impulse response h (t) to obtain the peak value and the peak frequency of each corresponding ultrasonic signal y (t). And determining the target unipolar excitation pulse according to the peak value and the peak value frequency of each ultrasonic signal y (t).
In one possible embodiment, when the relative bandwidth B of the high frequency ultrasonic transducer is not greater than 0.75, the target unipolar excitation pulse satisfies d ═ 0.766/f0、d1＝d2The peak of the ultrasonic signal can be maximized. At this time, the peak frequency fm of the ultrasonic signal approaches the center frequency f of the high-frequency ultrasonic transducer0(i.e. the frequency difference f between the two)0-fm＜0.1f0) I.e. for determining the peak value and peak frequency of the ultrasound signal of the target unipolar excitation pulse.
In one possible embodiment, when the relative bandwidth B of the high frequency ultrasonic transducer is greater than 0.75, the target unipolar excitation pulse satisfies d ═ 0.766/f0、d1＝d2At this time, although the peak value of the ultrasonic signal can be made maximum, the peak frequency f of the ultrasonic signal at this timemLower so that the peak frequency fmWith the centre frequency f of the high-frequency ultrasonic transducer0Frequency difference f0-fm≥0.1f0. If the peak frequency f of the ultrasonic signal is increasedmThe pulse width d of the target unipolar excitation pulse needs to be appropriately reduced. In particular, pulse reductionSpecific values of the stroke width d, from the predicted peak frequency fmThe specific numerical value of (2) is determined.
Step S230: and optimizing the circuit parameters of the high-frequency ultrasonic pulse generator according to the target unipolar excitation pulse.
In one possible embodiment, the determination of the target unipolar excitation pulse is based on the leading edge width and the trailing edge width of the unipolar excitation pulse.
Leading edge width d of high-voltage unipolar excitation pulse of high-frequency ultrasonic pulse generator1The expression is as follows:
d1＝1.24×2/(2πfα) (formula 2)
Wherein f isαIs the common base cut-off frequency of BJT of Marx circuit in the high-frequency ultrasonic pulse generator. In general, the characteristic frequency f is available from the BJT product ManualT. In BJTs, the characteristic frequency fTCommon base cutoff frequency fαAnd a common-emission cut-off frequency fβThe relationship of (1) is: f. ofα＝(1+β0)fβ，fT＝β0fβWherein, β0The common-emitter current amplification factor at low frequency of BJT is generally about one hundred order of magnitude, so fα≈fTEquation 2 can be written as:
d1＝1.24×2/(2πfT) (formula 3)
From this, the front edge width d1Characteristic frequency f of receiver BJTT. The leading edge width d can be determined by selecting a particular BJT model1So that the leading edge width d1The requirement of target unipolar excitation pulse is met.
After the BJT in the Marx circuit is conducted in an avalanche mode, the equivalent is an on-resistance RNAnd a conduction inductance LNAre connected in series. Taking the 5-stage Marx circuit as an example, as shown in FIG. 4, when BJT (T)1-T5) After the avalanche is conducted in sequence, the energy storage capacitor C1-C5The series connection is rapidly discharged, the equivalent circuit diagram is shown in FIG. 5, the conduction inductance L is omittedNAnd influence of the wire, to obtain an energy storage capacitor C1-C5The total voltage at both ends is expressed as:
wherein R ═ RL+5RN，RL5 is a load resistor, 5 is a Marx structural series, and the total capacity C of the energy storage capacitor is equal to C1//C2//C3//C4//C5In order to increase the discharge speed of the final Marx structure, the final energy storage capacitor C5The capacitance value of (2) is smaller than that of the energy storage capacitors of other stages. Therefore, the capacitor discharge time constant τ is RC (R)L+5RN) C. Thus, the trailing-edge width d of the high-voltage unipolar excitation pulse of the high-frequency ultrasonic pulse generator2The expression is as follows:
d2＝k·τ＝k·(RL+5RN) C (formula 5)
Wherein k is usually 3-5, and the on-resistance RNSmall, on the order of a few ohms to tens of ohms.
It is to be understood that when m-stage Marx structures are present, R ═ RL+mRN，C＝C1//C2//......//Cm，d2＝k·τ＝k·(RL+mRN)·C。
Therefore, the back width of the unipolar excitation pulse is influenced by the energy storage capacitor, and the back edge width of the unipolar excitation pulse can meet the optimal condition by changing the capacitance value of the energy storage capacitor.
In addition, the amplitude of the high-voltage unipolar excitation pulse and the supply voltage VCCThe Marx circuit is related to the number of stages and the energy storage capacitor, and the power supply voltage V can be changedCCAnd/or the Marx circuit stage number eliminates the influence on the amplitude of the high-voltage unipolar excitation pulse caused by the change of the trailing edge width by adjusting the energy storage capacitor.
Example one
The high-frequency ultrasonic pulse generator shown in fig. 1 is constructed and comprises a direct-current low-voltage source, a direct-current high-voltage source, a high-speed driving circuit, a Marx circuit, an isolation circuit and a transducer impedance matching circuit.
DC low voltage source goes highThe fast driving circuit provides a working voltage VDD。
The direct current high voltage source provides a BJT avalanche breakdown voltage BV approaching to the Marx circuitCESSupply voltage VCC。
The high-speed driving circuit is formed by connecting 4 paths of reverse Schmitt triggers in series, receives a TTL trigger signal, converts the TTL trigger signal into a driving signal and then sends the driving signal to the Marx circuit. As shown in fig. 6, the high-speed driving circuit uses 74AHCT14D chip, which is a high-speed silicon gate CMOS device, and can provide up to 6 inversion buffers with schmitt trigger function.
The Marx circuit consists of a 5-level Marx structure, uses BJT as a switch and is based on a supply voltage VCCSo that the BJT can operate in the avalanche region when it is turned on. As shown in FIG. 4, the Marx circuit includes a current limiting resistor RC1-RC5And RE1-RE4NPN type BJT switch T1-T5Dc blocking capacitor C0And an energy storage capacitor C1-C5. Wherein the 1 st-level Marx structure comprises RC1、T1、C0And C1。RC1First end is connected with VCC，RC1Second end is connected with C1First end and T of1Collector electrode of, C0Is connected to a drive signal, C0Is connected to T at the second end1Base, emitter and ground, C1Is connected to the next-level Marx structure (i.e., C)1As the output of the 1 st level Marx structure). The 2 nd-5 th-level Marx structures have the same device connection relationship, the 5 th-level Marx structure is taken as an example for description, and the 2 nd-4 th-level Marx structures are not described in detail. The 5 th-level Marx structure comprises RC5、RE4、T5And C5。RC5First end is connected with VCC，RC5Second end is connected with C5First end and T of5Collector electrode of, T5Base connection T of5Emitter, current limiting resistor RE4The first end of the first-stage Marx structure, the output end of the last-stage Marx structure, and a current-limiting resistor RE4Second terminal of (C) is grounded5Is connected to the subsequent circuit (i.e. C)5The second end of (1) is taken asOutput of a 5-level Marx structure).
It should be noted that, in order to increase the discharge speed of the final-stage Marx structure (i.e. the 5 th-stage Marx structure), the energy storage capacitor C in the final-stage Marx structure5The capacitance value of (2) is smaller than that of the energy storage capacitors of other stages.
As shown in FIG. 4, the isolation circuit is formed by a diode D1、D2And are reversely connected in parallel. Wherein D is1Is connected with D2And C and5second terminal (i.e. output terminal of Marx circuit), D1Is connected to the output terminal of D2And as the output end of the isolating circuit, outputs a high-voltage unipolar excitation pulse. The isolation circuit receives the high-voltage unipolar excitation pulse, isolates the influence brought by the ultrasonic echo signal and outputs the high-voltage unipolar excitation pulse.
When the circuit shown in FIG. 4 is not applying a drive signal, T1-T5In the off state, C1-C5Parallel charging, C1-C5Are all supply voltages VCCSupply voltage VCCNear avalanche breakdown voltage BVCES. After the high-speed driving circuit outputs the driving signal, T1Triggering avalanche conduction, thereafter T2-T5Over-voltage avalanche conduction occurs in turn at the output of the isolation circuit (i.e., D)1Output of) generates a momentary negative high voltage, i.e. a very steep pulse front, after which the energy storage capacitor C1-C5The series connection discharges quickly, and a very steep pulse trailing edge is generated at the output end of the isolation circuit. The discharge equivalent circuit is shown in FIG. 5, where RN1-RN5Are respectively T1-T5On-resistance of LN1-LN5Are respectively T1-T5On-state inductance of R0Is a wire resistance, L0Is a wire inductor, RLIs a load resistor. This produces a high voltage unipolar negative pulse with a narrower time domain and wider frequency domain coverage, and the pulse shape is shown in fig. 7.
As shown in fig. 8, the transducer impedance matching circuit uses an L-type matching network, and impedance matching is achieved by connecting a capacitor C in parallel and a series inductor L in series. The first end of the L is connected with the output end of the isolation circuit, the second end of the L is connected with the first end of the C, the second end of the C is grounded, and the high-frequency ultrasonic transducer is connected with the two ends of the C in parallel. The transducer impedance matching circuit receives the high-voltage unipolar excitation pulse and performs impedance matching on the high-frequency ultrasonic transducer, so that the output power of the pulse generator is converted into the transmitting power of the transducer as much as possible.
Example two
The high-frequency ultrasonic pulse generator of the first embodiment is optimized by the method shown in fig. 2. Determining the load connected with the parallel capacitor C in parallel as a 200MHz high-frequency ultrasonic transducer, and testing to obtain the center frequency f of the high-frequency ultrasonic transducer0177.5MHz, and a relative bandwidth B of 0.726.
According to the centre frequency f of the high-frequency ultrasonic transducer0Determining the pulse width d of the target unipolar excitation pulse to be 0.766/f04.315 ns. And when d is1＝d2The peak ultrasound signal is maximal at 2.158 ns. At this time, the ultrasonic signal peak frequency fmNear the transducer center frequency f0(i.e. f)0-fm＜0.1f0) The ultrasonic signal has an optimum peak value and peak frequency.
Obtained according to equation 3: d1＝1.24×2/(2πfT) 2.158 ns. Thereby obtaining the BJT characteristic frequency fT183.0 MHz. According to the characteristic frequency fTSelecting BJT to determine T in the high-frequency ultrasonic pulse generator of the first embodiment1-T52SC4617 by on semiconductor was used so that the leading edge width of the unipolar excitation pulse satisfied the target unipolar excitation pulse. In particular, the characteristic frequency f of 2SC4617T180MHz, breakdown voltage BVCEO＝50V。
According to equation 5: d2＝k·(RL+5RN) C-2.158 ns. Taking k as 3, RL＝50Ω，RN20 Ω, thereby obtaining C ═ C1//C2//C3//C4//C54.796 pF. In order to increase the final stage discharge speed, a final stage energy storage capacitor C is arranged5Is smaller than the energy storage capacitors of other stages, the high frequency super capacitor of the first embodimentIn acoustic pulse generators C1＝C2＝C3＝C4＝100pF，C55.934pF so that the trailing edge width of the unipolar excitation pulse satisfies the target unipolar excitation pulse.
Through the adjustment, parameter optimization of the pulse generator is completed aiming at the high-frequency ultrasonic transducer, so that the output unipolar excitation pulse is matched with the high-frequency ultrasonic transducer, and the optimal excitation effect is achieved.
The embodiment of the invention provides a high-frequency ultrasonic pulse generator and an optimization method, which introduces a Marx generator into the field of high-frequency ultrasonic excitation, improves the Marx generator and provides the high-frequency ultrasonic pulse generator based on a Marx structure. Aiming at a specific high-frequency ultrasonic application scene, the width and the front and back edges of the unipolar excitation pulse have important influence on the peak value and the peak value frequency of an ultrasonic signal, in order to enable the unipolar excitation pulse output by the pulse generator to be matched with the unipolar excitation pulse and realize optimal excitation, a target unipolar excitation pulse is determined firstly, and then the circuit parameters of the pulse generator are optimized according to the excitation pulse.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, so that it should be understood that the above-mentioned embodiments are only one of the embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A high frequency ultrasound pulse generator, characterized in that the pulse generator comprises:
the direct-current low-voltage source is used for providing working voltage for the high-speed driving circuit;
the high-speed driving circuit is used for receiving the TTL trigger signal and converting the TTL trigger signal into a driving signal;
the direct-current high-voltage source is used for providing power supply voltage for the Marx circuit;
the Marx circuit is based on BJT avalanche conduction and used for receiving the driving signal, driving the BJT avalanche conduction in the Marx circuit according to the driving signal and the power supply voltage and outputting a high-voltage unipolar excitation pulse;
the isolation circuit is used for receiving the high-voltage unipolar excitation pulse, isolating the influence brought by an ultrasonic echo signal and outputting the high-voltage unipolar excitation pulse for eliminating the influence of the echo signal;
and the energy converter impedance matching circuit is used for receiving the high-voltage unipolar excitation pulse influenced by the isolated ultrasonic echo signal and carrying out impedance matching on the high-frequency ultrasonic energy converter so as to convert the output power of the pulse generator into the transmitting power of the high-frequency ultrasonic energy converter.
2. The pulser of claim 1, wherein the supply voltage approaches a BJT avalanche breakdown voltage of the Marx circuit.
3. The pulser of claim 1, wherein the high-speed drive circuit is comprised of a series of multiple-way reverse schmitt triggers.
4. A pulse generator as defined in claim 1, wherein the isolation circuit is comprised of two anti-parallel diodes.
5. A pulse generator as defined in claim 1, wherein the transducer impedance matching circuit is an L-type matching circuit.
6. An optimization method based on the high-frequency ultrasonic pulse generator according to claim 1, characterized in that the method comprises the following steps:
establishing a triangular wave model of the high-voltage unipolar excitation pulse output by the high-frequency ultrasonic pulse generator; establishing a model of impulse response of the high-frequency ultrasonic transducer by adopting a cosine signal of Gaussian envelope;
traversing the high-voltage unipolar excitation pulses with a certain amplitude, and calculating the peak value and the peak frequency of the ultrasonic signal corresponding to each high-voltage unipolar excitation pulse to obtain a target unipolar excitation pulse;
and optimizing the circuit parameters of the high-frequency ultrasonic pulse generator according to the target unipolar excitation pulse.
7. The method according to claim 6, wherein the amplitude is constant, the high-voltage unipolar excitation pulses are traversed, a peak value and a peak frequency of the ultrasonic signal corresponding to each high-voltage unipolar excitation pulse are calculated, and a target unipolar excitation pulse is obtained, and the method specifically comprises:
performing convolution calculation on each high-voltage unipolar excitation pulse and the impulse response to obtain a peak value and a peak value frequency of the corresponding ultrasonic signal; and determining the target unipolar excitation pulse according to the peak value and the peak value frequency of the ultrasonic signal.
8. The method according to claim 6 or 7, wherein the target unipolar excitation pulse has a pulse width d of 0.766/f0Front edge width d1And a back edge width d2Are equal.
9. The method of claim 8,
the width d of the leading edge1The expression is as follows:
d1＝1.24×2/(2πfT)
wherein f isTIs the characteristic frequency of BJT in the high-frequency ultrasonic pulse generator.
10. The method as claimed in claim 8, wherein after the BJT avalanche conduction in the HF ultrasonic pulse generator, each Marx stage of the Marx circuit in the HF ultrasonic pulse generator is equivalent to an on-resistance RNAnd a conduction inductor LNAnd the energy storage capacitor are connected in series;
the width d of the back edge2The expression is as follows:
d2＝k·τ＝k·(RL+mRN)·C
wherein k is constant, τ is the discharge time constant of the energy storage capacitor, RLThe voltage is a load resistor, m is the stage number of a Marx structure in the Marx circuit, and C is the total capacity of m energy storage capacitors in the Marx circuit.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103633964A (en) * | 2013-02-27 | 2014-03-12 | 中国科学院电子学研究所 | High-reliability large-power nanosecond narrow pulse generating circuit |
| CN103888015A (en) * | 2014-04-17 | 2014-06-25 | 厦门大学 | High-density high-energy electric pulse generating device for aging treatment |
| CN108365743A (en) * | 2018-02-09 | 2018-08-03 | 上海理工大学 | A kind of Multi-path synchronous trigger circuit of the negatively charged pressure biasing of Magnetic isolation type |
-
2020
- 2020-08-26 CN CN202010871996.9A patent/CN112003591B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103633964A (en) * | 2013-02-27 | 2014-03-12 | 中国科学院电子学研究所 | High-reliability large-power nanosecond narrow pulse generating circuit |
| CN103888015A (en) * | 2014-04-17 | 2014-06-25 | 厦门大学 | High-density high-energy electric pulse generating device for aging treatment |
| CN108365743A (en) * | 2018-02-09 | 2018-08-03 | 上海理工大学 | A kind of Multi-path synchronous trigger circuit of the negatively charged pressure biasing of Magnetic isolation type |
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