In addition, the development of craft of profit from low power comsumption, high-powered silicon, module of pretreatment of partial beam synthesis is already compositive at general imitate or processor of number of appropriative of and rather than of mixture signal chip. In the meantime, advanced high speed serial or it is wireless interface reduced systematic position greatly complex degree, and can will as far as possible much RF data changes a system compositive chip (SOC) , CPU or GPU. The application of current and supersonic technology also is diagnosed from specific radiology expand, the real time other the bed is monitored and each domains such as examination of on the spot of medical treatment spot.

 

This applied guideline summed up the framework of supersonic system and principle, analysed the note that the system devises, summed up the advanced technique that uses at supersonic chip, explained medicine finally the imitate parameter of supersonic chip.  

 

1.Medicine exceeds acoustic imaging

 

Ultrasonic is the sound wave of 20KHz of prep above of a kind of frequency. Medicine exceeds acoustic imaging system to often use 1 MHz the frequency to 20 MHz, can achieve inferior millimeter class resolution. The first Taiwan businessman is used exceed acoustic imaging system to be born at 20 centuries 70 time, can offer real time 2D brightness or gray scale image. Nowadays, exceed acoustic imaging to depend on the advantage of security, cost effectiveness and real time respect, had become important medicine to become like the technology. Medicine exceeds sound system to be able to monitor infantile development effectively, also can use at diagnosing the disease of the splanchnic organ such as heart, hepatic, cystic, milt, pancreatic, kidney, bladder.

 

Typical supersonic system includes to press circuit of electric transducer, electron, image to show unit and DICOM (medical number is become resemble and correspond) compatible software. Of typical and supersonic system simplify block diagram is shown as follows.

 

Graph 1. Of typical and supersonic system simplify block diagram

 

2.Sound wave produces the principle with transmission

 

Supersonic transducer is the crucial component of supersonic system, by the component that suppress report, connector and composition of the structure that prop up. Piezoelectric effect is the phenomenon that the physical dimension that points to some kind of material follows the electric field that bring to bear on and changes, vice versa. Following place are shown, the most transducer in supersonic applying is double in all mode. Transducer is blasting off (mode) during change electric energy into mechanical energy. The mechanical wave of generation travels to medium, if medium is inhomogenous,can reflex. In receiving mode, receive catoptric machinery weaveform and become telegraphic name by transducer changeover.

 

Graph 2. Transducer vibration, sound wave travels and reflex

 

In transducer by electronic drive later, can generate sound wave and travel in medium. In medicine supersonic in, FDA (management board of food medicines and chemical reagents) the requirement is all the limitation that becomes contented like the system instantaneous, peak value and average strength.

 

We insert transducer sensitivity or transducer loss normally (IL) the definition is receive (Rx) and blast off (Tx) the rate between signal extent, following place show:

 

 

Transducer frequency decides by the Cm of velocity of sound in the ply of L of the material that suppress report and material:

 

 

The place before be like is narrated, commonly used frequency limits comes for 1MHz 20MHz. Be based on afore-mentioned equation, relatively the data with high-frequency transducer weaker need. Accordingly, compose builds extremely high frequency transducer to have certain challenge sex.

 

Transducer frequency is answered or bandwidth is another crucial parameter. As general regulation, be like transducer by pulse signal (namely short aiguille) incentive, the duration that receives echo decided the bandwidth of transducer. Have answer lickety-split (namely short echo) transducer is broadband transducer, vice versa. Normally in great majority application actor chooses wider bandwidth. Below same transducer frequency, broadband transducer can implement better axial resolution, because echo length decided the axial resolution of supersonic system. Meanwhile, broadband transducer applies to harmonic to become picture, become in this like mode next supersonic energy blast off with fundamental frequency, and image rebuilds by 2 harmonic that receive echo. If do not have the circumstance of wide bandwidth transducer to fall, transducer sensitivity nods 2f0 place to drop significantly in its overtone frequency. Because a lot of this transducer researcher are ceaseless exploration new material, new framework and new workmanship with improving transducer performance further.

 

In the inchoate level that exceeds acoustic imaging, the circuit of much passageway electron that is used at supersonic system already costly immature. Become through mechanical scanning means by electric machinery drive like sheet blast yuan transducer is used extensively at achieving 2 dimension (2D) image. Because the speed of rigid structure and precision are restricted, inchoate system cannot realize tall frame to lead or high accuracy is become picture. Nowadays, mature array transducer and technology of much passageway electron are supportable 64 go to 512 blast yuan transducer. With the electron scanning can be obtained for the foundation be as high as>100 frame / the image of the second. To realize electronic scanning, beam synthesizes a technology to apply at the beam of focusing transducer. Beam complex detail is falling discuss in the section. Become with optics similar like the system, supersonic system can implement optimal space resolution in focusing focus place. Basis application, one dimension (1D) array transducer includes array of sex of linear array, curved curve and phasic array. The main distinction between these transducer depends on structure of figuration of beam of light, into like limits and picture resolution. In addition, the transducer of newest 2D array that comprises by more than 2000 component is supportable real time is three-dimensional (3D) into picture. Place laying a plan is shown for sheet blast transducer of array of yuan of transducer, 1D and 2D array transducer.

 

Graph 3. Typical transducer. (A) single element transducer; B) 1D array transducer; (C) 2D array transducer (offer by USC, Vermon and Philips) .

 

3.Transducer index and picture quality

 

Mix any becoming similar like the system, picture quality is medicine exceeds the important level in acoustic imaging. Dimensional resolution mixes such as to resemble penetrating wait for collective parameter to basically pass wave of transducer index harmony to transmit theory to decide. Those who exceed acoustical image is fore-and-aft with transverse resolution and medium medium sound wave wavelengh becomes linear concern:

 

 

In equation, c is the velocity of sound in medium, zf is focal length, 2r is transducer aperture or diameter. When transducer by pulse signal drive when, τ-6dB is those who receive echo – the duration of 6dB pulse width. τ-6dB also concerns into linear with wavelengh λ . To broadband array transducer, we can compare the transverse resolution of 5MHz and 12MHz respectively, its job frequency comes for 5MHz 14MHz. Into it is 5 centimeters like deepness. Below two kinds of circumstances, 64 transducer blast yuan form effective aperture. The span between component is 0.3mm. The velocity of sound in medium is 1540m/s. Effective aperture dimension is 19.2mm. According toformulary, to the sound wave of 5MHz and 12MHz, λ is 0.31mm and 0.13mm respectively. According to afore-mentioned equation, transverse resolution is 0.8mm when 5MHz respectively, 0.33mm is when 12MHz. Accordingly, more the resolution with high-frequency application much better implementation.

 

Actually, be not through increasing transducer frequency to improve picture quality only completely feasible. On one hand, more the data suppressing report with high-frequency transducer weaker need, this needs more accurate production technology, and cost is higher. On the other hand, be like from the back paragraphic place is shown, relatively high-frequency sound wave is light in biology organization damply.

 

When medium is inhomogenous, the partial energy of sound wave can be in reflection in the border of two medium. Not catoptric sound wave continues to travel, be reflexed in next border till it, or complete attenuation. Reflection and transmission coefficient are fought by the acoustic resistance of these two kinds of medium (Z=ρc) difference decision. In equation, the density that ρ and C are medium respectively is harmonic fast, way of hypothesis wave transmission is perpendicular at border.

 

 

The watch is shown 1 times choose biology organization, water and airy character for place. Strong reflex signal can appear below the circumstance that differs extremely in two sound impedance. Skeletal density is high, velocity of sound is fast; Accordingly it always exceeds the strong reflex in acoustical image to organize implement. On the other hand, blood and hepatic acoustical impedance are similar, the reflex between these two kinds of organizations is very accordingly weak. Have the signal with the transducer ability faint collect of tall sensitivity only. If the watch is shown 1 times, signal is transmitting attenuation of the meeting in the process. Accumulate attenuation to increase as the addition that transmits a distance. With equation 7 computation attenuation, among them coefficient 2 reflected sound wave two-way transmission.

 

 

In the representative application that probes the organization inside body in ultrasonic, the dynamic limits between the echo that comes from human body surface and the echo that come from in-house organ exceeds 100dB very easily. We can assume average attenuation coefficient is 0.7dB/MHz×cm and 7.5MHz transducer. Be in the deepness place of 10cm, be based on equation 7, namely 7.5×0.7×10×2dB, the attenuation of computational earning 105dB. Hypothesis surface echo is 1Vpp, the extent of echo of the organ inside body is <10uVpp, very weak. This give typical examples shows supersonic signal has surface of skin of token of ability of extremely wide dynamic range to come the difference of the physiology structure of splanchnic organ. Because this needs complex electronic circuit in order to offer enough dynamic range, and this is not easy implementation below the budget of finite power comsumption.

 

Express 1: The model organizes the acoustics character with medium

 

4.Exceed acoustic imaging mode

 

When transducer receives echo, proper processing unit need changes these signal into ultrasonic to examine the apprehensible picture news of division or other and final user. Exceed acoustic imaging to use a few kinds to become will study an organization like mode feature, humoral distributing reach function of flow, organ to wait.

 

A mode and B mode

 

In the earliest supersonic system, the range that adopts indication echo and meantime region information will coach clinical diagnose. Namely A mode (amplitude mode) exceed acoustic imaging system, following plan institute are shown, it with one dimension progressive scanning is a foundation, . Because human vision is right image is more sensitive, because this development brightness or gray scale are become,resemble mode having more active clinical sense. Build 2D image for compose, need the beam in transducer of the scanning on location, and travel of scanning of many A mode is obtained during scanning. These scanning make one frame picture all right, the echo extent along scanning beam with linear or nonlinear means map arrives to be worth like element. The beam when transducer is enough when undertaking quickly scanning, can realize real time image. These image are called B mode (brightness mode) image, its established image of as parallel as scanning direction a cross section.

 

Graph 4. Scanning mode. (A) A mode scanning goes, (B) B mode image, (C) 3D beam scanning, and (D) B mode (child graph 1, 2, 3) with 3D (child graph 4) clinical image (offer by Philips)

 

The generation on sound system exceeds in newest commerce recently noveller and noveller into like mode (if 3D and 4D are become,resemble) , these are B mode expands into what resemble. 3D is become resembling is the overlay that gets picture of mode of B of many cross section with beam of scanning of 2 dimension means, as above pursues (C) and (D) be shown. In addition, 4D is become resemble be being become to resemble for real time 3D by the definition.

Duopule is supersonic

 

Most clinical and supersonic system includes another essential feature: Duopule is supersonic the information of going from place to place that uses indication blood. The Doppler effect described the wavelengh deflection that brings about as a result of the target motion in medium. If blast off from the acoustical source that is far from observer wave, criterion its wavelengh increases, vice versa. Accordingly, when sound wave travels and be reflexed by the athletic goal inside body, emissive pulse and the wavelengh that receive echo are different. This difference on the frequency is much general straps frequency to move, can use at the speed of computational mobile:

 

 

In equation, it is much general straps frequency to move, f0 is the central frequency of emissive pulse, c is the velocity of sound in medium, θ is the angle between supersonic beam and mobile.

 

Duopule is supersonic early in 20 centuries 50 time already were used at medical application. Current, it can evaluate blood stream and constituent movement. In going 60 years, a variety of much general strap a technology to provide different diagnostic information, include successive wave (CW) Duopule, pulse (PW) Duopule and chromatic much general are strapped. These much general strap the presence is bigger application difference between mode.

 

Graph 5. Successive wave (CW) Duopule measures configuration

 

Successive Boduopule is the technology that uses the earliest, much general of the extraction in connecting the echo that associate receives namely straps drift frequency to come true. Its measure institute of plan of setting as above to show, two transducer Tx and Rx were used in measuring. When Tx emits successive wave, rx receives the echo that comes from any reflector. For example, if Tx sends cosine wave to medium, criterion Rx detects those who come from mobile reflector move frequency cosine signal:

 

 

Among them the central frequency that ωc is transducer, ωd is the Duopule that introduces by mobile frequency moves (can extract through coming with first detector demodulation) . This kind of technology is measurable cause as a result of heart valve leak extremely high speed blood stream, and the blood stream of extremely low rate inside deep vein. To settle the challenge of the low phasic noise of CW circuit and low thermal noise, normally CW access needs alone imitate to handle circuit. . The place before be like is narrated, the axial resolution of supersonic image depends on echo pulse width. In CW operation, pulse width is infinity; Axial resolution is very accordingly poor, perhaps saying is to axial blood stream information is done average. Transverse resolution depends on the focusing area of two transducer coincide. Normally, the main drawback that CW measures is its finite space precision, because CW also can detect,have nothing to do to what irrelvant area arises signal. Generally speaking the function of CW module is system of divisional high end and low end crucial index of the system.

 

Graph 6. Duopule measures pulse configuration

 

Pulse (PW) much general straps a technology at 20 centuries 60 time are born, in order to solve the problem with CW space poor resolution. PW Duopuleji is become at similar B pattern like the setting, accordingly it is former B exceed a department to consolidate a new function. Demodulation and sampling maintain a technology to be used at extraction to spread information. PW much general straps systematic experiment to install institute of as above plan to show. In this system, need a transducer only, and shadow region region is shown went out by the axial resolution of transducer (pulse duration) the example bulk that decides with transverse resolution. Normally, transducer repeats frequency with specific cycle (PRF) send signal of 4-16 periodic sine, receive reflection signal. Be moved mediumly by blood stream as a result of reception signal of particle (like red blood cell and leucocyte) scattering, because of this time the reflection echo of 1 1 with time the reflection echo of 2 2 phasic appreciably are different. Magnify to receiving signal to undertake and handle in order to extract phase shift frequency. With CW Duopule is compared, PW Duopule detects finite be interested in area (ROI) medium velocity of flow, also use at B mode to become at the same time with transducer in all among them picture. Handle software through revising signal, much like PW of the implementation on platform general can be become to strap a function in B mode.

 

In pattern is being carved with PW much general in CW, spreading information is obtained from inside beam of a focusing, be similar to A mode to become picture. In 20 centuries 80 time, the 2 dimension information that researcher is based on chromatic much general to strapped a technology to finish blood stream to distributing is visible. Chromatic much general straps processing also is to be based on B mode / method of PW mode signal. From be interested in area to collect data of much frame RF. Because be interested in the blood in area,flow brings about image data difference exists between frame. inside the country the each other in auto-correlation and time domain is relevant two kinds of algorithm can extract data variance from inside RF data (namely blood stream speed and directional information) : . The color gradual change that the basis defines beforehand the blood stream information that corresponding ground map includes speed and direction. Normally, blue and gules code identify front and the blood stream that are far from transducer shift respectively. Use brighter color when velocity of flow increases, vice versa. The 2D of color map distributings from beginning to end overlay is on B mode image, show at the same time with real time individual anatomize structure and blood stream. It to diagnosing cardiovascular disease, if blood-vessel is out-of-the-way with heart valve countercurrent, extremely useful. Duopuletu resembles typical color as follows pursueing be shown, (B) the blood stream velocity of flow that shows carotid stricture is caused changes.

 

Graph 7. Many general straps color to resemble: (A) the image that with color Duopule and CW mode acquire (offer by Philips) ; (B) the chromatic much general that shows carotid stricture is strapped (offer by GE)

 

Duopule remains color an active research domain. Well-known, processing technology needs powerful computational capability related auto-correlation and each other. Developing new algorithm to analyse blood stream with inferior computational cost. Meanwhile, the newest progress of technology of profit from semiconductor, the digital signal processor that has lower power comsumption and taller computation capacity is applying at this domain.

 

Other into resemble mode

 

It is the mainest in supersonic system that much general of Duopule, PW straps B mode, CW and chromatic much general is strapped into resemble mode. What in be being diagnosed daily below brief introduction, we often use is other into resemble mode in order to get more comprehensive clinical information

 

Athletic mode (M mode) it is to be based on B mode; It can capture inside period of time the heart moves, indicate the function of blemish valve or ventricular antrum room.

 

Constituent harmonic is become picture (THI) at 20 centuries 90 time begin popularity, now is the standard in new system is become resemble mode. Harmonic signal travels by the sound wave in the organization lack fidelity and generation. In THI, extract these harmonic to improvement, bogus resembling decreases and believe a confusion of voices in order to implement image contrast and resolution to compare (SNR) increase. From 20 centuries 90 time end is mixed at the beginning of 21 centuries since, the technology such as encode drive also develops somewhat and application arrives clinical. Total place Zhou Zhiliang’s good axial resolution needs short pulse duration (namely low emissive sound energy) , and to increase SNR, we hope to increase pulse duration. Match filter and incentive code through what optimize, we still can make code incentive long pulse implements the axial resolution with short similar pulse.

 

By the gas of biology safety / the radiography agent that small bleb comprises can raise SNR and contrast significantly, because these small bleb are perfect acoustics reflector. Radiography agent increases to resemble conducing to a heart and vessels diagnosing. In addition, these small bleb are had than normal organization stronger nonlinear feature, apply to harmonic to become picture.

 

Medicine is supersonic it is a kind of safety and the medicine of low cost is become like the method, it is the good complement of MRI, optics and PET system. Become more can use every to be planted like mode system complementary like mode actor inferior position compositive in order to obtain optimal diagnostic information. For example, smooth acoustic imaging can penetrate the deepness that exceeds acoustic imaging into what resemble with optics tall contrast is united in wedlock. MRI leads another give a demonstration that supersonic cure is much mode method.

 

5. ultrasonic electronics

 

Undermentioned block diagram represents typical supersonic system. Main component includes high pressure to launch front of imitate of circuit, low noise, blast off and signal of circuit of receiver beam synthesis, number is handled unit, image shows and location and circuit of other form a complete set.

 

Graph 8. The block diagram of circuit of typical and supersonic electron

 

Supersonic emissive circuit and receive circuit

 

In current system, much passageway emitter is used at incentive array transducer. Become according to practicable like mode, emissive voltage comes in ±2V change between ±100V. Sometimes, to reduce systematic cost, switch of multichannel of use high pressure goes to switch of an emitter passageway much transducer component. Arrive in low end in in carrying a system, the high pressure that chooses to be based on square wave launchs circuit, because they are had tall compositive spend and low cost. In high-end system, amplifier of sex of high tension line can generate all sorts of complex weaveform. On transducer, high-pressured transmit and low-pressure echo are concomitant. Accordingly, t/R switch circuit is located in between high-pressured emissive circuit and low noise amplifier, its are main the function is amplifier of protective low pressure. Supersonic signal can transmit distance or time according to its and remarkable attenuation. Accordingly, in receiver, gain increases as supersonic transmission time and increase. This one main character calls time gain to compensate (TGC) , the tension that normally need shows as follows controls amplifier (VCA) . After enlarge and pretreatment, digitlize signal and deliver receiver beam synthesizer or successive wave (CW) Duopule handles unit, among them limits of frequency of first detector extraction (20Hz arrives 20KHz) medium much general straps signal.

 

Graph 9. Use at voltage of time gain compensatory to control amplifier

 

In going 30 years, equipment of supersonic front electron already upgraded from schism circuit for integrated circuit chip. Solution of front of of all kinds ultrasonic simplifies to the system is designed and reduce cost greatly.

 

Consider the extreme of equipment of supersonic front electron asks, for example > 100dB dynamic limits and 20Hz~>GHz job frequency, every small improvement needs to be on transistor class, chip class, circuit board class and systematic level undertake many research and development works. As similar as system of most mixture signal, good imitate output is the foundation of follow-up signal processing and picture improvement in quality from beginning to end. Low power comsumption, low noise and compact dimension are the first consideration matter that supersonic front electron designs.

 

Beam synthesizer

 

Beam synthesizer includes to blast off and receive beam synthesizer to realize electronic focusing and control many beam of yuan of transducer. , following plan institute are shown from a transducer blast yuan of distance to the target and from another blast yuan of distance to the target is different; Because this is in,send, be aimed at every blast yuan appropriately the signal that defer sends, emitter signal reachs a goal at the same time and highest sound intensity arises in order to make in target place, get the strongest echo namely. In receive level, the echo that receives through the butt joint uses proper delay, come from many transducer in order to realize linear overlay blast yuan echo, in order to realize highest sensitivity.

 

Graph 10. Use at be in (A) emissive photograph and (B) the transducer beam synthesizer that receives beam of the focusing in the photograph

 

Because send radio means,basically be numeric, because this emissive defer implementation is,pass the spot but array of process designing door (FPGA) or digital signal processor (DSP) wait for high speed tally to finish. Because receive the complexity of signal, receive beam synthesizer to need more algorithm to optimize apparently be able to come true. Inchoate be based on signal of circuit of schism transistor electron to handle ability finite. Accordingly, the imitate defer line that receiver beam synthesizes beam synthesizer to be combined in order to be based on inductance capacitance will come true. In 20 centuries 80 time, receiver beam synthesizer begins to use much passageway modulus to change chip and technology of digital beam synthesis.

 

Graph 11. Digital beam synthesizer is graphic

 

Sound system exceeds in current main trend in, receiving beam synthesizer is numeric commonly. Digital beam synthesizer is in normally the FPGA that has extremely high computation capacity, DSP, PC or GPU (graphical processing is unit) in implementation. The place before be like is narrated, bigger transducer aperture can implement much better resolution. Accordingly, sound system exceeds in high end in, 256 transducer component forms beam of light of a focusing, in order to acquire careful resolution image. The computational capability that needs because of synthesizer of beam of this high end is quite complex.

 

Biology organization exists in the respect such as appearance, density, velocity of sound heterogeneous sex. Computation of real time defer and the acoustics character that calibration can be based on an experience to organize and appearance. As a result of the importance that beam synthesizer designs and complexity, most ultrasonic company has his IP. Below the situation that does not affect beam to form function, simplify design of beam entity become a useful person remains a popular topic. Believe to grinding the supersonic system that delivers new beam synthesizer framework to will be used extensively at future.

 

Digital signal is handled

 

Supersonic signal needs many signal processing, so that extract each from inside primitive and supersonic data,become the information that wants like mode place. Main processing module includes B mode image to rebuild, spectrum information extracts the Duopule that is based on fast Fourier commutation, be based on auto-correlation and the color related each other coordinate of scanning of computation, supersonic image changes Duopule (2D is supersonic. Current, business uses processor, be like the spot but array of process designing door (FPGA) , digital signal processor (DSP) , be used extensively, . FPGA makes the system designs personnel to be able to undertake connecting a line forcedly to in-house and logistic door, optimize its algorithmic efficiency. On the other hand, DSP designs personnel to offer the standard computation module that defines beforehand for the system, can be changed in real time and optimize their algorithm. Change character, FPGA with hardware efficiency get victory, and DSP with software flexibility be in sb’s good graces. New signal processor, be like PC and GPU; FPGA of their computational ability prep above and DSP, and software development cost is mixed under FPGA greatly DSP however, as a result of the tall power comsumption of PC and GPU, they do not suit low power comsumption certainly portable system.

 

6.Imitate front chip devises medium craft alternative

 

Before any AFE are designed, semiconductor technology choice is the note of principal and crucial consideration that is based on design target from beginning to end. CMOS and BiCMOS craft are the most commonly used craft in design of supersonic imitate front. They have its oneself advantage each times medium, and apply to corresponding circuit piece.

 

BiCMOS (ambipolar CMOS) craft compares pure ambipolar technology at present more welcome, the high-powered ambipolar transistor that because it is included,is used at imitate design and the CMOS cell that are used at digital design. Ambipolar transistor applies to low noise amplifier to design, have exceed low 1/f noise, wide bandwidth and good power comsumption / noise efficiency. Bipolar craft still reduced circuit electric capacity, in order to obtain good total harmonic lack fidelity. Accordingly, be based on ambipolar or the amplifier of BiCMOS craft is comparing the amplifier that is based on CMOS craft so small that same function comes true below much area and lower power comsumption.

 

The 0.35um BiCMOS craft of heart state apparatus is used at research ambipolar affect with the function that amplifier designs between CMOS parts of an apparatus. Next graphs (A) make clear, the amplifier that is based on ambipolar transistor is in identical slanting can realize lower noise below buy electric current; It still explains ambipolar transistor is had exceed character of low 1/f noise, this is crucial to having modulation and the Duopule application that see tone circuit; (B) compare with similar CMOS design, ambipolar design reduced an area significantly. Of course, because the diagnostic dimension of semiconductor technology is reduced, in the area difference decrescent between 0.35um BiCMOS craft and <0.35um CMOS craft. However, will tell commonly, as a result of afore-mentioned advantages, 0.35um BiCMOS craft is extremely comfortable still design at amplifier.

 

Graph 12. Be based on CMOS and the comparison that BiCMOS craft designs

 

Have more number content and switch element when circuit (like middling speed ADC) when, CMOS craft suits more. Medicine is supersonic signal frequency lies inside 1~20MHz limits, its ADC sampling is led normally under 100MSPS, at present most CMOS craft can be handled easily. Use 0.18um~65nm CMOS technology, ADC design can come true much better compositive reduce with power comsumption. In addition, compare with comparable BiCMOS craft photograph, CMOS craft cost is normally lower, and the production with shorter implementation is periodic. All these ADC designs in showing CMOS craft applies to supersonic AFE.

 

Anyhow, should reduce noise / power comsumption is main goal when, the TGC amplifier in AFE of comfortable Yu Chaosheng designs BiCMOS technology, press namely accuse amplifier (VCA) design. On the other hand, CMOS craft is in the implementation in ADC design low power comsumption is mixed tall compositive spent good choice. Come in 0.18um especially the node of 65nm, compare with photograph of 0.35um BiCMOS craft, the cost that the CMOS technology that has library of complete and low-pressure number can have competition ability is obtained taller compositive degree.

 

Apparent, the combination of BiCMOS VCA and CMOS ADC can achieve <0.8nV/rtHz of a noise, the solution of outstanding imitate front of power comsumption <150mW/CH. This kind of combination needs special semiconductor technology not only, still need to enclose a technology advancedly. Place laying a plan is shown for solution of an imitate front, in same two chip are had in enclosing. Actually, OK still and compositive the chip of two above and many passive component. In addition, much chip module (MCM) can provide bigger flexibility for systematic design. For example, if have newer ADC or VCA solution, it can replace a solution in old AFE solution, and still maintain pin to arrive the compatibility of pin, in order to obtain much better function.

 

Graph 13. Much chip module is enclosed

 

In going 10 years, the engineering technology of ultrasonic AFE moves from 0.5um to 90nm, move to be mixed to BiCMOS only from CMOS CMOS, move from odd chip to the many chip that passive element has in enclosing. If plan institute is shown all these technologies reduced power comsumption greatly, promoted property and narrowed chip dimension

 

Graph 14.AFE is compositive spent development

 

7.The main parameter of supersonic imitate circuit

 

Supersonic signal has the characteristic of its oneself. No less than we are advanced and facial of substation discussion in that way, the dynamic range of 100dB exceeds via often can observing in the system. Consist in of circuit of clock of amplifier of circuit of circuit of low frequency frequency, high frequency number, low noise, low noise is same system, same on circuit board or same even chip. AFE design and systematic design must settle these challenges.

 

Overload restores

 

Overload signal is to show high pressure launchs pulse to send and receive switch through high pressure normally (T/R Switch) leak big signal is strong perhaps echo signal. If overload did not consider to restore in AFE design, they can reduce the transient state of LNA, PGA, ADC and CW circuit to answer function. Design personnel is faced with imitate to be below condition of budget of finite power comsumption, inside big dynamic range implementation instantaneous restores to answer and the challenge that answers function to agree. Regard a kind of relatively common design as plan, technology of enough current limliting voltage limiting uses in answering to send and receive switch to design in high pressure above all, the first class that this can eliminate pair of imitate front namely the overload influence of low noise amplifier. In LNA design, clamp diode can prevent LNA farther saturation normally.  

 

Analyse two kinds of common overload cases. Because high pressure sends and receive switch to guide,the first kind is, be in normally considering the dead band time that transcends acoustic imaging 3 control to 5us, because the overload of this supersonic imitate front restores time to must achieve small second measure level, . At present by base the high pressure of MOSFET sends and receive switch processing, allow < only<1Vpp emissive leak is direct; And the high pressure that is based on diode bridge to form sends and receive switch, its leak voltage can amount to 2Vpp. Because this most AFE design is,can process ~2Vpp overload signal, in order to satisfy all sorts of function that send and receive switch. Because come from the big reflex signal of hemal wall,circumstance of another kind of overload is, supersonic imitate front must restore instantly, in order to detect the small echo in blood. The 2nd kind of circumstance is extremely common in Duopule application, its function decided blood stream detects sensitivity and accuracy. Place laying a plan is shown for imitate blood-vessel mural strong echo, it is the reaction of the small signal that comes from blood next. Undermentioned signal has the dynamic range of 60dB, namely the signal of 5 periodic 250uVpp when signal of 5 periodic 250mVpp and 5MHz; Small signal configuration is have 0° or 180° phase shift. Place laying a plan shows the response for supersonic imitate front and 0° and 180° to answer the difference between, in be similar to Duopule application namely phasic detect similar. The extraction of small signal and phasic difference assured the good performance in Duopule application.

 

Graph 15. Overload restores (A) input signal; (B) output signal 

 

Be answered except fast overload and accurate phasic detect besides, for many times the consistency that overload restores to answer is strapped to spectrum much general and chromatic much general straps application also is crucial. Consistent overload restores to be able to reduce the spectrum noise in the system or chromatic noise. Everybody can evaluate consistency through coming from the overload of many signal to answer difference quite.

 

In addition, harmonic is become resembling is the standard configuration in most system. Pulse inverts to resemble be being used extensively. Because this system AFE assures,be opposite pulse and the overload that lose pulse to have semmetry are answered. Finally, in supersonic system often overlay the image of many different types facilitates diagnose, like duplex operation mode, namely B mode changes much general to carve pattern, even 3 in all mode. With. Each working mode use different hair to radio is pressed and occupy what compare for nothing to launch weaveform. Accordingly, AFE need answers two quickly or the different overload signal inside many image string. When mode of sudden switch image, different overload signal should not affect the consistency of AFE overload function.  

 

Duopule applies medium signal and noise modulation

 

Supersonic system is complex mixture signal system, have of all kinds number and imitate circuit. Digital signal and clock signal can disturb the imitate signal of systematic level or chip class. Additionally such as transistor is mixed of diode and so on nonlinear component is adjustable make noise, also can disturb RF signal.

 

Apply in supersonic Duopule in, the modulation effect in the system can affect picture quality and sensitivity. Much general straps signal frequency limits to arrive from 20Hz > 50Khz differs. In the meantime, the sequential signal of many systems also is inside this limits, the clock that be like frame, wait into clock resembling a string. These noise signal can pass ground connection, power source and control pin to enter chip. Study the modulation effect of chip class, be like: (PSMR) it is very important that power source modulation is compared. The noise signal that has certain frequency and range can bring to bear on to go up in power source pin. If be put in modulation effect, can find webbing signal. PSMR states for carrier wave and webbing signal the extent between is compared, following place show:  

 

Graph 16.PSMR (A) with IMD3 (B) description

 

Outside dividing PSMR, 3 rank the interference that make shift (IMD3) it is the crucial parameter that measures performance of mixture signal IC. In the meantime, in supersonic applying, with the input that measures at IMD3 signal has distinct range, its are represented respectively come from a static state to organize big echo and the much general that come from blood of going from place to place to strap small signal, its extent difference can be amounted to 20 control to 30dB. Systematic design personnel can use IMD3 to reckon the bogus that by Duopule place of mirror frequency signal produces resembles. Much general straps spectrum to show middling uses the 40 dynamic range to 50dB. Accordingly, the IMD3 of excel 50dBc should not affect systematic performance.  

 

Successive wave (CW) much general straps parameter

 

The crucial function of system of the high end in regarding as, successive Boduopule already began to become the mark of portable system to match. Compare with TGC method photograph, successive wave much general straps method to have the advantage that handles bigger dynamic range and lower phasic noise. In addition, because have these characteristics, beam synthesizes successive Boduopule to come true inside the country in imitate normally. A variety of beam synthesis methods are in supersonic system application, include first detector of passive defer line, active and passive first detector. In going a few years, the successive wave much general that is based on first detector straps a structure to depend on bulk small, come true easily and the good flexibility that supports many CW frequency and hold dominant position gradually. In addition, successive Boduopule beam synthesizer is compositive already go up in as same as TGC method chip. In addition passive first detector reduced power comsumption and noise not only, also satisfied the processing of successive Boduopule to ask, mix like gain of passageway of wide dynamic range, low phasic noise, accurate I/Q phasic match etc.

 

What method block diagram shows simplifying successive Boduopule as follows. Whole CW method includes the converter of electric current of LNA, voltage, passive first detector that is based on switch circuit, area low the adder that connects filter and clock circuit. Most module includes property of strict semmetry mix in phase orthogonal passageway, with realizing good mirror frequency is restrained and beam synthesizes precision.

 

Of graph 17.CW simplify block diagram

 

Undermentioned and graphic the principle that described first detector operation with equation.

 

Graph 18. The block diagram that first detector operates

 

In equation, the input that Vi(t) , Vo(t) and LO(t) are first detector respectively, output and signal of this locality oscillator. Vi(t) includes tall second harmonic; LO(t) represents square wave, its include odd harmonic weight, following type place show:

 

 

The basis is equational, come from LO(t) 3 rank and 5 rank harmonic but with these frequency band in Vi(t) medium 3 rank and 5 rank harmonic or broadband noise photograph modulation. Accordingly, the noise function of first detector can be reduced. To avoid this kind of undesirable effect, be outputted in LNA or harmonic needs to restrain circuit on input of first detector clock, in order to realize much better noise coefficient. According to above equation, the changeover loss of first detector is 20log2/ aboutπNamely – 4dB left and right sides.

 

Excel – 46dBc mirror frequency is restrained is CW into the expectation parameter in resembling. CW I/Q passageway matchs to also can conduce to mirror frequency heft. Document makes clear, the I/Q phasic error of 0.25° is attainable – 53dBc is restrained; And the I/Q gain error of 0.05dB can reach – 50dBc is restrained. They are the design target of CW method. Accordingly, the gain with strict need of CW I/Q method and phasic match. Low tolerance resistor (0.1% ) the active filter that is used at be based on operation amplifier normally.  

 

Le Yipin of typical CW much general arrives at 100Hz between 20KHz. Because mixing is characteristic, the velocity of flow of low blood of phasic noise dominant of CW signal method is spent. Accordingly, most AFE slants to regard main function as index for the CW phasic noise when 1KHz with carrier wave frequency.

 

Finally, the dynamic limits of CW method is based on input reference noise and signal of the biggest input:

 

 

To achieve good CW performance, need > the emitter of 160dBFS/Hz and limits of receiver circuit trends.

 

8.Summary

 

The medicine that exceeding acoustic imaging is a kind of safety is become like mode, have very large latent capacity, . The application other the bed that increasing on the spot checks needs low power comsumption, low noise and compact system. To produce the advantage of supersonic signal adequately, must choose proper technology in order to achieve the goal of low power comsumption, low noise and small size. BiCMOS craft applies to design of low noise amplifier, have exceed low 1/f noise, wide bandwidth and good power comsumption / noise efficiency; And CMOS craft realized high number density below low power comsumption. Both union is used enclose a technology advancedly, can offer the most advanced imitate front solution. To achieve needs ultrasonic parameter, if fast and consistent overload restores, low IMD3 and PSMR, accurate I/Q matchs, successive Boduopule surprises in first detector second harmonic is restrained etc, those who need to consider each parameter in chip to already arrived at a design is integrated optimize.

 

Bibliographical reference

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Xiaochen Xu, “Challenges And Considerations Of Analog Front Ends Design For Portable Ultrasound Systems” , 2010 IEEE Utlrasonics Symposium.  

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Xiaochen Xu, “Impact Of Highly Integrated Semiconductor Solutions For Ultrasound System” , 2016 Transducer Conference, university Of Southern California.

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Xiaochen Xu, etc. “Handbook Of Research On Biomedical Engineering Education And Advanced Bioengineering Learning” , ISBN. 978-1466601222, 2012.