Ultrasonic sender chip cipher scheme
Benefit from the thing that employs research and development of physics and electronics on the earth of field positive pole of the medical imaging, especially in the fields such as instrumentation, image are gathered and modeling etc.. Because of having no wound nature at all, supersonic wave occupies the special position in various imaging modes, it has offered a reliable method for the fact that the viscera organ is studied. Ultrasonic technology has been used for the medical purpose already for over half a century. However, such essential apparatus is bulky and costing an arm and a leg and specially using some discrete devices to make recently.
Because the technical progress of semiconductor technology, this kind of trend is changing. Now, can totally make ultrasonic transceiver with semi-conductive IC. IC technology of the low-voltage lets the ultrasonic receiver chip with prominent high gain and low noise performance become reality now. Similarly, on the higher voltage terminal, people pay close attention to driving the manufacture of the sender IC of the ultrasonic transducer day by day. This text has summed up some progress and a great deal of existing challenges of the ultrasonic sender chip design.
The ultrasonic system sums up: Send and receive the function
In brief, the operating principle of the ultrasonic system is to produce the acoustic wave used in patient’s body, then receive and deal with the reflected signal to form the image of patient’s body. Send to to the inner primitive acoustic wave of body producing from a transducer, it is generally electric impulse excitation produced by sender. Similarly, reflect acoustic wave is received by the transducer, then change the form of calling back, deal with the signal got finally, in order to confirm the internal structure of the relevant health placement.
There can be several kinds of different methods in the realization of the transmit path. This route may be made up of a beam forming device and a lot of level converter units, grid drivers and high voltage switches, its output is sent to the ultrasonic transducer. Generally speaking, the transducer is made by the piezoelectric material, it changes high-pressure electric signal into the acoustic wave, namely the final output of the system.
In some systems, in driving the transmit path of the output stage through the digital logic, receive the digital attribute of the holding signal from start to finish. However, you can establish and send signal to the transducer with an analog mode. It involves one and outputs the beam forming device to change into the digital-analogue converter (DAC) which imitates the form . Then, send to the transducer it, simulation amplified the signal used in producinged.
The receive path of the ultrasonic system, has used an analogy method. Because the amplitude of the received signal is well below sending a message, the forward end includes a low-noise amplifier, it is thereafter the control module of a certain gain to noise temperature ratio. After leaching the unrelated high-frequency part, an analog-digital converter (ADC) of signal passing Change into the digital form, but the output of this analog-digital converter is dealt with by beam forming device.
The other chiefs of the ultrasonic transceiver system include one carry on the mutual multiplexer to a plurality of passway activities, and one is controlled between transducer and transceiver electronic element signal flowrate is accepted / sent the switch. A key function accepted / sent the switch is to protect the receiver during sending the incident, because send the incident and involve the line voltage of high sending, it is higher than the endurance of the receiver module far.
The ultrasonic system requires: The transmit path challenges voltage range and operating frequency
Ultrasonic systems described can produce various signal pictures to meet the modal requirement of different imaging up till now. Under the extreme range, you can get B-type revealing and harmonic imaging and employ the high pressure (60- 100V) required , low duty ratio (0.5- 2.0%) Signal. Under another extreme condition, can obtain the continuous wave (CW) Undervoltage that the Doppler type imaging mode requires (3- 10V) , 100% of the duty ratio signals.
In other words, under the corresponding duty ratio condition, require the sender circuit of the ultrasonic system to produce & plusmn in 1- 20MHz fundamental range; 3V ± Output voltage of 100V.
Obviously, & plusmn that the sender exported; 100V needs some high voltage switches. When the sender includes one IC, this kind of requirement is changed into the high voltage transistor, and optimize it in order to bear the great electric field. Likewise, they are in undervoltage ‘ <10V) , CW ,
The wide-range of the output voltage is not the only difficult problem of making the ultrasonic sender device, and more challenges.
Conversion rate
According to voltage excursion and operating frequency range mentioned before, the sender must produce the conversion rate up to 8V/ns. Combine 100& Omega which represents the transducer; And 300pF model runs side by side and supports, the knowing sender will offer the transient current close to 3A in most harsh cases.
Harmonic distortion
It is a kind of sine signal that the ideal of the ultrasonic sender is outputted, it meets the highest voltage amplitude and operating frequency requirement. You can produce a rectangular pulse, but not establish such analog signal different to produce. The ones that are limit to the transducer are low-pass after straining wave property, this kind of pulse is reduced to only his harmonic the first several. In other even harmonics, the second harmonic wave is generally the root of the trouble. So, the inhibited quantity of the second-harmonic becomes the main Q factor of the ultrasonic sender.
Pulse symmetry and zero adjustment
The symmetry that we can understand ocularly the ultrasonic sender outputs is required. However, it is that an outcoming signal is not be a long impulse train that here needs understanding thoroughly. It may include a form positive pole and negative pole pulse pair, it is 0V before and after pulse pair. Likewise, the quality that the signal belongs to to 0V becomes essential. Sometimes, it is known as ” The damping ” The function, and have a enormous impact on some ultrasonic modes, for example, it is harmonic imaging of the main information source,etc. that the human body is non-linear.
So belong to to and 0V belonging to from plus pulse from minus pulse speed of speed become, determine the intersection of outcoming signal and linear factor of quality to take place by symmetry and they of 0V.
On resistance
It is essential to operation of the ultrasonic sender to output the resistance of the transistor-resistor logic under the conducting state. First of all, the on resistance has determined the rise or fall time of the outcoming signal with load, it presumes accessible output frequency. Secondly, power consumption of its direct influence. According to the above-mentioned voltage and current range, during sending the incident in supersonic wave, will present a large amount of power consumption. The intensity of this kind of power consumption depends on high pressure and low duty ratio and CW Doppler type imaging modal undervoltage and it of working continuously in situations such as B mode revealing or harmonic imaging,etc. Interaction of one.
The other important performance parameters of the ultrasonic sender system also include shaking and phase noise of the outcoming signal, and the delay between the passways is matched.
Appearance of the semiconductor
In the past few decades, semiconductor engineering was foundations that communication and computer industry are progressive. Now, they will bring the similar break-through to medical technology soon, especially in imaging will be employed. Supersonic wave is no exception, it witnesses and transfers from the discrete system that is used to using to a ongoing movement such as totally Integrated semi-conductive chip type solution. Because its inherent high speed, low power consumption and co dominant of small volume, semi-conductive IC can help the intersection of medical imaging and manufacturer shorten their product listing time, realize portability of terminal installation, improve product reliability and characteristic, keep the controllability of the cost at the same time.
Now, can realize and accept / send and accept / send the switch function by one piece IC solution. Some usable IC senders can produce & plusmn up to 8V/ns conversion rate at present; 100V output voltage, and the second harmonic distortion less than 40dBc. Through the active damping framework, can realize pulse symmetry and fast zero adjustment. For example, TX734 of TI is a sincere & plusmn; 90V, & plusmn; 2A, 3 grades, 4 passways, integrated senders with active damping function. This integrated ultrasonic pulse generator and AFE5851 ‘ A section of 16 passways of analog front end chips) And TX810 (a section of 8 passways are accepted / sent the switch) It is the example of the ultrasonic system IC solution.
In the past few decades, the medical imaging field made a lot of great progress. Act a kind of special role in the progress in ultrasonic technology, through proving it as a great deal of one kind of applied common diagnostic tools. These are in extensive application range, learn the imaging of blood vessel from the obstetrical department, the syringe needle in some procedures is guided, even include the treatment of some benign and malignant tumour. Semi-conductive IC technology is supporting the development of this kind with a kind of increasingly quick paces. Because of the appearances of various IC, have realized all main functions of the ultrasonic system, thus let the masses of clinician and other users enjoy important technical progress such as portability, high Kell factor and high product reliability.
Tags: DAC, discrete device, medical science, supersonic wave, The semiconductor
