Ultrasonic portable device Systems Division as well as future trends

In the early 1990s, portable phones were all the rage, with the rapid development of electronic technology, today's mobile phone can send emails and text messages, take pictures, check stock prices, schedule a meeting; of course, also can be anywhere in the world to talk to anyone.

Also in the medical field, previous so-called portable ultrasound system was mounted on the trolley for easy dragging; but today's medical ultrasound system is also continuing to miniaturization, and doctors referred to as the "new stethoscope".

Portable ultrasound system trends

Due to the excellent function, ultrasound markets on ultrasound system portability have very high requirements.

Portability of upgrade can not provide reliable power for remote applications using these devices, such as remote villages of clinical medical, emergency medical services, large animals, as well as bridges, large machinery and petroleum pipeline inspection, etc.

Ultrasound system can be divided into high, medium, low.

High-end ultrasonic system uses the latest technologies, meet the latest market requirements, and provide the best possible image quality. Midrange ultrasound system without sacrificing image quality, often have some of the high-end ultrasonic system. While the volume of the low-end ultrasound system is generally smaller, usually applied to clinical application-specific medical, etc. Ultrasonic signal links

Medical ultrasound beam forming is defined as the signal phase alignment and summation, the signal generated from a common source, but from multiple Ultrasonic sensors at different points in time.

In the CWD (continuous Doppler) path, the receiver channel summation phase and to extract a consistent information. Beamforming has two functions: one is the direction to the sensor, which is enhancing its gain; another is to define the body of the focus, the focus is echo location (Figure 1).

For Beamforming, you can use two distinct ways, that is, simulation Beamforming (ABF) and digital Beamforming (DBF).

ABF and DBF system the primary difference between the way complete Beamforming, either way you'll need a good match between channels. ABF is used in the "analog delay line" and the sum, which only needs one (very high) high-speed ADC. In the DBF system that requires multiple high speed and high resolution ADC. Sometimes in ABF system before using logarithmic amplifier ADC to compress the dynamic range. In the DBF system, should be as close as possible sensor unit acquisition signals and signal delay and numbers.

Because digital IC performance for very high speed continuous improvement, in collecting data, digital storage and the sum is the "perfect", so the match between channels is perfect; through the FIFO data in different locations in sum, you can easily form multiple beam and more flexible for these advantages, most modern image acquisition ultrasound systems often use DBF, besides analog delay line channel matching between the often poor, the number of delay taps are restricted and must be used to fine-tune the circuit.

But on the other hand, the ABF and advantages and disadvantages between the DBF is relative. Relative to the ABF, DBF requires multiple high speed and high resolution ADC (pulse Doppler requires approximately 60 dB of dynamic range, so you need at least 10 bit ADC), and the ADC sample rate has a direct impact on the resolution and the phase delay between channels regulating accuracy, the higher the sampling rate, the finer the phase delay; also because the use of multiple ADC and digital beam forming ASIC, so power consumption is high. System partition strategy

Although already exists many advanced electronics technology, but the design of ultrasonic system remains extremely complex.

For many years the manufacturer through design custom ASIC for complex systems. The solutions often include two ASIC, which covers the TGC path and Rx/Tx main part of the path, as shown in Figure 2. In a multiple-channel ADC and DAC VGA, widely used before this method is very common. The custom circuit allows designers to join some cheap and flexible features. Due to the integrated most of signal links, reduces the system uses a number of external components, the solution cost is low; but its disadvantage is that, over time, the development of lithography technology makes these ASIC can not meet the further decrease the volume and power consumption requirements. ASIC has a large number of gate circuits, their digital technology cannot function for integrated simulation and optimization; only a limited number of suppliers can custom ASIC devices, this will cause the designer to face some bottlenecks.

Ultrasound system portability are limited, but it is feasible.

Even so, this is the resolution of the system partition problem important first step. Portability refers not only to the volume of products, but also in terms of battery life, because these circuits on the requirements of the power consumption is very high. With four channels, and eight-channel TGC, ADC and DAC, volume and power consumption has been further reduced, but also with the new address portability system. Multi-channel devices allow designers to construct systems that are sensitive to the circuit in two or more printed circuit boards, you can reduce the system volume, and facilitates multiple development platforms, the reuse of the circuit. But this method also has drawbacks, system volume decrease also dependent on the system partition, multi-channel devices may make the PCB wiring is extremely cumbersome, forcing designers to use channel number fewer devices, for example from eight-channel ADC becomes a four-channel ADC and if the system volume is smaller, but also bring about the heat problem.

With the full path to the further integration of TGC, multiple channels, multiple component integration make design easier, this is because their PCB size and power consumption requires further reduced.

With more advanced integration of extensive use, can further reduce the cost and number of suppliers, system volume and power consumption. Reduce the heat emission system, can prolong laptop battery life in the cell. ADI company AD9271 ultrasound subsystem in order to meet the compact designed it with Mini-14 of 14 mm× mm× 1.2 mm package, each full of TGC channel 40 MSps down power consumption of only 150 mW. AD9271 use serial I/O interface to reduce PIN number, so that each channel has a total area of at least 1/3 reduction, power consumption is at least 25%. But in AD9271 can't meet each ultrasound system designers. The ideal solution would be more functional unit integrated into the probe, or make it as close to probe components. Note: the cable connecting the probe unit on dynamic range some adverse effects, and costs are relatively high. If the front-end electronics relatively close probe, you can reduce the impact of the loss of signal sensitivity of the probe, allows designers to reduce the system requirements of the LNA. You can also integrate the LNA to probe unit; or the VGA control probes and circuit board components. With shrinking the size of the device, the system can also be encapsulated into ultra small package. But the drawback of this method is that designers need to probe full custom design. In other words, the probe/electronic devices, custom design will enable designers to ASIC instance in technical bottlenecks and suppliers is limited.

Nowadays most of the ultrasound system company most of its intellectual property (IP) to probe and beam-forming technology, the use of multi-channel integration of commonly used devices, including a four-channel and 8-channel ADC to complete system that eliminates the need for high cost components, and streamlines the independent adjustment of TGC path and optimization.

In addition, you can also consider further integration with the rest of the ultrasonic system. In production license and market-oriented goals appropriate to these other signal links part of integration would be beneficial.

Conclusions of the

Pulse-echo techniques for early detection of large underwater hull and submarine, or inspection structures manufacture crack, ultrasound technology has been in daily life, their further widespread application is simply a matter of time.

Medical and industrial applications on portable ultrasound system for growing demand, various system on the device's compact and portability have similar requirements. As technology continues to progress, I believe that in the near future, users will be able to use mobile phones to send scanned images of the fetus.