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Outlook 2014: Analogue technology enables more advanced sensors

Moore's Law is the engine that drives the development of digital semiconductors. And as the processors in digital devices such as smartphones and tablets become more powerful, so developers find more uses for the analogue components that can sense and interpret the world around the user.

One consequence is that the number of sensors deployed in electronics systems is rising steadily. But this is only one part of the sensors story: more important is the increasing depth, richness, texture and realism that electronic sensors will bring to their representation of the world in the years to come.

This improvement in sensor performance will not only enhance the way existing electronics applications operate, it will also enable wholly new applications of electronics technology. And, unlike digital ICs, since these improvements do not depend on fundamentally new semiconductor technology, systems designers can plan for their use with great confidence.

Some important trends lie behind the adoption of more sensitive, accurate and precise analogue circuits.
• Green: averting the worst effects of global warming will require more energy efficient products and reduced carbon emissions.
• Convenient: Few products have sufficient basic functions. Consumers want convenience, comfort and usability and today's most successful devices provide a great user experience.
• Safe: machines are increasingly being used to extend human capabilities. Even cars will soon be expected to drive themselves. Machines that sense their environment realistically can operate safely within it.
• Personal: in fields such as healthcare, leisure and education, the decentralisation of previously monolithic services is being demanded by users and supported by providers.

These are big, multi-decade changes that will change many aspects of society, and not just its technology. But one of the effects will be a requirement for more detailed, accurate and reliable signals from electronic sensors.

Electric motors, for instance, consume a considerable proportion of the world's electricity supply. A big shift towards efficient brushless DC (BLDC) motor technology will lead to huge savings as wasteful AC induction motors get decommissioned. The field-oriented commutation schemes required in BLDC motors call for extremely accurate measurement of the rotor's position, even at high speed. More accurate and precise position sensors are needed to support this application.

In a different field, demand continues to grow for more and better artificial light in homes, offices and public spaces. Much of the new lighting equipment will use LEDs and this offers a chance to completely re-think how lighting schemes are controlled. New sensor-driven lighting equipment will turn on and off automatically when people enter or leave a room and change colour temperature automatically to match the body's circadian rhythms.

Accurate and sensitive optical sensors that can filter out optical noise will be the key to such applications.
In the field of safety, users will expect many kinds of machines to operate autonomously and safely – particularly when it cars can be made to drive themselves safely. In making machines interact safely with people and with other machines, systems designers will be calling on new generations of proximity, image and position sensors, as well as powerful digital signal processing to use the sense signals intelligently.

Personalisation and decentralisation is the last of the big trends. In medical care, for instance, this will see diagnostic and monitoring activity move from the hospital to the home, requiring new types of personal biological sensing devices. Heart-rate monitors, for instance, may draw on new optical sensing technology that can filter out the effects of vibration and ambient light, and interface to personal devices such as smartphones and smart watches.

There is a common thread running through the developments in all of these types of end equipment: the potential to benefit from sensors that offer more precision, linearity, sensitivity, stability and reliability than available today.

Evolution or revolution?
Surprisingly, the basis for the next generation of high-performance analogue ICs will largely be the industry's preferred process technology – CMOS. This means investments in equipment, processes, plants and know how will continue to be productive. But it will be a specialist CMOS, refined and optimised for analogue circuitry, supported by important packaging and assembly innovations.

In other words, standard CMOS processes will not meet future requirements for high-performance analogue ICs. ams, which owns and operates its own wafer fabrication facility in Austria, can draw on proprietary techniques and processes (CMOS, HVCMOS and SiGe), honed over the decades to provide greater linearity, lower noise, increased gain, better stability over a range of temperature and voltage, as well as reduced dark current and lower parasitics.

In fact, the performance of the electronic sensors we'll see in 2014 and beyond would not be possible without the process and packaging refinements made over many years of operation of a specialist analogue fab. And these improvements will lead to exciting developments in system design across a range of end products. Examples include:
• Position sensing: magnetic position sensors are used widely in BLDC motors because of their contactless operation. The Hall elements integrated in the chip provide a magnetic field with which a magnet affixed to the rotor interacts. While the basic principles of Hall sensing have been understood for decades, improvements to the design of the Hall elements inside the sensor, will improve their sensitivity and linearity dramatically.
• Colour sensing: today, light sensors are sensitive to broad segments of the light spectrum, loosely characterised as red, green and blue. It is clear, however, the technology can support more precise colour sensing of narrowly specified wavelengths. This opens new applications in fields such as medical diagnostics, spectrometry and chemical analysis, as well as more sensitive control of the colour temperature of lighting.
• Medical imaging: 3D chip packaging technology developed by ams supports stacked-die packages, combining different devices, such as a photodiode bonded to an A/D converter. In medical computer tomography, this improves the signal-to-noise ratio and resolution dramatically, providing doctors with sharper, more detailed images.

Using existing design and manufacturing resources, many more such developments will emerge in the future, supporting the drive of electronics OEMs to build products that are greener, safer, more reliable, more convenient and more personal.

The number of sensors deployed in electronics systems is rising steadily. But, in the view of ams, this is not the real story: more important is the increasing depth, richness, texture and realism that electronic sensors will bring to the representation of the world in the years to come.

This improvement in sensor performance is not only going to enhance the way existing electronics applications operate, it is going to enable wholly new applications of electronics technology. And since these improvements, unlike developments in digital ICs, do not depend on any fundamentally new semiconductor technology, systems designers can plan for their use with great confidence.

Drawing on high level analogue design and fabrication expertise, these sensors will, for the most part, be developed by specialist analogue IC producers that can control and refine their designs, processes and packaging in-house. And ams, Europe's biggest such manufacturer, looks forward to being at the centre of these developments.

ams
ams develops and manufactures high performance analogue semiconductors that solve its customers' most challenging problems. ams' products are aimed at applications which require extreme precision, accuracy, dynamic range, sensitivity, and ultra-low power consumption. It product range includes sensors, sensor interfaces, power management ICs and wireless ICs for customers in the consumer, industrial, medical, mobile communications and automotive markets.

With headquarters in Austria, ams employs more than 1300 people and serves more than 7800 customers. ams is the new name of austriamicrosystems, following the acquisition in 2011 of optical sensor company TAOS.

Thomas Riener is executive vice president and general manager, full service foundry, for ams.

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Thomas Riener

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