Smaller and More Accurate Sensors

Published:2011/7/12 3:18:00 Author:Phyllis From:SeekIC

Sensors were once used for measuring physical parameters like temperature and pressure exclusively. The usage of this device has been broaden considerably to automotive and consumer areas, as well as the aerospace and medical sectors.

For a long time, accelerometers have been a staple of the automotive world and perform a central role in airbag deployment and in navigation systems. But the sophistication of the applications is such that accelerometers are not always up to the job. Now companies are looking to design gyros into their systems. But price, performance and size requirements of these applications are seeing the adoption of MEMS technology.

The accelerometers were established in the late 1970s and have been produced by Finnish company VTI since the early 1990s. Recently, they have moved into the gyro market. Though the main market for its products is automotive, it is also active in industrial and medical applications. The company has a range of sensors in applications ranging from consumer to high end avionics.

In the medical market, its accelerometers are being used in pacemakers to enable a steady pulse. They can change the pulse rate according to the conditions. The requirements of consumer electronics companies were different, for example, to automotive companies, product life cycle is one example and there is also greater cost pressure. Meeting that pressure means we now manufacture products for consumer applications in Asia, where we can use standard processes and can scale products more easily.

Sensitivity is an important design parameter. The sensing element is manufactured by using a proprietary bulk 3d MEMS process, which enables robust capacitive sensors which are stable with low noise and power consumption. The detected signal is first converted into a phase difference, then into a voltage in the signal conditioning asic. An internal oscillator, reference and nonvolatile memory allows the sensor to operate autonomously within a system.

Designing a sensor system isn’t getting easier as engineers have more sensors and signal conditioning devices from which to choose. Looking to ease this task, National Semiconductor launched two configurable analogue front ends earlier this year, claiming the part will fast track signal path designs for sensors from a range of leading manufacturers. The related integrated circuit is TDA7565.

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