Low Power High Bandwidth Acceleration Sensors

Inhalt:
Along with the growing need for high performance sensors and technology for Industrie 4.0 applications, we have observed a rising demand for highly sensitive wideband acceleration sensors e.g. for use in industrial environments. Industrial applications such as bogie-monitoring and the monitoring of pumps or machine tools require fairly broad bandwidths in the range of 10…20 kHz and even above. Sensors with such a broad bandwidth and a digital output are not available on the market yet. There are a few MEMS sensors offered by a single manufacturer. These sensors, however, come with a 5 % bandwidth with a maximum of 10 kHz, an analog output, and are single axis elements only [1]. In contrast, most users request at least 2-axis high-bandwidth acceleration sensors with a digital output to be able to integrate them into smart industrial systems and applications. This paper reports on the enhanced micro-mechanical structures and improved integrated electronics to create high bandwidth acceleration sensors with a high signal to noise ratio and very low power electronics with digital output. This challenging aim was achieved by a very close co-design of MEMS and ASIC. We optimized our 2-axis micromechanical element with respect to its seismic mass, which was necessary to get an ultra-low noise sensor. Therefore, we preferred a large height of the micromechanical structure. Another aim was to reach a very high capacitive sensitivity while keeping the base capacitance as small as possible to aim for a small power consumption. Hence, a high aspect ratio technology was essential.