Summary
Due to the unparalleled simplicity of its sensor elements, its versatility due to a plurality of applicable materials and the availability of small and fairly low cost monolithic sensor interfaces, the acceptance of capacitive technology has constantly increased during the last years. This work addresses the design of a versatile sensor interface for capacitive sensors usable for automotive and industrial measurement problems. The interface is implemented in a 0.25 µm CMOS technology and provides mechanisms in order to cope with front end parasitic effects and external electromagnetic compatibility disturbers. The presented interface is used to evaluate the coupling capacitances of a spatial filtering sensor for flow velocity determination of liquid hydrogen.
Zusammenfassung
Diese Arbeit beschreibt die Entwicklung einer vielseitig anwendbaren Auswerteeinheit für kapazitive Sensoren, die in industriellen und automotiven Messaufgaben eingesetzt werden kann. Die Schaltung ist in einer 0,25-μm-CMOS-Technologie implementiert. Das Systemkonzept sieht entsprechende Mechanismen vor, um den in rauen Umgebungsbedingungen vorhandenen Parasitäreffekten sowie möglichen externen EMV-Störungen entgegenzuwirken. Die Auswerteeinheit wird in einem Anwendungsbeispiel zur Bestimmung der Durchflussgeschwindigkeit von flüssigem Wasserstoff mittels Ortsfrequenzfilterung verwendet.
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Bretterklieber, T., Zangl, H., Holler, G. et al. Versatile programmable integrated interface for robust capacitive sensors. Elektrotech. Inftech. 125, 132–137 (2008). https://doi.org/10.1007/s00502-008-0523-2
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DOI: https://doi.org/10.1007/s00502-008-0523-2
Keywords
- Capacitance to digital converter
- CMOS
- Offset compensation
- Design for electromagnetic compatibility
- Liquid hydrogen