Tests of the Sigma-Delta Converter Designed as a Part of Microsystem Dedicated to Water Pollution Monitoring

Keywords:
sigma-delta converter, Silicon microsystem

Abstract:
The presented structure is a result of authors’ research in the 5th European Programme SEWING (System for European Water monitorING). The aim of this project is to elaborate a small, cheap and generally accessible microsystem, which task is to measure water pollution in European lakes and rivers. The main part of this system is a set of CHEMFET sensors, which were described in previous authors’ papers; the other part is a processing unit, which is based on an analogue to digital converter (ADC). The assumption at the beginning was to elaborate a 12-bit ADC, which can be used in the microsystem. Such a converter has been designed in AMS 0.6mm CMOS technology. Additionally elaborated structure enables the choice of the order of modulator. It is possible to adjust from the 1st to 4th ADC order. The MASH structure of the converter was also designed. Due to this, it is possible to choose one from four accessible configurations of the converter. Manufactured chips were measured in The Department of Microelectronics and Computer Science at Technical University of Lodz. The measurements results are shown and discussed and also authors’ conclusions are presented in this paper.

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Nanotech 2005 Conference Program Abstract