Publication: Readout circuit of ph isfet sensor along with temperature compensation circuit for water monitoring enviroment system
Date
2012-06-01
Authors
Helmi, Zatil Aqmar
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Abstract
In this paper, a novel readout circuit of pH ISFET sensor water monitoring environment system is presented utilizing 0.18µm CMOS technology. It is designed along with temperature compensation circuit that provides a low output voltage variation over a wide temperature range. The overall design employs three major circuits, namely start-up circuit, temperature compensation and ISFET ROC. The objective of this project is to demonstrate that the ISFET can be adapted for successful operation to achieve a good sensitivity and thermal stability in pH sensing to obtain more reliable or trusted results. The readout circuit produced an output current that is linearly sensitive to pH value. All the design schematic was done using Cadence EDA Tools that are available in CEDEC. The general concept presentation is followed by a detailed analysis and simulation results. The main criteria for this project should achieve variation voltage less than 5mV operated under 1.8V supply to achieved reference voltage of 1.2 V at 27℃ . The results demonstrate that the readout circuit works reliably and it can work in low-voltage and consume low-power. So it is suitable for micro-sensor application. Thetemperature voltage has a simulated temperature coefficient of over the temperature range -50℃ to 125℃.