A CMOS Integrated CC-ISFET Device for Water Quality Monitoring Pawan Whig 1 and Prof. Syed Naseem Ahmad 2 1 Research Scholar, Department of Electronics and Communication Engineering, Jamia Millia Islamia, New Delhi-110025 India 2 Department of Electronics and Communication Engineering, Jamia Millia Islamia, New Delhi-110025 India Abstract This study presents a performance analysis of low power CMOS Integrated “Current Conveyor Ion Sensitive Field Effect transistor” (CC-ISFET). The study’s main focus is on simulation of power and performance analysis of ISFET device, which is used for water quality monitoring. This approach can improve calibration of device to a fairly wide range without the use of a high speed digital processor. The conventional devices generally used, consume high power and are not stable with temperature and frequency variations for long term monitoring. The conventional device [1] has a drawback of low value of slew rate, high power consumption, and non linear characteristics but in this novel design, the device exhibits a better slew rate, piece- wise linear characteristics, and seen consuming low power of the order of 5.7μW. The functionality of the circuit is tested using Tanner simulator version 15 for a 70nm CMOS process model. Very high speed integrated circuit Hardware description language (VHDL) code for the same scheme is simulated on Xilinx ISE 10.1 and various simulation results are obtained. The proposed circuit reduces total power consumption per cycle, increases speed of operation, fairly linear and is simple to implement.This device has a simple architecture, and hence is very suitable for water quality monitoring applications. Keywords: Slew rate, Calibration, Simulation, Monitoring, Ion Sensitive Field Effect Transistor, Simulation, Current Conveyors, Frequency compensation, Low power. 1. Introduction Monitoring the pH of water resources for water pollution is a typical and necessary task in today’s overdeveloped scenario. The normal pH for surface water systems is 6.5- 8.5 and for ground water system 6-8. Water with low pH is acidic, corrosive and contains several toxic materials which are very dangerous for health, but the water having pH more than 8.5 is called hard water which does not contain harmful materials but the long use of such kind of water can cause many problems [2]. With the invention of ISFET [3] there has been a rapid development of pH Measurement Instruments [4]. With the further advancement of semiconductor technology ISFET emerged as a standard device. In spite of the fact that ISFET Sensor has been developed 30 years ago [5], several drawback of ISFET sensor remained unsolved, such as phenomena of fluctuation with time and temperature variations. This causes in drift in the pH values, and result in poor and slow response of the device. The second phenomenon is pH dependent Temperature Coefficient and non linear temperature dependent mobility in MOSFETS of ISFET device. Also it was observed that in ISFET drift rate has an exponential incremental tendency with pH values as well as Temperature. In Urban water supply system, the water quality determining indices such as pH value and turbidity are monitored continuously. When the indices exceed the limiting value, the system will effectively handle the treatment against deterioration ensuring the safety of water. Water is vital for all known forms of life. Many research works have contributed to design water quality measuring devices. But it has always been a challenge to find a precise and accurate device for monitoring the quality of water. The concept of p[H] was first introduced by Danish chemist Soren Peder Lauritz Sorensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 after it became apparent that electromotive force in cells depended on activity rather than concentration of hydrogen ions. The pH is a measure of the acidity or basicity of an aqueous solution. The use of micro sensors for infield monitoring of environmental parameters is gaining interest due to their advantages over conventional sensors. In the field of micro sensors for environmental applications, Ion Selective Field Effect Transistors (ISFETs) has proved to be of special application. They are particularly helpful for measuring pH and other ions in small volumes and they can be integrated in compact flow cells for continuous measurements and monitoring [6]. Pure water is said to be neutral, with a pH close to 7.0 at 25 °C (77 °F). Solutions with a pH less than seven (7) are said to be acidic and IJCSI International Journal of Computer Science Issues, Vol. 9, Issue 4, No 2, July 2012 ISSN (Online): 1694-0814 www.IJCSI.org 365 Copyright (c) 2012 International Journal of Computer Science Issues. All Rights Reserved.