ISFET Fabrication and Design of On-chip Readout Circuit using 0.35μm Digital CMOS Technology

Prakash, MD and Santosh, M and Khanna, VK (2009) ISFET Fabrication and Design of On-chip Readout Circuit using 0.35μm Digital CMOS Technology. In: International Conference on Sensors & Related Networks (SENNET- 09), December 7-10, 2009, VIT, Vellore (TN). (Submitted)

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Abstract

Biomedical instruments are widely used in modern medical facilities. Among theseinstruments, pH measurement is a vital biomedical application. Biomedical sensors like ISFET are used to detect the pH level. In the current work, a detailed explanation of the ISFET fabrication is discussed. The fabricated ISFET by the proposed method is characterized. After characterization, ID curve is plotted for different pH solutions. A macro-model of the fabricated ISFET is prepared. This macro-model is used to design a readout and bias circuit. The bias circuit is used to provide constant current to ISFET, the current is controlled by a resistor. An opamp is used to source current. The output is taken through a differential amplifier. The output is almost rail to rail (3 V for 3.3 V supply). The op-amp used has a PSRR of 65 db and resistor used to control current is made process independent by parallel-series splitting of a poly-silicon resistor. The total circuit is simulated in cadence software using AMS (Austria Micro System) 0.35 μm technology having 3 metal layers and two poly-silicon layers.

Item Type:	Conference or Workshop Item (Paper)
Subjects:	?? TK ?? Semiconductor Devices > MEMS and Microsensors
Divisions:	Semiconductor Devices
Depositing User:	Mr. Jitendra Nath Bajpai
Date Deposited:	22 May 2013 11:37
Last Modified:	22 May 2013 11:37
URI:	http://ceeri.csircentral.net/id/eprint/138

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