ANALYSIS OF A MOS INTEGRATED GAS SENSOR USING A SURFACE-CHEMISTRY BASED MODEL

Abstract

To facilitate gas sensor design with the associated signal-conditioning circuitry, a previously developed gas adsorption model is implemented in the popular circuit simulation program SPICE. The model is based on the gas adsorption theory. With the adsorption model implemented in SPICE, the performance of a MOSFET gas sensor integrated with the associated circuitry can be studied. The analysis was applied to three sensors, namely, the H-2 sensor, the NH3 sensor and the CO sensor. A noise analysis of the sensors was also performed and their lower bounds of detectivity determined. A chopper-stabilized circuit was applied to the sensing circuitry. Simulation results show that noise in gas sensors can be reduced