A constant power heating circuit for integrated gas sensor application

This paper reports a novel circuit to supply constant heating power to the micro-hotplate for integrated gas sensor applications. The circuit is designed so that the heating power is maintained constant in spite of the change of heater resistance value due to process variations. By controlling the biasing current of the power control circuit, the heating power can be controlled linearly. The circuit is realized using CMOS. Simulation shows that the heating power can be controlled at /spl plusmn/0.4% with /spl plusmn/50% changes in heating resistance.