Interface IC for breath analyzer with four three-electrode metal-oxide gas sensors and a humidity sensor

摘要

This paper proposes an interface IC for a breath analyzer with four three-electrode metal-oxide gas sensors and a humidity sensor. The mode-changeable integrator is a common circuit for both the resistive sensing and the capacitive sensing. The proposed interface circuit covers a wide range of the resistance from 100 ohms to 2 Mohms and a capacitance range from 100 pF to 210 pF. The proposed circuit is designed in a TSMC 0.25-μm process where the power consumption is 5.2 mW and the read-out time is 0.2 ms. The size of the circuit is 1.12 mm2.