A Wide‐Range Resistance‐To‐Frequency Read‐Out Circuit for Resistive Gas Sensors

ABSTRACT This paper proposes a resistance‐to‐frequency conversion read‐out circuit tailored for gas sensors, adept at translating resistance values into corresponding output signal periods with minimal susceptibility to temperature and voltage fluctuations. The proposed circuit is distinguished by its extensive measurement range, economical power usage, compact chip area, and exceptional accuracy, all integrated through a synergy of current mirrors, an integrator, and a comparator. Realized with 180‐nm CMOS technology and functioning at a 1.8‐V supply voltage, the circuit adeptly measures resistance values from 4 kΩ to 1 GΩ, encompassing the resistance range of the most resistive gas sensors. The chip area is a modest 0.413 mm 2 , with the core read‐out circuit exhibiting a power consumption of merely 4 mW. Furthermore, the circuit achieves a commendable measurement accuracy of 0.1%.