A Low-Cost Low-Power Capacitive Humidity Sensor in CMOS Technology

Abstract

This paper presents a capacitive humidity sensor in CMOS technology. The humidity sensor element is implemented in standard CMOS technology without any further post-processing, which results in low fabrication cost. The sensor interface is based on a delta-sigma converter and can be easily reconfigured to compensate for process variation of the sensing element. The proposed humidity sensor is fabricated in 0.16μm standard CMOS process and the chip occupies 0.25mm 2 . The measurement result shows that this humidity sensor acquires a resolution of 0.1%RH in the range of 20%RH to 90%RH. The interface achieves a 12.5-bits capacitance-to-digital conversion and consumes only 9.6μW power at 1.2V supply voltage.