Design of Integrated Capacitive Humidity Sensor Based on UMC40 nm Process

With the decrease of the size of semiconductor, the humidity sensor can be miniaturized and integrated by CMOS technology, and the humidity sensor chip can be made in large scale and low cost. In this paper, the technology structure of integrated capacitive humidity sensor chip is designed and fabricated by using UMC40 nm semiconductor technology, it provides a reference for realizing the highly integrated technology of humidity sensor. This paper also analyzes the common micro-capacitance detection methods of humidity sensor, and combines the advantages of capacitor charge-discharge and pulse-width output stability, easy modulation and easy digital system interface, etc., a novel CMOS capacitive humidity sensor micro-capacitance detection circuit is designed by using UMC40 nm semiconductor technology. The CMOS circuit can convert the change of capacitance into pulse width, in which the pulse width is linear with the capacitance difference, and can produce periodic pulse sequence and output pulse width modulation signal, it can be easily connected with microcontroller or digital system without adding A/D conversion module to increase circuit complexity and power consumption. The circuit not only can detect the micro-capacitance of humidity sensor, but also has the advantages of low power consumption, linearity, high resolution and digitalization.