The Design and Fabrication of Capacitive Humidity Sensor Having Interdigit Electrodes and its Signal Conditional Circuitry

빗살형 전극을 가지는 정전용량형 습도센서와 그 신호처리회로의 설계와 제작

  • 박세광 (경북대 전자전기공학부) ;
  • 강정호 (경북대 대학원 전기공학과) ;
  • 박진수 (경북대 대학원 전기공학과)
  • Published : 2001.03.01

Abstract

For the purpose of developing capacitive humidity sensor having interdigit electrodes, interdigit electrode was modeled and simulated to obtain capacitance and sensitivity as a function of geometric parameters like the structural gap and thichness. For the development of ASIC, switched capacitor signal conditioning circuits for capacitive humidity sensor were designed and simulated by cadence using 0.25um CMOS process parameters. The signal conditioning circuits are composed of amplifier for voltage gain control, and clock generator for sensor driving and switch control The characteristics of the fabricated sensors are; 1) sensitivity is 9fF/%R.H., 2) temperature coefficient of offset(TCO) is 0.4%R.H./$^{\circ}C$, 3) nonlinearity is 1.2%FS, 4) hysteresis is 1.5%FS in humidity range of 3%R.H. ${\sim}$ 98%R.H.. The response time is 50 seconds in adsorption and 70 seconds in desorption. Fabricated process used in this capacitive humidity sensor having interdigit electrode are just as similar as conventional IC process technology. Therefore this can be easily mass produced with low cost, simple circuit and utilized in many applications for both industrial and environmental measurement and control system, such as monitoring system of environment, automobile, displayer, IC process room, and laboratory etc..

Keywords

sensor;humidity;capacitive;interdigit;ASIC

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