一种湿度传感器接口电路的分析与改进

介绍了一种本实验室开发的集成湿度传感器，它实现了湿敏电容和接口电路在一块芯片上的集成。重点分析了它的接口电路，基于施密特触发器构建，实现电、容值与频率值的转换。对样片进行了测试，电容值与湿度值近似为线性关系；但是，输出波形的占空比与理论值有较大的偏差。通过分析，给出了测试结果发生偏差的原因。最后，对施密特触发器的参数进行优化，重新对电路的结构进行了设计，实现了与实验室第二代湿度传感器的集成。

Analysis and Improvement of an Interface Circuit for Humidity Sensor

A new integrated humidity sensor is dealt with. The humidity-sensitive capacitance and the interface are integrated into one chip. The interface circuit, which is based on the Schmitt trigger, works as a capacitor-frequency converter. The capacitor and the relative humidity satisfied a linear relationship during testing, but the duty cycle of the output waveform displayed a large difference from theoretic calculation. The reason for the difference is analyzed. Circuit schematic and parameters are redesigned to realize the integration with a new humidity sensor designed in our laboratory.