Abstract: A CMOS compatible integrated humidity sensor is designed and fabricated.The humidity sensor and CMOS circuits are fabricated at the same chip.The humidity sensor employs an interdigital finger structure and a polyimide sensing material.A humidity sensing model is given.Because of minor capacitance variation during the full range,switched-capacitor techniques are employed in measurement circuits.The principle of the circuits is discussed,and simulation results are presented accordingly.The design,implemented in a 3μm polysilicon-gate CMOS,results in a good DC output at 5~35℃ and a long time stability.

Key words: switched-capacitor circuits, polyimide, CMOS compatible technology, humidity sensor