A high-accuracy digital readout technique for humidity sensor

A high-accuracy digital readout technique of capacitance difference for a capacitive-type humidity sensor is presented. Based on the sigma-delta (EA) technique, the structure detects the relative humidity by providing a digital readout of capacitance change it causes. Analysis shows that the structure is insensitive to circuit imperfections, thus permitting the realization of digital readout with good accuracy. A resolution as high as 20 bits is achievable. Simulation results are given to confirm the effectiveness.