A sensitive interface circuit with wide dynamic range for capacitive sensors

A novel readout circuit for capacitive sensors is presented. The circuit topology utilizes analog building blocks controlled by digital units, which leads to reduction in chip area and its power consumption while improving its robustness against interference. Moreover, another advantage of this interface circuit compared to the existing solutions is its high dynamic range thanks to the closed-loop configuration. Experimental results were obtained by pairing the topology realized in a CMOS 0.35μm technology with a capacitive relative humidity sensor developed in our lab where a voltage signal is produced proportionally to the relative humidity in the ambient.