Offset Compensation for Differential Charge-Based Capacitance Measurement

This paper presents a fully integrated differential Charge-Based Capacitance Measurement (CBCM) circuit de-signed to measure attoFarads capacitive variations to detect airborne Particulate Matter (PM). A novel method is presented for compensating the output offset of the CBCM electronic front-end in the range of 3.1-3.4V through the trimming of the bulk voltage of key transistors that are implemented in this topology. Experimental results on prototypes implemented using a 130-nm CMOS technology and driven by a 100-MHz clock confirm the validity of the proposed approach.