Fr. Riedijk et al., A DUAL-BIT LOW-OFFSET SIGMA-DELTA ANALOG-TO-DIGITAL CONVERTER FOR INTEGRATED SMART SENSORS, Sensors and actuators. A, Physical, 36(2), 1993, pp. 157-164
A signal-conditioning circuit is presented which converts the small si
gnal of a thermal-flow sensor into a digital signal. A balanced choppe
r with bipolar transistors combined with a class B sigma delta convert
er keeps the offset beneath 10 muV. Although the circuit has been desi
gned especially for a thermal-flow sensor with thermopiles, it is well
suited for other small-signal applications.