Combined air humidity and flow CMOS microsensor with on-chip 15 bit sigma-delta A/D interface

In this paper we present a batch fabricated multi-sensor chip for building control applications. A capacitive relative humidity sensor and a thermoelectric gas flow sensor have been integrated on a single chip together with a second order sigma-delta A/D converter, achieving 15 bit resolution. Both sensors are connected to the same sigma-delta modulator, without requiring any additional readout circuit. We report experimental results on a prototype realized with a commercial 2 /spl mu/m CMOS process.