Flexible architecture for CMOS sensor interfaces

The authors describe the design and implementation of an interface circuit for CMOS sensor systems. The objective is to provide a microprocessor compatible sensor on a single chip. A system architecture that minimizes analog content and where most of the signal processing is done digitally is illustrated. Great flexibility and robustness were achieved by the use of a sigma-delta modulator and by introducing the sensor element directly in the modulator´s first stage. Example applications for a magnetic sensor and a humidity sensor are presented