Analog circuits for sensors

This contribution is devoted to CMOS analog circuit design for integrated sensor systems. While today complex sensor signal processing tends to be implemented in digital domain, analog circuits still play a crucial role in sensor signal acquisition due to analog nature of sensory signals. Though sensor front-ends frequently employ analog circuits, e.g. for sensor signal conditioning and conversion, generation of bias and reference voltages and currents, and system interfacing, the most important circuit here - for both, on- and off-chip sensors - is the sensor readout, since it directly interfaces the sensor. At the beginning we review how the key sensor system specifications affect the system and circuit design. A particular attention will be paid to the noise, because it has a great influence on one of the most important parameters of sensor systems, namely the smallest resolvable input signal. On the other hand, it is by far the most difficult parameter to improve upon thus making low-noise circuit design mandatory. For this reason, noise reduction techniques are also of high importance. The contribution will conclude by addressing circuit design issues specific to sensor systems, such as correction of sensor nonidealities, calibration, and testing.