Smart Sensor Systems

2

Interface Electronics and Measurement Techniques for Smart Sensor Systems

Gerard C.M. Meijer

2.1 Introduction

In smart sensor systems, the functions of sensors and their interfaces are combined in an overall design. These functions include sensing, signal conditioning, analog-to-digital conversion, bus interfacing and data processing. Also, functions at a higher hierarchical level can be included, such as self-testing, autocalibration, data evaluation and identification. In many physical and chemical sensors, the information bandwidth is rather small, i.e. much smaller than that of the electronic part of the system. This allows the system designer to use a single electronic system to support many sensing elements, in order to perform multiple measurements. In addition he can use the surplus of available time/bandwidth of the electronic part to improve the system's accuracy, reliability and long-term stability or to lower the power dissipation. This chapter will discuss possible measurement techniques suited to achieve such a system improvement and ways to implement these techniques in smart-sensor-interface circuits. It will be shown how the application of advanced measurement techniques, such as nested chopping, dynamic element matching and autocalibration, can solve the traditional problems of electronic circuits, such as offset, 1/f noise, interference and long-term drift.

The systems under consideration consist of a number of multiplexed sensing elements, sensor-specific ...