Smart Sensor Systems: Emerging Technologies and Applications

Chapter 3Precision Instrumentation Amplifiers

Johan Huijsing

Electronic Instrumentation Laboratory, Delft University of Technology, Delft, The Netherlands

3.1 Introduction

This chapter gives an overview of techniques that achieve low offset, low noise, and high accuracy in CMOS operational amplifiers and instrumentation amplifiers. These techniques are essential for the accurate amplification of small sensor output voltages. It will be shown how auto-zero and chopper techniques can be used, both separately and in combination with each other, to achieve offset voltages lower than Frequency-compensation techniques will be described that result in straight first-order roll-off frequency characteristics in the multi-path architectures of chopper-stabilized amplifiers. Thus, these amplifiers can be used in combination with standard feedback networks.

The combination of an accurate voltage gain a low input offset voltage and a high common-mode rejection ratio (CMRR) is not easily implemented [1]. The closest type of amplifier that can achieve low offset and high CMRR is the operational amplifier (OpAmp). But the gain of an OpAmp is not well defined. it is normally so high that feedback ...