Reconfigurable Precision Instrumentation Amplifier for Universal Sensor Interface

Abstract:
This work describes the architecture of an instrumentation amplifier for a mixed-signal IC. It serves as a generic self-x interface between sensors of different type and digital signal processing. The purpose is to easily set up intelligent multisensor-systems with self-monitoring, calibrating and -repairing capabilities. Based on a novel self-calibrating concept, the function of the amplifier shows nearly temperature independent behavior (3nV/°C offset drift) as well as very low offset in the range of 100muV. The circuit is backed by a bandgap voltage reference and consists of several operational amplifiers, where the main amplifier contains an indirect current feedback topology. It has a gain of 1 - 100 that be adjusted without external resistors. Additionally, the common mode voltage of the rail-to-rail output can be programmed to adjust the signal to e.g. a subsequent analog-to-digital converter.