Principles of Instrumentation Amplifiers

This chapter is dedicated to the general principles of the Instrumentation Amplifier, a particular type of differential amplifier hereafter called IA. Its basic applications are reviewed. The definitions of Common-Mode Rejection Ratio (CMRR) as the most important property of IAs are discussed. It is shown that the CMRR definition is different in single output and fully differential circuits. The general formula for derivation of CMRR in cascaded stages is given. Then, the well-known classical 3-Op-Amp IA is studied. Its important parameters, limitations and disadvantageous are discussed. The chapter includes also a brief introduction and the classification of IAs developed with current-mode techniques here after called Current-Mode Instrumentation Amplifier (CMIA). © 2019, Springer Nature Switzerland AG