The floating capacitor as a differential building block

Abstract

This paper analyzes the advantages and limitations of using the floating(or flying-) capacitor technique as fully differential or differential input but single-ended output building block to implement voltage amplifiers, multiplexers and coherent amplitude demodulators. Theoretical analysis supported by experimental results show that the fully differential configuration has a better common mode rejection ratio (CMRR). However, if the signal, once amplified, must be single ended, then in amplifiers and some multiplexers it may be better to have a floating capacitor with single-ended output whilst in demodulators a floating capacitor with differential output yields a better CMRR.