Characterisation of an EMI-Improved Integrated Folded Cascode Amplifier Structure Using the EMIRR Measurement Method

In this paper, we analyse the robustness of operational amplifiers (OpAmps) against electromagnetic interference (EMI). Therefore we compare a standard folded cascode amplifier structure with an EMI-improved amplifier structure introducing a cross-coupled double differential input pair. We perform measurements on the manufactured test chip structures to determine general characteristics (gain, offset, gain-bandwidth product (GBWP) and phase margin), as well as EMI-related characteristics (EMI-induced offset respectively electromagnetic interference rejection ratio (EMIRR)). Based on these characteristics, we compare both structures with regard to their performance. Further on, we put the measurements into relation with our previous findings that we obtained from simulation.