Current-feedback amplifiers versus voltage operational amplifiers

Abstract

This paper compares the main performance parameters of the current feedback opamp (CFOA) with those of a conventional voltage opamp (VOA). To make the comparison effective, a folded cascode VOA is considered (which is characterized by similar features and topology) and the same power consumption was assumed for both amplifiers. The work confirms that the CFOA can provide higher bandwidth, albeit at the expense of reduced loop gain. Noise performance is also analyzed. Input-referred noise generators are determined and some peculiar CFOA features, having no equivalence in conventional opamps, have been highlighted. It is shown that the CFOA has slightly lower noise voltage, but a larger noise current. Simulations are given which are in very good agreement with expected results.