Recently, the very existence of current feedback as opposed to voltage feedback has been called into question. This article analyzes and tests simple versions of voltage and current feedback amplifiers and demonstrates some differences in their characteristics. The article provides an excellent overview of historical terminology and how the more modern terms came about and their dependence on context. These articles were originally published in audioXpress, July and August 2018.
Recently, the very existence of current feedback as opposed to voltage feedback has been called into question. This article employs bench tests, simulations, and equations derived from various circuits under investigation to address this controversy. In Part 1 of this article, the author designs, analyzes, simulates, builds, and tests simple versions of voltage and current feedback amplifiers and demonstrates some differences in their characteristics. Part 2, takes a detailed look at some commercially available current feedback amplifiers and voltage feedback amplifiers. As Chris Paul reinforces, "Current feedback is real. Unfortunately, it has multiple definitions. We must be aware of the context in which the term is used."
The article skillfully navigates the various confusing 'definitions' and provides an excellent overview of historical terminology and how the more modern terms came about and their dependence on context. The author's reasons for calling an opamp a CFA or a VFA make a lot of sense and the technical comparisons of the various opamp examples are quite insightful and valuable.
These articles were originally published in audioXpress, July and August 2018.
Download the two articles, now available here:
Part 1 - Untangling the Signal Path
Part 2 - A Detailed Examination of Current Feedback Amplifiers
