Recently, AudioXpress published an interesting article on the use of feedback amplifiers. The article is Michael Kiwanuka’s “Current Feedback and Voltage Feedback Fallacies” which appeared in June 2017, p32-37. The article purports to clarify certain ‘fallacies’ regarding four basic feedback configurations, using op amps.
The conclusions reached by the article really are most curious. Quoting directly from the final summation: ‘The terms “current feedback amplifier” and “voltage feedback amplifier” as presently used are wholly unfounded. ‘
This is a very odd conclusion, as it flies directly in the face of 3-4 decades of current feedback amplifier (CFA) history! In the attachment cited below, the bibliographic references document this point quite well, and will serve as Useful Background Reading. After careful study, readers should then be able to draw their own conclusions as to whether the feedback system used in conjunction with a given amplifier architecture employs current or voltage. A couple of CFA data sheets will help immeasurably, of course. In fact, this exercise should show just how CFAs operate.
Author MK also is critical of certain book authors on these subjects, namely Professor Sergio Franco and Walt Jung. Accordingly, we have authored a technical rebuttal document, cited below. This document is supported by other signatories, as noted within. This rebuttal has been forwarded to AudioXpress, along with a request that it be made available to their readership. We are hopeful that in time they will honor this request.
This is an update to this posting, as of 7/12/2017, including a newly revised technical rebuttal document. This revision includes links to the latest errata information from AudioXpress.
See this updated technical rebuttal document for the “Current Feedback and Voltage Feedback Fallacies”, Michael Kiwanuka, AudioXpress, June 2017, p32-37.
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