One of the main benefits of negative feedback is the ability to control the impedances in linear active networks (LANs). Traditionally in undergraduate courses, the design of a feedback circuit is cast in terms of a two-port analysis, since the closed-loop properties of the circuit are expressed in terms of the corresponding open-loop ones. Therefore, the designer can directly identify the proper feedback topology and adjust the amount of feedback based on the specified closed-loop performances. However, there are practical situations in which a two-port analysis may lead to incorrect results if applied inappropriately or cannot be applied at all. In this paper, the authors show how it is possible to achieve a better insight of these problems in the light of Blackman’s method. Moreover, after a derivation of the formula as a consequence of the superposition principle applied to a LAN, they discuss, with reference to some typical examples, the conditions that must be met for the correct application of the two-port method.
|Autori interni:||MARZOCCA, Cristoforo|
|Titolo:||On Impedance Evaluation in Feedback Circuits|
|Rivista:||IEEE TRANSACTIONS ON EDUCATION|
|Data di pubblicazione:||2002|
|Digital Object Identifier (DOI):||10.1109/TE.2002.804400|
|Appare nelle tipologie:||1.1 Articolo in rivista|