Open AccessNew method of finding exact frequency response for feedback amplifiers
Author(s) -
Chen ChungCheng,
Chen YenTing
Publication year - 2020
Publication title -
iet circuits, devices and systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.251
H-Index - 49
ISSN - 1751-8598
DOI - 10.1049/iet-cds.2020.0055
Subject(s) - thévenin's theorem , amplifier , frequency response , negative feedback amplifier , control theory (sociology) , operational amplifier , common emitter , mathematics , voltage , computer science , electrical engineering , equivalent circuit , engineering , bandwidth (computing) , telecommunications , control (management) , artificial intelligence
Due to feedback amplifier analysis simplification, Miller theorem, feedback theorem and Gray–Searle theorem are the most used tools on the calculation of the frequency response. However, they are only approximated results and then are invalid for overall closed‐loop voltage gain of the frequency response. The traditional feedback theory, Miller theorem and Gray–Searle theorem are troublesome due to the significant difficulty of using the Kirchhoff's voltage/current law and Thevenin equivalent theorem. Especially, the utilisations of the Kirchhoff's voltage/current law and Thevenin equivalent theorem will be impractical for the complicated differential amplifier with the active load that contains four dependent sources and three bridge elements. The study proposes exact and algebraic frequency response analysis of a feedback amplifier by using the authors series research‐Chen's Electric Unifying Approach with L'Hospital rule and Cramer's rule to take the place of those traditional approaches. Some experimental and mathematical results have exploited the fact that the proposed approach can yield the more effective and practical DC quiescent analysis with bias values and AC frequency response analysis with two junction charge‐storage capacitances for the common‐emitter amplifier with emitter resistance. Some experiments are provided to demonstrate the effectiveness of the proposed method.