Finding phase margin of feedback systems from closed loop AC simulations

Author

Ochoa, Agustin, Jr. ; Tang, Howard

Author_Institution

Xtreme Spectrum, Inc, Greenbelt, MD, USA

Volume

3

fYear

2000

fDate

2000

Firstpage

1228

Abstract

The stability of a feedback system is generally characterized with a point variable, the system phase margin. Phase Margin is a function of the system loop gain and is not always well defined. In this paper we show how to obtain the phase margin from the closed loop system response by translating the phase of this function with a simple algebraic relation. As the method utilizes a closed loop result and an exact algebraic translation, the results fully account for all loading and effects of feed-forward through the feedback and any reverse transmission through the active elements

Keywords

analogue circuits; circuit feedback; circuit stability; linear network analysis; signal flow graphs; transfer functions; SFG; algebraic translation; closed loop AC simulations; closed loop system response; closed loop transfer functions; feedback system stability; feedforward; linear circuits; point variable; signal flow graphs; system loop gain; system phase margin; Circuit stability; Circuit topology; Closed loop systems; Feedback circuits; Feedback loop; Flow graphs; Frequency estimation; Impedance; Phase measurement; Transfer functions;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 2000. Proceedings of the 43rd IEEE Midwest Symposium on

Conference_Location

Lansing, MI

Print_ISBN

0-7803-6475-9

Type

conf

DOI

10.1109/MWSCAS.2000.951436

Filename

951436