International Journal of Microwave and Wireless Technologies

Table of Contents - 2009 - Volume 1, Issue 01  

Original Article

Criteria for the evaluation of linear two-port stability using two geometrically derived parameters

Chinchun Menga1 c1, Hung-Ju Weia1 and Po-Hsing Suna2

a1 Department of Communication Engineering, National Chiao-Tung University (NCTU), Hsinchu, Taiwan, R.O.C. Phone: +886-3-5712121-54606; Email: onionpie.cm94g@nctu.edu.tw

a2 Department of Electrical Engineering, National Chung-Hsing University, Taichung, Taiwan, R.O.C

Abstract

Two geometrically derived stability parameters, µ′ (or µ) and ν′(or ν), are used to analyze the stability of a two-port network. The magnitudes of both µ′ (or µ) and ν′ (or ν) parameters determine geometrical relations between the stability circle and the unit Smith chart in the xs0393S (or xs0393L) plane. |µ′| (or |µ|) is defined as the minimum distance from the stability circle to the origin of the unit Smith chart in the xs0393S (or xs0393L) plane, while |ν′|(or |ν|) is defined as the maximum distance. Moreover, the signs of ν′ (or ν) and µ′ (or µ) parameters determine which region of the stability circle is stable (inside or outside) and whether the stable region includes the origin of the Smith chart, respectively. There are totally 12 situations between the stability circle and the unit Smith chart in the xs0393S (or xs0393L) plane by using µ′ (or µ) and ν′ (or ν) parameters. This paper classifies 12 situations in the xs0393S plane and also presents the corresponding practical two-port networks.

(Received March 14 2008)

(Revised November 07 2008)

(Online publication March 19 2009)

Keywords

  • Stability criteria;
  • S parameters;
  • Linear circuit;
  • Two-port network

Correspondence:

c1 ccmeng@mail.nctu.edu.tw