Upper limit for Rollet stability factor value

Thread Starter

jeslin issac

Joined Jun 24, 2017
In order to maintain unconditional stability, The Rollet factor(K) value should be greater than 1.
Does anyone know how far the value can go above 1 so that the stability condition is still satisfied?
I came across a particular LNA in Minicircuits which has a K value of nearly 12 at some frequencies whereas some others maintain values within 1 and 1.5.


Joined Sep 21, 2011
For unconditional stability k>1 and B must be +ve. When k>1 it will always be stable, so don't worry if you see numbers like k=12 etc. For a better idea of absolute stability use Mu and Mu' , these are geometrically derived parameters which indicate how stable you circuit is, the higher=more stable. One downside for this extra stability can be a lack of gain, as the designer may have used resistors to control any potential instabilities.