# Calculating the mu parameter for a 2-port device stability

1. ## Calculating the mu parameter for a 2-port device stability

When calculating the unconditionally stability of a 2-port device, is it enough to calculate the mu parameter (mu>1 => unconditionally stable) or do I have to calculate as well the accompanying parameter mu' (or mu_prime) and also see if that is >1? Or is the case so that whenever the mu>1, the mu_prime is >1 as well?

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2. ## Re: 2-port stability

Hi
mu and mu_prime must be>1

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3. ## Re: 2-port stability

I found the answer by myself:

"A related parameter μ' can also be used, it is always bigger than one when μ is, so it doesn't give new information for the purpose of determining unconditional stability"

source:

http://bmf.ece.queensu.ca/mediawiki/...plifier_Design

Similar conclusion I came as well as I read the original IEEE paper "A new criterion for linear 2-port stability using a single geometrically derived parameter" by Marion Lee Edwards.

So it enough if mu>1, there's no need to calculate mu_prime.

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