Stability factor *μ* of 2-port
network

[mu,muprime] = stabilitymu(s_params)

`[mu,muprime] = stabilitymu(s_params)`

calculates
and returns the stability factors *μ* and *μ′* of
a 2-port network. The input `s_params`

is a complex
2-by-2-by-*M* array, representing *M* 2-port
S-parameters.

`[mu,muprime] = stabilitymu(hs)`

calculates
and returns the stability factors for the network represented by the
S-parameter object `hs`

.

The stability factor, *μ*, defines the
minimum distance between the center of the unit Smith chart and the
unstable region in the load plane. The function assumes that port
2 is the load.

The stability factor, *μ′*, defines
the minimum distance between the center of the unit Smith chart and
the unstable region in the source plane. The function assumes that
port 1 is the source.

Having *μ* > 1
or *μ′* > 1
is the necessary and sufficient condition for the 2-port linear network
to be unconditionally stable, as described by the S-parameters.

Examine the stability of network data from a file:

% Calculate stability factor and conditions ckt = read(rfckt.passive,'passive.s2p'); s_params = ckt.NetworkData.Data; freq = ckt.NetworkData.Freq; [mu muprime] = stabilitymu(s_params); % Check stability criteria stability_index = (mu>1)|(muprime>1); is_stable = all(stability_index) % List frequencies with unstable S-parameters freq_unstable = freq(~stability_index);

Edwards, Marion Lee, and Jeffrey H. Sinsky, "A New Criterion
for Linear 2-Port Stability Using a Single Geometrically Derived Parameter," *IEEE
Transactions on Microwave Theory and Techniques*, Vol. 40, No. 12, pp. 2303-2311,
December 1992.

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