# How to find value of beta = (mu*Cox)(W/L)/2 of MOSFET in ngspice

How to find value of $\beta = \frac 1 2 \mu \cdot Cox \cdot \frac W L$ of MOSFET in ngspice? Is there any command that displays that? The 'show' command displays many parameters but it doesn't display value of beta's value. Is there any other way by which we can find its accurate value?

The SPICE deck determines these values; therefore, there is not a way to explicitly extract these values in ngspice. If you have a level 0 model, you can easily get these from the model file; otherwise, you find that $\mu$, for instances changes. What I would to is sweep the FET from the gate with the process voltage as $V_{ds}$. You can then do a quadratic fit from threshold to about a volt beyond.
You will need to dig into your MOSFET's .model file. W & L of course are parameters you set, $\mu \cdot Cox$ is known as KP in most model files, TOX is Oxide thickness.