> Jeff,
>
> A diode is most certainly an active device. Its properities
> change with exciting voltage and follow many parameters just
> as a transistor.
A diode is NOT an active device. It's properties changing with applied
voltage do not define whether or not it's active. Whether or not it is
capable of power gain is what determines if something is an active device,
and a diode isn't capable of power gain.
> And there are many ways to make a diode.
Silicon, germanium, and rusty flange bolts are but a few :-)
> You might be right about the ferrite. I am not sure why.
> Ferrite is a passive substance.
A device doesn't have to be active to be non-linear. A ferrite isolator is
an anisotropic (non-reciprocal) device, but it's still passive. In the RF
world, if S21 <> S12, the device may be either active OR non-reciprocal
passive. A ferrite isolator is the latter.
--- Jeff
