I'm wondering what determines the polarity conditions in a JFET - is it that this transistor can only operate when the p-n junction is in reverse biased polarization? If so, what about the states of operation that the transistor can be in? There are three of them, and the polarization mode is only one. Don't they result from additional polarity conditions?
While browsing through various books as well as websites, I came across a statement that says:
"JFET Transistors can only operate with a reverse bias of the p-n junction, so there is only one way of polarization":
-n-type junction
\$ U_{DS} > 0, U_{GS} < 0 \$
-p-type junction
\$ U_{DS} < 0, U_{GS} > 0 \$
But I have also encountered the definition that:
"Depending on how the unipolar transistor is polarized, it can operate in three different areas:
in the cut-off area - when \$ |U_{GS}| > |U_{P}|, U_{DS} \$ - any
in the active region - when \$ |U_{GS}| < |U_{P}|\$ and \$ |U_{DS}|\$ <= \$ |U_{DS} SAT| \$
in the saturation area - when \$ |U_{GS}| \$ < \$ |U_{P}| \$ and \$ |U_{DS}| \$ > \$ |U_{DS} SAT| \$ "
And it says that these areas of operation are methods of polarity at the same time (or more precisely, areas of operation are associated with different methods of polarity, but there is, after all, one) - I completely don't get that!
These definitions are confusing to me. So which one of them is correct? Is there one way to polarize as in the first definition? Does the second definition fit more with the ways of polarity? Could someone please clarify this for me?
