For VGS 0 V, the value of VDS at which ID becomes essentially
constant (point B on the curve in Figure 8–5(b)) is the pinch-off voltage, VP. For a given
JFET, VP has a fixed value. As you can see, a continued increase in VDS above the pinchoff
voltage produces an almost constant drain current. This value of drain current is IDSS
(Drain to Source current with gate Shorted) and is always specified on JFET datasheets.
IDSS is the maximum drain current that a specific JFET can produce regardless of the external
circuit, and it is always specified for the condition, VGS 0 V.