The equation of the pinch-off locus parabola and the parabolic transfer characteristic curve of Figure 7-37(b), which is known as Shockley's equation, is as follows:
Like the JFET, the region to the left of the pinch-off locus parabola on the drain characteristics is called the ohmic region, where the resistance between the drain and source can be controlled by the applied gate-to-source voltage VGs. As shown in Figure the transistor may occur at of VDs, causing large sudden increase in the drain current. The region between the ohmic and the and breakdown regions is the active region, also known as the region; in this region, the device is normally operated to amplify the small signal