FET Buffer Deviation Calculator
Tool Introduction:
JFET buffer (common-drain amplifier) is useful because it has a very high input impedance compared to a transistor.
N-channel FET buffer deviation
Equations:
IDS= IDSS(1-VGS/Vp)2
RS= VRS/IDS
VGS is called the gate-source cutoff voltage or cutoff voltage, and is represented by VGS (off). In the case of n-channel JFET, the VGS (off) value has a negative sign. It is difficult to measure the VGS of the actual JFET corresponding to ID = 0. When a small signal JFET is used in an amplifier, the VGS that reaches ID = 0.1-10μA is often defined as VGS (off).