fet buffer deviation calculator

VDD (V)
Desired V size=2>RS (V)
Vpor VGS(off) (pinch off voltage, negative) cut-off voltage (V)
IDSS (zero gate voltage drain current) zero gate voltage drain current (mA)
result:

IDS (mA)
RS (Ω)
VGS (V)

Equations:

IDS=

IDSS(1-VGS/Vp)2

RS= VRS/IDS

vgs is called the gate-source blocking voltage or cut-off voltage, expressed as 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 the amplifier uses a small-signal jfet, it will reach a vgs of id = 0.1-10μa. there are more cases where it is defined as vgs (off)