FET Buffer Deviation Calculator

A JFET buffer (common drain amplifier) is useful because it has a very high input impedance compared to a transistor.

<img src="http://drr.ikcest.org/static/upload/6e/6ea43358-ebd5-11e9-a882-00163e0618d6_m.jpg" />

Equations:

\( I_{DS}= IDSS(1-VGS/Vp)^2 \)

\(R_S= VRS/IDS \)

VGS is called the gate-source inter-blocking voltage or cut-off voltage and is shown by VGS (off). In the case of an n-channel JFET, the VGS (off) value has a negative sign. It is difficult to measure the actual JFET corresponding to the VGS of ID = 0. When the small-signal JFET used in the amplifier is reached, it will reach \ (ID = 0.1- The VGS of 10μA \) is defined as VGS (off).