5
Application Examples
118
Keysight U1401B User’s and Service Guide
The cutoff voltage of an n-channel JFET
To determine the cutoff voltage of an n-channel JFET:
1
Connect the red input probe lead to the drain.
2
Connect the black input probe lead to the source.
3
Connect the red output alligator lead to the gate terminal through a 100 k
Ω
resistor, and connect the black output alligator lead to the black input probe
lead.
4
Gradually decrease the voltage output from +
00.000
V to –
15.000
V. The R
DS
value will increase correspondingly (
5
Observe at what point the resistance reading becomes
OL
; the voltage bias
level at that point would be the cutoff voltage for the n-channel JFET.
Figure 5-11
N- Channel JFET