Hi guys,

I saw in Malvino's Electronic Principles that it is stated that Idss
and gfs (the transconductance/gain) are easy to measure, whereas
Vgs(off) is not and that manufacturers calculate it from this formula
(hope I've remembered it right)

Vgs(off) = -2*Idss/gfs

I've just checked out this assertion by measuring Vgs - v - Id for a
bunch of assorted FETs and found that I could easily establish the
pinch off voltage to within about 0.1V either way. Contrary to what
the book says, I personally have found it a simple matter to measure
Vgs(off). So why do they make out it's a big deal?

p.
--

"What is now proved was once only imagin'd." - William Blake, 1793.