[sdiy] Vco I did today...

[René Schmitz]

Hi Jim, Tim, and all!

>I don't think the J111 and 2N4391 are the same. J111
>shows 1nA Idoff, 2N4391 is 0.1nA.

To get to a valid conclusion, one must also state for what Vgs 
and Vds this Idoff is specified.

>You're right, Rdson and Idoff tend to be exclusive.
>But it makes sense; the combination can be thought of
>as the dynamic range of the FET. The question I have
>is: which is more important, Rdson or Idoff?

For a VCO the ratio of the two defines the maximum and minimum frequencies.
(Its not really Rdson, but rather Idss, because the FET acts as a constant 
current source for voltages above Vp, and turns into a "resistor" only for 
the last couple of volts. But then again Rdson and Idss are related too.)
They are both equally important. 

Cheers,
 René


-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159