High speed switching transistors

[Paul Burridge]

Which is/are the most significant parameter(s) to watch out for
governing/limiting the maximum decent speed of switching for
transistors operating at VHF and beyond?

Thanks, p.

 

[Robert]

F sub t for the frequency where the gain drops to unity where you have the
transistors hooked up to the test equipment.

F sub max for the frequency where the power gain drops to unity.

These are related to (among other things) the parasitic capacitances of the
devices. (Mostly) The larger these capacitances the lower the F sub t and F
sub max frequencies.

IIRC, there's more spread between those two frequencies for bipolar devices
than fets.