Tom says:
>If the device have a breakdown voltage of less than that, it will
> instantly fail. Just one RF cycle over the peak voltage
>breakdown will do it.
In the context we're discussing, this is very true. However, it's not a 'tablet
of stone' for all RF stages everywhere under all conditions, falling down at
UHF and beyond, where the time taken for breakdown to happen is much greater
than a half cycle of RF. This behaviour is exploited in some devices up in the
GHz and beyond region, although it's admittedly rather academic in terms of the
present discussion.
How far it can be exploited in semiconductor design is an interesting question,
which gets varying replies from semiconductor physicists working in the same
process development group.
It should be borne in mind that RF power transistors are the fastest fuses known
to man: the bigger (and thus generally more expensive) they are, the faster they
blow, in order to protect other cheaper and more readily replaced circuitry.
They are at their most delicate on the Saturday night of a holiday weekend when
no spares are available, and there's a new country on, or it's a contest where
you're doing well.
73
Peter G3RZP
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