[Amps] RF power transistor curve trace question
mmornhin at gmx.net
Sun Jun 14 13:55:47 PDT 2009
> When placed in the curve tracer it produces a pattern with almost
> horizontal trace, based step.
What are you tracing, exactly? Collector current versus base voltage, or
what? At what collector voltage, etc?
>I removed the devices from one of the ENI
> boards and checked the curves . They were rising with a pattern of
> between 0 and about 15 degrees, significantly different pattern. (the
> gain was close.)
> What determines the 'slope' in an RF power transistor?
I would think that the first transistor you traced isn't nearly as
heavily ballasted as the second. But I can't be sure if I don't know
exactly what you are tracing!
> What is its significance?
If the difference is the ballasting, then basically it means the "flat"
transistor is suitable for class-C service only, while the "non-flat"
one is suitable for linear service too.
If a transistor with no or not enough ballasting is used in linear
service, it will typically burn out from hotspotting.
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