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Design >> RF Design >> Breakdown voltage of BJT
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Message started by DDC on Jan 29^th, 2013, 7:42am

Title: Breakdown voltage of BJT
Post by DDC on Jan 29^th, 2013, 7:42am

Hello,

I have some problem. The collector-emitter-breakdown-voltage of my bjt ist 1.5 V, but I have to handle a supply of 3 V. In the datasheet I only find static values. What would happen, if the breakdown-voltage will only be overrided transient but not in dc case ? Is this possible ? I work at 2,4 GHz. Thanks for response.

Title: Re: Breakdown voltage of BJT
Post by sheldon on Jan 29^th, 2013, 5:14pm

DDC,

As I remember, the breakdown for transient or dc is the same.
However, you have not specified the Vce breakdown voltage.
Typically, the BVceo, collector-emitter breakdown voltage measured
with the base open, is the published value. In the older processes,
the BVces, collector-emitter breakdown voltage measured with the
base shorted to the emitter, was higher. If this is true for your
process, then it might be possible to operate the transistor at the
higher voltage, if you drive it from a low resistance source, BVcer.
You will need to select a resistor value that allows the transistor to
breakdown at more than 3V. Also this approach does not work when
the breakdown is due to punchthrough, that is, the collector depleting
through the base to the collector.

Having said all of that you should really consider whether the
process is appropriate for this application. Or using an architecture
that can support the voltage requirements, for example, totem
poling devices so no device operates with more than 1.5V.

Best Regards,

Sheldon