Collector-Base diode of BJT as an Ultra low leakage protection diode

Jun 12, 2009 2 Replies

Hello, I want to know, is there anyone here that has used a BJT instead of an ultra low leakage diode(


Yes; I think I mentioned that in another thread. I'm using BFT25's, whose c-b junction is about half a pF and has reverse leakage of roughly 30 fA at room temp and a few volts. That's hard to beat.

100 volts is trickier, but you should be able to find a small transistor that will get you to a pA maybe.

A neon lamp gets interesting here.

John

Hello John :) , Thanks for replying to my post, How about bootstrapping? then voltage won't be an issue(transistor c-b junction in series with a 1N4007). collector current(Ic) of BF25 is just 6.5 mA which is too low, I need at least 500mA. It makes sense to look among high speed transistor which have lower stray capacitance for such a purpose. About neon lamp, that's also sound interesting, I will investigate about that.

Regards, Ebrahim

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