Oops, yeah the REF02. (I'm always mixing up numbers.) I've used a few different zener references. I guess I always figure they are for when you want stability, and care less about accuracy. Zeners are nice in that they go both ways, a reference from either rail.
George H.
That is strange - from my bipolar experience I'd have expected such a fast device to be comparatively leaky.
Thanks for the tip!
Thank Phil!
I always assumed that RF parts must be leaky, for no rational reason. But they are very small, and that helps.
The 5 fA stuff was at about my measurement limit.
Beta is good at low currents, too. BFG25 is even better, beta about 100 at Ic of
1 uA.
Was. NXP discontinued most of the BFG parts last year, the dogs.
Cheers
Phil Hobbs
Yikes! What's a good photodiode cascode SOT143?
Digikey still has stock on BFT25, but the beta isn't as good at low currents.
I mostly use BFT25AWs or HFA3046es, or if they aren't fast enough, BFP640FESDs. Those zillion-gigahertz SiGe:C gizmos are still reasonably fast down into the nanoamps, though I haven't checked their betas very carefully. Once I recover from the irritation of writing cheques to the IRS, I'll get some of their faster brethren, the BFP840--an 80 GHz discrete!
Cheers
Phil Hobbs
Looks like Infineon has a zillion similar parts with BFG25 footprint: BFG520W/X, BFG505/X, BFG540/X, BFG590/X, BFG67/X, BFG92A/X, a few of which you can actually buy.
The NEC parts have incompatible pinouts, since they discontinued the "R" parts.
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