[Cryptech Tech] ASIC implementation page on wiki

[Bernd Paysan]

Am Freitag, 15. August 2014, 20:55:27 schrieb Benedikt Stockebrand:
> Hi Bernd and list,
> 
> sorry for the delay---I'm still kind of busy soldering up the boards
> after hours...
> 
> Bernd Paysan <bernd at net2o.de> writes:
> > * Avalanche diode noise: Depending on the process options, it might be
> > possible to have an internal avalanche diode.
> 
> The problem I see with that is that if we run into problems with some
> "improved", "low noise" diodes being slipstreamed into production, then
> we have one hell of a rollback to do.  With generic external 5 cent
> diodes (or BE junctions), the worst thing that can happen is that we
> wind up with a few reels of useless components that however can be
> replaced with a reasonably wide range of alternatives.

Nah, when you do an ASIC, you defined what kind of diode it is, not some 
vendor.  The process doesn't change, it is under your control.  And of course, 
all devices produced with an ASIC process undergo your test program, which 
means you test the amplitude and frequency range of the diode noise, and 
reject parts that are out of spec.  If you get a yield problem, the fab will 
alert you, and both fab and you will start searching for reasons.

Also, using an ESD component, which is meant to have an avalance breakdown 
means that you are damn'd sure that it is an avalanche diode, because a zener 
diode wouldn't protect your device (the essential feature of an avalanche 
diode is to reliably cut voltage spikes, the zener effect has a too high 
resistance to be effective).

When you have problems with off-the-shelf diodes, the best solution is to make 
the diodes yourself.  And in an ASIC process, you are more or less just doing 
that.  With that comes responsibility, of course.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part.
URL: <https://lists.cryptech.is/archives/tech/attachments/20140815/669964ab/attachment.sig>