[time-nuts] Photodiodes for high frequency OPLL

Attila Kinali attila at kinali.ch
Sat Mar 30 15:12:30 EDT 2013

On Sat, 30 Mar 2013 10:52:54 -0700 (PDT)
"J. Forster" <jfor at quikus.com> wrote:

> My understanding is that you want to operate photodiodes with high reverse
> bias for the best frequency response. The bias widens the space charge
> layer, thereby reducing the capacitance of the device. The high electric
> fields in the SCL region also sweeps the hole-electron pairs, produced by
> photon injection, out faster, hence improving the response as well. Such
> devices are best operated with very low capacity wiring into a virtual
> ground.

Could you elaborate on this circuit a little bit?
Some terms i could google for or pointers to books/papers to read?

> Of course, there are limits as, at some point, the device will avalanche.
> When that ocurrs, the device will have gain akin to a photomultiplier.
> Some devices are actually designed to operate in this mode, but, since the
> thing is so near to unstable requires careful control of temperature and
> oher parameters.

Yes, the avalanche photodiodes are meant for this operation.
Yes, there are kind of sensitive. But i think that's managable.

			Attila Kinali

The people on 4chan are like brilliant psychologists
who also happen to be insane and gross.
		-- unknown

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