Re: fADC

[Gerard Visser <gvisser@indiana.edu>]

Hi Fernando,
   I'll get some kind of block diagram together. It will be needed 
anyway, not only for the review; it's good to get it done now. I am 
expecting feedback from a vendor soon on some parts pricing, I'll 
probably wait for that first.
   I complete acknowledge, we did not discuss the two gains option with 
Mitch, and it would certainly be a change that requires some extra work 
from him. I guess I did not really appreciate that we would need such a 
large (~6) gain factor difference between cathodes and anodes, but it 
looks that way at least based on recent results. We need to nail this 
down further before asking Mitch to actually do anything about it. 
Perhaps it can be accomodated only at the ADC board, but as you know 
this is not optimal from the noise perspective. It may not matter very 
much though - we should be able to easily calculate and add the 
corresponding amount of extra noise into the measured samples and see 
how much the cathode position resolution is degraded, if at all.

	Gerard

p.s. I'll post the block diagram and spec slides to the portal in a few 
days, when I have it.

Fernando J. Barbosa wrote:
> Hi Gerard,
> 
>    Thanks for the specs on the fADC. A block diagram would be really 
> great and I would need it sometime within the next week (maybe 2). The 
> review is on March 6th but Elke would like to have the slides 
> distributed by the end of next week for comments. I am planning on 
> running the electronics slides by you to get your feedback.
> 
>    On another note, I called Mitch yesterday after he replied to my 
> email. He was surprised about the gain for the cathodes as that was 
> never mentioned to him. He will look at it after the prototype is 
> complete because it affects a lot of the design, as you know. It may be 
> that the x5 gain has to be provided on the fADC just like you do now. He 
> also didn't see a problem with sharing the spice net and it also helps 
> with reviewing the final design.
> 
> Best regards,
> Fernando