From S.L.Thomas@rl.ac.uk Mon May 12 11:40:13 2008
Date: Tue, 15 Apr 2008 16:25:18 +0100
From: "Thomas, SL (Stephen)" <S.L.Thomas@rl.ac.uk>
To: "Coleman-Smith, PJ (Patrick)" <p.j.coleman-smith@dl.ac.uk>,
     Thomas Davinson <td@ph.ed.ac.uk>,
     "Lazarus, IH (Ian)" <i.h.lazarus@dl.ac.uk>
Cc: "Strachan, J (Jonathan)" <j.strachan@dl.ac.uk>
Subject: RE: AIDA - Board drawing for comment

Patrick

The layout of the PCBs and connectors looks fine. Remember that there
needs to be provision for connecting ground or (preferably) the
amplifier reference voltage between the signal strips on the kapton.
This is important for reducing coupling effects between channels
(capacitance between strips is much worse than capacitance to ground or
Vref). The kapton layout would therefore be Vref/signal/Vref/signal...
with 0.3125mm pitch. The kapton connector doesn't necessarily have to be
on such a fine pitch. There only needs to be a single Vref connection
for the whole cable. This could be on the back surface with Vref strips
on the front side connected by vias.

I will give some more thought to the kapton layout, as the choice of
strip geometry will have a considerable impact on the amplifier coupling
and noise performance. For example, making strips very narrow would be
the best condition for low capacitance, but the added series resistance
would then make noise and coupling worse.

Steve




> -----Original Message-----
> From: Coleman-Smith, PJ (Patrick) 
> Sent: 04 April 2008 16:41
> To: 'Thomas Davinson'; Lazarus, IH (Ian); Thomas, SL (Stephen)
> Cc: Strachan, J (Jonathan)
> Subject: AIDA - Board drawing for comment
> 
> 
> Hi All,
> Please could you look at the attached drawing of the pcb that 
> will connect the ASIC mezzanine boards to the detector.
> The connectors and four pcbs are shown along with the start 
> of the wiring from one connector to the 0.625mm pitch kapton cable. 
> 
> The cable is shown merely as a set of pads at the appropriate spacing.
> 
> I would like your comments about wether this an acceptable 
> way of proceeding ?
> 
> As you will see the four pcbs are placed to give a 10mm gap 
> between the two main boards which should work with fitting 
> the larger decoupling capacitors between them. 
> 
> I look forward to your comments.
> 
> Tom and Ian,
> Please could you comment on the HDMI document.
> 
> Thanks all.
> 
> Regards
> Patrick
>