[Halld-tracking-hw] [Halld-electronics] ADC125 paper

[Gerard Visser]

Hi Chris,
	Cost delta for 14 bits vs. 12 is roughly $18 per channel (based on web pricing 
not a real quote in our full quantity). I'm sure that 14 bits is 'better' than 
12 but given realistic output noise levels from the preamp it probably is a 
fairly insignificant different. The errors in timing measurement I would bet are 
dominated by pulse shape variations on the <8ns scale and not by the raw bit 
resolution of the ADC. However, since we have a 14 bit board we can certainly 
try it both ways and quantify this, once a timing algorithm is fully developed.
	Thanks,

		Gerard

p.s. It's interesting to note the ADC chip power is *identical* in 14 and 12 bit 
versions, i.e. it's almost certainly the same silicon they are selling in the 
two products, just tested to two different levels and then probably a little 
one-time programming option applied to cut out the two LSB's. A nifty business 
strategy.


On 11/10/2010 3:23 PM, C. Cuevas wrote:
> Hi Gerard,
>
> I think the paper is in very good shape and the results are excellent given the
> density of the design. Out of curiosity, you mentioned that the (prototype)
> board was populated with 14bit A/D and that the boards for the experiment will
> be 12bit. Is that a cost decision or are the extra bits unnecessary for the
> application?
>
> Great to hear a pre-production quantity will be built in the not to distant future!
>
> Best regards,
> -Chris