Re: Flash ADC Status - Front-end Test Results (fwd from Dave Mack)

["Fernando J. Barbosa" <barbosa@jlab.org>]

Hi Elton,

    I have attached my responses to Dave Mack's questions.

Regards,
Fernando

    Fernando,


On Mon, 9 Jul 2007, Fernando J. Barbosa wrote:

 > > Hi Dave,
 > >
 > >     Thanks. The tests agree very well with the published data from the
 > > chip manufacturer for the 10-bit chip. This indicates that any "excess"
 > > noise due to the front-end circuitry is low and I am confident that the
 > > board will meet the 12-bit requirements. We plan to replace the 10-bit
 > > chips with their 12-bit versions soon and once we have tested the board
 > > completely.
 > >
    Thanks. I understand that different end-users may want different
ADC's. But I suspect the 12-bit version will be popular.

 > >     The cross-talk has been measured and there was none. One might 
argue
 > > that the graph does not show any cross-talk due to the scale but there
 > > was really no change to the base-line in the data. We will accumulate
 > > more data over the next few weeks, though.
 > >

    None?! That's impressive. Presumably that means it was below the
resolution of a 10 bit ADC. It could pop up in the 12-bit version. It's
also possible that your front end anti-aliasing filter is killing the
switching transients from fast rise- and fall-times. When signals have 1
nsec risetimes, they make the whole board jump. You've reduced that
possibility considerably.


 > >     As for the linearity, yes we need to quantize that. I don't have a
 > > 12-bit ramp generator and doing DNL with pure sine-waves requires quite
 > > some work.

    These aren't easy measurements. I'm not very interested in
linearity, but some users (those with calorimeters for example) will be.

    regards,

    Dave


 > > Dave Mack wrote:
 >> > >     Fernando,
 >> > >
 >> > >     The noise results are very impressive. Do you have any idea how
 >> > > this will map to a 12-bit ADC?
 >> > >
 >> > >     The linearity and cross-talk look promising but need to be
 >> > > quantified. Let us know when we can help.
 >> > >
 >> > >     congratulations,
 >> > >
 >> > >     Dave
 >> > >
 >> > >
 >> > >
 >> > > On Tue, 3 Jul 2007, Fernando J. Barbosa wrote:
 >> > >
 >> > >
 >>> > >> Hello everyone,
 >>> > >>
 >>> > >>     I have attached a test report on the characterization of the
 >>> > >> front-end section of the flash ADC. The fADC-250 prototype 
front-end
 >>> > >> meets or exceeds the design specifications.
 >>> > >>
 >>> > >>     There is still a lot of work ahead before we can release 
the ADC for
 >>> > >> user tests. Tests of the data processing section,  the energy sum,
 >>> > >> trigger, VXS and full VME readout and register settings are 
continuing.
 >>> > >>
 >>> > >>     Do not hesitate to contact me if you have any comments or 
suggestions.
 >>> > >>
 >>> > >> Regards,
 >>> > >> Fernando
 >>> > >>
 >>> > >>
 >>> > >>
 > >


Elton Smith wrote:
> Hall D Electronics:
>
>
>
> ---------- Forwarded message ----------
> Date: Mon, 9 Jul 2007 11:43:55 -0400 (EDT)
> From: Dave Mack <mack@jlab.org>
> To: Fernando J. Barbosa <barbosa@jlab.org>
> Cc: Bodo Reitz <reitz@jlab.org>, David Doughty <doughty@jlab.org>,
>      Elke-Caroline Aschenauer <elke@jlab.org>, Elliott Wolin <wolin@jlab.org>,
>      Elton Smith <elton@jlab.org>, Latifa Elouadrhiri <latifa@jlab.org>,
>      Robert Michaels <rom@jlab.org>, Serguei Boiarinov <boiarino@jlab.org>,
>      Stephen A. Wood <saw@jlab.org>, Volker Burkert <burkert@jlab.org>,
>      Xiaochao Zheng <xiaochao@jlab.org>, Chris Cuevas <cuevas@jlab.org>,
>      David Abbott <abbottd@jlab.org>, Ed Jastrzembski <jastrzembski@jlab.org>,
>      Hai Dong <hdong@jlab.org>, HallD _Tracking_HW <halld-tracking-hw@jlab.org>,
>      halld-electronics@jlab.org
> Subject: Re: Flash ADC Status - Front-end Test Results
>
> 	Fernando,
>
> 	The noise results are very impressive. Do you have any idea how
> this will map to a 12-bit ADC?
>
> 	The linearity and cross-talk look promising but need to be
> quantified. Let us know when we can help.
>
> 	congratulations,
>
> 	Dave
>
>
>
> On Tue, 3 Jul 2007, Fernando J. Barbosa wrote:
>
>   
>> Hello everyone,
>>
>>     I have attached a test report on the characterization of the
>> front-end section of the flash ADC. The fADC-250 prototype front-end
>> meets or exceeds the design specifications.
>>
>>     There is still a lot of work ahead before we can release the ADC for
>> user tests. Tests of the data processing section,  the energy sum,
>> trigger, VXS and full VME readout and register settings are continuing.
>>
>>     Do not hesitate to contact me if you have any comments or suggestions.
>>
>> Regards,
>> Fernando
>>
>>
>>     
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