Re: Minutes of the Conference Call of 13 Feb

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

Just added the mail lists.

Fernando J. Barbosa wrote:
> Hello everyone,
>
> This is a summary of the minutes of our recent conference call with 
> regards to the ASIC development:
>
> 1.  Status of the CDC and FDC and plans for the next year.
>
> The CDC and FDC full scale prototypes will be tested/ built over the 
> next 6 months. These tests may have to be supplemented with additional 
> simulations as the budgets are very tight and beam tests have not been 
> scheduled. Beam tests also require a considerable amount of resources.
>
> There won't be enough readout electronics, i.e. flash ADCs, to fully 
> instrument these prototypes. However, testing can proceed with the 
> present availability of electronics for qualifying the ASIC GAS-1 and 
> determining other requirements for GAS-2:
>    - CDC - 1 preamp card, 1 cable, 1 shaper board, 1 Struck flash ADC
>    - FDC - 2 preamp cards (1 cathode, 1 anode), 2 cables, 2 shaper 
> boards, 2 Struck flash ADCs.
>
> It is understood that the CDC could benefit from an additional preamp 
> card and the FDC could benefit from 3 additional cathode preamp cards. 
> Additional shapers will also be available for a total of 8 units.
>
> 2.  Status of the fADC125 and plans for the next year.
>
> Design of the ADC is proceeding and  3 prototypes will be procured 
> this Summer (June/July 2008). Seven additional modules will be 
> available later. This design will already include the VXS signal 
> distribution. This development won't be available nor necessary for 
> completing the tests leading to the GAS-2 specs.
>
> 3. Status of the ASIC design - GAS-2 and future plans.
>
> Output resistor networks will be replaced with resistors tied to a pad 
> for connection to +1.25V. This will reduce power and will be 
> convenient for testing the chips during production. This will be 
> implemented in a manner that won't be detrimental to the performance 
> already achieved with GAS-1.
>
> The external output resistors will be spec'd at  56 Ohm for the 
> present prototype preamp cards (equivalent internal 500 Ohm per 
> output). However, tests will be performed to verify the advantages of 
> back termination and the value of the resistors.
>
> If chamber crosstalk becomes an issue, especially the FDC cathodes, 
> the preamp card may be modified to take advantage of the A and B 
> inputs as a way of canceling the effect.
>
> The power dissipation of GAS-2 is expected to remain the same as in 
> the GAS-1.
>
> The gain stage (x5) has been implemented and the discriminator is 
> being simulated. Layout will proceed. There is a total of 8-10 week of 
> additional work and an additional 2 weeks for feedback before final 
> submission. As the next scheduled MOSIS submission is in early June, 
> all the tests and simulations on the FDC and CDC must be completed by 
> mid-April.
>
> 4. Tests leading to GAS-2
>
> All the tests performed so far show that the GAS-1 satisfies most of 
> the requirements for FDC and the CDC. However, no significant detector 
> tests have been performed that have determined the gain and dynamic 
> range requirements. These tests need to be performed and the results 
> well understood before April 2008, if we are to meet the June 2008 
> submission deadline.
>
> The FDC and CDC may need different gains: maybe additional gain 
> settings? We may be limited by the number of available pins on the chip.
>
> A few other things to consider: there is at least a 6 month turn 
> around from submission to having preamp cards (very aggressive) and 
> the following submissions are scheduled for August, October and December.
>
> Regards,
> Fernando
>
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