SIFT UPGRADE Marvin Johnson
Background • SVX 2 readout choice • wanted common readout electronics • Charge signal was roughly comparable to silicon • SVX 3 development precluded new SVX chip • Chip was “free” • SIFT development • UC Davis project • Subcontracted to commercial firm • design is not robust • component variation • external noise on threshold • parasitic C on SIFT output • SVX 2 has problems in MCM package
What’s Changed? • Biggest change is in FPGAs • Emulate SVX II for readout • Buffer 64 or 128 data points • Zero suppress the data on the fly. • Fast and inexpensive FLASH ADC converters • Existence of .25 micron designs at FNAL that can be dropped in to new chip designs
3 options • Direct SIFT replacement • SIFT replacement but include pipeline (18 channel) • Replace entire MCM without using the SVX II chip.
Direct Replace • Requires replacement of SIFT in existing MCM’s • Potentially the lowest cost • may have yield problems • Keeps problems with SVX • Input is always open • differential non linearity • Requires a lot of FNAL manpower • New process that has a great deal of unknown risks
SIFT+Pipeline • Only change is to add the pipeline delay to the SIFT • Allows the SVX to be cleared before charge transfer • Eliminates SVX pickup
NEW MCM • Mux analog out to a flash ADC • 10 bit Flash ADC, 2 channels/chip • 3 micro s total conversion time • allows 94 ns/conversion • Chip control from an FPGA • Make daughter board same footprint as MCM • Power consumption appears similar to current MCM • Solves both CFT and preshower in one board
Details • Pipe line is in 0.25 micron. • convert preamp to 0.25 • should part be made rad hard? • Use gate array to zero suppress and put data into SVX format • how to pack 10 bits into format. • Do we need 2 disc. levels? • If yes, how does it get to virtual SVX. • Do we implement digital controls? • how is down loading done? • How is power handled?
schedule and cost • TSMC submission in November • $175K for 10 wafers (6 guaranteed) • Share submission with BTEV pixel • get enough chips for project (if OK) • ~1000 chips/wafer • Packaging cost is $5/chip $15K • chip testing done at FNAL ~$30K • dual 12 bit ADC and FPGA for $30 • Daughter board+stuffing for $50. • pair of adapter boards cost $75. • Total for 2000 is $160K • Is 2000 enough? • Need 50% contingency at this stage • $307K total without TSMC cost • incremental cost over SIFT only is ~$200K assuming labor at FNAL is free. • Done 1 year after submission • need to cycle all AFE boards
Which Option? • FADC gets rid of DNL and readout problems. • Also reduces risk for changing the SIFT parts on MCM’s • FADC gives clean solution to CFT and Preshower • But, it costs more money. • Both solutions probably take the same time • SIFT replacement is more of an unknown • Need to try SIFT repair on 50 parts ASAP. • Chip designer needs to know what to do by the end of May