1. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 1 SLHC Optoelectronics Readout architectures Technologies for TX High speed multiplexing Packaging Radiation hardness and reliability testing

2. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 2 Architecture (1) Low speed links Like current SCT: 2 data links/module (redundancy)

3. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 3 Architecture (2) High Speed Links High speed MUX at end of supermodule. Data Concentrator 1 Data Concentrator 8 MUX LD Modules

4. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 4 Architecture for Pixels MCC reads out n pixel chips. For SLHC, pixel chip size similar  occupancies x10  data transmission rates x10. Pixels need 1-2 Gbits/s. Question: can we have a common architecture for pixels and strips?

5. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 5 Cost Estimates (1) Assume Strawman layout for strips –21824 modules barrel 11968 modules disks Low speed links: scale based on actual costs of SCT links + input from S-C Lee on commercial costs for opto- packages. Total for strips = 32.7 MCHF (components only).

6. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 6 Costs (2) High speed links Multiplex 30 modules  one fibre. Data rate ~3 GBits/s. Scale costs from actual costs of LHCb GOL/VCSEL readout at 1.6 GBits/s. Larger uncertainties here. No redundancy in this calculation. Estimated total cost for strips ~ 2 MCHF. This estimate is approximate but conclusion  High speed links costs << low speed links. Francois Vasey “you have to fill the bandwidth of the fibre to be cost effective”. Note a mixed solution with low speed fibres along supermodule and multiplexing to high speed links at the end of a stave would also be very expensive (only ~ 30% of the cost is for fibre).

7. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 7 Advantages Low Speed Links Grounding: separate ground for each module but –have to join grounds for serial powering –ATLAS SCT had common grounds for larger number of modules (40 or 52) in End caps with no significant change in noise (TTC Redundancy interlinks s/c DGND). –For barrel SCT had 100  redundancy links between DGND for neighboring modules in loop of 12 modules. No increase in noise seen.

8. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 8 Disadvantages Low Speed Links Cost much higher! Packaging more difficult (space constraints more severe) Single source for rad-hard SIMM fibre; might not be available for SLHC. Fragile fibres on detector are not good (had many fibre breakages, some not repairable). After mounting on detector, failures could not be replaced (  failures 4 or 5 years before start of operation were not recoverable). Mounting is very difficult, time consuming  labour costs high. Needs new chip set and we have nobody to work on it Nobody interested in links to work on this option.

9. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 9 Low vs High Speed Links Low speed versus high speed affects everything in system: –Fibres, transmitters, packaging  affects supermodule engineering. –We won’t make much progress until we make a decision. My suggestion: –Adopt high speed links as baseline. –Low speed links as fall back if we can’t solve noise problems for modules.

10. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 10 Technologies VCSELs @ 850 nm (ATLAS) + SIMM/GRIN fibre. EELs @ 1310 nm (CMS) + SM fibre. VCSELs @ 1310 nm (new) + SM fibre.

11. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 11 VCSELs @ 850 nm (1) Advantages: –Very radiation hard, very small threshold shifts at SLHC fluences (  next transparencies) –Easy to couple into MM fibres. Disadvantages –Needs custom packaging a la SCT/Pixel. –Bandwidth of SIMM fibre too low and GRIN fibre not radiation hard enough  mixed SIMM/GRIN fibre. –Needs custom fibres  concerns on cost and availability.

12. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 12 Radiation Hardness VCSELs See talk by Issever at LECC 2006 http://indico.cern.ch/contributionDisplay.py? contribId=47&sessionId=12&confId=574 No significant change in slope efficiencies up to SLHC fluence Small threshold shifts  transparency But some channels became sick after annealing @ 15 mA. Not understood  needs further studies…

13. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 13 Results – Threshold Shift (After-Before) ΔThreshold [mA] 10 days @ 10mA annealed and 5 days @ 15mA annealed LHC, annealed @ 20mA, proton implant

14. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 14 VCSELs @ 850 nm (2) Fibre Bandwidth –Very radiation hard SIMM fibre has low bandwidth > ~50 MHz km –Radiation tolerant GRIN fibre has higher bandwidth 1121 MHz km. –Splice 8m of SIMM fibre to ~ 80m GRIN fibre (as done for current Pixel readout). –Could operate up to ~ 5 Gbits/s. Demonstration of Bandwidth –Tests by KK Gan (OSU) See talk at LECC 2006 http://indico.cern.ch/contributionDisplay.py?contr ibId=48&sessionId=12&confId=574 –Scope photos of eye diagrams at 2 Gbits/s  transparency

15. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 15

16. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 16 EELs Advantages –Couple to SM fibre at 1310 nm  choice of commercial fibres that are sufficiently radiation hard and very high bandwidth. –Can survive SLHC fluences. Disadvantages –Higher thresholds than VCSELs and larger threshold shifts with radiation. –More difficult to couple to fibre but can be done by telecoms companies (as for current CMS).

17. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 17 Radiation damage EELs Threshold shift for SLHC worst case 2 10 15  cm 2 is ~105 mA. 70% of damage will be annealed during operation Threshold before irradiation ~ 4 mA.  after full SLHC fluence threshold ~ 36 mA (high!). K. Gill, SPIE 2002. http://cms-tk- opto.web.cern.ch/cms%2Dtk%2Dopto/tk/publications/wdocs/kg_spie 2002.pdf 300 MeV/c 

18. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 18 VCSELs @ 1310 Advantages –Best of both worlds. High bandwidth, availability of several sources of commercial radiation hard fibre. VCSELs @ 1310 nm expected to be very radiation hard. Disadvantages –New technology  concern about availability. –Need to verify radiation hardness and reliability. Major effort  in conjunction with CMS.

19. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 19 High Speed Multiplexing Current technology: GOL on 0.25  m CMOS. Operates at 1.6 GBits/s. Radiation hard. Should be possible to go faster with 0.13 or 0.09  m. CERN project aims to develop MUX ASIC. SMU also developing MUX as part of LOC.

20. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 20 CERN VBDL Proposal Versatile bi-directional links for ATLAS & CMS –Use for data, TTC and experimental control. –Following transparencies from P. Morerira, LECC 2006 talk http://indico.cern.ch/contributionDisplay.py?co ntribId=128&sessionId=22&confId=574

21. 21 Transceiver Module O/EO/E E/OE/O GBT DAQ Timing Trigger Experiment Control Common definition MCM containing the ASIC, optoelectronic components and optical and electrical connectors. Multi-protocol ASIC Qualified optoelectronic components (COTS) Configurable to multiple optical networks (user driven)

22. 22 Limiting Amplifier Specifications: Data rate: 3.60 Gbit/s Gain: > 55 dB Bandwidth > 2.52 GHz Equivalent input noise: < 1 mV Minimum input signal (differential): 10 mV Maximum input signal (differential): 600 mV Specifications: Data rate: 3.60 Gbit/s Gain: > 55 dB Bandwidth > 2.52 GHz Equivalent input noise: < 1 mV Minimum input signal (differential): 10 mV Maximum input signal (differential): 600 mV

23. 23 Limiting Amplifier Offset Cancellation Bias Gain Cell Gain Cell Gain Cell Gain Cell Output Buffer Size: 194  m × 194  m

24. 24 Limiting Amplifier 3.35 Gbit/s 1 Gbit/s

25. 25 CERN VBDL Summary (1) Versatile Link solution for: –Timing Trigger Links; –Data Acquisition Links; –Experiment Control Links. The system allows flexible link topologies: –Bi-directional –Uni-directional –Point-to-Point –Point-to-Multipoint

26. 26 CERN VBDL Summary (2) Specifications and Interfaces are still evolving for which we need the feedback of the potential users Some universal building blocks have already been prototyped: –Laser driver –Encoder/decoder: Line code and FEC –Limiting amplifier The Versatile Bi-Directional Link project has been proposed by the Microelectronics group as a CERN common development.

27. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 27 LOC LOC being developed by SMU for LAr @ SLHC Integrate electronics and laser/PIN on chip using SOS technology  see talk by Jingbo Ye at this workshop.

28. 28 Link-on-Chip Architecture Optical data Improve performance –No off-chip high speed lines –Flip-chip bonding reduces capacitance and inductance Reduce power consumption –No 50-Ohm transmission lines between chips Designed and Implemented in Silicon-on-Sapphire technology Targeting speed:>2.5Gbps Laser Driver serializer encoder Flip-chip bonding TX Parallel Data REFclock transmitter Module Photonic PIN Receiver Module TIA/LA De- serializer Decoder Parallel Data Clock/Data recovery Flip-chip bonding REFclock PLL and clock generator

29. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 29 Flipped OE devices on SoS substrate transparent sapphire substrate (UTSi) active CMOS layer quad PIN array flip chip attachment quad VCSEL array UTSi integrated photo detector MMF ribbon fiber VCSEL driver circuitry receiver circuitry UTSi integrated circuitry 200 um Flip-chip bonding of OE devices to CMOS on sapphire –No wire-bonds – package performance scales to higher data rates –Rugged and compact package

30. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 30 Transceiver IC with OE Devices and Link Performance at 2.0Gbps Transceiver link eye at 3.2Gbps

31. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 31 Packaging Non trivial because must be radiation hard, non-magnetic, low mass, low Z material and fit in available space Full custom packaging. Eg SCT opto- package or Pixel MT coupled arrays Find Telecoms company package that is compatible with our requirements (CMS)

32. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 32 Custom Packaging - SCT

33. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 33 12 way array with MT guide pins for coupling to 12 way ribbon fibre Used for Pixel on- detector and SCT/Pixel off-detector BOC

34. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 34 Telecoms Packaging CMS Analogue Opto Hybrid (AOH) 3 channels laser drivers, lasers and fibres

35. 35 CMS Laser Sub-Mount Compact: 4.5 * 4 * 1.3 mm 3 Fibre ends gold plated Active alignment: resistor pads used to solder fibre in location. Glue only for strain relief of fibre Radiation hard by design Removed for CMS (save $)

36. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 36 Pixel Links Consider option to keep similar architecture Number of links would be similar to current Pixel system and increase in luminosity  10 times higher data rate Need ~ 1 Gbit/s Develop similar architecture chips to current DORIC and VDC in 0.13  m See talk by K.K. Gan at this workshop

37. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 37 Common ATLAS/CMS WGs Theme a- Lessons learned and to be learned. –Collect info on successes and mistakes of the groups involved in the present detectors. Follow up on the technology choices made over 10 years ago. Produce a transparent account of the costs incurred. Create a repository for all publications. Monitor and follow up the performance and ageing of the installed links. Theme b- Radiation hardness and reliability of optoelectronic components. –Establish common procedures and common ways to represent the irradiation data, share facilities and coordinate irradiation runs, avoid redundant tests and share results. Theme c- Common optical link reference test bench. –Define a reference test system for multi-gigabit/s optical links. Define test procedures and evaluation criteria. Specify the interface to the links to be tested. Develop hard, software and FPGA-IP blocks. Purchase test equipment and build reference test bench. Test proposed SLHC links on common reference bench and evaluate with common criteria.

38. Tony WeidbergATLAS Tracker Upgrade Liverpool December '06 38 Outlook Much more work to do on radiation hardness: –Understand 850 nm VCSEL performance better –Compare damage factors in  /p/n tests. –Start testing 1310 nm VCSELs. –Continue fibre testing to SLHC doses –Test Si and InGaAsP p-i-n diodes to SLHC fluences Packaging –Custom versus modified COTs System issues –Need decision on low speed vs high speed links –If we adopt high speed links many detailed questions: How many modules/link? Do we want intermediate electrical multiplexing? How do we introduce some level of redundancy?