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Opto-Rx Measurements for Pixel Upgrade

Opto-Rx Measurements for Pixel Upgrade. M.Friedl, M.Pernicka HEPHY Vienna. What? Why? How?. Digital optical 320 Mb/s transmission is intended for pixel phase 1 upgrade Recycling of existing optical links possible? Sender side appears OK

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Opto-Rx Measurements for Pixel Upgrade

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  1. Opto-Rx Measurements for Pixel Upgrade M.Friedl, M.Pernicka HEPHY Vienna

  2. What? Why? How? • Digital optical 320 Mb/s transmission is intended for pixel phase 1 upgrade • Recycling of existing optical links possible? • Sender side appears OK • Most severe bandwidth limitation in12-way receiver (ARx12) ~100 MHz • Comparative test of digital transmission at 320 Mb/s between existing ARx12and Zarlink engineering sample • Each mounted on test board(clean environment) • ARx12 with external fast, self-biased,LVDS-output comparators (ADCMP604) ARx12 Comp. Zarlink M.Friedl, M.Pernicka (HEPHY Vienna)

  3. Sender / Receiver Setup AOH test setup Agilent 8110A pulse/pattern generator Receiver boards Tektronix DSA70804 Scope AOH (TOB type) M.Friedl, M.Pernicka (HEPHY Vienna)

  4. Test A – Unbalanced Periodal Signals Ton Tperiod • 40 MHz with variable duty cycle (Ton/Tperiod) • Considerable distortions up to misinterpretation due to threshold imbalance • Bad result. However: This is a very unrealistic situation… Example: 25% duty cycle represents repetitive unbalanced 1100 0000 code Receiver M.Friedl, M.Pernicka (HEPHY Vienna)

  5. Test B – Balanced PRBS @ 320Mb/s with Sequence of 0s or 1s • 15000 words of programmable pattern filled with PRBS14 (=balanced) • Programming 1s (or 0s) from the beginning of the pattern until remaining PRBS bits become corrupted • Amazing result: • Zarlink tolerates ~700 consecutive 1s (or 0s) without effect on subsequent pattern • With more than ~700 same symbols, subsequent single bits deteriorate or vanish completely (symmetric behavior) • ARx12 even tolerates ~3000 consecutive 1s • Perfectly suitable for pixel system, where even 20 consecutive 1s or 0s are extremely unlikely M.Friedl, M.Pernicka (HEPHY Vienna)

  6. Test C – Eye Diagram @ 320Mb/s (1) • Optical Head (analog) • Limited rise time (mostly due to pattern generator) • Stable timing • Solid eye opening M.Friedl, M.Pernicka (HEPHY Vienna)

  7. Test C – Eye Diagram @ 320Mb/s (2) • Zarlink (digital) • Perfectly fine • High bandwidth(Zarlink can do 1.6Gb/s) M.Friedl, M.Pernicka (HEPHY Vienna)

  8. Test C – Eye Diagram @ 320Mb/s (3) • ARx12+comparator (digital) • Narrow opening with • best settings of pulse generator (amplitude),AOH (offset) and Rx12(offset) • Unusable with non-optimal settings(where Zarlink still works perfectly well) M.Friedl, M.Pernicka (HEPHY Vienna)

  9. Test Conclusions • ARx12 performance is marginal – even on a lab test bench in a noise-free environment • Needs careful tuning of parameters in order to work • Hence we don’t recommend its use in a production system • Zarlink works very well – but is not a commercial product • Normally 850nm, this engineering sample has 1310nm photodiode • Francois is in contact with manufacturer to see if we can get 200 pcs. of 1310nm wavelength version • Alternative:ARx12 mechanics + photodiode with faster (digital) amplifier • Roland is in contact with manufacturer (Helix) M.Friedl, M.Pernicka (HEPHY Vienna)

  10. Modification of Pixel-FED (1) • Keep single slot size • Keep VME base board New daughter board(instead of 3 ADC cards)including Zarlink receiver • Don’t need to remove current ARx12  allowseasy swapping betweenold and new systems • Need new front panelin any case M.Friedl, M.Pernicka (HEPHY Vienna)

  11. Modification of Pixel-FED (2) Front panel ARx12 Old ADC card OLD ARx12 New daughter board NEW VME board Zarlink (mountedon daughter board) Need higher connectors than nowAvailable from different vendor (samples ordered for compatibility tests) M.Friedl, M.Pernicka (HEPHY Vienna)

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