Oct/07/2010 Pixel PP0 opto replacement issues 1 1

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PP0 Opto Replacement Issues

Philippe Grenier, Martin Kocian, Dave Nelson, Marco Oriunno, Su

Dong, Charlie Young

SQP / PP0 / Opto Numerology• Total 8 OSP and 8 ISP at each end.• Each pair of OSP+ISP=78+42=120 modules max, served by

6+6+6=18 opto-boards • Each opto-board serves 8 modules max and for a total of

288 opto-board slots (272 active boards) in the system

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Assumed scope: Replace [opto-board + fiber ribbon] with [electrical repeater + twisted pairs] while the rest of SQP more or less intact. New Opto-box on IDEP at ~6m away from PP0.

Current Opto-board I/O Summary• 80-pin J1 connector to PP0:

2 x 8 XCK Clock 2 x 8 DCI Cmd In4 x 8 DTO Data out 2 VPIN (no longer needed)2 VISET (no longer needed)2 NTC2 RST (no longer needed) 7 VVDC1 VVDC-sense 8 GND

•1 x 8 channel fiber ribbon for Cmd+clk •2 x 8 channel fiber ribbon for Data (B-board)

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2 x 6.5 cm2

Opto-electrical replacement options• Cmd link Optobox->PP0 variations

– Opto-box decode BPM, PP0 has LVDS repeater only.– PP0 includes BPM decoder and LVDS repeater.– PP0 pass through decoded Cmd data with no repeater.

• PP0 Electrical Transition Housing Variations– Electrical Transition Board: hosting LVDS repeaters to

replace opto-board, constraint to use same PP0 flex and 80 pin connector; twisted pairs soldered to ETB.

– No connector option: LVDS repeaters surface mount on PP0 flex; twisted pairs soldered to PP0. Too late, no time for PP0 flex redesign.

• Clk for each module separately from Opto-box (one clk pair per row fanout at PP0 impractical)

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PP0 Electrical Transition Space Check• Each Opto-board sized area of 2 x 6.5cm2 (8

modules) needs to host LVDS repeaters for – 8 Clk pairs– 8 Cmd in pairs– 16 Data out pairs 4 x 8-channel Bonn LVDS repeaters, each needs

package footprint for ~40 pins (assume preference for soldering packaged chip over wire bonds). Each LVDS repeater has ~1x1cm2 area for pin spacing>0.5mm.

Array of 64 solder pads for twisted wires also need to fit on the board. Using both top and bottom ?

• Radial profile also important

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Twisted Pair Wire Volume• Each Opto-board worth of 8 channels has

32 twisted pairs. Assuming AWG28 Cu-clad Al wires and packing factor of 2.5, this is a 3mm diameter bundle.

• Each SQP has 2x18=36 such twisted wire bundles at each end. Each side has 144 such bundles total.

• Material from all twisted pairs smeared over a shell of 15cm radius would be ~1.7% r.l. at perpendicular entry.

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Questions / Tasks• ETB Mechanical arrangement: board material /

thermal contact / cooling loop ? • Total power from LVDS repeaters ? • LVDS repeater packaging footprint/constraints

? • ETB layout to fit LVDS repeaters and wire

soldering pads. Double sided ? • Clarification of PP0 flex impedance• Grounding scheme between PP0 and Optobox.• Optobox end connection of large number of

twisted pairs has same problem as IBL, to be resolved.

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