1. BPIX/FPIX System and Services Planning
Charlie Strohman
Joe Conway, Yadira Padilla, Jim Alexander, Anders Ryd, Julia Thom
Cornell University
Phase 2 Pixel Electronics during TK Week
October 13, 2016

2. Outline Scope Goals Specification sources FPIX and BPIX geometry
Module and ROC inventory
Serial power chains and power cable selection
High Voltage
LpGBT chips: e-links, wiring, and fiber optics
LpGBT power
LpGBT packaging concept
Summary
October 13, 2016

3. Scope
For both FPIX and BPIX, account for all cables in the service cylinder and for all heat sources
DC and HV power for modules
LpGBT chips for control and readout
DC power for LpGBT chips
Optical fibers for control and readout
??? Am I missing anything?
For FPIX, plan all wire and fiber details for assembly
Other groups will handle BPIX construction details
Other groups will handle pixel module design
October 13, 2016

4. Goals Facilitate discussions to clarify specifications
Consider conflicting choices
minimizing material
minimizing power loss (heat) and voltage drops
minimizing failure effects
minimizing assembly complexity
Propose feasible baseline design choices that can be a starting point for further optimization
October 13, 2016

5. Specification sources
Inputs from:
“Outline and requirements of Phase 2 Pixel System and Read-Out Chip" version 2.0 by Jorgen Christiansen.
Meeting with stakeholders
October 13, 2016

6. Half Cylinder Geometry
Large Disks
Small Disks
Barrel
Service Cylinder Area
October 13, 2016

7. Dee Geometry
Each Z-layer consists of 2 Dees, one with the 1st and 3rd rings of modules (Odd Dee) and the other with the 2nd and 4th rings (Even Dee)
The Dees are carbon fiber(CF) sandwich structures with CO2 cooling tubes embedded in thermally conductive foam with CF face sheets on either side
Pixel modules are populated on both sides of the Dee to create a hermetic layer
The Dees will also host the LpGBTs and other electrical accessories in high-radius locations
Small Disc
Even Dee
Odd Dee
October 13, 2016

8. Module and ROCs (ReadOutChips) Inventory
4136 modules with ROCs
864/2736 on 96 rods in the barrel
1x2 modules on BL1 & BL2 : 2x2 modules on BL3 & BL4
9 modules per rod -> ASSUME asymmetric assembly w/ 4 on one end and 5 on the other end, not interdigitated!
1512/4592 on 28 small double-Dees (7 disks per end)
1x2 modules on rings 1 & 2 : 2x2 modules on rings 3 & 4
1760/5504 on 16 large double-Dees (4 disks per end)
1x2 modules on rings 1 & 2 : 2x2 modules on rings 3, 4 & 5
LR1
LR2
LR3
LR5
LR4
Large Dee
SR1
SR2
SR4
SR3
Small Dee
BL1
BL2
BL3
BL4
Forward Barrel
October 13, 2016

9. Serial Power Chains - Example
BPIX Layer 1
17.6v
17.0v
16.4v
1.45v
#10 wire
2.59 mm D
#18 wire
1.02 mm D
19.8v
Constant current supply
11 A
9 4-ROC clusters
0.0 V
bulkhead
FPIX Zmax
2.2v
2.8v
3.4v
50 m
2.5 m
2.9m
October 13, 2016

10. Serial Power Chains
402 chains are required if the following rules apply:
BPIX 74, small FPIX 168, large FPIX 160
All chains are elements of 4 ROCs in parallel
Either single 2x2 modules or pairs of 1x2 modules
Maximum chain length of 10 elements
All elements of a chain require roughly the same current
Current draw depends on radius
BPIX layers are independent of each other
chains can span rods in the same layer
FPIX rings are independent of each other
FPIX Dee’s are independent of each other
October 13, 2016

11. Serial Power Chains Possibilities for reducing the number of chains
Allow more than 10 elements per chain
Allow more than 4 ROCs in parallel per element
Since we have an 11 amp circuit for BPIX layer 1, why not use it to power 8 ROCs in parallel for FPIX?
Allow elements with vastly different current requirements to be in the same chain
FPIX ring 1 and ring 3
Allow elements on different Dees to be in the same chain
Would probably be an assembly nightmare
Drawbacks may include:
Higher source voltage
Wider failure effects
Waste heat
Wiring complexity
October 13, 2016

12. Serial Power Cable Selection
Tradeoff between amount of material vs. both heating due to I2R losses in the power cables and voltage drops.
Assume 3 wiring sections
Detector: wiring from a detector piece (rod or disk) to the end of the FPIX structure at Z=2.5 m.
Transition(Bulkhead): wiring from the end of the FPIX at Z=2.5 m to a junction point at Z=5 m where “small short” cables join to “large long” cables.
Outside – wiring from the junction point to the power supplies, assumed to be 50 m for this talk.
Calculate voltage drop and power loss for each chain
Depends on chain current, wire size, and length
Invent some criteria to choose wire size for each section
Voltage drop
Minimize copper
Minimize power
October 13, 2016

13. Serial Power Cable Heating
Various power losses for one selection of wires
Wire Size AWG (mm)
Watts Detector
Watts Transition
Watts Outside
BPIX Detector
18 (1.02)
448
BPIX Transition (bulkhead)
381
BPIX Outside
10 (2.59)
1451
FPIX(small) Detector
513
FPIX(small) Transition
571
FPIX(small) Outside
2176
FPIX(large) Detector 95
FPIX(large) Transition
335
FPIX(large) Outside
1276
Total
1056
1287
4903
October 13, 2016

14. High Voltage High Voltage level specification at end-of-life = 1 kV
Initially lower, but rising as radiation damage accumulates
Does wire insulation strength decrease with radiation damage?
What is the required current?
I need someone to point me to sources for suitable wire
Should we connect all modules in a chain in parallel or should each module have its own HV supply?
402 chains vs modules
Unless HV supplies have floating outputs:
The return current flows through the serial power wiring
The effective HV on each module depends on its position in a chain and on the chain current
Voltage will be monitored with a resistive divider at each module.
October 13, 2016

15. Constant current supply
High Voltage
BPIX Layer 1
16.4v
1.45v
19.8v
Constant current supply
11 A
High Voltage Supply
Total of 9 4-ROC clusters
0.0 V
Reference point for
non-floating HV supply
HV return
current path
3.4v
50 m
2.5 m
2.5m
8/30/2016

16. LpGBT Chips - eLinks Down-link: Up-link: Inventory:
1 down-link per module for control at 160 Mb/s
Up-link:
High data ROCs can require multiple up-links
Low data ROCs can aggregate data from others to share an up-link
Limited to 7 eLink ports on each LpGBT for 1.28 Gb/s
Inventory:
Barrel: up-links, 864 down-links, 284 LpGBTs
FPIX small disks: 3024 up-links, 1512 down-links, 504 LpGBTs
18 LpGBTs per small Dee wired as shown in next slides
FPIX large disks: 2080 up-links, 1760 down-links, 304 LpGBTs
19 LpGBTs per large Dee wired as shown in next slides
More simulation is required to verify the required number of links per module – affects many things!
October 13, 2016

17. LpGBT chips – Small Double-Dee Wiring
October 13, 2016

18. LpGBT chips – Large Double-Dee Wiring
October 13, 2016

19. Fiber Optic Cables Assumptions
2 fibers per LpGBT (1 control in, 1 data out)
Fibers are packaged in 12-fiber ribbons
Control and data are in separate ribbons
12-fiber ribbons do not span multiple Ds
12-fiber ribbons are packaged in 72-fiber cables
144-fiber cables are very inefficient
72-fiber cables do not span sections
independent cables for barrel, small disks, and large disks
Each of 4 quadrants are independent
October 13, 2016

20. Fiber Optic Cables Quadrant with Long Barrel (Use 158 of 288 fibers)
79 LpGBT need 2x72 control and 2x72 data
Quadrant with Short Barrel (Use 126 of 144 fibers)
63 LpGBT need 1x72 control and 1x72 data
Quadrant with Small FPIX (Use 252 of 432 fibers)
18 LpGBT per Dee need 2x12 control and 2x12 data
7 Dee per quadrant need 3x72 control and 3x72 data
Quadrant with Large FPIX (Use 152 of 288 fibers)
19 LpGBT per Dee need 2x12 control and 2x12 data
4 Dee per quadrant need 2x72 control and 2x72 data
Overall Cables per Quadrant
14 for each of 2 Long Barrel quadrants
12 for each of 2 Short Barrel quadrants
October 13, 2016

21. LpGBT Power Power for LpGBTs LpGBT Optics (Versatile Link+)
1.25 v, 0.6 A, 0.75W
Optics (Versatile Link+)
2.5 v, 0.12 A, 0.3 W
Baseline option
Local DC-DC using upFEAST2 and DCDC2S
Can power up to 7 or 8 LpGBT w/ Optics
Others to consider
“nearby” bulk 2.5 v supply and DCDC2S
“nearby” bulk 2.5V and 1.25V supplies
Serial power – chain of custom regulators that produce 2.5V and 1.25V
???
Considerations
Material – electronics vs cables
Remote sensing issues
October 13, 2016

22. LpGBT power
10/06/2016

23. LpGBT Power Cables Assume up to 7 LpGBT per upFEAST2
Quadrant with Long Barrel
79 LpGBT need 12 supplies
Quadrant with Short Barrel
63 LpGBT need 9 supplies
Quadrant with Small FPIX
18 LpGBT per Dee need 3 supplies
7 Dee per quadrant need 21 supplies
Quadrant with Large FPIX
19 LpGBT per Dee need 3 supplies
4 Dee per quadrant need 12 supplies
Overall Cables per Quadrant
45 power pairs for each of 2 Long Barrel quadrants
42 power pairs for each of 2 Short Barrel quadrants
October 13, 2016

24. LpGBT module concept LpGBT Versatile Link+
Paddleboard to interface twisted-pair cables to flex circuit
LpGBT and Fiber Module
18.1 mm x 48.6 mm x 5.4 mm thick (including eLink connectors)
Needs HDI technology (blind/buried vias) due to aggressive 0.5 mm
289 ball package
October 13, 2016

25. Summary – All BPIX/FPIX
4136 modules
12832 ROCs (readout chips)
402 serial power chains and supplies
402 or HV channels
1092 LpGBT chips
174 LpGBT power supplies
52 72-fiber bundles
Power
24 kW in detector modules
1 kW in LpGBT chips
1 kW wires within FPIX length
1.3 kW wires from FPIX to transition
5 kW wires from power supplies 50 m away
October 13, 2016

26. With apologies to The Statler Brothers “Flowers on the Wall”
Countin’ cables in the hall
That don’t bother me at all
Showin’ power-point at dawn, hope that they can’t hear me yawn
Smokin’ wire bonds and watchin’ chips go up in flames
Now don’t tell me…
Thank you!
October 13, 2016

27. Module Geometry Pixel Module Cooling Tube Thermally Conductive Foam
CF Face Sheet
Pixel chip
HDI
Modules are a layered construction from the RD53 collaboration for the pixel chip, ROC, Si Sensor, and HDI
Pixel chip bump bonded to Si sensor
Pixel chip wire bonded to HDI
Pixel chip is closest to mechanical support structure to aid cooling
Will likely be attached with Phase Change adhesive to allow removal of modules during assembly or maintenance (plus maybe mechanical fasteners)
Mechanical Support structure is a CF sandwich structure with CO2 cooling pipes embedded in thermally conductive foam with CF face sheets on both sides
Si Sensor
October 13, 2016