LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 1

Production of the LHCb Silicon Tracker Readout Electronics

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 2

Outline

Overview of the Readout Electronics

1st preproduction of Digitizer Board

Evaluation of performance Integration with LHCb hardware 2nd preproduction Conclusion

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 3

LHCb Silicon Tracker principle

Two distinct tracking systems based on silicon strip detectors, read out via the BEETLE chip

TT: full acceptance angle covered upstream of magnet

IT: only area of highest track densities around beampipe

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 4

Beetle readout chip

128 channel charge integrator polyimide readout hybrid carries 3

(IT) or 4 (TT) Beetle chips for sensors of 384 (IT) or 512 (TT) strips

See also: Talk of F. Lehner:

Hybrid Design, Procurement and Testing for the LHCb Silicon Tracker

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 5

ST Readout electronics

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 6

Service Box Overview

Digitizer Board

backplane

low-voltage power

sensor + readouthybrids

Digitizer Board

up to 16 hybrids/boards

Control Card

TTC ECS

5m copper cable Optical fibres

for physics data

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 7

Digitizer Board characteristics

6 layer PCB, halogen-free, 1.6 mm thickness, symmetric stack

single side mounting, no buried/blind vias smallest feature size 6 mil, smallest package 0603 5 BGA devices:

1x CS49 (0.8 mm pitch), 3-4x BGA144(1.0 mm pitch) no JTAG chain , no boundary scan differential traces have controlled impedance/length standard commercial connectors NO tuning points layout optimized for low-cost, high-yield, easy testing2 versions:

Trigger Tracker (4-chip readout), Inner Tracker (3-chip readout)

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 8

1. Preproduction run 17 boards produced and electrically tested in late 2004

(TT version) after assembly, all BGAs X-rayed: all solder joints ok! 2 bugfixes:

wrong reference voltage for line receiverAuto-Sync FPGA: shift register one cycle (25ns) too short

all boards except one immediately working:board #10 had ripped via under BGA (fixed)

changes for IT version preproduction (and final production): changed VCSEL biasing added QPLL RC-network for improved jitter stability

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 9

Digitizer Board

Power <5 W Only positive voltages: 2.5 V, 5.0 V

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 10

Beetle signal at ADC

Flat top 15 nsec wide (of 25 nsec max.)

measured with 5m twisted pair cable

plenty of ‘space’ to set ADC sampling point

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 11

Linearity

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 12

Sampling synchronicity I

supply all 16 inputs with ‘synchronous’ testpulse:testpulse generator sourcing 16 LVDS drivers

move sampling time by using TTCrx clock phase shifters (just like in experiment..)

transmit data via GOL+ optical fibres to DACs and scope record pulseheight of sampled edge vs. programmed

delay

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 13

Sampling synchronicity II

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 14

GOL VCSEL connection

VCSEL forward voltage with 2.5V anode voltage results in too low GOL current driver voltage level

only 2.5V and 5V available

reduced to 3.3V by low-impedance divider

blocked at VCSEL with 100nF||100pF

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 15

Eye diagram after 100m

Thanks to Paolo Ciambrone/LHCb Muon

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 16

Auto-sync Beetle DataValid

signal (almost) in parallel to analogue data to frame a triggered event

done via shift register in Actel antifuse FPGA (small version of rad-hard AX54SX32) incl. TMR+ majority voting

Results in at least one IDLE frame per event

Beetle analogue output

Beetle DataValid

Beetle data after digitization

DataValid after 200 ns delay

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 17

Radiation qualification

Expected radiation levels for Service Box location for 10 years:TID 15 krad, NIEL 2E12 n/cm2

all commercial devices individually radiation qualified (TID, NIEL and SEE) with proton and neutron irradiation according to LHCb radiation policy

System test: TT Digitizer Board + backplane re-tested in June 2005 with 60 MeV protons to 60 krad (PSI, Switzerland): analogue test pattern injected verification of function and performance no variations in module operation observed

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 18

Full Readout test

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 19

Full Readout test

LHCb-style readout (except LHCb Readout Supervisor + CPU farm)

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 20

Control Card

Under development by Universidade de Santiago de Compostela Provides TTC signals and slow control interface to each

Service Box and its associated frontend electronics First prototype functional (still being tested)

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 21

Breaking News: IT version

10 Digitizer Boards (IT version preproduction) were delivered last Wednesday

initial testing confirm out-of-the-box functionality

important step: re-validate eye diagram with new VCSEL bias!

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 22

Next steps

detailed testing of IT prototypes: last design verification launch production order after:

production+assembly time for all boards: ca. 8-10 weeks

all parts available except for VCSELs (LHCb common order placed, expected in November)

‘bird-food’ supplied by company, special components by us

start setting up test bench during production:basic functionality test (go-nogo)burn-in test (catch infant mortality)

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 23

Conclusion + Outlook

The preseries production for both versions of the ST Digitizer Board has been completed.

Bugfixes and lessons learned in the TT version were successfully included in the IT version.

Required functionality was verified and system compatibility with common LHCb hardware has been shown.

Preseries hardware is used to form teststands for the TT sensor module production (Zuerich) and the IT sensor production (CERN)

Final qualification pending, design will be released for full production in Q4/05.

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 24

SPARE SLIDES

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 25

Digitizer Board input stage

Bandwidth: 1.6 kHz (AC-Coupling) to 170 MHz (AD8129) Amplifier output range matches ADC input range

3x 1 k

22

39

39

2.5 V

2x 100 nF 8 bits+

-

gain: 11

differential signal from Beetle

AD8129 TSA0801

gain: 0.22impedance: 100 Ohm

100 nF

10 kVcm

Vref (ca. 1 V)

out

out

Output to GOL serializer

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 26

Clock tree

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 27

TFC distribution

Impedance controlled traces for LVDS signals

TTL traces only used for short (~ 2 cm) for fanning out

equal trace lengths to minimize ch-ch skew

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 28

Service Box: frame

Fully loaded weight: ca. 10 kg

Power disipation: ca. 150 W (70 W into mixed water cooled heatsink)

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 29

Service Box cooling

all linear regulators located close to each other

use common copper heatsink (mixed water) to cool all at once

isolate ground slug of regulator package (local ground!)

used for testing: CPU water cooling system: no active cooler, but fan-blown heat-exchanger

Test at full load results in 35 degC case temperature for 25 degC water (=ambient temperature)

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 30

IT mounting

Service Boxes outside acceptance

Mounted on common IT station frame

‘5m copper cables’ no not move

cables from Service Box away from detector move (cable chains)

LECC 2005, Heidelberg A. Vollhardt, EPF Lausanne/Switzerland 31

TT mounting

Service Boxes mounted outside acceptance to magnet

‘5m copper cable’ guided in cable chains to station halves

cables away from Service Box fixed in cable trays