vollhardt lecc2005

Production of the LHCb Silicon Tracker Readout Electronics : 

Production of the LHCb Silicon Tracker Readout Electronics

Outline: 

Outline Overview of the Readout Electronics 1st preproduction of Digitizer Board Evaluation of performance Integration with LHCb hardware 2nd preproduction Conclusion

LHCb Silicon Tracker principle: 

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

Beetle readout chip: 

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

ST Readout electronics: 

ST Readout electronics

Service Box Overview: 

Service Box Overview Digitizer Board backplane sensor + readout hybrids Digitizer Board up to 16 hybrids/boards Control Card TTC ECS 5m copper cable Optical fibres for physics data

Digitizer Board characteristics: 

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 testing 2 versions: Trigger Tracker (4-chip readout), Inner Tracker (3-chip readout)

1. Preproduction run: 

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 receiver Auto-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

Digitizer Board: 

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

Beetle signal at ADC: 

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

Linearity: 

Linearity

Sampling synchronicity I: 

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

Sampling synchronicity II: 

Sampling synchronicity II

GOL VCSEL connection: 

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

Eye diagram after 100m: 

Eye diagram after 100m Thanks to Paolo Ciambrone/LHCb Muon

Auto-sync: 

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

Radiation qualification: 

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

Full Readout test: 

Full Readout test

Full Readout test: 

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

Control Card: 

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)

Breaking News: IT version: 

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!

Next steps: 

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)

Conclusion + Outlook: 

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.

SPARE SLIDES: 

SPARE SLIDES

Digitizer Board input stage: 

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

Clock tree: 

Clock tree

TFC distribution: 

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

Service Box: frame: 

Service Box: frame Fully loaded weight: ca. 10 kg Power disipation: ca. 150 W (70 W into mixed water cooled heatsink)

Service Box cooling: 

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)

IT mounting: 

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)

TT mounting: 

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