Versatile Link+ Transceiver Production Readiness - TWEPP 2019 Santiago de Compostela Topical Workshop on Electronics for Particle Physics Lauri ...
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Versatile Link+
TWEPP 2019 Santiago de Compostela
Topical Workshop on Electronics for Particle Physics
Versatile Link+ Transceiver Production Readiness
Lauri Olantera on behalf of VL+ team
Versatile Link+ Project
Versatile Link+
• The Versatile Link Plus (VL+) provides a multi-gigabit optical physical data transmission layer
for the readout and control of High Luminosity LHC (HL-LHC) experiments
• The link components: VTRx+ transceivers, fiber cables and other passive components, and
commercial back-end transmitters and receivers
• Strong collaboration with lpGBT project: Versatile Link+ is protocol-agnostic, but it is
designed to be fully compatible with lpGBT Serializer/Deserializer
TWEPP 2019 lauri.olantera@cern.ch 2
Versatile Link+ Project
Versatile Link+
Laser Driver
Back-end transceivers
and system testing
VTRx+ module
reliability
CERN-EP-ESE:
VTRx+ module CERN-EN:
and opto die Passive components
TWEPP 2019 lauri.olantera@cern.ch 3
Versatile Link+ Project
Versatile Link+
After this talk:
Special Opto User Group meeting
This talk: VTRx+ transceiver Information to VL+ users and Q&A
CERN-EP-ESE:
VTRx+ module
and opto die
TWEPP 2019 lauri.olantera@cern.ch 4
VTRx+ transceiver
Versatile Link+
• Miniaturized and pluggable
• Electrical connector
• Optical pigtail
• Up to 4Tx+1Rx configuration
• configurable by channel masking
• Tx:
• 1×4 850 nm VCSEL array
• 5 and 10 Gb/s
• Rx:
20 mm
• InGaAs photodiode
• 2.5 Gb/s
• For harsh environment
10 mm
• Temperature: -35°C to +60°C
• Total dose: 1 MGy
• Total fluence up to 1×1015 n/cm2 and 1×1015 hadrons/cm2
TWEPP 2019 lauri.olantera@cern.ch 5
Connectivity
Versatile Link+
• Electrical connector
• Optical coupling block
• With our alignment process tolerances
• Low profile 40 pin connector
Transmitter components
Versatile Link+
Laser driver
Laser
array
TWEPP 2019 lauri.olantera@cern.ch 7
Laser driver
Versatile Link+
• LDQ10 quad laser driver
• Latest version 4: improvements in
• power on circuitry
• lower voltage drop from 2.5 V Ch 1 Ch 2 Ch 3 Ch 4
• power grid
• better channel uniformity
• IO cells
• latch-up protection
• New I2C block with Good 10G performance, no differences between channels
• Fuses for unique IDs
•
Laser driver under irradiation
Versatile Link+
• Tested under x-ray irradiation up to 3 MGy (3 x spec)
• Small reduction in output current at higher bias settings, but very little change in high speed performance
10 kGy 3 MGy
• Problems in the new I2C block observed in neutron test
1. SEUs observed in all registers
• replicated in two-photon laser test
• Memory elements correctly triplicated, but voters not • There will be LDQ10v5 with
• Improper constraining of the synthesiser is understood and will be • Improved electromigration resistance
corrected • Rad-hard I2C block
2. Randomly occurring communication issues • Redesign if the issues are well understood and fixable
• I2C communication got randomly stuck, which was resolved or
either by on its own (waiting from seconds to hour) or by power • Previous version which has been shown to be rad-hard
cycling
• We try to replicate and investigated in more detail next week in
heavy ion test
TWEPP 2019 lauri.olantera@cern.ch 9
VCSELs in our unique environment
Versatile Link+
• A number of VCSEL candidates (6 types from 4 manufacturers) Temperature testing:
have been extensively tested
• Temperature: -35°C to +60°C
• Neutron irradiation: 3×1015 n/cm2 (50% annealing and therefore
results at 1.5×1015 n/cm2 give realistic end-of-life performance)
• In cold both threshold current and forward voltage increases,
which limits the current range for modulation
• Selection of a component type with acceptable threshold currents
• Screening of wafers for small forward voltage
• Displacement damage Colours represent different VCSEL types
decreases optical output power Neutron irradiation (20 MeV):
and increases threshold current
and forward voltage
• Selection of a component type
with acceptable radiation
tolerance
• Wafer screening allows us to
select VCSELs with largest
margins for harshest conditions:
• Cold and high fluence
TWEPP 2019 lauri.olantera@cern.ch 10VTRx+ transmitter performance under irradiation
Versatile Link+
• Changes in high speed performance • The main mechanism limiting the transmitter
(speed and jitter) only at very high performance is reduced laser efficiency
fluences • If low threshold current and low forward voltage lasers
are used, reduced efficiency translates into reduced
modulation amplitude:
TWEPP 2019 lauri.olantera@cern.ch 11VTRx+ transmitter performance under irradiation
Versatile Link+
• Reduced modulation amplitude has to be
compensated by increasing laser drive
currents
• LDQ10 laser driver allows the compensation
so that specified optical modulation
amplitude is achieved up to the highest
fluence levels and VL+ power budget is
therefore not violated
• Transmitter end-of-life power consumption in
highest radiation environment:
• 6 mW + 50 mW per channel
Radiation
Start-of-life: damage: End-of-life:
OMA spec: –5.2 dBm – 1dB = –6.2 dBm
(300 uW) (240 uW)
TWEPP 2019 lauri.olantera@cern.ch 12Receiver components
Versatile Link+
Photo-
diode
TIA
TWEPP 2019 lauri.olantera@cern.ch 13TIA
Versatile Link+
• GBTIA is the baseline ASIC also for the VTRx+ receiver side
• GBTIA was already used in VTRx device (phase I upgrades)
• Designed for 5 Gb/s, now operated at 2.56 Gb/s
• Radiation hardness demonstrated up to the VL + levels:
Pre-irrad 1.2 MGy
TWEPP 2019 lauri.olantera@cern.ch 14InGaAs vs. GaAs photodiodes
Versatile Link+
• In case of photodiodes the selection is between different
Start-of-life responsivity at 850 nm
material families: GaAs and InGaAs GaAs
• Fundamental differences in operation under our unique
In cold and with longer wavelengths:
conditions
InGaAs
Radiation induced responsivity loss:
InGaAs
InGaAs
GaAs
InGaAs
Photodiode capacitance under irradiation:
• InGaAs brings temperature insensitivity and significantly better
tolerance to radiation induced responsivity loss
• Slower speed (2.56 Gb/s instead of previous 4.8 Gb/s) helps
with the penalties coming from the increased capacitance InGaAs
VTRx+ will use InGaAs photodiodes
TWEPP 2019 lauri.olantera@cern.ch 15VTRx+ receiver performance under irradiation
Versatile Link+
• With InGaAs photodiode receivers are practically temperature insensitive, but irradiation damage of the
receiver has a big impact on the link power budget
• Responsivity loss in photodiode (2 dB)
• Increased capacitance reduces the high speed performance resulting in an additional penalty of another ~2 dB
(at 2.56 Gb/s)
• The penalty due to increased
capacitance is strongly data rate
dependent
• Operation up to specified fluence only
with 2.56 Gb/s data rate
• Receiver power consumption: 100 mW
TWEPP 2019 lauri.olantera@cern.ch 16Power budget and Grades
Versatile Link+
• Upstream Power Budget is tight. Depending on link length and radiation environment, extended grade
components must be used
• VL+ will impose backend module types (more details Special Opto User Group meeting after this talk)
Standard Grade:
1.7×1014 n/cm2
1.7×1014 hadrons/cm2
Extended Grade:
1×1015 n/cm2
1×1015 hadrons/cm2
TWEPP 2019 lauri.olantera@cern.ch 17Prototypes and mechanical samples
Versatile Link+
• Prototype series of 380 units in production
• Final pinout and footprint, but based on LDQ10v3
• 450 CHF per module
• Allocation through electronics coordinators
• Ready to be delivered in the end of September
• Another prototype series later in Q4/2019
• Mechanical samples available
• Application note available:
• https://edms.cern.ch/document/2149674/1
TWEPP 2019 lauri.olantera@cern.ch 18Schedule overview
Versatile Link+
• Opto die (VCSEL and photodiode) tenders out
• Deadline for answers this week
• Module assembly tendering process also ongoing
• Deadline for answers mid September
• Users to give updated quantities and pigtail lengths in view of releasing the production contract
2019 2020 2021 2022 2023
Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2
Opto die Contract 1st QA Delivery 1st lot 2nd QA Delivery 2nd lot
Eng. run Wafer Test
LDQ10v5
GBTIA Order Wafer Test
~360 ~500
VTRx+ samples samples
Contract Pre prod. Pre prod QA Series production 2000 per month End of production (60000 units)
~800 Samples ~40 000 Total qty
lpGBT 2nd MPW Eng. run Production
samples available available available
TWEPP 2019 lauri.olantera@cern.ch 19Summary
Versatile Link+
• VL+ project has developed multichannel transceiver for harsh environment of LHC experiments
• All components (lasers, photodiodes, ASICs) and full module prototypes have been extensively tested
under irradiation and across the wide temperature range
• Penalties are understood and their effects to the link operation are minimized whenever possible
• Selection of best performing VCSEL types and screening of VCSEL wafers for low forward voltage
• Selection of InGaAs photodiode to maximize responsivity and temperature range
• or taken into account in the link specifications
• Standard and extended grades
• VL+ will impose backend module types
• Production to start in 2020 following pre-production and qualification
• Production completed by mid 2023 (total quantity 60000 modules)
TWEPP 2019 lauri.olantera@cern.ch 20You can also read
