1. Optical links in the 25ns test beam
1/15/2019
Optical links in the 25ns test beam
Karl Gill
CERN
Acknowledgements: O-link and MIC teams
Intro
myself
background - CMS, o-links, rad-effects
Objectives
In 2 hours, aim to describe and explain the most important damage effects:
for broad range of optoelectonics devices
with as much reference as possible to LHC applications and related R&D

2. CMS Tracker readout and control links
Final system
Analogue Readout
MS/s
FED
Detector Hybrid
Tx Hybrid 96
Rx Hybrid
processing
MUX A
APV 4
buffering
2:1 D
DAQ
amplifiers 12 12
pipelines C
128:1 MUX
Timing
PLL Delay
DCU
TTCRx
TTC
Digital Control
2000
FEC
Control 4 64
TTCRx
CCU
CCU 8
processing
buffering
CCU
CCU
Front-End
Back-End
K. Gill

3. X5 system test setup In the beam area: 4 modules, each including:
Si detector
4 APV6 chips
CCU card
TRI card
analogue optical link
timing/control ring
digital links to/from control ring
K. Gill

4. X5 analogue o-links - transmitter
1/15/2019
X5 analogue o-links - transmitter
4-channel laser package
4-channel analogue laser driver chip
4-ch transmitter daughter card
broad scope!
Large variety of applications with large number of components
ref
- LEB, other pubs by CERN related groups
- NSREC, RADECS, SPIE
Start with LHC links since bulk of components
4-way
laser package
K. Gill

5. X5 analogue o-links - fibre
1/15/2019
X5 analogue o-links - fibre
single mode optical fibre:
4-way ribbon pigtails at Tx, Rx
12-way fibres ribbons
with 12 way MT connectors
using only the 4 central fibres
96 fibre cable
8x12 ribbons
broad scope!
Large variety of applications with large number of components
ref
- LEB, other pubs by CERN related groups
- NSREC, RADECS, SPIE
Start with LHC links since bulk of components
96-way cable and
12-way optical ribbon and MT-connector
K. Gill

6. X5 analogue Links - receiver
1/15/2019
X5 analogue Links - receiver
4-way receiver
daughter-board
Receiver side:
optical ribbon connectors
4x 4-way receiver card
jumper cables to FED input
broad scope!
Large variety of applications with large number of components
ref
- LEB, other pubs by CERN related groups
- NSREC, RADECS, SPIE
Start with LHC links since bulk of components
K. Gill

7. X5 digital links 2 x 2-way transmitter and receiver
1/15/2019
X5 digital links
2 x 2-way transmitter and receiver
one unit located next to FEC, another inside beam area
broad scope!
Large variety of applications with large number of components
ref
- LEB, other pubs by CERN related groups
- NSREC, RADECS, SPIE
Start with LHC links since bulk of components
K. Gill

8. CMS Tracker readout and control links
Final system
Analogue Readout
MS/s
FED
Detector Hybrid
Tx Hybrid 96
Rx Hybrid
processing
MUX A
APV 4
buffering
2:1 D
DAQ
amplifiers 12 12
pipelines C
128:1 MUX
Timing
PLL Delay
DCU
TTCRx
TTC
Digital Control
2000
FEC
Control 4 64
TTCRx
CCU
CCU 8
processing
buffering
CCU
CCU
Front-End
Back-End
K. Gill

9. Analogue readout chain (without optical link)
1/15/2019
Analogue readout chain (without optical link)
TRI-card to FED (e.g. with copper link)
from
APV
APV output 50mA per MIP
120mV into FED per MIP (for link gain = 1)
+/- 750mV FED input range equivalent to 12.5MIP
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
K. Gill

10. Analogue optical link fibre/connectors laser photodiode receiver
1/15/2019
Analogue optical link
Each component contributes a gain factor:
fibre/connectors
laser
photodiode
receiver
laser driver
Expect spread of optical link gain ( overall):
losses at optical connections
variation of laser, receiver efficiency
Will have programmable gain compensation in final links
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
K. Gill

11. Nominal Optical vs Cu link gain
1/15/2019
Nominal Optical vs Cu link gain
Vin at FED (mV)
Go-link =
1500
GCu-link=1
1000
500 2 4 6 8 10 12
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
signal (MIPs)
Limited dynamic range (~4MIPs) for nominal o-link gain
Note, in final system Go-link will be ~1
K. Gill

12. 1/15/2019
Link gain attenuation
Potential divider added to attenuate input to link
Different values of R tried in X5
R=27W (A=21%), 91W (A=48%), 200W (A=66%)
test effect of spread in gain on system
noise penalty with large gain in optical link
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
K. Gill

13. Full chain Schematic of full analogue readout chain link integration:
1/15/2019
Full chain
Schematic of full analogue readout chain
current
offset
attenuation
laser
dc bias
Receiver output
offset
link integration:
connection then setting of gains and offsets
setup/calibration should be made automatic in future
16 (+4) readout channels instrumented in total
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
K. Gill

14. Gain + offset settings from TRI to FED
1/15/2019
Gain + offset settings from TRI to FED
e.g. for R=91W
adjustable TRI
dc baseline
Tick
210mV
-600
-300
+300
+600
Vout (TRI)
Tick
105mV
X 0.50 (adjustable divider, R=91W )
Vin (O-link)
-400
+400
adjustable laser
dc bias-point
X 3.0 (link-average)
Vout (O-link)
-1200
+1200
Tick
315mV
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
Vin (FED)
adjustable receiver
output dc offset
-750
+750
FED output
256
512
Tick
110 counts
Offset + gain settings should
be automated in future
K. Gill

15. APV analogue biaspoint
1/15/2019
APV analogue biaspoint
Vin FED (mV)
1500
overall
± n MIPs
dynamic range
digital header +
pipeline addr.
1000
VADJ
500
tick
analogue data
Time (a.u.)
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
Vadj at APVs set to correspond to 0V into FED
0V was ~256 ADC counts
K. Gill

16. Measured gain: link + divider
1/15/2019
Measured gain: link + divider
based on tick marks at TRI and receiver outputs
No 3rd gain setting
for CCU12, 14
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
O-link gain remains fixed at ~3, series resistor values at input changed
K. Gill

17. Lab measurement (gain)
1/15/2019
Lab measurement (gain)
Analogue link transfer characteristics (Note - no attenuation at input)
Many devices and technologies,
Many materials,
Have to limit the scope to devices/technologies relevent to LHC
though may include examples from space/nuclear applications R&D.
K. Gill

18. dynamic range measurements
1/15/2019
dynamic range measurements
Dynamic range defined as number of MIPs in 512 ADC counts
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
Here, 1MIP assumed to be 50mA into TRI card
this estimate close to spy channel Landau average
K. Gill

19. System dynamic ranges tested
1/15/2019
System dynamic ranges tested
<Go-link #1>=2.2
<Go-link #2>=1.6
Vin FED
(mV)
Nominal Go-link =
1500
GCu-link=1
1000
<Go-link #3>=0.95
500 2 4 6 8 10 12
signal
(MIPs)
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
dynamic ranges tested in X5:
approximately ±2.5MIPs, ± 4MIPs, ± 6MIPs
K. Gill

20. Optical link noise link contribution to noise in system measured
1/15/2019
Optical link noise
link contribution to noise in system measured
Preliminary result:
assumes 1MIP
= 50mA from APV
= 120mV from TRI
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
link noise as expected (close to lab measurements of links alone)
large noise value simply due to high link gain (G o-link~ )
gains will be better matched in final system (G o-link=1)
K. Gill

21. Effect of link gain on noise contribution
1/15/2019
Effect of link gain on noise contribution
Larger gain gives proportionally more noise
s(mV)
Vout(V)
High link gain
compensated in X5 by
adding potential divider
R=200W Þ G~1
d. range ~ 12MIPs
3.0 6
Go-link =3
Go-link =3 4
2.0
Go-link=1 2
1.0
Go-link=1
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
500
1000
500
1000
Vin-link(mV)
Vin-link(mV)
In X5, we attenuated input signal to link to obtain large dynamic range
However, link noise not attenuated ! (factor greater than final system)
K. Gill

22. Normalized link noise rms noise measured with scope at link output
1/15/2019
Normalized link noise
rms noise measured with scope at link output
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
Normalization according to usual lab procedure
rms divided by signal output for 800mV input amplitude
results close to lab values Þ good link installation
K. Gill

23. Lab measurement (noise)
1/15/2019
Lab measurement (noise)
CCU10
CCU14
Many devices and technologies,
Many materials,
Have to limit the scope to devices/technologies relevent to LHC
though may include examples from space/nuclear applications R&D.
CCU12
CCU11
Analogue link noise (lab measurement, normalized to peak signal)
K. Gill

24. Summary Successful integration of optical links in X5
1/15/2019
Summary
Successful integration of optical links in X5
16 (+4) analogue optical links installed
close to final components in most cases
various readout chain gains tested (o-link gain ~3)
from 5 to 12MIP dynamic range available
12MIP range similar to final system
noise contribution e for 5-12MIP range
should be close to 500e in final system with 12MIP range
2x2 bi-directional digital 40MHz links integrated
effect of bit-errors to be investigated in lab
Brief overview of
(I) optoelectronics technologies (found in LHC)
(ii) the various radiation environments that we should consider the effects of
Optoelectronics - sometimes called photonics - is defined as….
- definition
- several free magazines on Photonics developments
- Widespread applications also reflected in LHC project
K. Gill

25. Lab measurement (linearity)
1/15/2019
Lab measurement (linearity)
Analogue link linearity characteristics
Many devices and technologies,
Many materials,
Have to limit the scope to devices/technologies relevent to LHC
though may include examples from space/nuclear applications R&D.
K. Gill