1. TTC system for FP420 reference timing?
TTC = Timing Trigger Control
Sophie Baron (PH-ESS)
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

2. FP420 requirements for timing transmission
Bunch Clock and Orbit(?) to be transmitted
Level of radiations = ??
Clock monitoring between the 2 signals
10 ps rms jitter skew between the clocks in W and E
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

3. FP420 Collaboration meeting, Sept. 2006
Existing system
The TTC system
Rad-hard chips
Monitoring the phase between 2 optical signals
Various transmission schemes used by the TTC system
Typical jitter values
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

4. FP420 Collaboration meeting, Sept. 2006
TTC system in one slide
Transmission of…
Timing of the LHC from the RF source to the experiments
LHC Bunch Clock (40.078xx MHz)
Revolution Frequency (11.245x kHz)
Then combined inside the experiments with …
Trigger and Control signals
Used by front-end electronics and readout systems
…Using single optical fibres…
…and a lot of various components and modules…
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

5. Radiation hard components
TTCrx:
50ps rms
The TTCrx is now fabricated in the radiation-hard DMILL technology, which completely eliminates the possibility of a single- event latch-up, and should show a high immunity to single-event upset (SEU).
Tested up to : 8 Mrad (X-Rays) and – 5 x1013 n/cm2 (Neutrons)
QPLL:
10-15ps rms
Tested up to 10Mrad (Co-60 γ) n/cm2
TRR receiver:
Optical receiver from Truelight (Taiwan) selected for most of the TTC designs
Tested with the TTCrx at the same doses.
OK if the optical power level stays above -20dBm (0.1mW)
Optical Fibers:
sensitive to radiations (attenuation increases with the dose)
Special fibres validated for ATLAS and CMS at high radiation levels ( n cm-2 and total dose of 100 to 300 kGy)
Radiation hardness of multi-mode optical fibres for the ATLAS detector readout (June 1999,DG Charlton et all)
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

6. Clock differences Monitoring?
Comparator
control
Phase shift with temperature:
Typical value: shift of 25ps/degC/km
FP420 => 12ps/C per side if 420m on each side
Limit of the measurement:
The jitter between the W and E zones can not be monitored, as it is manly generated by the electronics doing the optical to electrical conversion
The measurement will only concern the phase shift between the 2 segments
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

7. FP420 Collaboration meeting, Sept. 2006
Transmission Schemes
Encoded
TTC inside the experiments (based on aTTCrx chip)
Advantage: Allows to encode the orbit signal (and control frames) to the MHz
Drawback: jitter increases with the quantities of encoded data
QPLL added to reduce the jitter of the recovered clock down to 10-15ps rms
Parallel
TTC backbone system
Orbit and clock on separate fibres
Advantage: very low jitter after the opto-electrical conversion (10ps) without using the QPLL
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

8. FP420 Collaboration meeting, Sept. 2006
Encoded Scheme [1]
Used to transmit Timing, Trigger and Control inside the experiments
Serial transmission
2 Channels are transmitted
A Channel:
Broadcasting Orbit (or L1a in experiments)
Low latency
Time critical signals
B Channel:
Framed & formatted commands and data (Hamming)
Broadcast or individually addressed
Internally used in the experiments
A & B are Time Division Multiplexed
BiPhase Mark encoding is used at Mbaud: balanced signal B* A
TDM Encoder
40MHz Clock
A B A B A B A B A B
+ BPM 1 A
Orbit B*
(Idle)
25ns
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

9. CH. A (pulse, Orbit or trigger) CH. B (serial data frame)
Encoded Scheme [2]
Encoder
& laser tx
Photodiode,
decoder &
clock recovery
Encoded Clock, A, B
TTCrq
TTCrx
TRR
QPLL
Decoded CH. B
Recovered
Clock
50ps rms cy2cy
Decoded CH. A
CH. A (pulse, Orbit or trigger)
CH. B (serial data frame)
40MHz Clock
TTCex
15ps rms cy2cy
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

10. FP420 Collaboration meeting, Sept. 2006
Parallel Scheme
Clock and orbit on parallel fibres
RF signal transmission scheme
Picture
RF_Tx_D
Picture
RF_Rx_D
Tx Board
Rx Board
Laser Types
OCP03: 300 $
OCP Tx 24: 600 $
Photodiode Types
OCP Rx 03: 230 $
OCP Rx 24: 300 $
TRR: 8 CHF!
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

11. Typical Jitter values – Parallel Scheme [1]
OCP Tx 03
Comparator
control C2 C3
TRR-1B43
+ fanout
+ECL driver
TRR-1B43
+ fanout
+ECL driver
C1/C2
12.4ps
C1/C3
12.4ps
C2/C3
6.5ps
Lecroy Wavepro 7100
1GHz
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006

12. Typical Jitter values – Parallel Scheme [2]
OCP Tx 03
Comparator
control C3 C2
OCP Rx 03
+ fanout
+ECL driver
OCP Rx 03
+ fanout
+ECL driver
C1/C2
11.5ps
C1/C3
11.4ps
C2/C3
4.0ps
Lecroy Wavepro 7100
1GHz
Sophie BARON, PH-ESS
FP420 Collaboration meeting, Sept. 2006