1. 9th Workshop on Electronics for LHC Experiments.
Amsterdam. September 29th - October 3rd, 2003
"Overview of the Read-Out
System for the CMS
Drift Tube Chambers."
Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.

2. RO Electronics of the CMS Detector Drift Tube Chambers2
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
RO Electronics of the CMS Detector Drift Tube Chambers
It is part of the electronics of the DT chambers of CMS muon detector:
(Readout + Trigger).
The aim is the time digitalization and data transmission to DAQ of the incoming signals from the Front-End electronics of the chambers.
The first two levels of this data acquisition system are being developed at CIEMAT (Madrid, SPAIN):
Read Out Server boards (ROS)
30 m. LVDS copper link
Towers
Read Out Boards (ROB)
DT chamber
DDU
USC55 Control Room
CMS DETECTOR
100 m. Optical link

3. ROB
READ-OUT BOARDS

4. Location in the CMS detector4
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
Location in the CMS detector
1 Superlayer Φ
1 Superlayer θ
Honeycomb
MINICRATE
ROB

5. ROB Time Digitalization5
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROB Time Digitalization
Vdrift ~ cte
Tmax drift time~400 ns >> Tbunch crossing 25 ns 1 2 3 4 
Overlapping
t  x 2 3 1 4
Bunch crossing
Drift Time
L1 Accept Latency
Trigger
Time measurement with respect to L1 Accept

6. ENVIRONMENTAL RADIATION6
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROB DESIGN PARAMETERS
RATES
40.08 MHz clock
10-34 cm-2s-1 luminosity, at 25 ns bunch crossing.
10 Hz/cm-2 charged particles rate.
L1 Accept reduces to 1 Hz/cm2 of muons => ~1 KHz/DT chamber cell.
250 DT-chambers, a total of 172,200 anode channels.
Overlapping triggers due to a drift time of ~450 ns.
Trigger latency of 3.2 s.
100 KHz triggers
neutron fluence 10 years < 1010cm-2
charged particles flux < 10 cm-2s-1
10 year integrated dose ~ 1 Gy
ENVIRONMENTAL RADIATION
Radiation hard devices are not going to be employed, radiation tests have to be performed to every component.
OTHERS
Stray magnetic fields, in the barrel region around 0.08 Teslas.
Limited maintenance for 10 years of operation.

7. HPTDC (High Performance Time to Digital Converter)7
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
HPTDC (High Performance Time to Digital Converter)
Developed by the CERN/EP-MIC group, and produced by IBM in 0.25 m CMOS technology.
 4 registers/channel before L1 buffer.
 4 L1 buffers of 256 words, each shared by 8 channels.
 Triggers stored in 16 words deep FIFO.
 256 words deep readout FIFO.

8. HPTDC features LHC clock operation (40.08MHz).
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
HPTDC features
LHC clock operation (40.08MHz).
Highly programmable which provides flexibility.
High integration, 32 channels per chip.
Overlapping trigger handling.
Trigger latencies (50 μs) large enough to accommodate our requirements (3.2μs).
Time resolution of ~265 ps RMS in low resolution mode (Required resolution~1ns)
Implemented in a radiation tolerant technology, up to levels of 30 Krad total dose with slight increase in power consumption.
Up to 2MHz hit rates, much more than our needs (noisy channels ~ tens of KHz).
Up to 1 MHz trigger rates, enough for 100 KHz maximum estimated.
Bunch and event identification.
JTAG port for programming and monitoring.
Flexible read-out interface: parallel, serial or byte-wise.
Error flags signalling lost of events, TDC internal errors, etc. and self-bypass on error.

9. Compromise between #boards and #unused channels.9
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROB ARCHITECTURE
READOUT INTERFACE DIAGRAM
4 HPTDC/ROB
Compromise between #boards and #unused channels.
 Clock synchronous token ring passing scheme where one TDC is configured as Master.
 Bypass on error mechanism implemented.
 An Altera FPGA manages the data_ready/get_data transmission protocol, slowing down the readout frequency to 20 MHz.
parity)
Serializer
clock
JTAG INTERFACE DIAGRAM

10. 10
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
OTHER ROB FEATURES
Power consumption: 2.5 V (0.5A) and 3.3V (0.5A) ~ 4 W.
Power supply protection circuitry:
In case of 2.5V current consumption over 1.5 A or 3.3V over 1A, power supply is disconnected, with powering on cycles every 700 ms (reduces to 10% power consumption).
Sensor on board for temperature, 2.5V and 3.3V voltage and 2.5 V current monitoring. (Maxim DS2438).
32 bits/HPTDC word
Master header and trailer
Error signaling
Timing and positional information (# TDC and # channel).
Byte-wise readout (8 bits data+1 parity+2 byte ID)
DS92LV1021 serializer (12 bits: 10 data + 2 start/stop) at 20 MHz.

11. ALTERA CPLD CONTROLLER11
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ALTERA CPLD CONTROLLER
Master of the Data_Ready/Get_Data protocol slowing down readout to 20 MHz.
Manages the channels enabling mechanism for testing chambers during spill interleaves, simulating artificial tracks.
Triple redundancy registers have been implemented (solves 1 bit upsets) and a single event upset counter for radiation tests.
LVDS pair for ROB-ROS link
LVDS clock signal
ROBUS (RO-MC control bus)
128 LVDS signals from DT chambers channels
(They are also retransmitted to trigger logic)
Independent powering up signals
(up to 7 ROB´s)
ROB address lines
JTAG lines
other control lines (test pulses...)

12. ROB VALIDATION TESTS Time resolution: ~ 265 ps12
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROB VALIDATION TESTS
Time resolution: ~ 265 ps
Neighbour channels crosstalk: Below half HPTDC bin resolution < ±0.35 ns
Irradiation tests at the Cyclotron Research Centre (UCL): 5·1010 p.cm-2 of 60 MeV protons. SEU: MTBFHPTDC = 3.8 days in the whole detector
MTBFALTERA = 3.4 days in the whole detector
Test beams at Gamma Irradiation Facility (CERN):
Oct. 01: test beam at GIF. Including a 25 ns structured beam
May. 03: One full Minicrate operational. No errors found.
TDC can stand high hit rates, including noisy channels (~MHz) and this only affects 1 group of 8 channels.
Temperature cycling:
Regulators (< 5mV/30ºC).
2.5 V current variations 0.4 mA/ºC.
Time shift: 900ps/70ºC (14ps/ºC). Max variation ~40 ps/ºC.
(30% due to LVDS-TTL receptors).
Lifetime test: ROB fully operational at 105ºC ambient temperature for 4 months (3100 hours).

13. MINICRATE MINICRATE 250 Minicrates 1500 ROB´s: -1440 Rob-12813
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
MINICRATE
250 Minicrates
1500 ROB´s:
-1440 Rob-128
-60 ROB-32
MB1
MB2
MB3
MB4
Power supply
40A
1.5A
to ROS
MINICRATE
TRB
TRB
TRB SB
Chamber signals
Link
board
RO-
Link
board
ROBUS
ROB
ROB
CCB
ROB
40 MHz CLOCK
RO-link
TTC+Slow control

14. ROS
READ-OUT SERVER

15. ROS Architecture 25 CHANNELS 1 wheel sector Memory FPGA ...... X 415
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROS Architecture
Memory
Token ring
Equalizer
CLC014AJE
Deserializer
DS92LV1212A
FIFO
IDT72V243
FPGA
......
X 4
CPLD
Equalizer
Deserializer
FIFO
# event
25 CHANNELS
1 wheel sector
......
......
X 7
GOL
Equalizer
Deserializer
FIFO
Optical Transmitter
......
X 4
CPLD
Equalizer
Deserializer
FIFO

16. 16
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROS description
9U board located inside racks in towers of the CMS detector.
Its task is the multiplexation of the data coming from the ROB´s of one whole sector of each wheel.
TOTAL:60 ROS: ROS/wheel
25 channels/ROS
it also accepts trigger data from the backplane
for testing and synchronisation purposes.
It also has a power supply protection circuit.
A pooling is done by a CPLD every 4 links to align events and fasten transmission.
A token ring connects all CPLD´s for data flow to optical link management.
ROB data format is modified to include additional information like ROB number and ROB/ROS link status (transmission errors and unlocks).
1MB memory for testing and data flow snapshots for traceability in case of TX errors.
ROB-ROS link: 30m copper AC coupled LVDS link RJ-45 cable from ROB´s.
Link bandwidth: 240 Mbps. Throughput: 16Mbps.
Measured BER < 10-15
ROS-DDU link: 100m optical link to DDU in USC55 control room.
GOL: 8B/10B Ethernet Slow (800 Mbps max. Bandwidth)
850 nm VCSEL Honeywell HFE419x-521 on 62.5/125 m
multimode fiber LC conectorized.
Link max. Bandwidth: 800Mbps. Throughtput: 270Mbps.

17. ROS-8 Prototype 6U VME board • 16Kbytes FIFO per channel.17
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROS-8 Prototype
6U VME board
• 16Kbytes FIFO per channel.
• 1Mword deep memory.
• Data accessible from VME, stored on memory or transmitted through 800Mbps copper link.

18. 18
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
ROS-8 Validation Tests
Irradiation tests at the Cyclotron Research Centre (UCL):
5·1010 p.cm-2 of 60 MeV protons.
SEU: MTBFFIFO = 2.3 days in the whole detector
MTBFEQUALIZ = 17.2 days in the whole detector
MTBFDESERIALIZER = 10.6 days in the whole detector
May 2003 Test beam at Gamma Irradiation Facility (CERN):
1 ROS-8 operated in VME mode connected to 1 Minicrate.
No errors found.

19. 19
“Overview of the Read-Out System for the CMS Drift Tube Chambers.” Fernández-Bedoya C., Marín J., Oller J.C., Willmott C.
Amsterdam. September 29th - October 3rd , 2003
9th Workshop on Electronics for LHC Experiments.
October 2nd, 2003
Conclusions
The final architecture of the read-out system for the CMS drift tube chambers is presented.
It consists on two types of boards:
ROB: for time digitalization
ROS: for merging data from ROB´s and transmitting to DDU.
The chosen architecture fulfil the experiment requirements of trigger and hit rate, radiation tolerance, limited maintenance and power consumption among others.