80mbit/s digital optical links for control, timing and ...€¦ · anne marie sandvik cern....

10.September 2002 Digital Optical Control System 1

80Mbit/s Digital Optical Links for Control, Timing and Trigger of the CMS Tracker

Part I. System OverviewPart II. Prototype Testing

Anne Marie SandvikCERN


Tracker Optical Links

A-Opto Hybridprocessingbuffering

TTCRx

ADC

Rx ModuleFED

TTCRx

FEC

PLL Delay

MUX2:1

PLL

APVamplifierspipelines128:1 MUX

Detector Hybrid

DCU

processingbuffering

12

96

3

8/12

64/96

Back-End

CCUCCU

CCU CCU

Control4

TTC

DAQ

Digital Control2300 links @40MHz

D-Opto Hybrid

12

Front-End

Analogue Readout40000 links @ 40MS/s

TRx Module


Tracker Requirements

Fibres to or from same optohybrid2Skew (ns)

rms0.5Jitter (ns)

10-910-12Bit-error-rate

802Speed (Mbit/s)

To share analogue readout link components1310 nmWavelength (nm)

NotesMaxTypMinItem

•Tracker environment – T ~ -10°C

– B = 4T

– 150kGy & 3x1014 π/cm2 radiation dose

– 10 years min. lifetime


System implementation

96121 12

Final p-i-n diodes and back-end Transceiver still to be procured


Part Two

Prototype testing


Prototype Testing• DOH (3/5 Parts) • TRx (5/10 Parts)

Commercial 4 way2.5 Gbit/s Transceiverfrom NGK Optobahn

ASIC made at CERNDimensions:

Footprint: 35x25mmHeight : 5mm

XMinimum Data Rate

XReset

XXSaturation

XXSensitivity

XXOptical Power

NGK TransceiverDigital optohybridMeasurements


Measurement setup DOH

Optical attenuators

BERT

Reference Optohybrid

Optohybrid under test

I2C

Ck DaDa Ck

I2C

A

A


TRx test setup

Reference OptohybridI2C

BERT

TRx

Ck DaDa Ck

A


Tx Characteristics

-12

-10

-8

-6

Sign

al A

mpl

itude

[dBm

]

-10 -9 -8 -7 -6 -5 -4 -3 -2Average launched power [dBm]

DOH Typical eye-pattern from TRx

Average launched power: -6.7dBm

-12

-10

-8

-6

Sign

al A

mpl

itude

[dBm

]

-10 -9 -8 -7 -6 -5 -4 -3 -2Average launched power [dBm]

TRx

Signal Amplitude: -8.5dBm


10-11 10

-8 10

-5 10

-2

BER

-35 -30 -25 -20 -15 -10 -5Average Launched Power [dBm]

Rx Sensitivity & Saturation

Example of bit-error-rate versus average launched power

Typ.Operating

Range

Sens

itivi

ty

Satu

ratio

n


Rx characteristics•DOH

•RX40 Specs •Sensitivity ~ -20 dBm•Saturation ~ -3dBm

•TRx spec :•Sensitivity ~ -18 dBm•Saturation ~ -5 dBm

-28

-24

-20

Sens

itivi

ty [d

Bm]

-6 -4 -2 0 2Saturation Level [dBm]

DOH

-28

-24

-20

Sens

itivi

ty [d

Bm]

-6 -4 -2 0 2Saturation Level [dBm]

TRx


Full link

• Optical power margins measured in each channel – optical attenuation increased to point where errors occur or link fails

- From DOH to TRx - From TRx to DOH- Clock: ~17.5dB - Clock: ~9.5dB- Data: ~17.5dB - Data: ~ 10dB

• Two Links tested with attenuation for 15 hours without any errors BER < 3* 10-13

• Full link made with DOH, TRX, 100m cable + 3 ‘patch-panels’

BERTNGK-

OptobahnTRx

CERNDOH

D

D

CK

CK

out

in Tx

RxTx

Rx

A

Electricalconnections

100m opticalfibre ribbon

MPO-12

FC/PC


Summary• 80Mbit/s digital links developed at CERN for CMS Tracker control

– will also be used by ECAL, Preshower and Pixels

• Philosophy has been to (re)use analogue link components

• Extensive testing of the prototype DOH and NGK-TRx – Devices work well and compatible with intended link system– Testing procedures in place for production

• Full prototype link with DOH, TRX and realistic cabling tested– operates with a large safety margin – BER < 10-12

• The remaining specs and interfaces to be frozen end of 2002, procurement of devices to start in 2003


• More information on the Digital Optical Links:

http://cern.ch/cms-opto

80mbit/s digital optical links for control, timing and ...€¦ · anne marie sandvik cern....

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