Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
MOST Interconnectivity, 2003; 1E. Zeeb, REM/CO
Silica fiber based physical layer for MOST
Eberhard ZeebDaimlerChrysler AGOptoelectronic Systems
MOST Interconnectivity, 2003; 2E. Zeeb, REM/CO
Content
• Why silica-fibers for MOST ?
• PCS fibers and 850 nm VCSELs: basics and advantages
• State-of-development of PCS/VCSEL components for MOST
MOST Interconnectivity, 2003; 3E. Zeeb, REM/CO
Optical data bus in cars: currently used technologies
200 µm
9 µm, Telecom50 µm, Datacom
Key component :• PMMA fibers with
1 mm core diameter Advantage: • large core fiber diameter⇒ low cost connectors⇒ high coupling efficiency using LEDs
Restrictions:• only point-to-point links• link length < 20 m• beding radius > 25 mm• T < 85°C• data rate < 150 MBit/s
MOST Interconnectivity, 2003; 4E. Zeeb, REM/CO
13 dB
distribution of LED output power distribution of
receiver saturation
MOST - power budget limitations
distribution ofreceiver sensitivity
< 2 · 2.5 dB loss atdevice connectors
Ca. 2 dBsystem margin
6 dB leftfor cabling harness
< 2 dB lossfor each in-line connector
< 0.3 dB/m lossof PMMA cable
MOST Interconnectivity, 2003; 5E. Zeeb, REM/CO
Future challenges for MOST Phy
• temperature range >> 85 °C•compatible to standard electrical wire installation (e.g. no length and bending restriction) •easy expansion of network (e.g. subsequent installation of components)•plug/unplug-and-play of components (e.g. seats with integrated displays)•easy to maintain (testability, repair concepts)
• passive optical by-pass functionality (failure-tolerance)• lower-cost
• increase of data rate
MOST Interconnectivity, 2003; 6E. Zeeb, REM/CO
Temperature requirements in cars
Passenger compartment: -40 ... +85 °C
Roof module: -40 ...+105°C
Engine compartment: -40...+125°C
0 10 20 30 40 500
20
60
100
140
tem
pera
tur
[°C]
time [days]
42,0 42,2 42,4 42,6 42,8 43,00
20
40
60
80
100
120
140
tem
pera
tur
[°C]
time [days]
Short term temperature peaks above 125 °C
e.g. Stop-and-Go
Example: Engine compartment
MOST Interconnectivity, 2003; 8E. Zeeb, REM/CO
400 500 600 700 800 900
1
0,1
0,01
0,001
SI PMMA
PFGI-POF
10
atte
nuat
ion
(d
B/m
)
wavelength (nm)
PC
PCS
standard silicaPros/cons PC:
+ temperature range up to 125°C
— attenuation > 1dB/m
Pros/cons perflourinated PMMA:+ low attenuation
+ high bandwidth— temperature < 70°C— high costs (even compared to silica)
— „small“ core diameter (125 µm)
Other Polymer Optical fibers
MOST Interconnectivity, 2003; 9E. Zeeb, REM/CO
Multi core glass fibers
advantages:• temperature range up to 300°C• wave length 800 - 900 nm• bending radius 5 mm
but:• same attenuation as POF• coupling to fiber bundle ?• connector losses ?
MOST Interconnectivity, 2003; 10E. Zeeb, REM/CO
Advantages
• large bandwidth: > 1 GHz • 20 m• temperature range: up to 125 °C• low attenuation: ca. 0.005 dB/m• 850 nm compatible (COTS)
PCS
PMMA500 nm
650 nm
400 500 600 700 800 900wavelength (nm)
fiber
att
enua
tion
(dB/
m) 10
0.001
0.01
0.1
1
850 nm
claddingsilicacore
inner jacketouter jacket
200µm
230µm
500µm
NA = 0,37
Polymer Clad Silica fibers: waveguides for automotive applications
MOST Interconnectivity, 2003; 11E. Zeeb, REM/CO
Advantages of VCSELs compared to
LEDs:- high output power- high wallplug efficiency- low driving currents- large modulation bandwidth- low beam divergence
edge-emitting lasers:- on wafer testability- simplified packaging- two-dimensional arrays- low threshold currents- circular, low divergence beam- wide operating temp. range- large modulation bandwidth- long lifetime (no COMD)
VCSEL
LEDedge emitting laser
active layeractive layer
Bragg-reflector
Bragg-reflector
VCSELs: ideal light sources for interconnects in cars
MOST Interconnectivity, 2003; 12E. Zeeb, REM/CO
Point-to-Point Link within MOST Ring
SP1 SP2 SP3 SP4
MOST DeviceMOST Device
MostNetworkTransceiver
EOC OECOEC MostNetworkTransceiver
EOC
<----------- Power Budget ----------->for Automotive Cabling
PCS Phy for MOST
• Package dimensions compatible to current MOST devices• Pinning unchanged to current MOST LED-transceivers
1st step: simple replacement of PMMA - phy by PCS-phy
MOST Interconnectivity, 2003; 13E. Zeeb, REM/CO
- Yazaki has prototype PCS connectors and cables
- Prototypes are currently functioning in a MOST ring
Prototype Connectors
- 2+0 Integrated Header
- 2+4 Integrated Header
- 2+0 Pigtail
- 2+4 Pigtail
- FOT is compatible with existing MOST footprint
Yazaki Prototype PCS Connectors
MOST Interconnectivity, 2003; 14E. Zeeb, REM/CO
• Precision mold manufacturing technology
• Engineered polymers used for ferrule material
• Laser welding, crimp, and adhesive system ferrules designed
PCS Ferrule Prototypes
MOST Interconnectivity, 2003; 17E. Zeeb, REM/CO
Concept of a PCS - Fiberfor automotive application
Core +Cladding ø
230µm
PA12-”Buffer”ø1,51+/- 0,04 mm
PA12-Jackedø2,3+/- 0,07 mm
(optional)
Optimised for contact and connector termination / Crimp,Laser
MOST Interconnectivity, 2003; 19E. Zeeb, REM/CO
Comparison of power budget (point-to-point MOST link)
POF/LED system PCS/VCSEL system
Min. optical output power
Min. receivable power
Fiber transmission loss
In-line connector loss
Header connector loss
Dynamic Range
-10 dBm
-24 dBm
0.3 dB/m
2 dB
2.5 dB
14 dB
-5 dBm
-26 dBm
< 0.01 dB/m
< 2 dB
< 2.5 dB
21 dB
MOST Interconnectivity, 2003; 22E. Zeeb, REM/CO
Specification work on PCS Phy should start now
- SP1: All specified parameters stay unchanged !
- SP2: Difference to current MOST specification; all other parameter unchanged !
Peak Wavelength: 800nm ... 900nm (typ. 850nm)Optical output power: -1.5dBm ... –5.0dBmPower within a far field angle of 22° (NA = 0.37) and a diameter of 200 µm !Laser class 1 has to be fulfilled !
- SP3: Difference to current MOST specification; all other parameters unchanged !
Peak wavelength of input signal: 800nm ... 900nm (typ. 850nm)Receivable optical power range for datarecovery: -26dBm ... –2dBmPower within a far field angle of 22° (NA = 0.37) and a diameter of 200 µm !
- SP4: All specified parameters stay unchanged !
MOST Interconnectivity, 2003; 23E. Zeeb, REM/CO
Additional features of MOST I using PCS layer
MOSTnetwork
ECU
ECU
ECU
ECU
ECU
Y-coupler
Diagnosis tool
additionalterminal
ECU
•passive plug-and-play connector•passive diagnosis port•passive „listen only devices“
• no length restriction of PCS cable• several in-line connectors (e.g. for comfortable installation)• bending radius within cable harness < 10 mm• temperature range of cable 125 °C