Silica fiber based physical layer for MOST · Silica fiber based physical layer for MOST Eberhard...

MOST Interconnectivity, 2003; 1E. Zeeb, REM/CO

Silica fiber based physical layer for MOST

Eberhard ZeebDaimlerChrysler AGOptoelectronic Systems


Content

• Why silica-fibers for MOST ?

• PCS fibers and 850 nm VCSELs: basics and advantages

• State-of-development of PCS/VCSEL components for MOST


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


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


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


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


aperture angle about 80 °

Mechanical bending


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


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 ?


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


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


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


- 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


• Precision mold manufacturing technology

• Engineered polymers used for ferrule material

• Laser welding, crimp, and adhesive system ferrules designed

PCS Ferrule Prototypes


Integrated PCS Header


PCS Pigtails


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

E. Zeeb, REM/CO

Implementation of PCS in existing interfacedimensions

POF / PCS


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


E class car with PCS MOST ring network


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 !


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


Summary

PCS based physical layer for MOST

- overcomes limitations of current PMMA solution

- several suppliers work on MOST compatible components

- Spec for MOST 1 PCS-phy will be established

- series introduction as MOST I phy already considered

Silica fiber based physical layer for MOST · Silica fiber based physical layer for MOST Eberhard...

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