Transcript Final Presentation

Final Report
1394b:Optoelectronic Data
Communications
Group G9:
Tiffany Lovett, gte291r
Tornya Moore, gte668r
Mareisha Winters, gte824t
ECE 4006C
April 23, 2002
Key features of 1394?
• It is a hardware and software standard for
transporting data at 100, 200, or 400 Mbps
• It is a digital interface - no need to convert
digital data into analog
• It is physically small and can replace larger,
more expensive interfaces
• It is easy to use
Key features of 1394?
• It is hot pluggable - users can add or remove
1394 devices while the bus is active
• It is inexpensive
• It is a scaleable architecture - can mix 100,
200, and 400 Mbps devices on a bus
• It has a flexible topology
• It is non-proprietary - there is no licensing
problem to use for products.
1394 Cable
• Is a small, thin serial
cable
• Contains six wires:
two of the wires carry
power; the remaining
four wires are grouped
into two twisted signal
pairs
How 1394 Works
• Supports both asynchronous and isochronous data
transfers
• 1394 device requests control of the physical layer
• Asynchronous: The address if the sender & receiver is
transmitted by the packet data. Once the receiver
accepts the packet, an acknowledgement is returned to
the original sender
• Isochronous: The sender requests an isochronous
channel with a specific bandwidth. Isochronous channel
IDs are transmitted followed by the packet data. The
receiver monitors the incoming data’s channel ID
Why 1394b?
• 1394b is a revision of the initial 1394 standard
• 1394b is twice the speed, and allows for longer
distances
• It provides new connection options such as Plastic
Optical Fiber, Glass Optical Fiber and UTP-S.
Previously 1394 could only be connected via
copper cabling
• 1394b is a prime choice for connecting personal
computers with digital devices (i.e. cameras, DVD
players, and camcorders)
Photodetectors
• Optoelectronic device that senses and measures the output of
a typical light source
• There are three steps in the photodetection process:
(1) absorption of optical energy and generation of carriers
(2) transportation of the photogenerated carriers across the
absorption region
(3) carrier collection and generation of a photocurrent
• The three main types are photoconductors, PIN photodiode,
and Avalanche photodiodes
• For high-speed applications the PIN photodiode is the best
choice because it has no internal gain and can attain very
large bandwidths.
Design Considerations for the Photodetector
• Two candidates:
– Lasermate RSC-M85A306
– Hamamatsu S5973
• Responsivity-measures how much light input is
required to produce a given current
• Capacitance of the photodiode must not exceed the
maximum input capacitance of the MAXIM
board.
• Rise/Fall Time
Comparison of Two Photodiode Candidates
Lasermate RSC-M85A306
Hamamatsu S5973
Design of the Photodetector
Board
• Both unconnectorized and connectorized photodectector
were used in the circuit.
• The resistance for the unconnectorized is 53.1 and for the
connectorized it is 66.4
• According the data on Murata’s website, the ideal value for
both of the capacitors is .01F.
Design of the Photodetector
Board (cont’d)
• Once all of the components were gathered
they were mounted on the board and
soldered onto the board.
Connectorized
Unconnectorized
Testing
• Tested the connectorized photodetector board by
connecting it to the GTS 1250 and then to the Agilent
board.
• The board did not produce an eye diagram.
• To analyze why no eye diagram was produced, simple
average value singles were looked at along with Fourier
analysis and incoming data stream.
• Received a signal from the connectorized photodetector
but did not get a signal from the unconnectorized
photodetector.
Testing (cont’d)
• Simple square wave test with connectorized photodetector
Testing (cont’d)
• Spectrum analysis with photodetector not connected
Emitters
• Three types are LEDs, Edge emitting lasers, and
VSCELs
• LEDs produce light by a process known as
spontaneous emission, resulting in incoherent light
• Lasers produce light by stimulated emission,
which results in coherent light
• For high-speed applications VCSELs are superior
to LEDs and Edge emitting lasers because they
achieve high data rates easier and they are less
expensive
Design Considerations for the VCSEL
• Two candidates:
– Honeywell HFE4380-521
– Honeywell HFE4384-522
• Threshold current-minimum amount of current needed for
the VCSEL to emit light
• Slope Efficiency-tells how many amps it takes to produce a
given power output
• Rise/Fall Times
Comparison of Two VCSEL Candidates
HFE4380-521
HFE4384-522
Link Budget Analysis
• Will the system work for the proposed link?
• For this project the purpose of the link budget is to
determine whether the transmitter and receiver system
provide sufficient current to drive the post amp.
• Link Budget = Power Incident on Photodetector x
Responsivity of the Photodetector
• Power Incident on Photodetector = [Modulation Current of
Transmitter x Slope Efficiency of VCSEL] – Losses Due to
Connectors and Fiber
Link Budget Analysis (Cont’d)
HFE4380-521HFE4384-522
Ith(m
A)
6
6
DCbiasoflaser(m
A)
7.2
7.2
SlopeEfficiency(m
W
/m
A)
0.04
0.15
M
odulationCurrentofTX(m
A)
30
30
RangeofPowerOutput(m
W
)
0.288-1.2 1.08-4.5
RangeofPowerOutput(w/ Loss)(m
W
)
0.144-0.6 0.54-2.25
ResponsivityofLaserm
atePD(A/W
)
0.4
0.4
ResponsivityofHam
am
atsuPD(A/W
)
0.47
0.47
RangeofCurrentfromLaserm
atePD(uA) 57.6-240
216-900
RangeofCurrentfromHam
am
atsuPD(uA) 67.7-282 253.8-1057.5
Design of the VCSEL Board
• In order to minimize reflections the VCSEL circuit had to
have a total resistance of 50
• A surface mount resistor of 25 was placed in series with
the VCSEL. Which has a typical resistance of 25
• A DC bias T (2k resistor in series with the 5V power
supply) was connected to the circuit to allow connect to the
AC coupled GTS 1250 pattern generator
Design of the VCSEL Board
(cont’d)
• Once all of the components were gathered
they were mounted on the board and
soldered onto the board.
Testing
• The two pieces of equipment that will be used to verify the
functionality of the components are the Tektronix GTS
1250 pattern generator and Tektronix 7000 Series
Oscilloscope.
Testing (cont’d)
• Initially tested the Agilent opto-electronic board from the
previous semester to generate an eye diagram
• GTS 1250 was connected to the transmitter portion of the
board,the oscilloscope was connected to the receiver
portion, and a fiber cable was used to loop the receiver and
transmitter together
• Tested the VCSEL board by connecting it to the GTS 1250
and then to the Agilent board
• Tested the VCSEL board with the MAXIM transmitter
board
Testing (cont’d)
• Block diagram of test setup for VCSEL
Testing (cont’d)
• Eye diagram of Agilent board
Testing (cont’d)
• Eye diagram of VSCEL board
Testing (cont’d)
• Eye diagram of VSCEL board with 1394b TX MAXIM
board
Design of Etched Board
• Using the design software SuperPCB an etched board was
designed and created.
SuperPCB layout of etched board
top layer of etched board
Testing
• The VCSEL components were mounted on the board, but
no eye diagram appeared when tested
• It was determined that the traces on the board exceed the
maximum amount allowed therefore a new etched board
must be created with the appropriate trace lengths
Bottom layer of etched board
Top layer of etched board
Conclusion
• The VCSEL board worked according to the design and
specifications and an eye diagram was produced with both
the Intel/Agilent board and the 1394b MAXIM transmitter
board
• The photodetector board was unable to produce an eye
diagram mainly because no signal could be identified from
the photodetector.
• Another possible problem with the photodetector board is
that the circuit itself could be wrong
• These problems should be looked into in further detail
before further testing can begin