Transcript Senior Design 4006C Group G7 Final Report

Senior Design 4006C
Group G7
Final Report
1394b – Receiver
The new generation of FireWire.
Luke Starnes (gte874d)
Aparna Trimurty (gt9794a)
Jeff Schlipf (gte877e)
Background - 1394
• 1986 – Apple started FireWire
• IEEE 1394-1995 accepted on December 12,
1995
• IEEE 1394a accepted in 2000
• Late 1996 work began on new standard –
1394b
• Draft for 1394b submitted to IEEE in 2001
1394 – Advantages over
competition
• Versatility
• High Speed
• Isochronous
• Low Cost
• User Friendly
• Peer-to-Peer
• All Digital
• Includes power for device in cable
1394a – Specifications
• Speeds up to 400Mbps
• 4.5 meter cable
1394b - improvements
• Transmit Further (up to 100 meters)
• Faster (Speeds up to 1.6 Gbps)
• Cost Reduction.
• Smaller connector.
Project Goals
• Stage 1:
- Create working Gigabit 1394 module
• Stage 2:
- Use receiver/post-amp kits to replace
OE module
• Stage 3:
- Design our own reciever/post amp
board
Stage 1
• Purpose: testing an optomodule out of its original
environment(TI card) by placing it on a evaluation
board built by the group.
• TI 1394b card never arrived, but the Opto-Emitter
(OE) module used on card was the Agilent
technologies HFBR-53D5, which was available.
Agilent OE module schematic
Built OE Module Board
Loop Back Testing Procedures
• GTS 1250 GBIC test
system pattern
generator
•Textronic TDS 7154
Digital Phosphor
Oscilloscope
Results using PRBS7 data pattern
•Eye diagram produces shows a slight scar,
possibly from solder error
Results using K28.7 data pattern
•Less complicated data pattern produced
perfect eye.
Stage 2
• Testing of the receiver MAXIM evaluation kits:
- MAX 3266 (Transimpedance Amplifier or TIA)
- MAX 3264 (Limiting Amplifier/Post Amp or LA)
• This step of the design process is to provide
groups not only with an understanding of the
boards but also a basis for stage 3, which is an
original RX PCB design.
MAX3266 chip Layout
MAX3266 chip includes:
• A TIA which converts an input current from the
PhotoDiode to an output voltage.
• A DC cancellation circuit which is used to center the
signal around zero. This is done through low
frequency feedback.
• Voltage amplifier which converts the single-ended
signal into a differential one
• Output Filter which is a single pole low pass filter
that is used to limit the circuit’s bandwidth and
improve noise performance
• Output Buffer which is designed as a 100W
differential load between OUT+ and OUT-
3266 Evaluation Kit
• Simply hook your Photodiode into J1 and your
Limiting Amplifier into J2 and J3 and your ready
to test
Testing the MAX3266 Kit
•MAX 3266
power connector
design- can
connect to a
regular AC
adaptor.
Result of Testing MAX3266 Kit
•Perfect Eye diagram for TIA using
PRBS7 data pattern
Max3264 – Limiting Amplifier
MAX3264 chip includes:
• Offset correction and low pass filtering to reduce
input offset
• The power detector here looks at the signal from
the input buffer and compares it to a threshold set
by the TH resistor. The Resistor value will depend
on the Loss Of Signal (LOS) desired
• The signal is outputted to an output buffer also has
a control module with two pins for Level (amplify
current from 16mA to 20mA by connecting pin to
GND) and Squelch (when connected to VCC it
holds out+ and out- at a static voltage whenever the
input signal power drops below the LOS threshold
MAX3264 Evaluation Kit
•Simply connect your TIA to J4 and J5 and J2 and
J3 to your output and your ready to go. LOS
threshold programming also done here.
Testing the connected TIA and LA Kits
•MAX 3264- changed
connectors of ac
adaptor to match
board connector.
•Caused by a lack of
accurate 5V power
supplies.
Result of connected TIA and LA Kits
• Perfect eye is received from TIA + LA test
with the PRBS7 data pattern
Stage 3
• Purpose: the design and fabrication of a
functional and cost effective receiver board
based on the MAXIM board
• In allowing for varied applications many
components are ineffective for each specified
application of the chip. All redundant
components are omitted to provide a cost
effective solution for a 1394b RX board.
Old Design of TIA and LA from
Evaluation Kits
Modifications
• 1. The Level pin was grounded on the 3264 to maximize
output voltage.
• 2. The Squelch pin was grounded on the 3264 to disable
squelch. It is important to see all signals in testing, no matter
how small they may be.
• 3. The CAZ1 and CAZ2 pins on the 3264 are left open. In the
specification sheet it is stated that for gigabit Ethernet these
pins should be left open.
• 4. The Filter pin was left open on the 3266 to enable DC
cancellation.
• 5. The Loss-of-Signal circuit was omitted to further simplify the
board. This also allowed for the TH pin to be left open as this
simply sets the threshold of the LOS circuit.
Modifications (cont.)
• 6. The power filtering inductors were omitted. This was
possible based on the fact that three separate supplies will be
used and long power cords will be used between the board
and the power supplied.
• 7. A single 1nF capacitor is used for decoupling the power
supplies. Based on the use of three separate supplies 1nF
should suffice.
• 8. Decoupling capacitors for the input and output of the
circuit as well as between the TIA and LA chips were left in to
maintain a good signal.
We need to determine current going
into system from PhotoDector (PD) is
adequate to support system and still
maintain an open eye throughout
•Current design
•Resistors given values by
specs of chip
•Rpd = 50W
•Ipd= 340uAp-p
•This is unacceptable
•New Design
•R1, R2, and R3 are
removed and replaced with
new R1
•Ipd = 80uAp-p
•This is acceptable, new
R1 = 66.7ohm
New Modified Design
SuperPCB Software Layout
•This is the SuperPCB layout that produced the
Gerber file given to Bob House for the new
modified design
Parts needed:
#
Part Description
Manufacturer Part
Number
Price
(all
)
To Obtain
4
.01uF capacitor – 0805
ECJ-2VB1H103K
$.97
Order from
Digikey
3
1nF capacitor – 0805
ECU-V1H102MEN
$.97
Order from
Digikey
1
.1uF capacitor – 0805
ECJ-2VF1E104Z
$1.06
Order from
Digikey
2
100 Ohm resistors –0805
ERJ-6GEYJ101V
$.80
Order from
Digikey
1
67 Ohm resistor –0805
ERJ-6GEYJ680V
$.80
Order from
Digikey
1
50 Ohm resistor –0805
ERJ-6ENF49R9V
$.90
Order from
Digikey
3
SWC Power Supply
Connector
RAPC722
$3.12
Edgar ordered
some
3
Jameco SMA connectors
901-143-6
N/a
A bag in lab
Final Soldered Receiver PCB
Gnd
Vcc
•Bob House fabricated board with all
components soldered
Testing the Board
•Initial testing revealed board had a high
impedance mismatch and give skewed results
•Putting thumb over output appears to reduce
this effect and outputs appear more normal
Reduced Impedance
Impedance Mismatch
Mismatch
Future Considerations and
Recommendations
•We feel a new board should be fabricated
perhaps perfessionally with the following
improvements:
•
Separate the space between the SMA connectors on output by .25
inches in order to test both outputs at once.
•
The ground of the output SMA’s needs to be tied to central ground.
•
The 2 ground pins of the 3266 need to be tied to ground.
•
Create 2 separate input networks that can be chosen by a jumper
•Using a bit error rate tester to help in
troubleshooting