Differential COnneCtOr
fCn-260(D) Series
roHS Compliant
microGiGaCn
TM
Stacking Connector
n
featureS
• High speed matched impedance (100Ω) differential
signal connector
• Low cross talk
• 2-step sequential mating of contacts
• Self alignment feature
• Hot plugable
• RoHS compliant
n
SpeCifiCatiOnS
It em
Sp ec i f i c at i o n s
-55˚ C to +105˚ C
AC 0.1A (signal)
AC 0.5 A (ground)
AC 30 V
80m ohms max. (signal)
40m ohms max.(ground)
1000Mohms minimu m
AC 500V for 1 minute
100 cycle s
50 N maximum (24 pair )
5 N minimum (24 pair )
Operating temperature
range
Current rating
Voltage rating
Contact resistance
Insulation resistance
Dielectric withstanding
voltage
Durability
Insertion force
Withdrawl force
fujitsu's fCn-260(D)
Differential Signal Connector
As network speeds increase, designers
are moving to differential interconnects
for network switches and hubs, as well
as for connections between components
in high-speed computer clusters,
video systems, test equipment, and
real-time medical equipment (MRI,
etc.). Conventional connectors do not
support the speed and signal integrity
requirements of these applications. By
implementing a connector specifically
for high-speed, high-density, board-to-
board differential applications, designers
can take advantage of a differential
interconnect instead of more costly fiber
optic or coax alternatives.
Differential signals use two conductors
to carry signals that are compliments of
one another. This arrangement reduces
noise effects because any noise
introduced by interference or crosstalk
appears in both signals (common-mode
noise) and is ignored by differential
http://us.fujitsu.com/components
n
MaterialS
It em
Insulator
Conductor
Plating
Specifications
subject to change
Mat er i al s
LCP Resin (UL94V-0 )
Copper Allo y
Contact: Au Plating (PAGOS)
Au over Pd-Ni plating
Dimensions are in millimeters (inches)
microGiGaCn
TM
fCn-260 (D) Series
receivers. With noise voltages less of a problem,
differential signals can use a small voltage swing
that switches between LOW and HIGH values
extremely quickly --hence the appeal of differential
signals for high-speed networking and clustering.
Differential connector characteristics can exceed
the requirements of upcoming 1-Gbit applications
and extend to next-generation applications at
speeds upwards of 4.4 Gbps. As a result, system
and board vendors who adopt such a connector can
look forward to legacy usage that spans multiple
product generations.
The signal transmission path of connectors has
not always been a critical issue when choosing
an interconnect method because the connector's
electrical signal path is short compared to cables
or printed circuit board assemblies. In applications
utilizing high-frequency signals, however,
connectors can have a significant effect on signal
integrity. Connectors for high-speed applications
must be designed to achieve optimal performance
through the minimization of crosstalk and
susceptibility to noise influences.
networking hubs incorporate many boards that
must be interconnected via short-run cables.
These internal cables often have to transfer data at
speeds significantly higher than those of the actual
network, so even today's 10/100-Mbit networks
need high-speed internal interconnects with
excellent signal integrity. In addition, any system
that uses an external fiber optic connector probably
requires an internal, board-to-board connector
system that works at the highest possible speeds.
Fiber optic and coax interconnect systems
obviously meet the internal performance
requirements, but the cost is high. Differential
interconnects meet both the performance and
cost goals but until recently, no connectors were
available that provided high-density connections
at gigabit speeds. In addition, connector test
methodologies from the past cannot give
reliable and repeatable results of the differential
connector's performance in high-speed systems.
Therefore, new test methodologies must be
developed based on the unique characteristics of
these emerging high-speed applications.
Differential signal applications
The shift from mainframe environments to
networked client/server enterprises has made
networks a critical bottleneck for improving system
performance. Emerging technologies such as
high-speed server farms, video conferencing,
and greater use of graphical interfaces is pushing
networks toward performance of 1 Gbit/sec and
higher. The IEEE 802 committee is releasing 1.028-
Gbit Ethernet standards to meet this requirement.
One of the key challenges for switch, hub, video
equipment, and server manufacturers is to find
a board-to-board connector system that allows
signals to transfer at gigabit speeds over an
affordable interconnect system that furnishes
specific matched-impedance characteristics.
Applications such as servers are now moving
to extremely high-speed interfaces (often
based on Fibre Channel) between computer
backplanes and disk subsystems that require
advance interconnects between boards. Similarly,
High-speed differential interconnect
characterization
In the past, connector manufacturers "de-
imbedded" the connector from the test PCB's
to show just the electrical characteristics of the
connector and did not include any parasitic
effects associated with solder joints on a through
hole contact lead, or the effects of the contact
post (compliant or non-compliant pin) in a plated
through hole. While this test methodology was
acceptable for slower system speeds, today's
differential interconnects demand much more
focused attention on system and board effects.
The requirements for testing today's high-speed
differential interconnects are demanding with
good reason. Connectors and other traditionally
"electrically small" components are no longer small
when considering presently available signaling
technologies with 100ps risetimes and multi-gigabit
data rates. Among these requirements are very
well-designed test boards needed for accurate
measurement and characterization. This data is
Specifications
subject to change
Dimensions are in millimeters (inches)
http://us.fujitsu.com/components
2
microGiGaCn
TM
fCn-260 (D) Series
used to develop SPICE or other models and to
provide detailed data to the design community.
Typical high-frequency test boards designed by
Fujitsu include:
l
well-controlled impedance, matched-Iength
test traces (with "real-world" widths and
spacings)
calibration/reference lines that mimic the test
traces
connector region entities (pads, pins, vias)
that reflect actual system board
implementations
low discontinuity test connectors (these give
access to the measurement equipment) of
sufficient bandwidth to meet the testing needs
(e.g. SMA, 55MB, etc.)
l
include signal edge and amplitude losses,
skews, propagation delays, and interconnect
bandwidth. At times, frequency domain data
(such as S-parameters) adds insight into these
measurements and may be preferred by some
customers. However, differential measurements
in the frequency domain must be approached
with caution and specialized knowledge.
l
l
Differential pairs must be well-matched in
order to minimize skew and maintain the
proper impedance. Calibration lines of lengths
"L" (where L is the length of the test traces
between the article under test and the test
connectors) and 2L provide the opportunity to
calibrate out the board effects (if necessary)
as well as to make "reference" measurements
to test the goodness of an interconnect.
These reference measurements are especially
important when determining transmission
fidelity. Fujitsu Components attempts to use
standard, commonly available FR-4 type board
materials (better performers than some believe)
whenever possible; however, there are times
when so-called "low loss" board materials may
be required, such as for long paths running at
gigabit speeds.
In addition to very good test articles, test
equipment must be selected that will provide for
the measurements required at the bandwidths
needed. Measurements may be completed
for differential interconnects running at 100
Mbps, 625 Mbps, 1 Gbps, 2.5 Gbps or beyond
depending on the system being designed. Fujitsu
Components typically measures for single-ended
and differential impedance (using a "TDR"),
transmission fidelity, crosstalk, and eye pattern
performance among other measures of quality.
Typical transmission parameters quantified
Specifications
subject to change
Dimensions are in millimeters (inches)
http://us.fujitsu.com/components
microGiGaCn
TM
fCn-260 (D) Series
Figure 1
Basic Concept for Differential Transfer
Sectional View (Connection area)
1.5 mm
0.75 mm
Patent pending
Virtual ground
plane
+
+
+
1.27 mm
Differential pair contact
-
-
-
Ground/Power contact
Figure 2
PCB Routing -Test Card
Measurement
pair
S1+
S1-
S2+
Drive pairs
S2-
S3+
S3-
SMA connector
footprints
Edge coupled
differential pairs
PCB Routing - Test Card
Measurement
pair
S1+ S1-
Drive pairs
S2+ S2-
S3+ S3-
SMA connector
foot print
6“ test pattern
Edge coupled
differential pairs
Adapter card socket
foot printcard
3” test pattern
Specifications
subject to change
Dimensions are in millimeters (inches)
http://us.fujitsu.com/components
microGiGaCn
TM
fCn-260 (D) Series
TDR Results (Impedance Tr 50ps)
(Test Card + Stacking Connector)
(Area of connector)
Test Card
Area of connector
Test Card
92.3 to 109.8 Ohms
TDR data includes connector footprint and test board
Single Pair Cross talk @ 50 ps T rise
Aggressor
Differential Signal Components
(Tr=46.4 ps, 3 inches PCB calibration line)
Adjacent Connector Pair
Near End Cross talk
(~6.0 mV /500mV=1.2%)
Adjacent Connector Pair
Far End Crosstalk
(~3.5 mV /500mV=0.7%)
Aggresssor line +
Victim line +
Victim line -
Differential Near End Cross talk
Aggresssor line -
Victim line +
Victim line -
Differential Far End Cross talk
Data includes test SMA connector and
test boards
Cross talk data includes connector footprint and test board
Specifications
subject to change
Dimensions are in millimeters (inches)
http://us.fujitsu.com/components
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