1 Dimensions are in millimeters (inches) www.fcai.fujitsu.com Specifications subject to change DIFFERENTIAL CONNECTOR FCN-260(D) Series microGiGaCN TM Stacking Connector ■ 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 ■ SPECIFICATIONS ■ MATERIALS 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 m e t I s n o i t a c i f i c e p S e r u t a r e p m e t g n i t a r e p O e g n a r C ˚ 5 0 1 + o t C ˚ 5 5 - g n i t a r t n e r r u C ) l a n g i s ( A 5 . 0 C A ) d n u o r g ( A 1 C A g n i t a r e g a t l o V V 0 3 C A e c n a t s i s e r t c a t n o C ) l a n g i s ( . x a m s m h o m 0 8 ) d n u o r g ( . n i m s m h o m 0 4 e c n a t s i s e r n o i t a l u s n I m u m i n i m s m h o M 0 0 0 1 g n i d n a t s h t i w c i r t c e l e i D e g a t l o v e t u n i m 1 r o f V 0 0 5 C A y t i l i b a r u D s e l c y c 0 0 1 e c r o f n o i t r e s n I ) r i a p 4 2 ( m u m i x a m N 0 5 e c r o f l w a r d h t i W ) r i a p 4 2 ( m u m i n i m N 5 m e t I s l a i r e t a M r o t a l u s n I ) 0 - V 4 9 L U ( n i s e R P C L r o t c u d n o C y o l l A r e p p o C g n i t a l P ) S O G A P ( g n i t a l P u A : t c a t n o C g n i t a l p i N - d P r e v o u A
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1Dimensions are in millimeters (inches) www.fcai.fujitsu.comSpecificationssubject to change
DIFFERENTIAL CONNECTOR
FCN-260(D) Series
microGiGaCN TM Stacking Connector
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
SPECIFICATIONS
MATERIALS
Fujitsu's FCN-260(D)Differential Signal Connector
As network speeds increase, designersare moving to differential interconnectsfor network switches and hubs, as wellas for connections between componentsin high-speed computer clusters, videosystems, test equipment, and real-timemedical equipment (MRI, etc.).Conventional connectors do not supportthe speed and signal integrityrequirements of these applications. Byimplementing a connector specificallyfor high-speed, high-density, board-to-board differential applications, designerscan take advantage of a differentialinterconnect instead of more costly fiberoptic or coax alternatives.
Differential signals use two conductorsto carry signals that are compliments ofone another. This arrangement reducesnoise effects because any noiseintroduced by interference or crosstalkappears in both signals (common-modenoise) and is ignored by differential
2Dimensions are in millimeters (inches) www.fcai.fujitsu.comSpecificationssubject to change
interconnects between boards. Similarly,networking hubs incorporate many boards thatmust be interconnected via short-run cables.These internal cables often have to transfer data atspeeds significantly higher than those of the actualnetwork, so even today's 10/100-Mbit networksneed high-speed internal interconnects withexcellent signal integrity. In addition, any systemthat uses an external fiber optic connector probablyrequires an internal, board-to-board connectorsystem that works at the highest possible speeds.
Fiber optic and coax interconnect systemsobviously meet the internal performancerequirements, but the cost is high. Differentialinterconnects meet both the performance and costgoals but until recently, no connectors wereavailable that provided high-density connections atgigabit speeds. In addition, connector testmethodologies from the past cannot give reliableand repeatable results of the differentialconnector's performance in high-speed systems.Therefore, new test methodologies must bedeveloped based on the unique characteristics ofthese emerging high-speed applications.
In the past, connector manufacturers "de-imbedded" the connector from the test PCB's toshow just the electrical characteristics of theconnector and did not include any parasitic effectsassociated with solder joints on a through holecontact lead, or the effects of the contact post(compliant or non-compliant pin) in a platedthrough hole. While this test methodology wasacceptable for slower system speeds, today'sdifferential interconnects demand much morefocused attention on system and board effects.
The requirements for testing today's high-speeddifferential interconnects are demanding with goodreason. Connectors and other traditionally"electrically small" components are no longer smallwhen considering presently available signalingtechnologies with 100ps risetimes and multi-gigabitdata rates. Among these requirements are verywell-designed test boards needed for accurate
receivers. With noise voltages less of a problem,differential signals can use a small voltage swingthat switches between LOW and HIGH valuesextremely quickly --hence the appeal of differentialsignals for high-speed networking and clustering.
Differential connector characteristics can exceedthe requirements of upcoming 1-Gbit applicationsand extend to next-generation applications atspeeds upwards of 4.4 Gbps. As a result, systemand board vendors who adopt such a connector canlook forward to legacy usage that spans multipleproduct generations.
The signal transmission path of connectors has notalways been a critical issue when choosing aninterconnect method because the connector'selectrical signal path is short compared to cables orprinted circuit board assemblies. In applicationsutilizing high-frequency signals, however,connectors can have a significant effect on signalintegrity. Connectors for high-speed applicationsmust be designed to achieve optimal performancethrough the minimization of crosstalk andsusceptibility to noise influences.
Differential signal applications
The shift from mainframe environments tonetworked client/server enterprises has madenetworks a critical bottleneck for improving systemperformance. Emerging technologies such as high-speed server farms, video conferencing, andgreater use of graphical interfaces is pushingnetworks toward performance of 1 Gbit/sec andhigher. The IEEE 802 committee is releasing1.028-Gbit Ethernet standards to meet thisrequirement.
One of the key challenges for switch, hub, videoequipment, and server manufacturers is to find aboard-to-board connector system that allowssignals to transfer at gigabit speeds over anaffordable interconnect system that furnishesspecific matched-impedance characteristics.Applications such as servers are now moving toextremely high-speed interfaces (often based onFibre Channel) between computer backplanes anddisk subsystems that require advance
microGiGaCN TM FCN-260 (D) Series
3Dimensions are in millimeters (inches) www.fcai.fujitsu.comSpecificationssubject to change
measurement and characterization. This data isused to develop SPICE or other models and toprovide detailed data to the design community.Typical high-frequency test boards designed byFujitsu include:
calibration/reference lines that mimic the testtraces
connector region entities (pads, pins, vias)that reflect actual system boardimplementations
low discontinuity test connectors (these giveaccess to the measurement equipment) ofsufficient bandwidth to meet the testing needs(e.g. SMA, 55MB, etc.)
Differential pairs must be well-matched in orderto minimize skew and maintain the properimpedance. Calibration lines of lengths "L"(where L is the length of the test traces betweenthe article under test and the test connectors)and 2L provide the opportunity to calibrate outthe board effects (if necessary) as well as tomake "reference" measurements to test thegoodness of an interconnect. These referencemeasurements are especially important whendetermining transmission fidelity. FujitsuTakamisawa attempts to use standard,commonly available FR-4 type board materials(better performers than some believe) wheneverpossible; however, there are times when so-called "low loss" board materials may berequired, such as for long paths running atgigabit speeds.
In addition to very good test articles, testequipment must be selected that will provide forthe measurements required at the bandwidthsneeded. Measurements may be completed fordifferential interconnects running at 100 Mbps,625 Mbps, 1 Gbps, 2.5 Gbps or beyonddepending on the system being designed. FujitsuTakamisawa typically measures for single-endedand differential impedance (using a "TDR"),transmission fidelity, crosstalk, and eye patternperformance among other measures of quality.
Typical transmission parameters quantifiedinclude signal edge and amplitude losses, skews,propagation delays, and interconnect bandwidth.At times, frequency domain data (such as S-parameters) adds insight into thesemeasurements and may be preferred by somecustomers. However, differential measurementsin the frequency domain must be approachedwith caution and specialized knowledge.
microGiGaCN TM FCN-260 (D) Series
4Dimensions are in millimeters (inches) www.fcai.fujitsu.comSpecificationssubject to change
Figure 1
Figure 2
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+
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1.27 mm
+
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0.75 mm1.5 mm
Patent pending
Ground/Power contactDifferential pair contact
Virtual ground plane
Sectional View (Connection area)Basic Concept for Differential Transfer
Edge coupleddifferential pairs
SMA connector footprints
Drive pairs Measurementpair
S1+ S1- S2+ S2- S3+ S3-
PCB Routing -Test Card
SMA connectorfoot print
Drive pairs Measurementpair
S1+ S1- S2+ S2- S3+ S3-
Adapter card socketfoot printcard
6” test pattern 3” test patternEdge coupleddifferential pairs
PCB Routing - Test Card
microGiGaCN TM FCN-260 (D) Series
5Dimensions are in millimeters (inches) www.fcai.fujitsu.comSpecificationssubject to change
Single Pair Cross talk @ 50 ps T rise
Aggressor Differential Signal Components(Tr=46.4 ps, 3 inches PCB calibration line)
Adjacent Connector PairNear End Cross talk(~6.0 mV /500mV=1.2%)
Adjacent Connector PairFar End Crosstalk(~3.5 mV /500mV=0.7%)
Aggresssor line -
Aggresssor line +
Data includes test SMA connector and test boards
Victim line +
Victim line -
Differential Near End Cross talk
Cross talk data includes connector footprint and test board
Differential Far End Cross talk
Victim line +
Victim line -
TDR Results (Impedance Tr 50ps)
(Test Card + Stacking Connector) (Area of connector)
Test Card
TDR data includes connector footprint and test board92.3 to 109.8 Ohms
Area of connector Test Card
microGiGaCN TM FCN-260 (D) Series
6Dimensions are in millimeters (inches) www.fcai.fujitsu.comSpecificationssubject to change
Eye Pattern@625 Mbps
Pseudo-Random Bit Stream (PRBS) excitation fromHP8133A-02 3GHz Pulse Generator
Test Card + Stacking Connector
Measurement Input : 250mV
6 inches test card
800ps(50% bit time)
1584ps
Jitter: 20ps(Pk-Pk)Height: 238 mV
All data includes connector footprint and test board
North and South AmericaFujitsu Components America, Inc.250 E. Caribbean DriveSunnyvale, CA 94089 U.S.A.Tel: (1-408) 745-4900Fax: (1-408) 745-4970Email: [email protected]: www.fcai.fujitsu.com