3 – Key Components Description and Operation
16
IGLOO2 FPGA Evaluation Kit User Guide
SERDES0 Interface
The SERDES0 is having four lanes connected as below:
1. Lane0 is directly routed to the PCIe connector.
•
TX Pad
trace
AC Coupling
trace
via (to bottom layer)
trace
PCIe connector pad
•
RX Pad
trace
PCIe connector pad
2. Lane1 is used for loopback testing. This path is routed between the Tx and Rx with a 6 inch trace and 2
vias.
•
TX Pad
via (to Bottom layer)
trace
AC Coupling
trace
via (to top layer)
RX pad
3. Lane2 routed to SMA connectors.
•
TX Pad
trace
AC Coupling
trace
SMA connector pad
•
RX Pad
trace
via (to bottom layer)
trace
via (to top layer)
SMA connector Pad
4. Lane3 is routed to Marvell PHY (88E1340S).
•
TX pad
trace
AC Coupling
trace
via
trace routed in (6th layer)
via (to top layer)
Marvel PHY pin
•
RX pad
via
trace routed in 6th layer
via (to top layer)
trace
AC Coupling
trace
Marvel PHY pin
SERDES0 reference clock 0 is routed directly from the PCIe connector to IGLOO2 FPGA.
SERDES0 reference clock 1 is routed from the onboard 125 MHz clock oscillator and optionally routed from SMA
connectors through LVDS Mux/Buffer chip.
Expected SERDES reference clock specifications:
•
Voltage level: 3.3 (± 0.3)V
•
Differential LVDS
Symmetry: 50% (± 10%)
Rise/Fall Time: 1nsec Max @ 20% to 80% of supply (3.3 V)
Output Voltage Levels: “0”=0.90 Minimum, 1.10 Typical
“1”=1.43 Typical, 1.60 Maximum
Differential Output Voltage: 247 mV Minimum, 454 mV Maximum