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You can select the rising edge option with the Quartus II MegaWizard Plug-In Manager. The
LVDS_diffioclk
clock that is generated by the left and right PLLs clocks the data realignment and deserializer blocks.
The following figure shows the LVDS datapath block diagram. In SDR and DDR modes, the data width from
the IOE is 1 and 2 bits, respectively.
Figure 5-42: Receiver Data Path in LVDS Mode
rx_in
Bit Slip
Deserializer
rx_inclock / tx_inclock
LVDS Receiver
FPGA
Fabric
rx_out
rx_outclock
IOE supports SDR, DDR, or non-registered datapath
IOE
2
Note: All disabled blocks and signals are grayed out
LVDS Clock Domain
DOUT
DIN
DOUT
DIN
Fractional PLL
+
–
(LOAD_EN,
diffioclk)
2
10
10
3 (LVDS_LOAD_EN,
LVDS_diffioclk, rx_outclock)
diffioclk
10 bits
maxiumum
data width
Receiver Clocking for Cyclone V Devices
The fractional PLL receives the external clock input and generates different phases of the same clock.
The physical medium connecting the transmitter and receiver LVDS channels may introduce skew between
the serial data and the source-synchronous clock. The instantaneous skew between each LVDS channel and
the clock also varies with the jitter on the data and clock signals as seen by the receiver.
LVDS mode allows you to statically select the optimal phase between the source synchronous clock and the
received serial data to compensate skew.
Related Information
Guideline: Use PLLs in Integer PLL Mode for LVDS
on page 5-12
Differential I/O Termination for Cyclone V Devices
The Cyclone V devices provide a 100 Ω, on-chip differential termination option on each differential receiver
channel for LVDS standards. On-chip termination saves board space by eliminating the need to add external
resistors on the board. You can enable on-chip termination in the Quartus II software Assignment Editor.
All I/O pins and dedicated clock input pins support on-chip differential termination, R
D
OCT.
I/O Features in Cyclone V Devices
Altera Corporation
CV-52005
Receiver Clocking for Cyclone V Devices
5-68
2014.01.10