Related Information
Guideline: Use PLLs in Integer PLL Mode for LVDS
on page 5-12
Emulated LVDS Buffers in Cyclone V Devices
The Cyclone V device family supports emulated LVDS on all I/O banks:
• You can use unutilized true LVDS input channels as emulated LVDS output buffers (eTX), which use
two single-ended output buffers with an external resistor network to support LVDS, mini-LVDS, and
RSDS I/O standards.
• The emulated differential output buffers support tri-state capability.
Differential Transmitter in Cyclone V Devices
The Cyclone V transmitter contains dedicated circuitry to support high-speed differential signaling. The
differential transmitter buffers support the following features:
• LVDS signaling that can drive out LVDS, mini-LVDS, and RSDS signals
• Programmable V
OD
and programmable pre-emphasis
Transmitter Blocks
The dedicated circuitry consists of a true differential buffer, a serializer, and fractional PLLs that you can
share between the transmitter and receiver. The serializer takes up to 10 bits wide parallel data from the
FPGA fabric, clocks it into the load registers, and serializes it using shift registers that are clocked by the
fractional PLL before sending the data to the differential buffer. The MSB of the parallel data is transmitted
first.
To drive the LVDS channels, you must use the PLLs in integer PLL mode.
Note:
The following figure shows a block diagram of the transmitter. In SDR and DDR modes, the data width is
1 and 2 bits, respectively.
Figure 5-35: LVDS Transmitter
tx_out
tx_inclock
IOE supports SDR, DDR, or non-registered datapath
LVDS Transmitter
FPGA
Fabric
tx_in
tx_coreclock
Serializer
10 bits
maximum
data width
LVDS Clock Domain
DIN
DOUT
Fractional PLL
IOE
+
–
2
3
10
(LVDS_LOAD_EN, diffioclk, tx_coreclock)
Related Information
Guideline: Use PLLs in Integer PLL Mode for LVDS
on page 5-12
Altera Corporation
I/O Features in Cyclone V Devices
5-63
Emulated LVDS Buffers in Cyclone V Devices
CV-52005
2014.01.10