Related Information
Clock Networks and PLLs in Cyclone V Devices
Transceiver Datapath Interface Clocking
There are two types of design considerations for clock optimization when interfacing the transceiver datapath
to the FPGA fabric:
• PCS with FIFO in phase compensation mode – share clock network for identical channels
• PCS with FIFO in registered mode or PMA direct mode – refer to
AN 580: Achieving Timing Closure in
Basic (PMA Direct) Functional Mode
, for additional timing closure techniques between transceiver and
FPGA fabric
The following sections describe design considerations for interfacing the PCS transmitter and PCS receiver
datapath to the FPGA fabric with FIFO in phase compensation mode.
Related Information
AN 580: Achieving Timing Closure in Basic (PMA Direct) Functional Mode
Transmitter Datapath Interface Clocking
The write side of the TX phase compensation FIFO makes up the transmitter datapath interface. The
transmitter datapath interface clock clocks this interface.
The following figure shows the transmitter datapath interface clocking. The transmitter PCS forwards the
following clocks to the FPGA fabric:
•
tx_clkout
—for each transmitter channel in a non-bonded configuration
•
tx_clkout[0]
—for all transmitter channels in a bonded configuration
Figure 2-16: Transmitter Datapath Interface Clocking for Transceivers
TX
Phase
Compensation
FIFO
tx_coreclkin
(User Selected Clock)
tx_clkout
Transmitter Data
Transmitter Data
Parallel Clock
FPGA Fabric
Transmitter PCS
tx_clkout
(Quartus II Selected Clock)
All configurations that use the PCS channel must have a 0 parts per million (ppm) difference between write
and read clocks of the transmitter phase compensation FIFO.
For more information about interface clocking for each configuration, refer to the T
ransceiver Custom
Configuration in Cyclone V Devices
and
Transceiver Protocol Configurations in Cyclone V Devices
chapters.
Note:
You can clock the transmitter datapath interface with one of the following options:
• The Quartus II-selected transmitter datapath interface clock
• The user-selected transmitter datapath interface clock
To reduce GCLK, RCLK, and PCLK resource utilization in your design, you can select the user-
selection option to share the transceiver datapath interface clocks.
Note:
Altera Corporation
Transceiver Clocking in Cyclone V Devices
2-21
Transceiver Datapath Interface Clocking
CV-53002
2013.05.06