2–118
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Receiver Modules
Receiver Phase Compensation FIFO Buffer
The receiver phase compensation FIFO buffer (
Figure 2–96
) is located at
the FPGA logic array interface in the receiver block and is used to
compensate for phase difference between the receiver clock and the clock
from the PLD. The receiver phase compensation FIFO buffer operates in
two modes: low latency and high latency. In low latency mode, the FIFO
buffer is four words deep. The Quartus II software chooses the low
latency mode automatically for every mode except the PCI-Express PIPE
mode (which automatically uses high latency mode). In high latency
mode, the FIFO buffer is eight words deep.
Figure 2–96. Receiver Phase Compensation FIFO Buffer
Note to
Figure 2–96
:
(1)
The receiver clock can either be the recovered clock or the transmitter CMU clock,
depending on whether the rate matcher is used or not.
In Basic mode, the write port is clocked by the recovered clock from the
CRU. This clock is half the rate if the byte deserializer is used. The read
clock is clocked by the associated channel’s recovered clock.
1
The receiver phase compensation FIFO is always used and
cannot be bypassed.
In four-channel (×4) and eight-channel (×8) bonding modes, all the read
pointers are derived from a common source so that there is no need to
synchronize the data of each channel in the PLD logic.
Receiver Phase Compensation FIFO Error Flag
Depending on the transceiver configuration, the write port of the receiver
phase compensation FIFO can be clocked by either the recovered clock
(
rx_clkout
) or transmitter PLL output clock (
tx_clkout
or
coreclkout
). The read port can be clocked by the recovered clock
(
rx_clkout
), transmitter PLL output clock (
tx_clkout
or
Receiver Phase
Compenstation
FIFO
datain[31..0]
To PIPE
or PLD
dataout[31..0]
Control Signals Out [3..0]
Control Signals In [3..0]
From Byte
Ordering
Block
Slow-Speed
Receiver Clock or
Divide by 2 Version
(1)
rx_clkout or
coreclk_out
from PLD