
Chapter 10: Low Latency PHY IP Core 10–5
Additional Options Parameters
November 2012 Altera Corporation Altera Transceiver PHY IP Core
User Guide
Table 10–4 lists Standard and 10G datapath widths for the FPGA fabric-transceiver
interface, the PCS-PMA interface, and the resulting frequencies for the
tx_clkout
and
rx_clkout
parallel clocks. In almost all cases, the parallel clock frequency is described
by the following equation:
frequency
parallel clock
= data rate/FPGA fabric-transceiver interface width
1 The FPGA fabric-transceiver interface width is always 128 bits for the GT datapath.
Additional Options Parameters
The parameters on the Additional Options tab control clocking and datapath options.
Both bonded (×N) and non-bonded modes are available. In bonded modes, a single
PLL can drive all channels. In non-bonded modes, each channel may have its own
PLL.
Table 10–4. Datapath Width Support
FPGA Fabric-Transceiver
Interface Width
PCS-PMA Interface Width
tx_clkout and rx_clkout
frequency
Standard Datapath 10G Datapath
8 8 — data rate/8
10 10 — data rate/10
16 8 or 16 — data rate/16
20 10 or 20 — data rate/20
32 16 32 data rate/32
40 20 40 data rate/40
50 — 40 data rate/50
(1)
64 — 32 data rate/32
(2)
64 — 64 data rate/64
66 — 40 data rate/66
Note to Table 10–4:
(1) For this datapath configuration, the
tx_clkout
frequency generated by the Low Latency PHY is the data rate /40. You must generate a /50
frequency clock from the /40 clock and feed this clock back into the
tx_coreclkin
. The
rx_clkout
frequency generated by the Low Latency
PHY is /40 of the data rate. You must generate a /50 frequency from the recovered clock and feed this back into the
rx_coreclkin
.
(2) For this datapath configuration, the
tx_clkout
frequency generated by the Low Latency PHY is the data rate/32. You must generate a /64
frequency clock from the /32 clock and feed this clock back into the
tx_coreclkin
. The
rx_clkout
frequency generated by the Low Latency
PHY is the data rate/32. You must generate a /64 frequency from the recovered clock and feed this back into the
rx_coreclkin.
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