2–112
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Receiver Modules
Polarity Inversion
The 8B/10B decoder has a PCI Express compatible polarity inversion on
the data bus prior to 8B/10B decoding. This polarity inversion inverts the
bits of the incoming data stream prior to the 8B/10B decoding block to fix
potential P-N polarity inversion on the differential input buffer. You use
the optional
pipe8b10binvpolarity
port to invert the inputs to the
8B/10B decoder dynamically from the PLD.
Byte Deserializer
Use the byte deserializer (
Figure 2–89
) to convert the one- or two-byte
interface into a two- or four-byte-wide data path from the transceiver to
the PLD logic (refer to
Table 2–22
). The PLD interface has a limit of
250 MHz, so the byte deserializer is needed to widen the bus width at the
PLD interface and reduce the interface speed. For example, at 6.375 Gbps,
the transceiver logic has a double-byte-wide data path that runs at
318.75 MHz in a ×20 deserializer factor, which is above the maximum
PLD interface speed.
Figure 2–89. Byte Deserializer
When using the byte deserializer, the PLD interface width doubles to
40-bits (36-bits when using the 8B/10B encoder) and the interface speed
drops to 159.375 MHz.
Byte Deserializer
datain[19..0]
To Byte
Ordering
Block
dataout[39..0]
Control Signals out [3..0]
Control Signals in[1..0]
From 8B/10B
Decoder
Slow-Speed
Receiver CRU
Slow-Speed
Receiver CRU
or Divide by 2 Version
÷
2
Table 2–22. Byte Deserializer Input and Output Widths
Input Data Width (Bits)
Deserialized Output Data Width to the FPGA
Logic Array (Bits)
20
40
16
32
10
20
8
16
Содержание Stratix II GX
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