Altera Corporation
2–33
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
The byte serializer takes in a 40-, 32-, 20-, or 16-bit-wide input from the
phase compensation FIFO buffer and serializes it to 20, 16, 10, or 8 bits,
respectively (refer to
Table 2–7
). At the same time, the clock frequency is
doubled.
After serialization, the byte serializer transmits the least significant byte
to the most significant byte. Always use the transmitter digital reset to
reset the byte serializer FIFO pointers whenever the transmitter PLL loses
lock. Refer to
“Reset Control and Power Down” on page 2–214
for further
details on the reset sequence.
Figure 2–24
shows byte serializer input and output signals when
serializing a 20-bit input to 10 bits. The
tx_datain
signal is the input
from the FPGA’s logic array that has already passed through the
transmitter phase compensation FIFO buffer.
Figure 2–24. Transmitter Byte Serializer
In
Figure 2–24
, the LSB is transmitted before the MSB in the transmitter
byte serializer. For the input of D1, the output is D1
LSB
and then D1
MSB
.
8B/10B Encoder
The 8B/10B encoder (refer to
Figure 2–25
) is part of the Stratix II GX
transceiver digital blocks and lies between the byte serializer and the
serializer. The 8B/10B encoder operates in two modes: single-width and
double-width and can be bypassed if the 8B/10B encoder is not used. In
single-width mode, the 8B/10B encoder generates a 10-bit code group
Table 2–7. Byte Serializer Input and Output Data Widths
Input Data Width
(Bits)
Output Data Width After Byte Serialization
(Bits)
40
20
32
16
20
10
16
8
D1
LSB
D1
MSB
D2
LSB
D2
MSB
datain[19..0]
dataout[9..0]
D1
D2
D3
{10'h3E0, 10'h2A0}
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10'h2A0
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10'h3E0
10'h318
10'h3C7
{10'h318, 10'h3C7}
{10'h2AA, 10'h333}