2–142
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Multiple Protocols and Data Rates in a Transceiver Block
Using Two TXPLLs
If the desired data rates and/or protocols cannot utilize a single TXPLL
within a single transceiver block, the other TXPLL within that transceiver
block may be able to support the additional data rates and/or protocol
configuration.
This is useful if combining channels operating in single-width and
double-width modes, or two Quartus II software-defined protocols (for
example, Basic, GIGE, SONET/SDH, SDI, or PCI Express [PIPE] modes)
in the same transceiver block. You can configure channels in the same
protocol group from individual ALT2GXB instances, or you can configure
the whole group in a single instance.
The example in
Figure 2–108
will not be able to share a single TXPLL due
to incompatible primary data rates. Since there are only two different
primary data rates, you can merge the four channels into a single
transceiver block. It is assumed that the channels sharing the same TXPLL
will meet the requirements described in the above example. For the
channels not sharing the same TXPLL, the PLL parameters may be
different; for example, different data rate, reference clock input frequency,
reference clock input pin, and PLL bandwidth. Also, the primary data
rates need not be a multiple of the other TXPLL primary data rate. The
transceiver block-based signals will have to be the same across all
channels.
In addition to the primary data rate differences, the mode of operations
also differs which require the use of separate TXPLLs. The 4 Gbps
channels operate in a double-width mode while the 2 Gbps and 1 Gbps
channels operate in a single-width mode (due to the sub 3.125 Gbps
primary data rate).