The serial link simulations involve a
parametric sweep:
- Corners: The IBIS-AMI models
for Tx/Rx are characterized as Fast/Typ/Slow corners. The different Deterministic
and Random Jitter budgets are built in to the models using these corners.
- Transmitter Presets: These are
specific to each standard and control the coefficients in the transmitter Decision
Feedback Equalizer (DFE). These presets also model the level of de-emphasis in the
transmit amplifier which are required to equalize the overall system-level response
across different frequencies and counteract the impact of ISI (Inter-symbol
interference). It is recommended using a parametric sweep and simulate for all
different transmitter presets for a given Serial Link protocol. This is due
to the fact that the best eye observed can be highly dependent on the system impulse
response and therefore different presets could yield the best results on different
systems.
- Data Patterns: It is
recommended to use PRBS23 or PRBS31 patterns to validate the system, in order to
excite larger levels of ISI.
- LIBPATH Definition: Ensure
that the “LIBPATH” variable in the Rx IBIS-AMI model is set correctly, to point to
the local data directory, which points to the Rx CTLE files as shown in Figure 1-2. The name of this variable might change from simulator to simulator. However, the
directory always needs to point to the local copy.