Altera JNEye User Manual
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• FIR => CTLE => DFE— (default) Optimizes the link performance by finding the optimal transmitter
setting, receiver equalization setting, or both. This method prioritizes the transmitter equalization,
such as pre-emphasis, de-emphasis, or FIR-based, over receiver equalization schemes. However, the
optimization algorithm is also capable of detecting and utilizing optimal receiver equalization. In
practice, this usually implies that most of the "heavy-lifting" in channel compensation is performed by
the transmitter equalization.
• FIR => CTLE & DFE—Extends the FIR => CTLE =>DFE method by enabling RX DFE (Decision
Feedback Equalizer) when RX optimization is performed. This method exploits DFE capabilities by
possibly reducing the channel compensation from CTLE (depending on the channel characteristics).
• CTLE => FIR => DFE—Prioritizes the receiver's CTLE capability over the transmitter's equalization.
Most of the channel compensation is performed by the receiver's CTLE while the TX equalization
provides additional compensation if needed. RX DFE is adapted in the final stage. This method is
supported in non-IBIS-AMI devices. For Altera transmitters, you can manually set initial TX FIR
configurations so the link optimizations can yield better solutions more quickly when the initial
conditions are proper.
• CTLE => FIR & DFE—Extends the CTLE => FIR => DFE method by joint-optimizing TX pre-
emphasis/FIR and RX DFE. This method allows co-optimization between the TX FIR and RX DFE.
For Altera transmitters, you can manually set the initial TX FIR configurations so the link optimiza‐
tions can yield better solutions more quickly when the initial conditions are proper.
Use the following guidelines for choosing the best link optimization method:
• FIR => CTLE => DFE is a good choice for most applications or channels for time efficient link
optimizations. It is the default link optimization method in JNEye.
• For heavy insertion loss channels such as when insertion loss > 25 dB at Nyquist frequency, FIR =>
CTLE => DFE provides good coverage.
• For strong impedance discontinuities, CTLE => FIR => DFE methods provide better performance in
general.
• For large crosstalk noises, choose FIR => CTLE & DFE for high loss channels or CTLE => FIR & DFE
for moderate loss applications.
Notes:
• JNEye supports link optimization for selected IBIS-AMI models for the link optimization modes and
the methods shown above. Refer to the IBIS-AMI model support sections for details.
• For a transmitter equalization sweep simulation, JNEye provides batch simulation capability using the
JNEye Batch Simulation Controller tool. Refer to the JNEye Batch Simulation Controller section for
details.
FOM of Link Optimization
Use this menu to select the figure of merit (FOM) for optimizing the serial link. There are three options:
Area, Width, and Height. The signal conditioning mechanisms, which include transmitter pre-emphasis,
de-emphasis, and receiver equalizers, use these selections to optimize the waveform so that it has the best
eye diagram opening in terms of area, width, or height.
Compliance Mask
JNEye plots link compliance eye diagram masks after the simulations are completed. Use a compliance
mask to examine whether the waveform or eye diagram meets the receiver's requirements at certain
conditions (such as BER target). PCI-Express 8GT receiver eye masks are provided.
Note: Device intrinsic jitter can be included in the link simulation by using the Characterization Data
Access function in JNEye. When both transmitter and receiver jitter are extracted from the
Characterization Data Access and included in the simulation, the simulation results at the end of
UG-1146
2015.05.04
Link and Simulation Setting
2-15
Functional Description
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