Altera LVDS SERDES Transmitter / Receiver - Manual (Page 57)

For Stratix IV devices:
RCCS = 100 ps (pending characterization)
SW = 300 ps (pending characterization)
TUI = 1000 ps
Total RCCS = RCCS + Board channel-to-channel skew= 100 ps + 200 ps
= 300 ps
RSKM= TUI - SW - RCCS
= 1000 ps - 300 ps - 300 ps
= 400 ps > 0
Because the RSKM > 0 ps, receiver non-DPA mode must work correctly.
Obtaining the RSKM Report
For LVDS receivers, the Quartus II software provides the RSKM report showing SW, TUI or LVDS
period, and RSKM values for non-DPA mode. You can generate the RSKM report by executing the
report_rskm command in the TimeQuest Timing Analyzer.
To obtain the RSKM report, follow these steps:
1. In the Quartus II software, under the Tools menu, click TimeQuest Timing Analyzer.
2. From the TimeQuest Timing Analyzer, under Reports, select Device Specific and click Report RSKM.
Note: In the TimeQuest timing analyzer tool, the
report_TCCS
and
report_rskm
commands are not
available when you are using SERDES in LEs. The commands are only available for transmitter and
receiver with dedicated SERDES.
The Quartus II software automatically places the SERDES logic at the best location to meet timing
requirements. Therefore, you are not required to perform placement constraints on the ALTLVDS IP core
logic. However, you are recommended to perform timing budget evaluation for the overall LVDS
interface in your system to ensure the sampling window specifications are met.
The LVDS transmitter and receiver functions with the ALTLVDS IP core are characterized and
guaranteed to function correctly within the LVDS system specification (meeting TCCS and SW
parameters). Therefore, timing constraints are not required for the SERDES logic using the ALTLVDS IP
core. However, if the timing result does not fulfill the requirement or the design needs to be fine-tuned to
improve the margin, timing constraints may be necessary.
The setup time (T
SU
) and hold time (TH) for the LVDS channels as reported in the Quartus II timing
report are based on the compiled design and served as a timing reference. You must not use these
parameters in the timing report for the sampling window estimation. For sampling window specification,
refer to the device datasheet for more information.
Related Information
The Quartus II TimeQuest Timing Analyzer, Volume 3: Verification, Quartus II Handbook
Obtaining the TCCS Report
For LVDS transmitters, the TimeQuest Timing Analyzer provides a TCCS report, which shows TCCS
values for serial output ports.
UG-MF9504
2014.12.15
Obtaining the RSKM Report 57
LVDS SERDES Transmitter/Receiver IP Cores User Guide Altera Corporation
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