09-16-2017 10:56 AM
I'm trying to export an IBIS file for a DDR4 interface implemented on xcku040 device. When I change the EQUALIZATION property of DDR related I/O ports from EQ_LEVEL2 to EQ_NONE in the Package View, a new constraint file is generated at the top level. I can validate that new values are reflected in the database by entering the
get_property EQUALIZATION [get_ports ddr4_sdram_dq[*]]
After implementation I export the new ibis model, and compare it with the previous one (which I generated with different equalization values) and the only difference between the two are the file name, file generation dates.
However, if I change the PRE_EMPHASIS values for output transmitters and generate a new IBIS, file changes and a new model is referenced for the ports for which the PRE_EMPHASIS value has changed.
I understand that EQUALIZATION is a receiver parameter. At page 189 of ug912 2015.4 the following note is given :
The EQUALIZATION values are not specifically calibrated. The recommendation is to run simulations to determine the best setting for the specific frequency and transmission line characteristics in the design.
09-16-2017 12:44 PM
I presume the change of the EQUALIZATION property has no effect on how the inputs and outputs behave, only on the interpretation of the received data, so in contrast to the PRE_EMPHASIS property, the electrical I/O interface will not change regardless of the setting.
Hope this helps,
09-17-2017 03:34 AM
Why does ug912 recommends to run simulations? The recommendation is at the definition of the EQUALIZATION parameter, and starts with the word "Important".
Receiver equalization is clearly an important parameter for signal integrity analysis.