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AR# 22531

MIG 007/1.x, Timing Closure - Are there suggestions for improving timing when the MIG output fails to meet timing?

Description

Keywords: MIG, 1.22, 1.3, 1.4, does not meet, fails, timing

The design that MIG generates does not meet timing. What suggestions do you have to resolve this issue?

Solution

The current design generated from either MIG 1.x or MIG 007 can fail to meet timing during Timing Analysis. The original intent of these designs is to be used as reference only and is not guaranteed to meet timing. The frequency of the overall design is based on the banks that are used for data, address, and control signals.

Suggestions to meet timing:
- Limit address signals to fewer banks in packages with a high number of unbonded pads and PPC components.

- Place the controller in an Area Group near the selected banks.
- For Spartan-3 designs, increase the NET MAXDELAY constraints by the difference in the maximum performance of the memory and the actual performance of the design. If you asked for 133 MHz, but the maximum performance of the memory is 167 MHz, you can increase the NET MAXDELAY constraints by 30 percent. (MIG 1.5 makes the MAXDELAY values frequency dependent when possible and the UCF has comments for the cases where it was not possible).
AR# 22531
Date Created 09/04/2007
Last Updated 04/06/2009
Status Archive
Type General Article