Fitter Error When Compiling DDR2 Designs Below 240MHz in DDR2 and DDR3 SDRAM Controller with UniPHY

Description

For DDR2 designs operating at frequencies of 240MHz or less, the Fitter might display the error message: Can’t place Top/Bottom or Left/Right PLL.

Resolution

The workaround for this issue is to turn on the Remove Duplicate Registers synthesis option.