Why is the fractional multiply factor (K) value entered in the Altera_PLL megafunction ignored?

Description

Due to a problem in the Quartus® II software version 12.1 and earlier, the fractional multiply factor (K) that you enter in the Altera_PLL megafunction may be ignored or changed to a different value. This problem affects Altera_PLL megafunctions using fractional mode, and changes the output frequency of the PLL.

Resolution

To work around this problem, modify the .pll_fractional_division parameter in the auto-generated <Altera_PLL name>_0002.v file to match your desired value. After you compile your project, verify the correct value was used by viewing the PLL Usage Summary in the Compilation Report file.

To simulate the Altera_PLL megafunction, modify the same parameter in the <Altera_PLL name>.vo file.

This problem is scheduled to be fixed in a future release of the Quartus II software.