Mixed-Mode Clock Manager (MMCM) Module (v1.00a) Data Sheet(DS737) - 1.0 English - The MMCM primitive in Virtex-6 parts is used to generate multiple clocks with defined phase and frequency relationships to a given input clock. The MMCM module is a wrapper around the MMCM_ADV primitive that allows the MMCM to be used in the EDK tool suite.