The OSERDES primitive (actually a MASTER-SLAVE pair of primitives) is used in a standard mode; 6-bit input parallel data synchronous to a 208 MHz global clock buffer source (BUFG) is clocked into the OSERDES. Internally within the OSERDES, the data is serialized and output at a rate of 1.25 Gbps. The clock source used for the serial data is a 625 MHz clock source using a BUFG global clock buffer at double data rate.
- The 625 MHz BUFG and 208 MHz BUFG clocks for serial and parallel data are both derived from the same MMCM so there is no frequency drift.
- The use of the BUFG global clock buffer for the parallel clock is a requirement of the OSERDES; when using a BUFG clock for serial data, a BUFG clock source, derived from the same MMCM source, must be used for the parallel data to satisfy clock phase alignment constraints within the OSERDES primitives.