How does DDR-SDRAM transfer data twice during a clock cycle?

DDR-SDRAM, or double data rate synchronous dynamic RAM, achieves its performance by transferring data on both the rising and falling edges of the system clock signal.1

While traditional SDRAM only transmits data once per clock cycle—typically on the rising edge—DDR-SDRAM effectively doubles the data throughput by utilizing both transitions of the clock pulse. This mechanism allows the memory to provide greater efficiency and bandwidth compared to its predecessors without requiring a proportional increase in the clock frequency itself.1