How are DDR2 IO speeds related to clock speeds?

Answer 1

DDR2 memory operates at double data rate, meaning it can transfer data on both the rising and falling edges of the clock signal. The IO speed of DDR2 is effectively twice the clock speed; for example, if the clock speed is 400 MHz, the data transfer rate can reach 800 MT/s (megatransfers per second). This relationship allows DDR2 to achieve higher bandwidth while maintaining lower clock speeds compared to single data rate memory technologies. Overall, the effective data rate is a direct function of the clock frequency due to the dual-edge transfer capability.