The advantage of DDR2 over DDR SDRAM is the ability for much higher clock speeds, due to design improvements. With a clock frequency of 100 MHz, "SDR-SDRAM" transfers data on every rising edge of the clock pulse, thus achieving an effective 100 MHz data transfer rate.
Unlike SDR, both DDR and DDR2 transfers data on both the rising and falling edge of the clock, at points of 0.0 V and 2.5 V (1.8 V for DDR2), achieving an effective rate of 200 MHz (and a theoretical bandwidth of 1.6 GB/s) with the same clock frequency. DDR2's clock frequency is further boosted by electrical interface improvements, on-die termination, prefetch buffers and off-chip drivers. However, latency is greatly increased as a trade-off. The DDR2 prefetch buffer is 4 bits wide, whereas it is 2 bits wide for DDR and 8 bits wide for DDR3
** memory prices may vary based on the fluctuation of the memory market. please contact us with accurate pricing to give you; the consumer, the vey best shopping experience possible.
