DRAM speeds go off the deep end
I was reading an article in Electron Design (04/14/05, pg 46) about DRAM speeds ("DRAM Advances Splinter to meet many system needs"). I was amazed at the new speeds for DRAM. I thought things stopped at about 166Mhz. Apparently not so. There is now DDR, DDR-2 and soon to be DDR-3. The seeds go from a pedestrian 100Mhz up through 1.6GHz. Last time I checked 1.6GHz was RF territory. I guess you need to be an antenna person to design SDRAM layouts.
I was confused, so I made a little table. It scared me.
| Style | Cycle time | Data bandwitdth | Speed grades |
| SDRAM | 7.5ns | 0.1 Gbits/s | 133, 143, 166Mhz |
| DDR | 5-7.5ns | 0.2-0.4 Gbits/s | 100, 133, 166, 200, 266, 333, 400Mhz |
| DDR-2 | 3-5ns | 0.4-0.8 Gbits/s | 400, 533, 667Mhz |
| DDR-3 | ? | 0.8-1.6Gbits/s | 800, 1600Mhz? |