eDRAM

eDRAM stands for "embedded DRAM", a capacitor-based dynamic random-access memory integrated on the same die as an ASIC or processor. The cost-per-bit is higher than for stand-alone DRAM chips but in many applications the performance advantages of placing the eDRAM on the same chip as the processor outweighs the cost disadvantage compared with external memory.

Embedding memory on the ASIC or processor allows for much wider buses and higher operation speeds, and due to much higher density of DRAM in comparison to SRAM, larger amounts of memory can be installed on smaller chips if eDRAM is used instead of eSRAM. eDRAM requires additional fab process steps compared with embedded SRAM, which raises cost, but the 3× area savings of eDRAM memory offsets the process cost when a significant amount of memory is used in the design.

eDRAM memories, like all DRAM memories, require periodic refreshing of the memory cells, which adds complexity. However if the memory refresh controller is embedded along with the eDRAM memory, the remainder of the ASIC can treat the memory like a simple SRAM type such as in 1T-SRAM.

eDRAM is used in IBM's POWER7 processor, Intel's Haswell CPUs with GT3e integrated graphics, and in many game consoles and other devices, including Sony's PlayStation 2, Sony's PlayStation Portable, Nintendo's GameCube, Nintendo's Wii, Nintendo's Wii U, Apple Inc.'s iPhone, Microsoft's Zune HD, and Microsoft's Xbox 360.

External links

• http://www.cs.unc.edu/~jp/DRAM.pdf
• Day dawns for eDRAM
• http://www.necelam.com/edram90/
• http://www.findarticles.com/p/articles/mi_qa3751/is_200501/ai_n9521086
• http://arstechnica.com/news.ars/post/20070214-8842.html
• http://www.allbusiness.com/electronics/computer-electronics-manufacturing/6302349-1.html
• http://www.realworldtech.com/iedm-2010/3/