A long-awaited change for CPU designsIBM has recently revealed the fastest system-on-a-chip eDRAM technology at ISSCC. The new technology is ready to replace the obsolete SRAM memory found in Level 1, 2 and 3 caches on today's CPUs.
eDRAM benefits from IBM's silicon-on-insulator technology for low power and improved performance. Currently, eDRAM modules are implemented in 65nm SOI designs to improve the memory performance of on-processor memory controllers. According to IBM, eDRAM will soon be ready for the move to 45nm, and we can expect to start seeing it integrated in the company's CPUs as soon as 2008.
"As semiconductor components have reached the atomic scale, design innovation at the chip-level has replaced materials science as a key factor in continuing Moore's Law. Today's announcement further demonstrates IBM's leadership in this critical area of microprocessor design innovation," said Dr. Subramanian Iyer, IBM's Distinguished Engineer and director of 45nm technology development.
Although eDRAM tends to be a little bit slower than conventional SRAM, it only occupies one-third the space and it's using one-fifth the power. In standby, the chip could use only 1/5 the current power draw, since DRAM requires less power to store data. In addition, embedded DRAM provides increased cache memory capacities, excellent buffering for larger graphics files and improved multi-tasking.
Here is a list of the most important specifications for IBM's eDRAM technology:
- Cell size: 0.126 mm2
- Power supply: 1 V
- Availability: 98.7%
- Tile: 1K RowX16 Col X146 (2Mb)
- AC power: 76 mW
- Standby keep alive Power: 42 mW
- Random cycle time: 2ns
- Latency: 1.5ns
While the eDRAM technology could soon hit the PC market, it is already found in Nintendo's Wii and Microsoft's Xbox 360 consoles. Both consoles feature ATI-powered GPUs which have been designed to take advantage of specially designed eDRAM modules.