NEC, Tohoku University promote CAM-on-MRAM use

NEC Corp. and Tohoku University will take the stage at the Symposia on VLSI Circuits and Technologies to present several papers detailing the use of magnetoresistive RAM non-volatility with content addressable memories (CAMs). The papers focus on one CAM that involves non-volatile operation based on a moving domain wall form of MRAM, and another that is considered an area- and power-efficient form of ternary CAM (TCAM).

The spin-CAM uses the vertical magnetization of vertical domain wall elements in a cobalt-nickel active layer in order to secure non-volatile storage of CAM data.

The researchers have built a 16Kb Spin-CAM test chip in a 90nm process with 5ns search cycle time and a 6.6micron2 memory cell. Use of this new CAM enables the development of electronics that start instantly and consume zero electricity while in standby mode. The circuit has a write current of 200microamps in 90nm process technology.

Such circuits have been created before but at lower performance than traditional CAMs. In order for CAMs to be both non-volatile and to maintain a high speed, two complementary spintronics devices, spinning in opposite directions to one another, were connected within the same cell. In addition two three-terminal devices are used to separate the read current path from the write current path.

The research team is working to reduce the program current and make the domain wall move with a 50microamp current in a cobalt-iron-boron active layer. Domain-wall motion will scale further with geometry said Dr. Tadahiko Sugibayashi, senior manager of the Green Innovation Research Laboratories at NEC Corp. who is a co-author on the paper with Professor Hideo Ohno of the center of integrated spintronics research at the Univesity of Tohoku.

- Peter Clarke
??EE Times