Memory Modem has proprietary error correction, signal processing and flash management

May 2, 2012

Technology startup DensBits has focused years of technology development on three areas that can reduce costs for enterprise solid state drives (SSDs), client SSDs and consumer products like smart phones and pad computers. The company likens the advances in its new Memory Modem technology to that which transformed wire-line telecommunications speeds and reliability during the past decade, hence the name ‘Memory Modem.’

NAND Flash foundry owners Samsung, Toshiba/SanDisk, Micron, Intel and Hynix have all focused on shrinking the lithography of the memory products and increasing the number of bits in a NAND cell to reduce costs. Indeed, going from 24 Nanometer to 19 Nanometer cells roughly cuts costs in half. Going from a single bit per cell (SLC) to two bits per cell (MLC) halves costs again. Adding a third bit per cell, sometimes referred to as TLC, gets another 33% cost reduction at the die, or individual chip level.

But technical problems arise as the geometry shrinks and more bits are stuffed into a given cell. The result is greatly reduced use life of the part, usually measured in program-erase (PE) cycles, as well as greatly increased access times, measured in latency. DensBits attacks this with three proprietary areas of technology it has developed that represent some 60 patents.

Error Correction Coding (ECC) is critical to FLASH management. It basically consists of some fancy math that computes information that will tell you if an error exists in a given block of memory but also has the information necessary to correct the error by rewriting the block. DensBits has developed what it calls multi-dimensional codes which are covered by some 25 patents, and represent what DensBits calls a scientific breakthrough. In addition, digital signal processing (DSP) is another technology that DensBits developed to increase the use life of a given chunk of memory covered by 17 patents. Finally, a series of management functions covered by 18 additional patents include the capability greatly speed up the EP function, which is the Achilles’ heel of SSDs when it comes to the speed of writing data. This is the first time, to our knowledge, that all three strategies have been deployed in context with flash control.

The results are impressive. Combining the three technologies can increase MLC PE cycles by a factor of 25, and TLC PE cycles can be doubled. What this means is that junk TLC FLASH that would have been relegated to thumb drives can be used in cell phones, pads, and Ultra-Books while commercial grade MLC can go into enterprise drive applications. This represents a great cost reduction opportunity in all product areas.

Rather than setting out to build its own line of controllers or SSDs, DensBits market strategy is to offer the Memory Modem as a silicon core to be incorporated with other logic to become a memory card controller or SSD controller. In either case, additional functionality will need to be added for interfacing as an eMMC, SAS or SATA device, not to mention packaging issues.

Initially DensBits will be targeting the flash foundry owners as well as SSD and system manufacturers under a licensing model. A future business could involve providing chip-level integrations of the modem. The technology could begin showing up in end products in about a year. – James E. Bagley