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Samsung calls on NAND Flash for handsets

Posted: 01 Mar 2001 ?? ?Print Version ?Bookmark and Share

Keywords:nand flash memory? nor flash? data storage? 3g phones? sram?

samsung Electronics said it has started offering NAND Flash memory, used mostly as data storage memory in Flash cards, as an alternative to NOR Flash devices in multichip packages aimed at cellphone makers.

Though it may not have the random-access performance of NOR-type code Flash devices, NAND may provide cellphone makers with a way to get to higher densities at a lower cost.

"There was a worry about shortages of high-density NOR in the summer, and some felt they should have a fallback position," said Alan Niebel of Web-Feet Research Inc. "If the NAND approach functions according to speed, it may be a low-cost alternative. NAND tends to be cheaper than NOR overall in the marketplace, though that does not mean the silicon manufacturing costs are cheaper."

Higher density, lower cost

As the latest Internet-browsing phones and forthcoming third-generation (3G) phones pack more volatile and nonvolatile memory to keep up with new services, cellphone makers are looking to boost memory density while keeping costs and power consumption to a minimum. "The higher-density Flash is needed," said Niebel. "It is not only for protocol setups but also for messaging, voice answering, GPS, storing different fonts and Web access."

As one of only a handful of NAND-type Flash memory suppliers, Samsung may find even the small slice of the market it gets to be a lucrative one. The company believes the wireless handset market will reach 420 million units in 2000 and will continue to grow 30 percent a year. Samsung expects the market for 3G handsets to hit 50 million units by 2003.

The company claims to have already shipped engineering samples of stacked multichip modules with 8Mb of SRAM and a 64Mb NAND device.

The devices come packaged in an 8-by-13-by-1.2mm BGA with 69 signals. The NAND and SRAM share I/O and control pins, and the pin-out will accommodate SRAM as dense as 64Mb and NAND-type Flash chips with 512MB of storage capacity, according to Samsung.

The mcp is set to operate between 2.4V and 3V. Designed with 0.18?m geometry rules, the 8Mb SRAM has an access time of 85ns.

The NAND access speed will likely be slower than NOR Flash, although slower Flash speeds may not be a problem for "middle of the road" applications, Niebel said.

"The main problem with NAND is the initial read. You are getting up to 50?s for the initial read, then 50ns for subsequent reads," he said. "NOR's initial read can be as low as 70ns and up to 150ns, and then the subsequent reads in burst or page mode can go down to the twenties or teens with some of them."

Samsung plans to extend its NAND offering for cellphones even further. In the first quarter, the company will introduce an MCP with 32Mb of what it calls unit transistor RAM and 64Mb of NAND Flash.

? Anthony Cataldo

EE Times

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