ISSCC 2009 / SESSION 27 / SRAM AND EMERGING MEMORY / 27 . 4 27 . 4 A 90 nm 12 ns 32 Mb 2 T 1 MTJ MRAM
نویسندگان
چکیده
Since MRAM cells have unlimited write endurance, they can be used as substitutes for DRAMs or SRAMs. MRAMs in electronic appliances enhance their convenience and energy efficiency because data in MRAMs are nonvolatile and retained even in the power-off state. Therefore, 2 to 16Mb standalone MRAMs have been developed [1-4]. However, in terms of their random-access times, they are not enough fast (25ns) [1] as substitutes for all kinds of standalone DRAMs or SRAMs. To attain a standalone MRAM with both a fast random-access time and a large capacity, we adopt a cell structure with 2 transistors and 1 magnetic tunneling junction (2T1MTJ), which we previously published for a 1Mb embedded MRAM macro [5]. We need to develop circuit schemes to achieve a larger memory capacity and a higher cell-occupation ratio with small access-time degradation. We describe the circuit schemes of a 32Mb MRAM, which enable 63% cell occupation ratio and 12ns access time.
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