Katsuaki Isobe

A 70nm 16Gb 16-level-cell NAND Flash Memory

A 16 Gb 16-level-cell (16LC) NAND flash memory using 70 nm design rule has been developed. This 16LC NAND flash memory can store 4 bits in a cell which enabled double bit density comparing to 4-level-cell (4LC) NAND flash with the same design rule. New programming method achieves 0.62 MB/s programming throughput.

A 70 nm 16 Gb 16-Level-Cell NAND flash Memory

A 16 Gb 16-level-cell (16LC) NAND flash memory using 70 nm design rule has been developed . This 16LC NAND flash memory can store 4 bits in a cell which enabled double bit density comparing to 4-level-cell (4LC) NAND flash, and quadruple bit density comparing to single-bit (SLC) NAND flash memory with the same design rule. New programming method suppresses the floating gate coupling effect and enabled the narrow distribution for 16LC. The cache-program function can be achievable without any additional latches. Optimization of programming sequence achieves 0.62 MB/s programming throughput. This 16-level NAND flash memory technology reduces the cost per bit and improves the memory density even more.

A pseudo multi-bank DRAM with categorized access sequence

A new architecture which realizes the large bandwidth with virtually the same core circuitry as a conventional DRAM is proposed. The improved row block activation scheme combined with a categorized access sequence improves the bandwidth of the DRAM even with the shared sense amplifier scheme. The data efficiency of the random read/write mixed cycle is improved by the proposed delayed write operation, which fills the write to read command gap effectively. The proposed architecture is successfully examined in the 128 Mbit test vehicle fabricated with a 0.15 /spl mu/m CMOS process.

A 19 nm 112.8 mm

NAND flash memory is widely used in digital cameras, USB devices, cell phones, camcorders and solid-state drives. Continuous lowering of bit cost, increasing flash-memory-die densities and improving performance have helped to expand flash markets. Recently, there are two different directions to meet market demands. One is lowering bit cost and increase memory density to the utmost limit, which is achieved by 4b/cell [1] or 3b/cell [2]. The other is focusing on high performance and high reliability. To meet both demands, we develop a 19nm 112.8mm2 64Gb 2b/cell NAND flash memory with the smallest die size ever reported. 15MB/s programming throughput and 400Mb/s/pin 1.8V Toggle Mode interface [3] are achieved for the first time. Die Micrograph and features are shown in Figure 25.1.1.

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A new Delay Locked Loop (DLL) using a Digital-to-Analog Converter with the Parallel Variable Resister (PVR-DAC) has been developed. The PVR-DAC successfully manages the current controlled-delay element (CCDE) and achieves a fine time-based resolution. The DLL adopting PVR-DAC has been simulated. It realizes a time-based resolution of 18 ps, an operation frequency range of 143 MHz through 333 MHz, with the maximum power consumption of 20 mW at 1.5 V, and also achieves the small circuit area of 0.5 mm/sup 2/.