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Imbalance-Tolerant Bit-Line Sense Amplifier for Dummy-Less Open Bit-Line Scheme in DRAM

Authors :
Byungkyu Song
Seong-Ook Jung
Suk Min Kim
Source :
IEEE Transactions on Circuits and Systems I: Regular Papers. 68:2546-2554
Publication Year :
2021
Publisher :
Institute of Electrical and Electronics Engineers (IEEE), 2021.

Abstract

In a conventional open bit-line scheme of DRAM, the edge subarrays (MATs) located at both ends of the cell array block contain alternated real and dummy bit-lines, unavoidably leading to an additional area overhead. To reduce the area overhead, one edge MAT can be eliminated by converting the dummy bit-lines of the other edge MAT into real bit-lines. This strategy causes the conventional bit-line sense amplifiers (BLSAs) in the MATs located at both ends of the cell array block to have a much smaller complementary bit-line capacitance than a true bit-line capacitance. Thus, the sensing operation of a conventional BLSA with this unbalanced bit-line capacitance experiences various problems: sensing voltage decrease, data flipping, and asymmetric equalization. To solve these problems, we propose a novel sensing circuit that can operate effectively even under unbalanced bit-line capacitance, thus suggesting the possibility of an open bit-line scheme without dummy bit-lines. Our proposed dummy-less open bit-line scheme can save approximately 4% of the array height. Compared with the conventional unbalanced BLSA, the proposed BLSA increases the sensing voltage by more than 100%, reduces the voltage peaks by 30% during the data transfer, and reduces equalization time by 1.2 ns in HSPICE Monte Carlo simulation.

Details

ISSN :
15580806 and 15498328
Volume :
68
Database :
OpenAIRE
Journal :
IEEE Transactions on Circuits and Systems I: Regular Papers
Accession number :
edsair.doi...........1948f7881559cc86ebfd0ee07ff3e85f
Full Text :
https://doi.org/10.1109/tcsi.2021.3063183