Generation of Accurate Reference Current for Data Sensing in High-Density Memories by Averaging Multiple Pairs of Dummy Cells

• Published in: IEEE journal of solid-state circuits Vol. 46; no. 9; pp. 2148 - 2157
• Main Authors: Ohsawa, T., Hatsuda, K., Fujita, K., Matsuoka, F., Higashi, T.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 1T-DRAM; Applied sciences; Arrays; Circuits; Degradation; Design. Technologies. Operation analysis. Testing; Detection; Dummies; Dummy cell; dummy cell averaging; Electronics; Exact sciences and technology; floating body cell (FBC); floating body random access memory (FBRAM); Integrated circuits; Integrated circuits by function (including memories and processors); Logic gates; Monte Carlo methods; Monte Carlo simulation; MOSFET circuits; Random access memory; random dopant fluctuation; reference current; retention time distribution; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; sense amplifier; Sense amplifiers; Sensors; Signal to noise ratio; signal-to-noise ratio (SNR); Performance evaluation; Monte Carlo method; Averaging method; Dummy cell; dummy cell averaging; floating body cell (FBC); signal-to-noise ratio (SNR); IT-DRAM; High density; Random access memory; Retention factor; retention time distribution; Sense amplifier; reference current; floating body random access memory (FBRAM); Non volatile memory; Integrated circuit; Numerical simulation; Large scale; random dopant fluctuation; Floating body; Monte Carlo simulation; Dynamic random access memory; Signal to noise ratio
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2011.2147050

Methods to generate an accurate reference current by averaging multi-pair dummy cells' currents for distinguishing the data in sense amplifiers (S/As) of a large scale memory with resistance change cell is presented and analyzed. The predicted characteristics are confirmed by comparing them with measurement results of the functionalities and the retention time distributions in a floating body random access memory (FBRAM). The methods are found to be especially effective in situations where signals are seriously degraded such as in sensing the signals of tail bit cells in retention time distributions, making the retention time performance of the FBRAM improved drastically. The sense amplifiers which can accommodate the dummy cell averaging methods are identified to find a necessary condition for a S/A to afford the methods.