US 9,812,193 B2
Threshold estimation using bit flip counts and minimums
Christopher S. Tsang, Santa Clara, CA (US); Frederick K. H. Lee, Mountain View, CA (US); Xiangyu Tang, San Jose, CA (US); Zheng Wu, San Jose, CA (US); and Jason Bellorado, San Jose, CA (US)
Assigned to SK Hynix Inc., Gyeonggi-do (KR)
Filed by SK Hynix Inc., Gyeonggi-do (KR)
Filed on Sep. 9, 2014, as Appl. No. 14/480,988.
Claims priority of provisional application 61/901,960, filed on Nov. 8, 2013.
Prior Publication US 2015/0131376 A1, May 14, 2015
Int. Cl. G11C 11/56 (2006.01); G11C 16/26 (2006.01); G11C 16/34 (2006.01)
CPC G11C 11/5642 (2013.01) [G11C 16/26 (2013.01); G11C 16/3404 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A method for estimating an optimal threshold, comprising:
using a processor to determine a bit flip count for each bin in a plurality of bins, including by: (1) performing a first read on a group of solid state storage cells at a first threshold that corresponds to a lower bound for a given bin and (2) performing a second read on the group of solid state storage cells at a second threshold that corresponds to an upper bound for the given bin;
determining a minimum including determining a minimum bin corresponding to a bin having a lowest bit flip count, by using the bit flip counts corresponding to the plurality of bins; and
using the minimum to estimate an optimal threshold, including setting the estimate of the optimal threshold to be the center of the minimum bin.