Patent ID: 9042194
Filing Date: 2015-05-26
Classification: G11C

Abstract:
1. A refresh method for a volatile memory device including a plurality of memory cells arranged in an array having a plurality of rows and a plurality of columns, each row corresponding to a respective address, the refresh method comprising: refreshing memory cells of a first set of rows of the array at a first refresh rate having a first refresh period, the first refresh rate being a lower rate having a longer refresh period than a second refresh rate having a second refresh period, wherein each memory cell in the first set of rows of the array has a retention time longer than the first refresh period; and refreshing memory cells of a second set of rows of the array at a third refresh rate having a third refresh period, the third refresh rate being a higher rate having a shorter refresh period than the second refresh rate having the second refresh period, wherein at least one memory cell of each row of the second set of rows has a retention time longer than the third refresh period and shorter than the first refresh period wherein the first refresh period is two times the length of the second refresh period, wherein the second refresh period corresponds to a refresh period defined in a standard for the volatile memory device.