Patent ID: 9147491
Filing Date: 2015-09-29
Classification: G11C

Abstract:
1. A method for operating a memory array comprising multi-level memory cells, wherein the multi-level memory cells include (i) pilot cells having predetermined data and (ii) multi-level data memory cells to store user data, the method comprising: receiving (i) signal samples from one or more of the pilot cells, and (ii) signal samples from one or more of the multi-level data memory cells; based on the signal samples from one or more of the pilot cells and without using signal samples from the multi-level data memory cells, computing (i) estimated mean values of level distributions of the multi-level memory cells and (ii) estimated variance values of level distributions of the multi-level memory cells; based on the signal samples from one or more of the multi-level data memory cells and without using signal samples from the pilot cells, updating (i) the estimated mean values of level distributions of the multi-level memory cells and (ii) the estimated variance values of level distributions of the multi-level memory cells; based on the updated estimated mean values of level distributions of the multi-level memory cells and the updated estimated variance values of level distributions of the multi-level memory cells, computing (i) optimal or near optimal mean values of level distributions of the multi-level memory cells and (ii) optimal or near optimal detection threshold values of level distributions of the multi-level memory cells; and based on the optimal or near optimal mean values of level distributions of the multi-level memory cells, writing data in the multi-level data memory cells.