Mixed parallel-dichotomic serial sensing method for sensing multiple-levels non-volatile memory cells, and sensing circuit actuating such method

摘要

A method for sensing multiple-levels non-volatile memory cells which can take one programming level among a plurality of m=2n (n = 2) different programming levels, provides for biasing a memory cell (MC) to be sensed in a predetermined condition, so that the memory cell (MC) sinks a cell current (IC) with a value belonging to a discrete set of m distinct cell current values (IC0-IC15), each cell current value (IC0-IC15) corresponding to one of said programming levels. The sensing method also provides for: simultaneously comparing the cell current (IC) with a prescribed number of reference currents (IR1,IR2,IR3) having values comprised between a minimum value and a maximum value of said discrete set of m cell current values (IC0-IC15) and dividing said discrete set of m cell current values (IC0-IC15) in a plurality of sub-sets of cell current values, for determining the sub-set of cell current values to which the cell current (IC) belongs; repeating step a) for the sub-set of cell current values to which the cell current (IC) belongs, until the sub-set of cell current values to which the cell current (IC) belongs comprises only one cell current value, which is the value of the current (IC) of the memory cell (MC) to be sensed.