A memory device with time-shifting based emulation of reference cells

摘要

A memory device (100;400) is proposed. The memory device includes a plurality of memory cells (Mc), means (115-145) for comparing a set of selected memory cells with at least one reference cell (Mr 0 -Mr 2 ;Mr) having a predefined threshold voltage, the means for comparing including means (115,120) for applying a biasing voltage having a substantially monotone time pattern to the selected memory cells and to the at least one reference cell, means (130) for detecting the reaching of a comparison current by a cell current of each selected memory cell and by a reference current of each reference cell, and logic means (145) for determining a condition of each selected memory cell according to a temporal relation of the reaching of the comparison current by the corresponding cell current and by the at least one reference current, wherein the means for comparing further includes means (220;520 j ;320 o -320 2 ,322;620 j ,622 j ) for time shifting at least one of said detections according to at least one predefined interval to emulate the comparison with at least one further reference cell having a further threshold voltage.