Sensing circuit for semiconductor memories

Abstract

A sensing circuit is provided. The sensing circuit is adapted to determine when a cell current flowing trough a selected memory cell exceeds a reference current during an evaluation phase of a sensing operation. The sensing circuit is adapted to be coupled to at least one selected memory cell through a respective bit line. The sensing circuit includes: an access circuit node adapted to be coupled to the bit line; precharging circuitry adapted to be activated in a precharge phase of the sensing operation preceding the evaluation phase, so as to bring a voltage of said access circuit node to a reference voltage; a reference circuit node coupled to the access circuit node and arranged to receive the reference current. The sensing circuit further includes an evaluation circuit node coupled to the reference circuit node through a first current to voltage converter, adapted to sink a current flowing from the reference circuit node to the evaluation circuit node and to produce a corresponding voltage difference between the reference circuit node and the evaluation circuit node, wherein the current is nearly equal to the reference current substantially at the end of the precharge phase; comparator circuitry is provided, adapted to compare the voltage of the access circuit node with the voltage of the evaluation circuit node and to provide a corresponding comparison signal whose time pattern indicates when the cell current exceeds the reference current. The first current to voltage converter is an electronic device having essentially the behavior of a diode.