US 2014/0369132 A1 · DIFFERENTIAL CURRENT SENSE AMPLIFIER AND METHOD FOR NON-VOLATILE MEMORY

Abstract

The selected bit line in a non-volatile memory carries a cell conduction current to be measured and also a leakage current or noise due to weak coupling with neighboring array structures. In a first phase, a sense amplifier senses the bit line current by discharging a capacitor with the combined current (cell conduction current plus the leakage current) over a predetermined time. In a second phase, the cell conduction current is minimized and significantly the leakage current in the selected bit line is used to recharge in tandem the capacitor in a time same as the predetermined time, effectively subtracting the component of the leakage current measured in the first sensing phase. The resultant voltage drop on the capacitor over the two sensing phases provides a measure of the cell conduction current alone, thereby avoiding reading errors due to the leakage current present in the selected bit line.

Claims18

Dependent claims

A method of sensing a conduction current of a memory cell of a non-volatile memory comprising:

providing a bit line for accessing the memory cell, the bit line having a first bit line current constituted from the conduction current of the memory cell and a current due to noise;
precharging a capacitor to a first predetermined voltage above a reference voltage;
in a first sensing phase, discharging the capacitor with the first bit line current for a predetermined period of time wherein the first predetermined voltage decreases to a second voltage;
in a second sensing phase, minimizing the conduction current of the memory cell so that the bit line has a second bit line current significantly constituted from the current due to noise, and charging the capacitor with the second bit line current for a same time as the predetermined period of time, wherein the second voltage increases to a third voltage;
and
comparing the third voltage with the reference voltage to give a measure of the conduction current of the memory cell.

3 more elements

A sensing circuit for sensing a conduction current of a memory cell of a non-volatile memory comprising:

a bit line for accessing the memory cell, the bit line having a first bit line current constituted from the conduction current of the memory cell and a current due to noise;
a bit line voltage circuit for maintain the bit line at a predetermined voltage;
a capacitor;
a precharging circuit coupled to said capacitor to precharge the capacitor to a first predetermined voltage above a reference voltage;
in a first sensing phase, a first set of signals enables said capacitor to be coupled for discharging by the first bit line current for a predetermined period of time wherein the first predetermined voltage decreases to a second voltage;
in a second sensing phase, where the memory cell has the conduction current minimized so that the bit line has a second bit line current significantly constituted from the current due to noise, and a second set of signals enables said capacitor to be coupled for charging by the second bit line current for a same time as the predetermined period of time, wherein the second voltage increases to a third voltage;
and
a comparator for comparing the third voltage with the reference voltage to give a measure of the conduction current of the memory cell.

5 more elements

Dependencies are inferred from the claim text.

Differential current sense amplifier and method for non-volatile memory

Life of this patent

Differential current sense amplifier and method for non-volatile memory

Life of this patent

Abstract

Claims18