A non-volatile storage device in which current sensing is performed for a
non-volatile storage element with a negative threshold voltage. A control
gate read voltage is applied to a selected word line of a non-volatile
storage element, and source and p-well voltages are applied to a source
and a p-well, respectively, associated with the non-volatile storage
element. The source and p-well voltages exceed the control gate read
voltage so that a positive control gate read voltage can be used. There
is no need for a negative charge pump to apply a negative word line
voltage even for sensing a negative threshold voltage. A programming
condition of the non-volatile storage element is determined by sensing a
voltage drop which is tied to a fixed current which flows in a NAND
string of the non-volatile storage element.