The present invention presents a scheme for sensing memory cells. Selected
memory cells are discharged through their channels to ground and then
have a voltage level placed on the traditional source and another voltage
level placed on the control gate, and allowing the cell bit line to
charge up. The bit line of the memory cell will then charge up until the
bit line voltage becomes sufficiently high to shut off any further cell
conduction. The rise of the bit line voltage will occur at a rate and to
a level dependent upon the data state of the cell, and the cell will then
shut off when the bit line reaches a high enough level such that the body
effect affected memory cell threshold is reached, at which point the
current essentially shuts off. A particular embodiment performs multiple
such sensing sub-operations, each with a different control gate voltage,
but with multiple states being sensed in each operation by charging the
previously discharged cells up through their source.