A non-volatile memory device has individual pages of memory cells to be
sensed in parallel. The memory device includes a source level tracking
circuit coupled to receive a predetermined word line voltage from a word
line voltage supply and the voltage level at the aggregate source node of
one or more pages and coupled to provide to word lines of the memory an
output voltage during the sensing operation, where the source level
tracking circuit includes an op amp whereby the output voltage is the
word line voltage offset by an amount to track the voltage level at the
aggregate node and compensate for source bias errors due to a finite
resistance in the ground loop.