A memory sensing circuit and method that can achieve both a wide read
margin and a fast read time. Roughly described, a target cell draws a
target cell current from a first node when selected. The target cell
current depends on the charge level stored in the target cell. A
reference cell draws a reference cell current from a second node when
selected, and a current difference generator generates into a third node
a third current flow positively dependent upon the difference between the
target cell current and the reference cell current. The current
difference generator also generates into a fourth node a fourth current
flow negatively dependent upon the difference between the target cell
current and the reference cell current. A sense amplifier has its first
input connected to the third node and a second input connected to the
fourth node.