Design of a sense circuit for low-voltage flash memories

A new sense circuit directly sensing the bitline voltage is proposed for lo w-voltage flash memories. A simple reference voltage generation method and a dataline switching method with matching of the stray capacitance between the dataline pairs are also proposed. A design method for the bitline clamp load transistors is described, taking bitline charging speed and process m argins into account. The sense circuit was implemented in a 32-Mb flash mem ory fabricated with a 0.25-mu m flash memory process and successfully opera ted at a low voltage of 1.5 V.