Device for sensing data in a multi-bit memory cell using a multistep current source

摘要

A device and method for sensing data in a multi-bit memory cell of a memory cell array unit is provided where each memory cell has at least two threshold voltage levels. The device can include a multistep current source unit to provide quantized voltages, each having a width smaller than a threshold voltage distribution in a selected memory cell, according to a current flowing through the selected memory cell. An analog-to-digital converter compares the quantized voltages from the multistep current source unit with a plurality of reference voltages to provide a state of the memory cell in binary form. The device and method for sensing data in the multi-bit memory cell uses the quantized voltages to increase sensing reliability, increases sensing speed and increases a gap between the quantized voltages relative to the threshold voltage distribution.