Quasi-volatile memory with enhanced sense amplifier operation

Abstract

A semiconductor memory device is implemented as a string of storage transistors with sense amplifier connected drain terminals and floating source terminals. In some embodiments, a method in the semiconductor memory device applies a bit line control (BLC) voltage with a voltage step down to the bias device during the read operation to reduce the settling time on the bit line, thereby shortening the access time for data read out from the storage transistors. In other embodiments, a method in the semiconductor memory device including an array of strings of storage transistors uses a current from a biased but unselected bit line as the sense amplifier reference current for reading stored data from a selected bit line. In one embodiment, the sense amplifier reference current is provided to a referenced sense amplifier to generate a sense amplifier data latch signal.