Patent ID: 7483305

Claim:
A threshold voltage measurement circuit, comprising: a reference current generator configured to internally generate a reference current and operably coupled to a bit line, wherein an input of the reference current generator is operably coupled to a first PAD; a NAND string including a plurality of non-volatile memory cells operably coupled together in a series configuration, a first end of the series configuration operably coupled to the bit line and a second end of the series configuration operably coupled to a ground voltage; a bit line pre-charge circuit operably coupled to the bit line and configured to store a reference voltage charged on the bit line; and a comparator configured to compare a voltage on the bit line and the reference voltage and generate a logic signal, wherein a first input of the comparator is operably coupled to the bit line and a second input of the comparator is operably coupled to the bit line pre-charge circuit; wherein the voltage on the bit line is at least partially dependent on both a cell current through the NAND string and the reference current.