2t2c signal margin test mode using a defined charge and discharge of bl and /bl

Abstract

A semiconductor memory test mode configuration includes a first capacitor for storing digital data. The first capacitor connects a cell plate line to a first bit line through a first select transistor which is activated through a connection to a word line. A second capacitor for storing digital data connects the cell plate line to a second bit line through a second select transistor which is also activated through a connection to the word line. A sense amplifier is connected to the first and second bit lines for measuring a differential read signal on the first and second bit lines. A constant current mover, for example a constant current sink or source, is connected to the first bit line through a third transistor for changing the amount of charge on the first bit line when the third transistor is turned on to reduce the differential read signal.