We propose the use of a capacitor couple structure to control the effective threshold voltage (Vth) and its application to Vth fluctuation compensation in flip-flop sense amplifiers for multi-gigabit DRAMs. Our proposed sense amplifier functions correctly at up to a 500 mV fluctuation in Vth for the transistor pair in the latch. It does not require extra charging time in the sensing operation for compensation. In addition, the sense-amplifier speed is independent of the Vth value, so our S/A can also compensate the sensing speed fluctuation. This Vth control method and Vth-compensated sense amplifier opens up the possibility of utilizing transistors with gate lengths of less than 0.1 /spl mu/m, where the Vth variations could not be reduced.