Offset-Compensation High-Performance Sense Amplifier for Low-Voltage DRAM Based on Current Mirror and Switching Point

The transistor offset from sense amplifiers affects the sensing performance in dynamic random-access memory (DRAM). Although various offset-compensation methods are available, the voltage mismatch remains large, and some methods are susceptible to timing variation. To improve the compensation effect and stability, we propose a current-mirror and switching-point compensation sense amplifier. The amplifier compensates one bit-line voltage to the switching point of an inverter and adjusts the other bit-line by a current mirror during compensation. The configuration is robust against timing variation. Moreover, the voltage of complementary bit line considerably changes due to the high gain of the switching point. Simulation results show that the voltage mismatch can be improved by 90% compared with that of a boosted reference voltage sense amplifier. In addition, the increased bit-line differential voltage can improve the sensing speed. At a low supply voltage of 0.75 V, the sensing yield improves by 11% compared with that of a boosted reference voltage sense amplifier and by 16% compared with that of an offset-cancellation sense amplifier.