A gated sense amplifier (GSA) consisting of a low-V_t gated preamplifier (LGA) and a high-V_t sense amplifier (SA) is proposed. The gating scheme of the LGA enables quick amplification of an initial cell signal voltage (v_S0) because of its low V_t and prevents the cell signal from degrading due to interference noise between data lines. As for a conventional sense amplifier (CSA), this new type of noise causes sensing error, and the noise-generation mechanism was clarified for the first time by analysis of v_S0. The high-V_t SA holds the amplified signal and keeps subthreshold current low. Moreover, the gating scheme of the low-V_t MOSFETs in the LGA drives the I/O line quickly. The GSA thus simultaneously achieves fast sensing, low-leakage data holding, and fast I/O driving, even for sub-1-V mid-point sensing. The GSA is promising for future sub-1-V gigabit dynamic random-access memory (DRAM) because of reduced variations in the threshold voltage of MOSFETs; thus, the offset voltage of the LGA is reduced. The effectiveness of the GSA was verified with a 70-nm 512-Mbit DRAM chip. It demonstrated row access time (t_RCD) of 16.4ns and read access (t_AA) of 14.3ns at array voltage of 0.9V.