Design of logic-compatible embedded DRAM using gain memory cell

In this work, we present an embedded DRAM utilizing logic-compatible 2T gain cell. The memory cells are composed of a high-V_TH write NMOS and a standard read NMOS. Due to the combination of low off-leakage write device and high mobility read device, this NMOS-based hybrid gain cell provides much improved data retention and read performance. At 1.2 V and 85 °C, the proposed bit-cell achieves 1.1× longer standby retention and 4.4× longer write disturbance retention compared to the PMOS-only 2T cell. The memory arrays operate with a logic-compatible supply voltage; /CS controlled 128-row refresh; and nondestructive read with speed comparable to 6T SRAM but 65 % smaller cell area. Design results from a test chip in a 130 nm logic CMOS technology exhibit the effectiveness of the proposed embedded memory techniques.