A Split-Path Sensing Circuit for Spin Torque Transfer MRAM

As process technology scales down, sensing becomes difficult during read operations because the supply voltage, i.e., VDD, decreases and the process variation increases. Thus, a high enough sensing yield cannot be obtained with a conventional sensing circuit in deep submicron process technology. In this brief, a split-path sensing circuit is proposed to achieve a large enough sensing margin by using a variable reference voltage. The proposed sensing circuit is verified using Monte Carlo HSPICE simulation with industry-compatible low-leakage 45-nm model parameters. The proposed circuit has a sensing yield of 99% for 1-Mb memory with a sensing time of 1 ns and a sensing yield of 99% for 32-Mb memory with a sensing time of 3 ns.