A 64Mb MRAM with clamped-reference and adequate-reference schemes

A 64 Mb spin-transfer-torque MRAM in 65 nm CMOS is developed. A 47 mm
²
die uses a 0.3584 ¿m
²
cell with a perpendicular-TMR device. To achieve read-disturb immunity for the reference cell, a clamped-reference scheme is adopted. An adequate-reference scheme is implemented to suppress read-margin degradation due to the resistance variation of reference cells.