7.4 A covalent-bonded cross-coupled current-mode sense amplifier for STT-MRAM with 1T1MTJ common source-line structure array

Abstract

In this paper, we present a sensing scheme for STT-MRAM with 1T1MTJ common SL structure array: covalent-bonded cross-coupled current-mode sense amplifier (CBSA). The CBSA can fit in conventional DRAM array architecture and use two normal cells in adjacent BLs, one for storing data “1” and the other for storing data “0”, for generating reference currents for CBSA. There are 64 CBSAs in a row of 8k cells, where one CBSA and two references BLs are shared by adjacent 128 BLs. STT-MRAM cell is directly accessed instead of page opening as in DRAM. By introducing CBSAs as sensing schemes, read-access time can be reduced to under 10ns with strong robustness against wide random variations of MTJ cell resistances with a small TMR.