A Word Line Pulse Circuit Technique for Reliable Magnetoelectric Random Access Memory

Hochul Lee, Albert Lee, Shaodi Wang, Farbod Ebrahimi, Puneet Gupta, Pedram Khalili Amiri, Kang L. Wang

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

A word line pulse (WLP) circuit scheme is proposed toward the implementation of magnetoelectric random access memory (MeRAM). The circuit improves the write error rate (WER) and cell area efficiency by generating a better write pulse compared to conventional bitline pulse (BLP) techniques in terms of the pulse slew rate and amplitude. For the voltage-controlled magnetic anisotropy-induced precessional switching of the magnetic tunnel junction (MTJ), the write pulse shape has a large impact on the switching probability. Typically, a square shape pulse results in higher switching probability compared to that of a triangular shape pulse with long rise and falling edges, since the square shape pulse causes a more stable precessional trajectory of the free layer magnetization by providing a relatively constant in-plane-dominant effective field. Compared to the BLP scheme, the WLP can generate a better square shape pulse by eliminating discharge paths under the pulse condition, using the gain of the access transistor, and effectively diminishing the capacitive loading which needs to be driven. A macrospin compact model of voltage-controlled MTJ shows that the WLP can improve WER by {10}^{7} times and allow MeRAM to have four-Time improvement in area efficiency of driver circuits compared to the BLP.

Original languageEnglish (US)
Article number7873350
Pages (from-to)2027-2034
Number of pages8
JournalIEEE Transactions on Very Large Scale Integration (VLSI) Systems
Volume25
Issue number7
DOIs
StatePublished - Jul 2017

Keywords

  • Magnetic tunnel junction (MTJ)
  • magnetoelectric random access memory (MeRAM)
  • voltage controlled magnetic anisotropy (VCMA)
  • word line pulse (WLP)
  • write error rate (WER)

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture
  • Electrical and Electronic Engineering

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