Skewed Straintronic Magnetotunneling-Junction-Based Ternary Content-Addressable Memory—Part I

Abstract

This paper presents a ternary content-addressable memory (TCAM) cell based on a skewed straintronic magnetotunneling junction (MTJ) switch. A straintronic magnetotunneling junction (s-MTJ) is a three-terminal switch, where the resistance between two of the terminals switches when a potential is applied to the third (gate) terminal that induces strain in the magnetostrictive free-layer. An s-MTJ is a highly energy-efficient switch that would dissipate only ~aJ of energy during switching. This paper discusses a novel variant of s-MTJ, namely skewed s-MTJ (ss-MTJ), where the MTJ switching can be controlled by two gate terminals. The current through an ss-MTJ is minimum when the potentials at the first and second gate terminals ( ${V}_{2}$ and ${V}_{3}$ , respectively) obey the relation ${V}_{3} = {V}_{2}+{V}_{F}$ . Here, ${V}_{F}$ is a fixed voltage (“offset voltage”). Current in an ss-MTJ increases steeply when ${V}_{2}$ and ${V}_{3}$ deviate from the above “match” condition. This unconventional ${I}$ – ${V}$ characteristic of an ss-MTJ is exploited to design a non-Boolean TCAM cell based on just one transistor, one trench capacitor, and one ss-MTJ. We also discuss search and write operations in the ss-MTJ-TCAM cell, and show that the cell requires very small voltages to operate because of the unique ${I}$ – ${V}$ characteristics of the ss-MTJ.