A 5T-2MTJ STT-assisted Spin Orbit Torque based Ternary Content Addressable Memory for Hardware Accelerators

TL;DR

This paper introduces a novel 5T-2MTJ STT-assisted SOT-based ternary CAM that demonstrates high accuracy and efficiency at the device, circuit, and application levels, suitable for hardware accelerators.

Contribution

It presents a comprehensive design and evaluation of a new non-volatile ternary CAM using spintronic devices, from device simulations to application benchmarking.

Findings

Achieves a search error rate of 3.9x10^-11 for exact search.

Demonstrates high performance and accuracy in CAM-based recommendation systems.

Validates the design through extensive device, circuit, and application-level simulations.

Abstract

In this work, we present a novel non-volatile spin transfer torque (STT) assisted spin-orbit torque (SOT) based ternary content addressable memory (TCAM) with 5 transistors and 2 magnetic tunnel junctions (MTJs). We perform a comprehensive study of the proposed design from the device-level to application-level. At the device-level, various write characteristics such as write error rate, time, and current have been obtained using micromagnetic simulations. The array-level search and write performance have been evaluated based on SPICE circuit simulations with layout extracted parasitics for bitcells while also accounting for the impact of interconnect parasitics at the 7nm technology node. A search error rate of 3.9x10^-11 is projected for exact search while accounting for various sources of variation in the design. In addition, the resolution of the search operation is quantified under various scenarios to understand the achievable quality of the approximate search operations. Application-level performance and accuracy of the proposed design have been evaluated and benchmarked against other state-of-the-art CAM designs in the context of a CAM-based recommendation system.