Circuit-Level Evaluation of the Generation of Truly Random Bits with Superparamagnetic Tunnel Junctions

TL;DR

This paper evaluates a circuit-based method for generating truly random bits using superparamagnetic tunnel junctions, demonstrating low energy consumption and addressing read disturb effects, with promising implications for energy-efficient randomness in computing.

Contribution

It provides the first detailed circuit-level analysis of superparamagnetic tunnel junctions for random bit generation, including effects of read disturb and whitening processes.

Findings

Read disturb effect is small and naturally corrected by whitening.

Superparamagnetic tunnel junctions can generate random bits at 20 fJ/bit.

Energy efficiency is orders of magnitude better than CMOS solutions.

Abstract

Many emerging alternative models of computation require massive numbers of random bits, but their generation at low energy is currently a challenge. The superparamagnetic tunnel junction, a spintronic device based on the same technology as spin torque magnetoresistive random access memory has recently been proposed as a solution, as this device naturally switches between two easy to measure resistance states, due only to thermal noise. Reading the state of the junction naturally provides random bits, without the need of write operations. In this work, we evaluate a circuit solution for reading the state of superparamagnetic tunnel junction. We see that the circuit may induce a small read disturb effect for scaled superparamagnetic tunnel junctions, but this effect is naturally corrected in the whitening process needed to ensure the quality of the generated random bits. These results suggest that superparamagnetic tunnel junctions could generate truly random bits at 20 fJ/bit, including overheads, orders of magnitudes below CMOS-based solutions.