SPINBIS: Spintronics-Based Bayesian Inference System With Stochastic Computing

Abstract

Bayesian inference is an effective approach for solving statistical learning problems, especially with uncertainty and incompleteness. However, Bayesian inference is a computingintensive task whose efficiency is physically limited by the bottlenecks of conventional computing platforms. In this work, a spintronics based stochastic computing approach is proposed for efficient Bayesian inference. The inherent stochastic switching behaviors of spintronic devices are exploited to build stochastic bitstream generator (SBG) for stochastic computing with hybrid CMOS/MTJ circuits design. Aiming to improve the inference efficiency, an SBG sharing strategy is leveraged to reduce the required SBG array scale by integrating a switch network between SBG array and stochastic computing logic. A deviceto-architecture level framework is proposed to evaluate the performance of spintronics based Bayesian inference system (SPINBIS). Experimental results on data fusion applications have shown that SPINBIS could improve the energy efficiency about 12× than MTJ-based approach with 45% design area overhead and about 26× than FPGA-based approach.

Energy-efficient Design of MTJ-based Neural Networks with Stochastic Computing

“…The bitstream passed all the 15 tests. The Stochastic Computing Correlation (SCC) measurement adopted in SPINBIS [22] yields SCC values within ±0.01 for our bitstreams, which is very close to the ideal value of 0.…”

“…Additionally, the MTJ-based random number generator designed in Reference [58] passed 12 out of the 15 NIST SP-800 statistical tests. And the work in Reference [22] tests the suitability of using MTJs for generating Stochastic Numbers and finds low levels of self-and crosscorrelation among the generated bitstreams.…”

Brain-Inspired Hardware Solutions for Inference in Bayesian Networks

“…It is implemented by hybrid CMOS/MTJ technologies named spintronic-based Bayesian inference system (SPINBIS) ( Figure 7C ). The aim of proposing the SPINBIS is to enhance the stability of SBG and to use a smaller number of SBGs ( Jia et al, 2020 ). The outcome probability of each SBG is predetermined and is then multiplexed through the switch matrix, which is a crossbar array.…”

Non-Binary Spin Wave Based Circuit Design

“…(i) Leakage wall 5,6 , (ii) Reliability wall 4 , and (iii) Cost wall 4,5 . Therefore, to keep the pace with the exploding market needs, novel alternative technologies are under investigation, e.g., graphene [7][8][9][10] , memristors [11][12][13][14][15] , and spintronics [16][17][18][19][20] . Different spintronics technologies have been developed based on, e.g., magnetization switching 21 , Skyrmions generation 22,23 , rectified tunnel magnetoresistance 24 , anomalous Hall effect, and negative differential resistance magnetic tunnel junctions 25 .…”