Efficient Implementation of Mahalanobis Distance on Ferroelectric FinFET
Crossbar for Outlier Detection
Abstract
The developments in the nascent field of
artificial-intelligence-of-things (AIoT) relies heavily on the
availability of high-quality multi-dimensional data. A huge amount of
data is being collected in this era of big data, predominantly for AI/ML
algorithms and emerging applications. Considering such voluminous
quantities, the collected data may contain a substantial number of
outliers which must be detected before utilizing them for data mining or
computations. Therefore, outlier detection techniques such as
Mahalanobis distance computation have gained significant popularity
recently. Mahalanobis distance, the multivariate equivalent of the
Euclidean distance, is used to detect the outliers in the correlated
data accurately and finds widespread application in fault
identification, data clustering, single-class classification,
information security, data mining, etc. However, traditional CMOS-based
approaches to compute Mahalanobis distance are bulky and consume a huge
amount of energy. Therefore, there is an urgent need for a compact and
energy-efficient implementation of an outlier detection technique which
may be deployed on AIoT primitives, including wireless sensor nodes for
in-situ outlier detection and generation of high-quality data. To this
end, in this paper, for the first time, we have proposed an efficient
Ferroelectric FinFET-based implementation for detecting outliers in
correlated multivariate data using Mahalanobis distance. The proposed
implementation utilizes two crossbar arrays of ferroelectric FinFETs to
calculate the Mahalanobis distance and detect outliers in the popular
Wisconsin breast cancer dataset using a novel inverter-based threshold
circuit. Our implementation exhibits an accuracy of 94.1% which is
comparable to the software implementations while consuming a
significantly low energy (13.56 pJ)