  We propose a novel Hamming distance tolerant content-addressable memory
(HD-CAM) for energy-efficient in memory approximate matching applications.
HD-CAM implements approximate search using matchline charge redistribution
rather than its rise or fall time, frequently employed in state of-the-art
solutions. HD-CAM was designed in a 65 nm 1.2 V CMOS technology and evaluated
through extensive Monte Carlo simulations. Our analysis shows that HD-CAM
supports robust operation under significant process variations and changes in
the design parameters, enabling a wide range of mismatch threshold (tolerable
Hamming distance) levels and pattern lengths. HD-CAM was functionally evaluated
for virus DNA classification, which makes HD-CAM suitable for hardware
acceleration of genomic surveillance of viral outbreaks such as Covid-19
pandemics.
