A New Approximate Sum of Absolute Differences Unit for Bioimages Processing

An inexact 6-transistor full adder (FA) cell is presented. It is low-power and gives full-swing outputs because of the applied gate diffusion input (GDI) along with the dynamic threshold (DT) techniques. The FA which has three errors is used in a 10-transistor inexact 4:2 compressor based on the stacking circuit idea. The implementation by a 16-nm carbon nanotube field-effect transistor (CNTFET) technology shows a small area of 0.027 and $0.045~\mu \text{m}^{\mathrm{ 2}}$ for the FA and compressor, respectively. A new approximate sum of absolute differences (SADs) block is presented by the FA and compressor. The average power, power-delay-product (PDP), and peak signal-to-noise ratio (PSNR) of the SAD are 6.80 mW, 33.86 nJ, and 42.98 dB, respectively, which confirm its efficiency for bioimages difference detection.