Subthreshold implementation of a 2D CNN Gabor-type focal plane filter

We describe the implementation of a focal plane CNN array for computing the outputs of orientation selective filters similar to Gabor filters using weak inversion transistor circuits. Both the scale and the orientation selectivity of the filter can be tuned electronically. We exploit the concept of the transistor as a pseudo-conductance or diffuser and use current, rather than voltage to represent signals of interest. This design enables energy efficient computation of the filter responses. Test results from a 12×14 pixel array fabricated in 1.2 μm technology are presented