A high-resolution CMOS image sensor with Hadamard transform function

This paper proposes a high-resolution CMOS image sensor, which has Hadamard transform function. This Hadamard transform circuit consists of two base generators, an array of pixel circuits, and analog-to-digital converters. In spite of simple composition, a base generator outputs a variety of bases, a pixel circuit calculates a two-dimensional base from one-dimensional bases and outputs values to common line for current addition, and analog-to-digital converter converts current value to digital value and stabilize a common line voltage for elimination of parasitic capacitance. We simulated these circuit elements and optimized using SPICE. Basic operations of this Hadamard transform circuit are also confirmed by simulation. A 256 × 256 pixel test chip was designed in 4.73mm × 4.73mm area with 0.35μm CMOS technology. A fill factor of this chip is 42% and dynamic range is 55.6 [dB], Functions of this chip are Hadamard transform, Harr transform, projection, obtaining center of gravity, and so on.