Correlation image sensor: two-dimensional matched detection of amplitude-modulated light

In this paper, we describe a novel imaging device, the correlation image sensor, whose pixel circuit consists of a photodetector and source-coupled MOS transistors with individual capacitive loads and readout switches. It accepts differential or three-phase reference signals to produce one or two correlation integrals between the incident light intensity and the reference signals. The correlation results stored as charges in the capacitors are read out via MOS scanning circuits. We describe a functional model of the circuit and a quadrature detection method of amplitude-modulated light. We fabricated 64×64 and 100×100 pixel devices and obtained a correlation signal-to-noise ratio of 34 dB and a phase accuracy of 0.85° using only two-frame integration. We also describe application methods of this sensor to cross-correlation imagers, amplitude modulation-phase modulation demodulation imagers, and correlation matching imagers.