Camera pixel for coherent detection of modulated light

Abstract

A CMOS pixel with local processing suitable for use in a modulated light camera is described. The pixel was designed to detect sinusoidally modulated light within the frequency range of 500 kHz–25 MHz. It consists of a photodiode, a transimpedance amplifier, a mixer and an active 150 Hz bandpass filter. It is a prototype design capable of further size reduction suitable for tiling into an array for imaging purposes. This allows the modulated light component of a frequency far in excess of the frame rate to be detected at the pixel level.