Standard techniques used for measuring the photocurrent of an SOI phototransistor have failed due to two main reasons: the first being the low signal-to-noise ratio and the second being the slow transient. In this paper, the partially depleted silicon on insulator (SOI) metal-oxide-semiconductor field effect transistor (MOSFET) has been used as a light intensity sensor. Using a novel technique of measurement enables us to embed this phototransistor in the delta-sigma loop. The presented circuits implement a first-order delta-sigma modulator with limited number of transistors maximizing the fill factor. Measured data show that the implemented pixels were sensitive to flux densities as low as 3 mW/m(2) with a resolution of 7.5 bits.