Abstract
A processing device for position sensing includes a plurality of light sensors, a signal processing unit, a current mirror unit and a transforming unit. The light sensors are spaced and sense light field to generate a plurality of position sensing current signals. The signal processing unit receives the position sensing current signals, provides a load isolation, so as to generate a first current signal and a second current signal, the second current signal is transmitted to a node, and the first and second current signals respectively correspond to a first group and a second group of the light sensors. The current mirror unit mirrors the first current signal to a third current signal and the third current is transmitted to the node. The transforming unit transforms a differential current signal formed by the second current signal and the third current signal on the node to a voltage signal.