A position-sensitive photodetector device includes a grid of series-connected photodetectors that are electrically coupled to either a vertical photodetector array (VA photodetectors) or to a horizontal photodetector array (HA photodetectors). The VA and HA photodetectors are arranged in an alternating sequence along rows and/or columns throughout the grid. A horizontal-position readout line is electrically coupled to a termination of each vertical photodetector array, and a vertical-position readout line is electrically coupled to a termination of each horizontal photodetector array.