Industrial production-line robots require high-resolution sensors to measure the position of robotic actuators so that the tools can be accurately guided onto the work piece. A photo diode array together with an external light source is often used as a sensor in this application. This chip contains a line of photo diodes together with a series of sample and hold (S/H) circuits which take a snapshot of the readings of each photo diodes at the same instant and then outputs these integrated analogue values serially from a single output. The S/H circuits are important because the sensitivity of each element to the light quanta is dependant on the integration period; without the S/H the last element would show the highest sensitivity.