Linear Photodiode Array with Serial and Addressable Real-Time Output Capability

This paper describes the design and operation of a linear photodiode array which combines a conventional serially scanned output with a parallel output capability in which any photodiode may be addressed for real-time observation. Three such arrays of 128 photodiodes each were designed in order to evaluate different novel circuit techniques. These techniques were principally concerned with maximizing sensitivity and minimizing response time in the parallel access arrays and upward dynamic range extension in the serial arrays. Incorporating these techniques led to a response time of less than 50 ns for parallel access and dynamic gain control of 46 dB for serial access. The maximum integration time for the serial arrays was found to be typically 5 s.