A Data Acquisition System Design for a 160x128 Single-photon Image Sensor

Abstract

Image sensors with deep subnanosecond timing resolution in combination with high sensitivity are required in many advanced imaging applications, from fluorescence lifetime imaging microscopy (FLIM) to range finding. Integrated single-photon avalanche diode (SPAD) technology with increasing on-chip functionality offer an attractive solution to these applications. The improved capability of such massively parallel sensors introduces significant challenges in terms of off-chip data acquisition, thus necessitating an efficient solution. In this thesis an advanced data acquisition system is developed for the megaframe chip, a 160x128 SPAD array capable of detecting time-of-arrival of single photons with picosecond resolution. The architecture includes processing pixel data on FPGA, while a novel DDR2 SDRAM memory controller utilizes multiple memory banks for accelerating data processing. The developed acquisition system outperforms the present system, leading to 80 times improved frame accumulation in low light conditions. The improved data acquisition renders the system suitable for TDC non-linearity characterization, with observed DNL within ±1 LSB range across 160x64 active pixels. When validated for range finding applications the design enables distance measurement up-to 3 meters with millimeter precision. The system was also used to successfully perform FLIM experiment.MSc Embedded SystemsMicroelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc