TACImager: A high frame rate 320 x 256 SPAD time to amplitude converter array with adjustable time zoom

Neil Finlayson, Luca Parmesan, Neale A.W. Dutton, Neil J. Calder, Robert K. Henderson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract / Description of output

Single-photon avalanche diodes (SPADs) in the form of high-resolution imaging pixel arrays are used in 3D cameras, motion-tracking, biomedical and time-correlated single photon counting (TCSPC) applications. Rapid spatial and temporal zoom onto objects of interest is an attractive feature. We present here novel high-speed time-zoom functionality achieved with the digital readout mode of the TACImager, a 256 x 256 TCSPC image sensor array based on sample and hold Time to Amplitude Converter (TAC) pixels. A column-parallel flash Analogue to Digital Converter (ADC) is implemented in the TACImager to support fast digital readout, allowing per-pixel, 3-bin TCSPC histogramming at frame rates of 4 kfps. New results related to this high-speed mode of operation are presented. The TACImager utilises a global ramp voltage as a timing reference, allowing time-zoom to be achieved through dynamic adjustment of comparator voltages, ramp offset voltages and ramp waveforms. We demonstrate the influence of fixed pattern noise in the pixels and column parallel ADCs on the results.

Original languageEnglish
Title of host publicationEmerging Imaging and Sensing Technologies
EditorsKeith L. Lewis, Richard C. Hollins
ISBN (Electronic)9781510603882
Publication statusPublished - 25 Oct 2016
EventEmerging Imaging and Sensing Technologies - Edinburgh, United Kingdom
Duration: 28 Sept 201629 Sept 2016


ConferenceEmerging Imaging and Sensing Technologies
Country/TerritoryUnited Kingdom

Keywords / Materials (for Non-textual outputs)

  • fixed pattern noise
  • Single Photon Avalanche Diode
  • Single Photon Counting
  • SPAD
  • TAC
  • Time to Amplitude Converter
  • time-of-flight


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