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19 February 2004 CMOS photodetection system with variable-time synchronous detection
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For sensitive fluorescence detection requiring weak signal recovery, we propose a novel digital synchronous detection method. It is based on a voltage/time duality concept which, compared to a conventional approach, consists of transformation of constant sampling rate with voltage measurement into variable-time sampling with constant threshold voltage. This Variable-Time Synchronous Detection (VTSD) method ensures a constant SNR over a large dynamic range, with optimised measuring rate. It can be implemented without any precise analogue-to-digital converter. A CMOS photodetection system with implementation of this VTSD method together with charge amplification is designed and tested. The results confirm its ability to recover photocurrent signals at femto-Ampers levels.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Patrick Pittet, Guo Neng Lu, Michel Pitaval, and Laurent Quiquerez "CMOS photodetection system with variable-time synchronous detection", Proc. SPIE 5251, Detectors and Associated Signal Processing, (19 February 2004);

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