19 April 2000 Cross-talk reduction and efficiency of integrated photodiodes shown by an integrated edge detector
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Proceedings Volume 3950, Optoelectronic Integrated Circuits IV; (2000) https://doi.org/10.1117/12.382174
Event: Symposium on Integrated Optoelectronics, 2000, San Jose, CA, United States
This paper describes the limits for the efficiency of integrated photodiode arrays in a standard CMOS-process. It shows that an efficiency of more than 60% is not possible for wideband incident light. The efficiency depends on the area of the diodes, the distance between the diodes and the depth of the diode junction. The resulting efficiency of integrated photodiodes in a 0.8 micrometers -CMOS-process is shown. For these photodiodes two ways of crosstalk reduction between photodiode arranged in a line or a 2D array are introduced. Injecting a substrate current between the diodes, the cross-talk can be reduced in a controlled way by the magnitude of the current. Another possibility is to embed every diode in a separate well. The advantages and disadvantages of both systems are discussed. Finally, an application of integrated photodiodes in an edge detector IC is presented. This 6 mm2 circuit has been manufactured in a 0.8 micrometers process using embedded photodiodes for crosstalk reduction. The circuit performs a position measurement of a shade edge or contrast edge imaged onto its photodiode array. With its all-analog signal processing, even semitransparent media can be detected without precision tradeoffs.
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Ingo Martiny, Ingo Martiny, Ruediger Leuner, Ruediger Leuner, Bernhard Wicht, Bernhard Wicht, "Cross-talk reduction and efficiency of integrated photodiodes shown by an integrated edge detector", Proc. SPIE 3950, Optoelectronic Integrated Circuits IV, (19 April 2000); doi: 10.1117/12.382174; https://doi.org/10.1117/12.382174

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