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Proceedings Paper

Multiplexed avalanche photodiode arrays for radiation imaging
Author(s): Mitchell L. Woodring; Richard Farrell; James F. Christian; Alex I. Kogan; Michael R. Squillante; Gerald Entine; David K. Wehe
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Paper Abstract

Development of monolithic arrays of multiplexed, high-gain avalanche photodiodes suitable for use in a spectroscopic radiation-imaging device is underway at RMD. To dramatically reduce the electronics required to support a large array of discrete pixels, we have utilized a unique property of avalanche photodiodes and the method in which they are produced to develop a relatively simple readout scheme using row-column addressing. By adding a step to the avalanche photodiode creation, it is possible to place two, separate diode contacts onto the back of each photodiode in the array. These isolation diodes allow the readout of an entire row or column of photodiodes through a common readout line. A data-decoding matrix uniquely determines the position in the array while simultaneously supporting the goal of reducing the number of signal readout lines and support electronics. This approach reduces the number of pre-amplifiers, pulse-shaping circuits, and sample-and-hold stages from n2 to 2n (n pixels on a side) per array. Recent research has been carried out with 14 × 14 pixel, planar-processed avalanche photodiode array having pixels 2.00 mm on a side with 2.25-mm pitch. These arrays will be paneled to form the photodetector of a radiation imager of approximately 100-cm2 photosensitive area. To reduce the contribution of noise from each pixel to the common readout lines, research is being carried out to develop a discriminator with an adjustable threshold for each avalanche photodiode readout connection. Initial performance results from multiplexed arrays, a discussion of the active discrimination contacts, and the current status of the imager research project are given.

Paper Details

Date Published: 10 January 2003
PDF: 9 pages
Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); doi: 10.1117/12.455977
Show Author Affiliations
Mitchell L. Woodring, Radiation Monitoring Devices, Inc. (United States)
Richard Farrell, Radiation Monitoring Devices, Inc. (United States)
James F. Christian, Radiation Monitoring Devices, Inc. (United States)
Alex I. Kogan, Radiation Monitoring Devices, Inc. (United States)
Michael R. Squillante, Radiation Monitoring Devices, Inc. (United States)
Gerald Entine, Radiation Monitoring Devices, Inc. (United States)
David K. Wehe, Univ. of Michigan (United States)

Published in SPIE Proceedings Vol. 4784:
X-Ray and Gamma-Ray Detectors and Applications IV
Ralph B. James; Edwin M. Westbrook; Roger D. Durst; Larry A. Franks; Arnold Burger; Edwin M. Westbrook; Roger D. Durst, Editor(s)

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