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- Llopart Cudié, Xavier, et al.
(author)
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Medipix2, a 64k pixel readout chip with 55 μm square elements working in single photon counting mode
- 2002
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In: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 49, s. 2279-2283
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Journal article (peer-reviewed)abstract
- The Medipix2 chip is a pixel detector readout chip consisting of 256×256 identical elements, each working in single photon counting mode for positive or negative input charge signals. Each pixel cell contains around 500 transistors and occupies a total surface area of 55 μm×55 μm. A 20 μm width octagonal opening connects the detector and the preamplifier input via bump-bonding. The preamplifier feedback provides compensation for detector leakage current on a pixel by pixel basis. Two identical pulse height discriminators are used to create a pulse if the preamplifier output falls within a defined energy window. These digital pulses are then counted with a 13-bit pseudo-random counter. The counter logic, based in a shift register, also behaves as the input/output register for the pixel. Each cell also has an 8-bit configuration register which allows masking, test-enabling and 3-bit individual threshold adjust for each discriminator. The chip can be configured in serial mode and read out either serially or in parallel. The chip is designed and manufactured in a 6-metal 0.25 μm CMOS technology. Preliminary measurements show very good agreement with simulations.
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