June 27, 2021 to July 1, 2021
Europe/Brussels timezone

18k Pixel Readout IC for CdTe Detectors Operating in Single Photon Counting Mode with Interpixel Communication

Jun 29, 2021, 1:50 PM
Zoom (Online)



Oral presentation Front end electronics and readout Oral presentations


Pawel Grybos (AGH University of Science and Technology)


This paper presents a readout integrated circuit (IC) of pixel architecture called MPIX (Multithreshold Pixels), designed for CdTe pixel detectors used in X-ray imaging applications. The MPIX IC of the area of 9.6 mm x 20.3 mm is designed in a CMOS 130 nm process. The IC core is a matrix of 96 x 192 square-shaped pixels of 100 µm pitch. Each pixel contains a fast analog front-end followed by four independently working discriminators and four 12-bit ripple counters. Such pixel architecture allows photon processing one by one and selecting the X-ray photons according to their energy (X-ray color imaging). To fit the different range of applications the MPIX IC has 8 possible different gain settings, and the IC can process the X-ray photons of energy up to 154 keV. The MPIX chip is bump-bonded to the CdTe 1.5mm-thick pixel sensor with a pixel pitch of 100 um (see Fig.1) To deal with charge sharing effect coming from a thick semiconductor pixel sensor, Multithreshold Pattern Recognition Algorithm is implemented in the readout IC [1]. The implemented algorithm operates both in the analog domain (to recover the total charge spread between neighboring pixels, when a single X-ray photon hits the pixels border) and in the digital domain (to allocate a hit position to a single pixel). The example of the measured integral spectra with three different X-ray energies is shown in Fig. 2.

[1] P. Otfinowski, et al., 2019 JINST 14 C01017

The authors acknowledge funding from the National Science Center, Poland, contract No. UMO-2016/21/B/ST7/02228.

Primary authors

Pawel Grybos (AGH University of Science and Technology) Mr Rafal Kleczek (AGH University of Science and Technology) Piotr Kmon (AGH University of Science and Technology) Aleksandra Krzyżanowska (AGH University of Science and Technology) Dr Piotr Otfinowski (AGH University of Science and Technology) Robert Szczygiel (AGH University of Science and Technology) Miroslaw Zoladz (AGH University of Science and Technology)

Presentation materials