Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>This paper discusses the application-specific integrated circuit prototype dedicated to readout of hybrid pixel X-ray detectors. The circuit is fabricated in 28 nm CMOS technology and occupies 1.1 × 1.1 mm<jats:sup>2</jats:sup> of silicon area. Each of 8 × 4 pixels present in the prototype includes an analog front-end and a digital block with two ring oscillators and their supporting circuits. The circuit can operate in single-photon counting mode or time-based measurement mode. The paper discusses in detail the design decisions that influenced the final in-pixel ring oscillator architecture and layout. Measurement results are presented which demonstrate the performance of ring oscillators as well as regular operating modes of the chip: single photon counting and time-over-threshold measurement.
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