Speaker
Description
X-ray imaging systems designed for X-ray spectroscopy, based on semiconductor strip sensors, have recently been a key research area. A major objective is to enhance spectroscopic and spatial resolution [1–3]. In spectroscopic applications, short-strip silicon detectors are widely employed due to their low capacitance and leakage current. Using a strip pitch below 100 μm enables high spatial resolution, which is crucial for energy-dispersive X-ray detection [3]. The Charge Sensitive Amplifier (CSA) has been optimized for a detector capacitance of approximately 1.5 pF, with a shaping amplifier default peaking time of about 1 μs, controlled via switchable settings.
To minimize noise, both internal sources (related to front-end electronics) and external disturbances in the radiation imaging system were analyzed [4]. Maintaining a noise level below 50 electrons rms is a key design goal, alongside low power consumption (below 10 mW per channel) and a compact layout. To accelerate processing of incoming events (more than 100 kps/ch), a continuous-time resistive CSA feedback combined with a digital feedback reset is utilized. These approaches align with previous advancements in low-noise charge-sensitive preamplifiers used in high-resolution X-ray spectrometry.
The prototype integrated circuit was designed and fabricated in 180 nm CMOS technology, incorporating eight charge-processing channels, biasing circuits, reset and baseline restoration logic, and a calibration system. This work presents the design, characterization, and measurement results of the strip sensor readout circuit, contributing to the ongoing development of high-performance silicon-based X-ray detectors.
- P. O’Connor and G. De Geronimo, “Prospects for charge sensitive amplifiers in scaled CMOS,” Nucl. Instrum. Methods Phys. Res. Sect. A Accel. Spectrom. Detect. Assoc. Equip., vol. 480, no. 2–3, pp. 713–725, 2002, doi: 10.1016/S0168-9002(01)01212-8.
- R. Ballabriga et al., “Photon counting detectors for X-ray imaging with emphasis on CT,” IEEE Trans. Radiat. Plasma Med. Sci., vol. 5, no. 4, pp. 422–440, 2021.
- P. Wiącek et al., “Position sensitive and energy dispersive X-ray detector based on silicon strip detector technology,” J. Instrum., vol. 10, no. 4, pp. P04002–P04002, 2015, doi: 10.1088/1748-0221/10/04/P04002.
- W. Zubrzycka and K. Kasiński, “Noise considerations for the STS/MUCH readout ASIC,” GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, 2018.
The authors acknowledge funding from the National Science Centre (Research Project 2020/37/N/ST7/01546).
| Workshop topics | Front-end electronics and readout |
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