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A Study of ΔΣ-CDS Algorithm for X-ray CCD Applications
摘要： Correlated double sampling (CDS) circuits are essential to processing the X-ray charge-coupled devices (CCDs) that have been used in the modern X-ray astronomical field. For spectroscopy observations, the energy resolution is of decisive importance. In this paper, a comprehensive study of the CDS algorithm based on the incremental ΔΣ technique, named ΔΣ-CDS algorithm hereafter, is studied. Theoretical and practical aspects for modulations and demodulations for applications with different pixel rates (PRs) are discussed. The concepts of differential cascade-of-integrator (DCoI) filter and truncated cascaded-integrator-comb (TCIC) filter are extensively investigated from both time-domain and frequency-domain analyses. The operating principles, prototype design and experimental results are addressed. As a prototype for 100 kHz PR, a readout integrated circuit (ROIC) is designed. When tested with the target X-ray CCD–CCD236 using a 1 μCi 55Fe radioisotope, the ROIC achieves an energy resolution characterized by the full-width-at-half-maximum (FWHM) as 132.4±2.4 eV at 5.9 keV which is very close to the 121 eV limit of CCD236.
关键词： X-ray CCD,TCIC,ΔΣ-CDS,ROIC,DCoI
更新于2025-09-23 15:22:29
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[IEEE 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS) - San Jose, Costa Rica (2020.2.25-2020.2.28)] 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS) - Advancing Uncooled Infrared Imagers Using An Open-Circuit Voltage Pixel
摘要： A topology leveraging a photodetector in the forward bias region generating an open-circuit voltage is proposed. Connecting the anode of the photodetector to the gate of a MOSFET device operating in the subthreshold region provides the basis for a new open-circuit voltage pixel (VocP). Theoretical analysis outlining the effective photodetector response and performance benefits is described. An integrated circuit (IC) with direct-injection pixels modified to support the VocP front-end and analog output readout fabricated in a CMOS 0.18 μm technology is also presented. The IC allows testing of mid-wave infrared (IR) photodiodes operating in both the photocurrent and VocP modes. The VocP pixel is compared to a traditional reverse bias current mode photodetector configuration. Simulation, modeling, and measurement show improved sensitivity and faster response time for the VocP over direct photocurrent detection.
关键词： model,ROIC,open-circuit voltage,readout,MWIR,Mid-wave,Voc
更新于2025-09-23 15:21:01