arXiv subjects

Olivier Rossetto

Publications and source records attributed to Olivier Rossetto.

7 recordsLinked to original sources

arXiv2026

CONCERTO : Optimization of readout electronics

The CONCERTO millimeter-wave spectral-imaging instrument was deployed on the Atacama Pathfinder EXperiment (APEX), where it acquired science data between April 2021 and May 2023. The instrument features two focal-plane arrays, each composed of 2400 Microwave Kinetic Inductance Detectors (MKIDs). Each array is divided into six feedlines containing 400 MKIDs each, with each feedline read out by a dedicated FPGA-based board, KID_READOUT. The next-generation instrument aims to double the detector count per feedline, increasing it from 400 to 800 MKIDs. Achieving this requires a substantial scaling of the readout architecture and poses two key challenges for KID_READOUT: maintaining readout signal integrity and constraining firmware resource usage, as a direct upscaling of the existing design would exceed the available FPGA capacity. To overcome these limitations, we developed a Python-based, cycle-and bit-accurate digital twin of the full FPGA digital signal processing chain. This model enabled a detailed investigation of internal signal behavior and provided quantitative guidance for firmware optimization. Leveraging these insights, we identified the source of two spurs present in CONCERTO data and significantly reduced their amplitudes. At the same time, we achieved substantial reductions in firmware resource usage-39.0%pt in LUTs, 20.3%pt in flip-flops, and 28.98%pt in DSP slices-without degrading readout performance. The resulting architecture supports more than 800 MKIDs per feedline on the same hardware platform while preserving readout signal quality, offering a scalable and resource-efficient solution for future high-resolution millimeter-wave astronomical instruments.

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arXiv2026

CONCERTO: Characterization of analog readout electronics

CONCERTO is a millimeter-wave imaging instrument that operated on the Atacama Pathfinder Experiment (APEX) telescope from April 2021 to May 2023. Its primary scientific objectives include the study of galaxy clusters through the Sunyaev-Zel'dovich (SZ) effects, the observation of Galactic star-forming regions, and the first measurements constraining the power spectrum of dusty star-forming galaxies. The instrument consists of two detector arrays, each comprising 2400 Microwave Kinetic Inductance Detectors (MKIDs). Each of the two arrays comprises six feed-lines and is read out by six KID_READOUT electronic boards, each capable of reading out one feed-line coupled to 400 frequency-multiplexed MKIDs. As the demand for higher-resolution millimeter-wave imaging continues to grow, future instruments aim to significantly increase the pixel count, with more than 800 detectors per feed-line. However, the MKID readout electronics chain is inherently complex, making it difficult to fully understand its performance limits and optimization margins. To address this challenge, we initiated a modeling effort that first focused on the digital section of KID\_READOUT. In this phase, we developed a digital twin of the FPGA-based signal processing chain, which led to substantial performance improvements. The present paper extends this modeling strategy to the analog readout chain. It presents the characterization and behavioral modeling of all analog components, allowing us to identify the elements that limit the frequency multiplexing factor, determine the dominant noise contributors, and highlight areas for improvement in signal conditioning for the future-generation board. Together, these developments establish, to the best of our knowledge, the first consolidated digital-and-analog behavioral framework of an MKID readout architecture, implemented in a unified Python-based modeling environment.

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arXiv2026

A Digital Twin of the FPGA Digital Signal Processing Chain for MKIDs Readout: Root-Cause Analysis and Mitigation of Spurs

The KID_READOUT board, developed for the CONCERTO millimeter-wave astronomy instrument, implements FPGA-based digital frequency multiplexing to read out large arrays of Microwave Kinetic Inductance Detectors (MKIDs). The complexity of the implemented multirate DSP chain, which combines tones synthesis, interpolation, digital frequency translation, polyphase filter-bank (PFB) channelization, and digital down-conversion (DDC), makes analytical performance optimization difficult. To address this, we developed a cycle-and bitaccurate, Python-based digital twin of the FPGA readout firmware DSP chain. Using this model, we identified the origin of previously measured and unexplained spurs in the readout channels, tracing them to periodicity mismatches between the excitation and analysis paths and to insufficient suppression of negative-frequency components by the DDC filters. Based on these insights, we implemented a mitigation strategy that aligns the periodicities and improves the DDC filter characteristics, effectively eliminating the spurs with a minor increase in FPGA resource usage.

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arXiv2021

DIAMASIC: A multichannel front-end electronics for high-accuracy time measurements for diamond detectors

This paper describes the design and testing results of an 8 channels preamplifier-discriminator circuit based on a resistive feedback Transimpedance Amplifier architecture and a Leading-Edge Discriminator stage for fast high-accuracy time measurement systems. The circuit has been designed in a 130 nm CMOS technology. It is intended to be used as a Front-End-Electronics for measuring the Time Of Flight using diamond detectors. The size of the chip is 1.27x1.22mm2 and the total power consumption of one channel is 1.5mW with a power supply of 1.2V. Testing results shows a timing jitter of about 80ps for a 10fC input charge pulse.

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arXiv2021

Performance of CVD diamond detectors for single ion beam-tagging applications in hadrontherapy monitoring

In the context of online ion range verification in particle therapy, the CLaRyS collaboration is developing Prompt-Gamma (PG) detection systems. The originality in the CLaRyS approach is to use a beam-tagging hodoscope in coincidence with the gamma detectors to provide both temporal and spatial information of the incoming ions. The ion range sensitivity of such PG detection systems could be improved by detecting single ions with a 100 ps ($σ$) time resolution, through a quality assurance procedure at low beam intensity at the beginning of the treatment session. This work presents the investigations led to assess the performance of Chemical Vapor Deposition (CVD) diamond detectors to fulfill these requirements. A $^{90}$Sr beta source, 68 MeV protons, 95 MeV/u carbon ions and a synchrotron X-ray pulsed beam were used to measure the time resolution, single ion detection efficiency and proton counting capability of various CVD diamond samples. An offline technique, based on double-sided readout with fast current preamplifiers and used to improve the signal-to-noise ratio, is also presented. The different tests highlighted Time-Of-Flight resolutions ranging from 13 ps ($σ$) to 250 ps ($σ$), depending on the experimental conditions. The single 68 MeV proton detection efficiency of various large area polycrystalline (pCVD) samples was measured to be $>$96% using coincidence measurements with a single-crystal reference detector. Single-crystal CVD (sCVD) diamond proved to be able to count a discrete number of simultaneous protons while it was not achievable with a polycrystalline sample. Considering the results of the present study, two diamond hodoscope demonstrators are under development: one based on sCVD, and one of larger size based on pCVD. They will be used for the purpose of single ion as well as ion bunches detection, either at reduced or clinical beam intensities.

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arXiv2021

New design approach of Front-End Electronics for high-accuracy time measurement systems used in particle detection

This paper discusses a detailed design approach to determine the optimal input impedance (Rin) and bandwidth (BW) for current preamplifiers in Front End Electronics (FEE) of high-accuracy time measurement systems used in particle detection. Our study shows the effect of the input impedance Rin including the parasitic interconnection inductances of bonding wires between the detector and the FEE. We explain also the development of a new mathematical model for the estimation of the timing jitter of the current preamplifier in the case of using a low capacitor detector (Cd) as diamond. Different simulations based on developed MATLAB Simulink behavioral models are done in addition to an electric simulation of a transimpedance amplifier (TIA) designed in a 130 nm 1P8M CMOS technology which demonstrates the accuracy of the design approach and the timing jitter estimation model.

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arXiv2021

Systematic high-level design of a fifth order Continuous-Time CRFF Delta Sigma ADC

In this paper we present the development of a Systematic high level design model based on MATLAB scripts. It is integrated into a graphical behavioral model toolbox for the synthesis and simulation of a Continuous-Time Delta Sigma ADC. For this, we decided to use a Model-based design approach which it is adopted to address problems associated with designing complex control and signal processing systems such as the case of Continuous-Time Delta Sigma ADC. The goal of our study is the design of a 10 bit ENOB ADC for energy measurement systems used in particle identification through a new generation of detectors based on diamond. Results of the synthesis of a proposed fifth order Continuous-Time Delta Sigma ADC modulator for 10-bit ENOB ADC based on a Cascaded Resonators Feedforward architecture and simulations of the dispersion of its components (due to fabrication process) using the proposed tool are demonstrated and discussed.

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