WP 7.3: 4D and 5D techniques

Contacts:

  • Marek Idzik, AGH University of Krakow
  • Louis d'Eramo, CERN
  • Giacomo Zecchinelli, BOSTON University
  • Sophie Baron, CERN
  • Javier Galindo, ITAINNOVA

Indico link

Project 7.3a: High performance TDC and ADC blocks at ultra-low power

This project aims to develop ultra-low power high performance TDC and ADC blocks for use in a wide range of future particle physics experiments.

In newly designed particle physics detection systems, there is a growing demand for detectors with ever-increasing speed, high channel density, and precise measurement of time and signal amplitude in each channel. This can be done only when time or amplitude domain digitization is done at ultra-low power per channel. An ultra-low power, area-efficient, high-speed Analog-to-Digital Converter (ADC) and precise Time-to-Digital Converter (TDC), are two essential components of a high-performance SoC readout ASIC. Many multi-channel readout ASICs in different detectors at LHC and other future experiments require a high-performance medium-high resolution (10-14 bits) ADC with a sampling rate of 40 MSps or higher, and a precise (∼ 10ps) ultra-low power compact TDC. With technology scaling, the TDC quantization resolution is not affected by reduced supply voltage and can be designed flexibly by tuning the latency of the delay cells, making the TDC an appropriate candidate for low supply applications. The project will address the development of high-performance TDC and ADC blocks in technologies commonly used by the detector community, such as 130/65/28 nm CMOS, for a variety of detectors in future HEP experiments. Other blocks directly related to ADC/TDC, essential for their high performance (like opamps, serializers) or possibly front-end electronics, will also be part of the project. Since the developed blocks can be used in a high radiation environment with doses reaching many hundreds of Mrad, radiation hardness verified technologies will be used during design and precautions will be taken to improve radiation hardness. Where relevant, the radiation hardness tests will also be performed.

The project will feature various topics to be addressed by different collaborators.

  1. ADC design,
  2. TDC design,
  3. Design of analog blocks essential for ADC or TDC (e.g. opamp),
  4. Design of digital blocks essential for ADC or TDC (e.g. DLL, PLL, serializer),
  5. Front-end electronics design : full channels with preamps, ADCs and TDCs.

The achieved results will be communicated through reports, conference presentations, scientific articles. Completed ADC and TDC blocks will be documented and documentation will be available to the community. The availability of the developed blocks would require further consideration, both due to licensing or radiation hardness restrictions, as well as intellectual property issues. The project is originally planned to last 3 years. As the development of high-performance ADC and TDC blocks will continue with architectural and technological improvements, it is planned to extend it after 3 years.

Contributors: AGH (PL), CEA IRFU (FR), CPPM (FR), DGIST(KR), ICCUB (ES), IP2I (FR), OMEGA (FR), SLAC (US), TU GRAZ (AT)

Project contact person: Marek Idzik, AGH University of Krakow

Project 7.3b1: Strategies for characterizing and calibrating sources impacting time measurements

This project aims to study and propose generic data-driven calibration strategies for the time measurements in detectors requiring high precision timing. These include simulation, impact studies and data-based calibration strategies of phase variations in all or part of the detector timing distribution tree (for example jumps due to resets in the electronics system and or temperature dependent phase drift), as well as the calibration of the front-end TDC timewalk and non-linearities.

In view of the unprecedented High-Luminosity conditions of the LHC, both ATLAS and CMS experiments have planned to upgrade their detectors, adding precise timing information to resolve the bunch crossing structure. This information is particularly essential in the forward region, where the tracking resolution is degrading.

For ATLAS, the High Granularity Timing Detector (HGTD) aims at complementing the new all-silicon Inner Tracker (ITk) of ATLAS, for pseudo rapidity between 2.4 and 4.0. Composed of four layers of Low Gain Avalanche Diodes (LGADs) it can provide an average time resolution per track ranging from 30 ps to 50 ps at the end of the HL-LHC phase. The CMS experiment proposes two new detectors, the High Granularity Calorimeter (HGCAL) and the MIP Timing Layer (MTD), which is composed of the Barrel Timing Layer (BTL) and the Endcap Timing Layer (ETL). The HGCAL sensors provide measurements of both energy and timing, with an expected resolution of about 30 ps for high energetic electromagnetic and hadronic showers. Similarly to HGTD, the ETL consists of 2 layers of LGAD sensors with an expected resolution ranging from 35 ps to 60 ps at the end of life.

While the sensors are giving an important contribution to the total time resolution (ranging from 25 to 30 ps for a MIP (Minimum Ionizing Particle) detector), external effects, such as the LHC clock distribution and stability have an important impact to the measurement. To reach the precision required by the different experiments to affect the physics, it is thus crucial to understand the source of these biases to act on them. Furthermore, the universal character of these effects and their recent investigations, implies to have a common strategy between the different experiments and could pave the way to the design of future detectors.

In this project, we propose to study generic data-driven calibration strategies for this purpose. This includes:

  • Developing a coherent simulation of all the factors impacting the time measurement;
  • Constructing a set of figures of merit to asses the calibration;

  • Studying the impact of the different factors and their mitigation, including (but not limited to):

    • phase variations in all or part of the detector timing distribution tree, like jumps due to resets in the electronics system and or temperature dependent phase drift;

    • timewalk effect of the TDC and other non-linearities.

Given the habits of the two experiments involved, this work will be conducted as a general forum of exchange of non sensitive information. It will help to foster collaboration at a higher scale, similar to the current High Precision Timing Distribution project, with a slightly different scope.

The project will be co-managed by two chairs, one from ATLAS and one from CMS. For 2024: - co-chair: Louis d'Eramo, CERN - co-chair: Giacomo Zecchinelli, Boston University

Contributors: CERN (CH), LPCA (FR), Boston University (US)

Project contact persons: Louis d'Eramo, CERN and Giacomo Zecchinelli, Boston University

Project 7.3b2: Timing Distribution Techniques

This project aims to study and propose strategies to optimize and assess ultimate precision and determinism of timing distribution systems for future detectors. The precision target of upcoming timing detectors is now enforcing new figures of merit to be taken into account in addition to the traditional random jitter, such as clock phase stability and determinism (at picosecond level). Such metrics are systems- and COTS-specific and need to be carefully assessed. In addition generic solutions shall be provided to mitigate the various kinds of instabilities brought by the selected components. This project will be carried out in tight collaboration with its counterpart project based on simulation (7.3b1): Strategies for characterizing and calibrating sources impacting time measurements.

With the increase of luminosity in future colliders, the need of timing detectors with very high resolution is rapidly increasing. This requires the collision clock signal to be distributed with very high precision and stability (o(ps)) However, high determinism of clock and data recovery solutions at picosecond levels is not a high priority of COTS manufacturers. Limits need therefore to be explored for these solutions and implementation must be carefully studied and optimized in order to achieve this challenging goal. The project will feature various topics to be addressed by different collaborators in order to cover several aspects of this topic.

These are:

  • Explore limits for these solutions: Develop and compare implementations on different COTS and custom platforms. Assess their ultimate performance.
  • Carefully study and optimize implementation: Study and implement solutions to improve phase stability and mitigate non-determinism
  • Explore alternative ways of distributing timing. This project will be handled as a forum where results, plans, ideas and challenges will be openly and regularly shared between the participating teams. It will be chaired on a rotating basis.

Contributors: Bristol University (UK), CERN (CH), CIEMAT (ES), CPPM (FR), IJCLAB (FR), ITAINNOVA (ES), CSIC (ES), Nikhef (NL), University of Minnesota (US)

Project contact persons: Sophie Baron, CERN and Javier Galindo, ITAINNOVA