Optimization and Performance Characterization of the Second Generation Fermilab Constant Fraction Discriminator Readout ASIC

Journal Article · Mon Dec 22 00:00:00 EST 2025 · No journal information

OSTI ID:3011989

Apresyan, Artur ^[1]; Wu, Shuoxing ^[1]; Xie, Si ^[2]; Peña, Cristián ^[1]; Zimmerman, Tom ^[1]; Los, Sergey ^[1]; Zenger, Todd ^[1]; Ye, Zhenyu ^[3]

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1. Fermilab
2. Fermilab; Caltech
3. LBL, Berkeley

We present the optimization and performance characterization of the second-generation Fermilab Constant Fraction Discriminator ASIC (FCFD), designed for the readout of AC-coupled low-gain avalanche detector (LGAD) strip-sensors. The FCFD is explicitly engineered to be insensitive to signal-amplitude variations, thereby removing the need for time-walk correction that is required in other LGAD time-stamping readout ASICs. This updated version, referred to as FCFD1.1, incorporates several enhancements over the first iteration to address key challenges in AC-coupled LGAD front-end design. We outline the primary readout-ASIC design considerations for these applications, describe the methodology used to evaluate critical sensor and system parameters, and summarize the additionally implemented features. Performance measurements using injected charge signals and minimum-ionizing particles in test-beams demonstrate a time resolution of approximately 40 ps and a position resolution of roughly \SI{15}{\micro\meter} when tested with beam particles uniformly over the active area of the sensor.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Caltech
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: 89243024CSC000002
• OSTI ID: 3011989
• Report Number(s): FERMILAB-PUB-25-0926-CMS-ETD-PPD; oai:inspirehep.net:3095516; arXiv:2512.19930
• Journal Information: No journal information, Journal Name: No journal information
• Country of Publication: United States
• Language: English