Chapter 2
Front-End Electronics
The currently installed front-end electronics for both TPC and MCH is the same as
what was installed during the commissioning of ALICE in 2008. The planning and
ASIC designs, however, started long before this. A lot has improved in the electronic
industry since then. We have devices with lower power, more accurate and efficient
ADCs, and faster digital electronics.
This section reviews the existing electronics and presents the design requirements
for the new system. The devices are compared to the requirements and a digital
specification is formulated.
2.1 Heritage
The design and specifications for the SAMPA chip builds on the existing frontend electronics of the TPC, which uses the PASA [1] analogue front-end chip and
the ALTRO [2–4] sampling and digital signal conditioning chip. These chips were
purposely designed for use in the ALICE TPC. To reduce complexity, and improve
noise and signal integrity, the PASA chip was built with a fixed polarity, gain and
shaping time, even though this somewhat constrained the detector applications that
the chip could be used for. At a later stage the Programmable Charge Amplifier
(PCA16) [5] was designed at CERN, which provided programmability for all the
settings.
Further development was driven by the needs of the future Linear Collider
(ILC/CLIC) to have a compact solution where the analogue front-end was integrated with the digital. This ended with combining the features of the PCA16 with
the ALTRO and creating the Super ALTRO (S-ALTRO) [6–9]. The design kept the
programmability of the PCA16 and implemented a digital design that more or less
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
A. Velure, A Digital Signal Processor for Particle Detectors, Springer Theses,
https://doi.org/10.1007/978-3-030-71559-5_2
11
Front-End Electronics
The currently installed front-end electronics for both TPC and MCH is the same as
what was installed during the commissioning of ALICE in 2008. The planning and
ASIC designs, however, started long before this. A lot has improved in the electronic
industry since then. We have devices with lower power, more accurate and efficient
ADCs, and faster digital electronics.
This section reviews the existing electronics and presents the design requirements
for the new system. The devices are compared to the requirements and a digital
specification is formulated.
2.1 Heritage
The design and specifications for the SAMPA chip builds on the existing frontend electronics of the TPC, which uses the PASA [1] analogue front-end chip and
the ALTRO [2–4] sampling and digital signal conditioning chip. These chips were
purposely designed for use in the ALICE TPC. To reduce complexity, and improve
noise and signal integrity, the PASA chip was built with a fixed polarity, gain and
shaping time, even though this somewhat constrained the detector applications that
the chip could be used for. At a later stage the Programmable Charge Amplifier
(PCA16) [5] was designed at CERN, which provided programmability for all the
settings.
Further development was driven by the needs of the future Linear Collider
(ILC/CLIC) to have a compact solution where the analogue front-end was integrated with the digital. This ended with combining the features of the PCA16 with
the ALTRO and creating the Super ALTRO (S-ALTRO) [6–9]. The design kept the
programmability of the PCA16 and implemented a digital design that more or less
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
A. Velure, A Digital Signal Processor for Particle Detectors, Springer Theses,
https://doi.org/10.1007/978-3-030-71559-5_2
11