1. ALICE INDUSTRIAL AWARD for its collaboration to the ALTRO Chip
to STMicroelectronics
for its collaboration to the ALTRO Chip
ALTRO, one of the world’s most advanced Data Acquisition System-on-Chip for the ALICE Experiment
The ALICE Experiment involves high energy collisions between various types of heavy ions. In order to study the tens of thousands of resulting particles created by a single collision, the ALICE Collaboration is building a sophisticated detector (the Time Projection Chamber, or TPC) containing nearly 600,000 tiny sensors, each capable of responding to the presence of an individual electron. The signal from each of these sensors must be amplified, converted to digital format, and pre-processed by the front-end electronics, which is located deep underground on the Time Projection Chamber.
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STMicroelectronics has made available to the ALICE Collaboration one of its most advanced circuits (TSA1001). This circuit was integrated into the ALTRO chip designed by the CERN PH-ED group. About 50,000 ALTRO chips have been produced in site of Crolles (France) with the 250nm CMOS process.
One of the most critical challenges in designing the TPC was to minimize the size and power consumption of the front-end electronics beyond the present capability of the integrated circuits (ICs) commercially available. This challenge motivated the development of an dedicated IC (Aplication Specific Integrated Circtuis, or ASIC) that embeds in a single chip the circuits to digitise, process, compress and store the information of a high number of channels.
ALTRO CHIP
Production site in Crolles (France)
The result is ALTRO (ALice Tpc Read Out) chip, which integrates in a single chip 16 low-power Analogue-to-Digital Converters (ADC) plus more than 6 millions transistors of digital processing circtuitry and around 800 kbits of data memory.
The ALTRO chip
In one single chip, the analogue signals from 16 channels are digitised, processed, compressed and stored in a multi-acquisition memory.
The Result of 4 Years of Development
4cards
16 ch
135 mm
1998
CHANNELS / CHIP: 1
POWER / CH: 120mW
PRICE / CH: CHF
Integrated ADCs
20 mm
4 PQFP 100
8 SSOP 28
24 mm
1999
CHANNELS / CHIP: 4
POWER / CH: 80mW
PRICE / CH: CHF
2001
CHANNELS / CHIP: 1
POWER / CH: 16mW
PRICE / CH: CHF
ALTRO has been developed in three steps: 1) the first implementation was entirely based on commercial components (1998); 2) in 1999 the first attempt to miniaturize the circuit was done developing a 4-channel ALTRO, but still with external ADCs; 3) the design and the prototype of the final version of the ALTRO chip were accomplished in 2001.
The Analogue-to-Digital converters embedded in the chip have a 10-bit dynamic range and a maximum sampling rate of 40MHz.
ALTRO ARCHITECTURE
After digitisation, a pipelined Data Processor is able to remove from the input signal a wide range of perturbations, related to the non-ideal behaviour of the detector, temperature variation of the electronics, environmental noise, etc. The signal is then compressed by removing all data below a programmable threshold, except for a specified number of pre- and post-samples around each peak.
The ALTRO Design Team (CERN – PH / ED)
From left to right: Luciano Musa (Project Leader), Antonio Jimenez, Raul Esteve and Bernardo Mota
ALTRO CHIP LAYOUT
Eventually data is stored in a multi-acquisition memory that has a readout bandwidth of 300Mbyte/sec. The chip, is implemented in a 0.25mm CMOS technology, has an area of 64mm2 and a power consumption of 320mW.
On 19 June 2002, the ALICE Collaboration assigned the first industrial award to ST Microelectronics for the excellent collaboration in the design and production of the ALTRO chip.
STMicroelectronics made available to the ALICE collaboration the design of one of its most advanced circuits (TSA1001). This was integrated into the ALTRO chip designed by the CERN PH-ED group.