Description of the SAltro-16 chip for gas detector readout

The S-ALTRO prototype chip is a mixed-signal integrated circuit designed to be one of the building blocks of the readout electronics for gas detectors. Its architecture is based in the ALTRO (ALICE TPC Read Out) chip, being its main difference the integration of the charge shaping amplifier in the same IC. Just like ALTRO chip, the prototype architecture and programmability make it suitable for the readout of a wider class of detectors. In one single chip, 16 analogue signals from the detector are shaped, digitised, processed, compressed and stored in a multi-acquisition memory. The Analogue-to- Digital converters embedded in the chip have a 10-bit dynamic range and a maximum sampling rate up to 40MHz. 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. Moreover, the Data Processor is able to suppress the pulse tail within 1μs after the peak with 1‰ accuracy, in order to improve their identification. 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. This produces non-zero data packets. Eventually, each data packet is marked with its time stamp and size - so that the original data can be reconstructed afterwards - and stored in the multi-acquisition memory that has a readout bandwidth of 300Mbyte/sec. This document addresses the algorithms, the circuital implementation, the mode of use and operation, the physical implementation and performance of the S-ALTRO prototype.