Performance of the ALTRO chip on data acquired on an ALICE TPC prototype

Abstract

The Alice TPC Readout (ALTRO) chip is a mixed-signal ASIC, designed for the readout of the Time Projection Chamber (TPC) detector for the ALICE experiment at the CERN LHC. In one single chip, the analogue signals from 16 channels are digitized, processed, and stored in a multi-acquisition memory. In particular, ALTRO implements a set of signal processing algorithms to correct for various perturbations, which might be superimposed to the detector signal. Among these correction schemes are a tail cancellation filter and a baseline correction circuit. This paper addresses the performance of the ALTRO signal processing algorithms, as measured in a system consisting of 1024 channels and connected to a prototype of the ALICE TPC detector, to acquire cosmic ray signals. These measurements allow to conclude on some of the characteristics of the signal ion tail and on the effectiveness of the ALTRO signal processing, with emphasis on tail cancellation and baseline restoration. These tests show that the system meets all design requirements.