Design and performance of the ALICE TRD front-end electronics

The Transition Radiation Detector (TRD) of the ALICE experiment at CERN incorporates 1.2 million channels which are individually read out and processed. The front-end electronics (FEE) utilizes two custom chips: an 18 channel analog preamplifier and shaper (PASA) and a mixed-signal chip, performing 10 bit analog-to-digital conversion, event buffering and local tracking (TRAP). Both chips together are packaged as a 4×4cm2 ball grid array multi chip module (MCM). More than 65 k of these will be integrated on the detector. In fall 2004, a small prototype implementing 140 MCMs was successfully tested at CERN. The MCMs demonstrate an ADC performance of 9.5 effective bits while the digital back-end is operating, including four RISC processors. The electronic noise of the PASA mounted on the detector was measured with the digital back-end to be below 1200 electrons.