DIRAC: A DIgital Readout Asic for hAdronic Calorimeter

Gaseous detectors (Glass Resistive Plate Chambers, Micromegas or Gas Electron Multiplier) are foreseen as the active part of a hadronic calorimeter for a high energy physics experiment at the International Linear Collider. Requirements for physics lead to a highly granular hadronic calorimeter with up to several millions channels with probably only hit information (digital calorimeter). A 64-channel readout ASIC dedicated to gaseous detectors has been designed and tested. Each channel of the chip is made of a 2-gain charge preamplifier, a DC-servo loop, 3 latched comparators and a digital memory. Configuration and readout are fully digital, indeed six 8-bit DACs are embedded to control comparators thresholds. Power down circuitry has been included in order to decrease power consumption and reach 10 μW per channel. To achieve low cost electronics, a cheap CMOS 0.35 μm foundry process has been chosen and the floorplan has been designed to decrease printed circuit board costs. First tests beam of detectors equipped with this chip have been done. An enhanced chip has been submitted to foundry this autumn.