LARGE DYNAMIC RANGE INTEGRATED FRONT-END ELECTRONICS FOR PHOTOMULTIPLIER TUBES

A full custom analog CMOS circuit for obtaining a photomultiplier readout with a 16 bit resolution over 7 volts has been developed. It is part of the R&D program for the photomultiplier tube front-end readout of the Pierre Auger Observatory northern site. It performs signal duplication and amplification with three gains: 0.15, 1 and 6. Each amplifier has a resolution of 10 bits and can measure signals with durations of several microseconds with a good baseline stability, for an input charge of up to tens of nano-Coulombs. The amplification is performed by current feedback amplifiers with a bandwidth of 60 MHz. The input impedance, adapted to the coaxial cables, is stable over the whole working range.