The upgraded readout system of the MAGIC telescopes

As a part of the 2011-2012 major upgrade, the readout system of the the MAGIC Cherenkov telescopes has been updated. New fully programmable receiver boards was designed and installed. The new boards allow very fine tuning of the level-O digital trigger signals, in terms of discrimination threshold, trigger width and relative trigger delay. New sampling electronics was also installed. The core of the new digitization system is the DRS4 waveform digitizer, a switched capacitor array which allow ultra-fast sampling with a limited cost and power consumption. The new readout system shows very satisfactory results in terms of performance (noise, linearity, time resolution, etc.) and reliability. Clever online raw data pre-processing routines are applied at DAQ level. The ultra-fast sampling speed (2 GSample/s) allows a signal integration window of 3 ns only.