KLauS: A Low-power SiPM Readout ASIC for Highly Granular Calorimeters

The CALICE collaboration is developing concepts for highly granular calorimeter systems for future linear collider experiments. The high density of readout channels together with little space for cooling infrastructure limit the front-end power consumption to 25 μW per channel, which is achieved by power-pulsing the front-end electronics. We present the development of KLauS, a 36-channel low-power mixed-mode ASIC for charge readout of Silicon Photomultipliers (SiPMs). Each channel consists of an analog front-end for charge integration, a 10/12- bit ADC to digitize the pulse height information and a TDC for time-stamping. An equivalent noise charge below 5 fC is measured, which is sufficient for the single-pixel signal of novel low-gain SiPMs. A dynamic range of 460 pC is achieved, allowing charge measurements over the full signal range of sensors. The BGA packaged ASIC is presently being installed and tested in the front-end base unit of the analog hadron calorimeter prototype of CALICE. Design details and characterization results are presented.