An ASIC for SiPM/MPPC readout

We have developed an application specific integrated circuit (ASIC) suitable for the readout of up to 64 silicon photomultipliers (SiPM) or multi-pixel photon counters (MPPCs). The ASIC can be used with SiPMs/MPPCs and scintillators for energy spectroscopy and timing of ionizing radiation and provides important functionality for SiPMs: The preamplifier input potential can be programmed to adjust the bias voltage for the SiPMs connected to the input. The input charge range is relatively large (-20 pC to 55 pC) and the input noise can be as low as 1 fC. The ASIC triggers, if one of the input signals exceeds the threshold voltage, and the signal amplitude can be sampled. For all readout channels the ASIC delivers the signal amplitude, i.e., photon energy, and the time between the trigger and the sample. The ASIC has a programmable register to configure digital-to-analog converters for the preamplifier input potentials, the trigger thresholds, the internal bias setting and other functionality. Many ASICs can be combined for the readout of multiple arrays of SiPMs/MPPCs. The preamplifier input is designed for capacitive load of up to 300 pF and a dark current of up to 10 μA. We have produced and tested the ASIC connected to MPPCs and LYSO scintillators. The article describes the functionality of the ASIC and shows energy spectra measured with radioactive sources.