Using Analog-to-Digital Converter ADC1413D for high-resolution gamma-ray spectroscopy

14-bit Analog-to-Digital Converter ADC1413D as operated at 100 MS/s is here evaluated for high-resolution gamma-ray spectroscopy using the germanium crystals of the AGATA/GALILEO detectors. The performance of the chip in terms of noise is studied as a function of the amount of analog DC offset applied before digitization. Such a DC offset is considered for the purpose of dynamic range optimization. The quality of the ADC voltage reference is found to be paramount in this regard. Best results are obtained using an external voltage reference as strongly filtered for noise suppression. The in-chip voltage reference is found to be almost adequate for the considered application but a stronger internal filter would help. In fact when using the internal voltage reference the energy resolution as evaluated on the 59.54 keV line of ²⁴¹Am worsens by up to 18%, when a DC offset of -36% Full Scale is enforced. No such effect is observed when using the filtered external reference.