Clock and data alignment scheme for readout electronics prototype of PandaX-nT

Purpose This work proposes a clock and data alignment scheme for the readout electronics system of the future PandaX-nT dark matter detection experiments. Since the waveform information of the photomultiplier signal is obtained by accumulating all acquisition channels of the front-end digitization module (FDM), it is required that each FDM acquisition channel should be synchronized.
Methods The readout electronics system is composed of a clock distribution module, 64 FDMs, and 4 data acquisition (DAQ) modules. The multi-board synchronous acquisition circuit can provide the same REF CLOCK and SYSREF signal for multiple FDMs boards to ensure the alignment of the sampled data collected by the analog-to-digital converter. The data aggregation circuit can ensure that the sampled data of multiple FDM boards are aligned with each other when they are aggregated to the DAQ board.
Results and conclusions The functional verification test results show that the synchronization between the prototype electronics channels is less than 80 ps, thus enabling to meet the requirements of the readout electronics prototype of PandaX-nT.