A high density time to digital converter module for BESIII end-cap TOF upgrade

This paper describes the high precision time measurement for the end-cap time of flight (ETOF) upgrade of a Beijing Spectrometer (BESIII). After upgrade, ETOF will be built using Multigap Resistive Plate Chambers (MRPC) and will have 1728 readout channels which is a big challenge for the readout electronics. The time resolution of the readout electronics system is required to be better than 25 ps.