Digital part of PARISROC2: A photomultiplier array readout chip

PARISROC is the front-end ASIC designed to read 16 photomultiplier (PM) tubes for neutrino experiments. It's able to shape, discriminate, convert and readout data in an autonomous and channel-independent mode. The tests made on PARISROC1 have shown some limitations on time measurements and on hit rate capability. In order to correct these points, the digital part of PARISROC2 has been completely modified to add new features and improvements. First, it integrates a new time to amplitude converter with less than 1 ns resolution. Secondly, conversion and readout has been speeded-up by a factor of 4 to handle the PM hit rate. The chip was received in February 2010.