A readout ASIC for the R3B silicon tracker

A 128-channel event-driven ASIC is described which reads out the R³B (Reactions with Relativistic Radioactive Beams) silicon micro vertex tracker. Ionizing particles with energies in the range of 40keV-50MeV are detected, digitized and read out with 12 bit resolution, and time stamped with up to 5ns precision. The ASIC copes with signal charges and detector leakage currents of both polarities and allows charge sharing to be taken into account by reading out the charge from neighboring channels. The ASIC can recover quickly from signals up to 1Gev, can store up to 32 events and can be easily daisy-chained to reduce parallel connections. Outputs can be Manchester encoded to allow for capacitive coupling of the data, and a 128-bit OR of all the channel hits provides a fast trigger output.