Development of radiation hard readout electronics for LHCb

The experiment LHCb is under development at CERN and aims to measure CP-violation in the B-Meson system at very high precision. The experiment makes use of a vertex detector that is equipped with silicon microstrip detectors. A chip suitable for the readout of this detector has been developed in a working group at the ASIC-laboratory Heidelberg. This readout chip 'Beetle-1.0' contains 128 analog input stages of a charge sensitive preamplifier, a pulse shaper and a buffer. The analog signal is fed into a comparator, from which a fast trigger signal can be derived. The following pipeline, realized as an array of gate capacitances, can be used to either store the analog output of the input amplifiers or to store the digital comparator output. External trigger signals mark events that have to be read out and the according pipeline location is stored in a derandomizing buffer. Pending events are read out from the pipeline via a charge-sensitive, resetable amplifier and an analog multiplexer, which serializes the signals with a factor of 32:1, 64:1 or 128:1, depending on the readout mode. The data are driven off-chip via a current buffer. For the use of the Beetle in the vertex detector of LHCb, the chip has to withstand a radiation dose of about 10 MRad. This has been achieved by the use of a deep submicron CMOS with a feature size of 0.25um and an enclosed layout geometry of nMOS transistors. In the context of this thesis, essential components of the analog readout chain of the Beetle-1.0 have been developed. For that, results of intensive measurements with the HELIX128 readout chip have been used. Also, parts of the SCTA readout chip have been modified to make it usable for the LHCb experiment.