Electronics for pixel detectors

In future High Energy Physics experiments, particularly for the Large Hadron Collider at the European Organization for Particles Physics, Geneva, a pixel detector gives the advantage of particles location in two dimensions without ambiguity. The SMM ''Silicon Multichip Module'' realized for the Very Forward Tracker of the Delphi experiment in the Large Electron Positron collider will be described. This pixel detector is an association of a matrix of P+N diodes flipped to a matrix of complete electronics chains (one for each diode), both connected into an hybrid device. The electronic cell includes a charge preamplifier, a shaping filter, a discriminator with threshold control, a gate, a latch and three switches for sparse readout. Since the small number of hit pixels, an intelligent sparse readout system realizes a zero skipping by reading only hit pixels. This readout logic implements a true sparse scan in two dimensions localization. To reduce the dead area between chips, all lines inside the electronic chip are routed to a single edge where connection pads are implemented. A test procedure checks for good chips and allows chips with equal characteristics to be associated inside the same module.