A SPICE model for Si microstrip detectors and read-out electronics

We have developed a SPICE model of silicon microstrip detector and its read-out electronics. The SPICE model of an AC-coupled single-sided polysilicon-biased silicon microstrip detector has been implemented by using a RC network containing up to 19 strips. The main parameters of this model have been determined by direct comparison with DC and AC measurements. The simulated interstrip and coupling impedance and phase angle are in good agreement with experimental results, up to a frequency of 1 MHz. We have used the PreShape 32 as our read-out chip for both the simulation and the measurements. It consists of a charge sensitive preamplifier followed by a shaper and a buffer. A current pulse, simulating the charge signal of an ionizing particle, has been applied to one end of a single strip. Its propagation along the strips and the read-out electronics has been experimentally studied and compared to the SPICE results in order to assess the quality of the model. The SPICE parameters have been adjusted to fit the experimental results obtained for the configuration where every strip is connected to the read-out electronics and kept the same for the different read-out configurations we have considered. By adding 2 further capacitances simulating the parasitic contributions between the read-out channels of the PS32 chip, a satisfactory matching between the experimental data and the simulated curves has been reached on both rising and trailing edges of the signal. Such agreement deteriorates only for strips far from the strip where the signal has been applied.