Interfacing a SiPM to a current-mode front-end: Effects of the coupling inductance

A current-mode approach is often used when designing front-end electronics for Silicon Photomultipliers, to cope with the peculiar features of this kind of detectors. Very low input resistance Rin and bandwidth BW as large as possible are classic design choices for the preamplifier, since it is commonly assumed that timing accuracy performance are optimized if this strategy is adopted. In our study, we show that this design approach leads to non-optimal results, due to the unavoidable presence of parasitic interconnection inductance between the detector and the front-end electronics. An approximate model, able to reproduce the behavior of the resulting circuit during the fast rising edge of the output pulse, has been employed to analyze the influence of the interconnection inductance on the slope of the signal. Thus, considering a typical current-mode preamplifier, based on a BJT current buffer, the existence of Rin-BW pairs which optimize the timing accuracy of the detection system has been demonstrated.