Design of current mode front-end amplifiers with optimal timing performance for high-gain photodetectors

When a current-mode approach is exploited to readout high-gain photodetectors, preamplifiers with input resistance as low as possible and very large bandwidth are commonly used to optimize the time resolution of the detection system. In our study we show that, due to the effects of the parasitic inductance associated with the interconnection between the detector and the front-end electronics, extremely low input resistance and very large bandwidth are not optimal design choices, as commonly assumed. To support the study, we refer as an example to a detection system based on a Photo-Multiplier Tube read-out by a simple BJT common base current buffer and demonstrate by simulation the existence of values of input resistance and bandwidth which optimize the timing accuracy of the system.