Low-power low-noise BJT amplifier for nuclear applications

This work present an analysis of the peculiar characteristics of the front-end electronics for radiation detectors employing bipolar transistors, taking into account the noise, speed and power-dissipation constraints. It is shown that, in a first approximation, the optimum processing time is inversely proportional to the dissipated power P_d of the front-end stage, while the optimum noise performance can be made almost independent on P_d. The noise characteristics of a bipolar transistor having a maximum cut-off frequency of 8 GHz have been experimentally determined, and discussed in relation with the low-power requirements. A prototype of a charge amplifier operated with a single power supply of 3 Volt and a dissipation of 600 μW has been tested and showed a ENC=470 electrons r.m.s. at 10 ns RC-CR shaping and with a total input capacitance of 6 pF