Performances of operational amplifiers in front-end electronics for nuclear radiation detectors

Abstract

Operational amplifiers in charge sensitive configuration are an attractive solution for front-end electronics in cost-sensitive radiation detection systems. The noise performances of several JFET input operational were tested in a charge-sensitive configuration. Some rather old devices reached noise performances low enough for detection of x and γ rays in application were extreme energy resolution is no required as, for instance, dosimetry and ambient monitoring applications. On the contrary the devices with the best specification for noise and speed shown an excess noise when used in a charge sensitive configuration with the low feedback capacitor required by this application. By matching the impedences seen at both input of the amplifier, the noise is reduced near to the theoretical value. The origin of this fact seems to be a non white equivalent current noise generator, whose origin is in the first stage bias circuit. Datasheet parameters are not sufficient, at least in some cases, for computing the actual noise of a charge preamplifier built with an operational amplifier

Low cost front-end readout electronic for instrumentation used in neutron experiments

“…Secondly, the Op-amp generates higher noise because it has two input noise sources which are provided by its two differential inputs. Despite this noise issue, by proper selection of Op-amp with better noise performance and Lombigit et al 2813 being able to match both input impedances, makes the FET-input Op-amp a viable choice as an active device for the CSP (Cerizza et al, 2004). Gaussian filter perform better than common filters (Bessel and Butterworth) in terms of magnitude, pulse duration, ripple and undershoot (Panjkovic, 2009).…”