Low noise, high count rate charge amplifier with detector embedded front-end transistor and continuous reset

Detector front-end circuits for spectroscopy applications have to provide a precise and stable amplification of the signal pulse and a reset path for the accumulated signal and leakage current. In the case in which very high energy resolutions are required in conjunction with high count rate capabilities, the required stability in the amplification is only given by a charge amplifier and its front-end should be integrated on the detector chip in order to minimise parasitic capacitances. A two-chip system has been designed and produced. The front-end nJFET, the feedback capacitance and the reset mechanism are integrated on the detector chip. The other components of the charge amplifier are designed on a second chip produced in BiCMOS technology to be coupled to the detector chip