Abstract: A charge-sensitive amplifier is disclosed for use in amplifying signals from a particle detector. This includes a field effect transistor having a gate, source and drain, the gate being connectable, using a gate pad, to the particle detector, for the receipt of said signals. Also included is an amplifier having an input connected to the drain or source of the field effect transistor and an output connected through a feedback capacitor to the gate of the field effect transistor. The gate pad of the field effect transistor is made to be integral with the feedback capacitor so as to reduce the capacitance of the device.