A Low Noise Preamplifier Using a Tetrode FET in a Novel Feedback Arrangement

This paper describes a low noise n-channel tetrode field effect transistor circuit in which the d.c. input and output voltages of a current integrator are held close to zero. This is achieved by a feedback network to the substrate gate of the tetrode FET. An analysis is made of the circuit arrangement. The application for the circuit configuration is for use in low-noise input stages of nuclear pulse preamplifiers and low frequency preamplifiers used with optical and acoustical detectors. The mutual conductance of the tetrode FET through the input gate is typically 50 mS.