The field-effect transistor-its characteristics and applications

The characteristics of the junction gate field-effect transistor and the basic relations among its parameters are described. Some figures of merit are derived in terms of its physical parameters and the limitations considered. Applications in nuclear instrumentation are discussed. Some advantages of field-effect transistors are in high input impedance, low noise at very low and medium frequencies, and a wide operating temperature range (-200°C to +100°C). In addition, the field-effect transistor represents a new circuit element - voltage (charge) controlled conductance with fast response. Field-effect transistors are particularly suitable for low noise amplifiers at low and medium frequencies, for high input impedance amplifiers (as for integrators), for charge-sensitive amplifiers, and for analogue multipliers. They can also be applied as controllable feedback elements.