Abstract: A field-effect transistor comprises an ancillary electrode in addition to the source, gate and drain electrodes. In this device, a semiconducting body bears source, gate and drain metallizations which define a main transistor. The metallization of the drain is separated into two parts which are separated by a channel on which is placed a second gate metallization defining a secondary transistor. The two parts of the drain are coupled by this secondary transistor, the channel of which is separated from the main channel. The secondary transistor can be used to control the gain of the main transistor or to modulate its amplitude signal or to mix two frequencies addressed on the two gates.

Abstract: An ultra-high frequency transistor is mounted in a hermetically sealed package in order to be made usable and in order to improve its performance characteristics to the optimum level. To diminish the noise factor of an ultra-high frequency transistor, the geometrical dimensions of the gate must be reduced. But the transistor changes its impedance and maximum frequency and can no longer be used in a package or at the external impedance of the circuit. It has to be pre-matched by having a choke mounted between its gate, its drain and the corresponding external connections. Each choke consists of a long metallic wire, forming a hairpin, soldered inside the package between the gate metallization and the internal end of its external connection or between the drain metallization and the internal end of its external connection. The invention can be applied to low-noise ultra-high frequency amplifiers.