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.

Abstract: The invention relates to an ultra-high frequency oscillator operating in the X band. The oscillator circuit comprises a common gate-connected field effect transistor. The source connected tuning circuit comprises a variable capacitor of the varactor type controlled by a voltage and a choke in parallel. The control voltage is decoupled from earth by a capacitor. According to the invention, the transistor, the varactor and the capacitor are integrated into the same box or case in the form of a micromodule. The capacitor acts as a base for the transistor and the varactor, which are welded in juxtaposed manner. The length of the connection between the varactor and the source of the transistor has a minimum value, which makes it possible to broaden the linear frequency band as a function of the control voltage.

Abstract: A process allowing the position and the dimensions of the grid of a field-effect transistor as well as the gaps between source and grid, grid and drain to be fixed as early as the first masking operation. To this end, a mask is formed comprising source, grid and drain windows by using a first insulating or semi-insulating material then the three windows are filled by means of a second material. The ohmic source and drain contacts are deposited in the corresponding windows reopened by selective etching of the second material effected after masking the first part of the layer situated above the non-reopened window. Second selective etching after masking of the contacts allows a Schottky-type grid contact to be deposited.

Abstract: A component of the "hybrid-circuit" type comprising an active component, such as a very-high-frequency field-effect transistor, and a sealed housing, intended for operating as an amplifier in a large frequency band, in the range from 1 to 20 Gc/s. In this hybrid component, are accomodated in the same housing, by using in particular the ceramic elements of the base situated on the periphery of an earth return aperture containing the active component, metallizations forming lines having distributed constants. Moreover, to obtain a low standing-wave ratio on these lines, lumped circuit elements are placed inside the housing in the closest vicinity of the active component.