Abstract: The invention provides a variable capacity diode with a plane structure so that it may be formed in an integrated circuit, this diode has, on the substrate, three coplanar regions. The first and second uniformly doped regions support the contact making metallizations. The transition region has a variation of doping level, low at one end and high at the other end. This variation is obtained by implantation by means of a focused ion beam, with constant energy and sweeping at increasing doses, which allows a hyperabrupt profile to be obtained. The diode is a p-n junction of Schottky contact diode.

Abstract: The invention relates to a variable capacitance element operating in the ultra-high frequency range. In order to integrate this element on to an integrated circuit chip, the element is designed so that the control voltage does not interfere with the ultra-high frequency signal and has neither filters nor shock chokes which are not integrable. The element according to the invention utilizes the junction capacitances variation of at least one diode, reverse-biased by a voltage across a resistor, the high frequency signal being at the diode anode. The element construction comprises an active zone in a semiinsulating substrate. Two metallizations partly cover the active zone and form therewith at least one diode. A projection to the active zone forms the resistor, to which is applied the control voltage. The diodes are p-n junctions of schottky diodes. The semiconductor material is Si or from the III-V group. Application to oscillators, filters, phase shifters, etc. in ultra-high frequency equipment.