Abstract: The invention relates to an arrangement of two cascaded transformers, i.e. an impedance transformer (24) and a balance-unbalance transformer, also referred to as balun transformer (26). A relatively simple, inexpensive, small and efficient construction of this arrangement is achieved by mounting both transformers (24, 26) on a single core (50) of a magnetic material. The arrangement according to the invention can be used in CATV networks, more specifically in CATV modules and optical receivers for use in such CATV networks.

Abstract: A transformer having a core of soft magnetic material around which a first winding and a second winding are wound and a leakage inductance based on the magnetic coupling between these windings. The effective leakage reactance is minimized by adding a third transformer winding serially connected to a capacitor, the latter of which is varied to reduce the leakage reactance over a broad frequency range.

Abstract: The transformer comprises an annular core (1) of a soft-magnetic material on which there are provided a first winding and a second winding. The second winding comprises n turns more than the first winding. The first winding consisted of a first conductor (3) and a second conductor (5), the second winding consisting of a third conductor (7). The three conductors (3, 5, 7) are twisted over a part of their length so as to form a cable (9) wherefrom a common winding is formed which includes at least a part of the second winding and substantially the entire first winding. Near one end of the common winding there are provided n additional turns of the first conductor (3) and near its other end there are provided n additional turns of the second conductor (5). The corresponding end portions of the first and second conductors (3, 5) are electrically interconnected in order to form terminals (13, 19) of the first winding, and the end portions of the third conductor (7) form terminals (11, 15) of the second winding.

Abstract: A semiconductor device having a semiconductor body includes a field effect transistor and an active transistor region with two electrode zones, one of which surrounds the other, and an island zone which is situated therebetween. These zones enclose channel regions over which there are provided gate electrodes, the first one of which surrounds the second. The gate electrodes are connected to bond pads present outside the active transistor region. The first gate electrode is interrupted at the area of the connection from the second gate electrode to a bond pad, both its ends being connected to another bond pad. Even at very high frequencies, the transistor exhibits a high gain, a high transconductance and a low input attenuation.