Marconi Communications Gmbh

Reliance Comm/tec Corporation

Glenn Yancey

Philip L Dillon

William I Chen

Mark Szewczul

A communications system including an over-voltage and over-current surge protection circuit is provided that passes high frequency signals between transmitting and receiving devices with low attenuation. The protection circuit includes a current limiter and over-voltage protection device. The over-voltage protection device includes a diode device comprising a set of anti-parallel diodes, which is connected in series with a shunt device. The over-voltage protection device is coupled between a signal transmission line and ground. The current limiter is coupled between the transmitting and receiving devices.

Reduced-loss, high-frequency signal transmission system utilizing an over-voltage and over-current protection device

A circuit for increasing the apparent inductance presented by a transformer to a differential signal. The circuit may be used in a battery feed interface circuit for providing battery power to a subscriber's telephone or in a current sink interface circuit for providing a low impedance DC loop closure toward a telephone line feed circuit while maintaining a high impedance for differential AC signals. In either usage the inductance multiplier circuit always multiplies the primary inductance of the transformer by a factor which is one plus a positive number. The transformer has three windings. The multiplication is accomplished by a current source which provides to the third winding a current which flows therein in a manner so as to oppose the current flowing in that winding due to the voltage induced in that winding when the first and second windings are excited by the differential AC signal.

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Burleson, TX, United States of America

Glenn Yancey