Alcatel

Olivier Latte

Herman Joris Casier

Patrick Wouters

Dani&euml;l Sallaerts

Daniël Sallaerts

A hybrid circuit that couples a broadband modem to a POTS or ISDN telecommunication line (TL) and includes a transformer bridge circuit (TBC) that includes a bridge circuit (BC). The bridge circuit includes four legs formed by impedance matching networks and parts of the transformer, and a differential drive amplifier (DRV) that performs impedance synthesis. A secondary winding (TS) of the transformer is magnetically coupled to the first and the second primary windings and is electrically coupled to the telecommunication line. First and second impedance dividers (Zhin, Zhoutand Zhin, Zhout) are connected to the various nodes to provide outputs to a receive amplifier (RCV). The impedance matching networks (Zm; Zm) include various passive and reactive components that together provide an impedance value selected based upon the line impedance reflected into the primary windings (TP; TP) of the transformer. To perform the impedance synthesis, the drive amplifier (DRV) is a differential drive amplifier having feedback inputs (FB&#x2212;, FB+) to which the third (C) and fourth (D) nodes are connected.

Hybrid circuit for a broadband modem

A hybrid circuit that couples a broadband modem to a POTS or ISDN telecommunication line (TL) and comprises a transformer bridge circuit (TBC) that includes a bridge circuit (BC). The bridge circuit is constituted by four legs of which a first (A) and a second (B) nodes, that do not belong to a same leg, are connected to the two outputs of a differential drive amplifier (DRV) that performs impedance synthesis. A first leg is made of a first impedance matching network (Zm ) connected between the second node (B) and a third node (C). A second leg is made of a first primary winding (TP ) of a transformer and is connected between the third (C) and the first (A) nodes. A third leg is made of a second impedance matching network (Zm ) connected between the first node (A) and a fourth node (D). A forth leg is made of a second primary winding (TP ) of the transformer and is connected between the fourth (D) and second (B) nodes. A secondary winding (TS) of the transformer is magnetically coupled to the first and the second primary windings and is electrically coupled to the telecommunication line. A first impedance divider (Zhin , Zhout ) is connected between the third (C) and first (A) nodes and has a first central node (E), whilst a second impedance divider (Zhin , Zhout ) is connected between the fourth (D) and second (B) nodes and has a second central node (F). A receive amplifier (RCV) has inputs connected to the first (E) and second (F) central nodes. The impedance matching networks (Zm ; Zm ) include various passive and reactive components that provides together an impedance value selected based upon the line impedance reflected into the primary windings (TP ; TP ) of the transformer. To perform the impedance synthesis, the drive amplifier (DRV) is a differential drive amplifier having feedback inputs (FB&minus;, FB&plus;) to which the third (C) and fourth (D) nodes are connected.

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Groot-Bijgaarden, Belgium

Olivier Latte