US 7,002,931 B2 · Power efficient line driver with high performance echo cancellation for 1000BASE-T

Abstract

A 1000BASE-T transceiver linked to an unshielded twisted pair (UTP) through a transformer currently transmits and receives outgoing and incoming signals via the UTP. The transceiver employs an energy efficient class B or AB line driver supplying asymmetric output currents to the transformer's primary winding terminals so that the transformer's secondary winding induces the outgoing signal on the UTP. Resistors couple the transformer's primary winding terminals to inputs of separate amplifiers producing a differential output signal mimicking the incoming 1000BASE-T signal. Since both the incoming and outgoing signals contribute to voltages appearing at the transformer's primary winding terminals, echo cancellation circuits provide additional compensating signals to the amplifier inputs for canceling echo in each amplifier input due to the resistive and reactive loading on each driver output current and arising from the asymmetric nature of the class B or AB driver's output currents.

Claims28

Dependent claims

An apparatus for concurrently transmitting an outgoing differential signal on a twisted pair in response to an input signal and for amplifying an incoming differential signal arriving on the twisted pair to produce an output signal, the apparatus comprising:

first, second, third and fourth nodes (N1–N4);
a first resistor (R1) coupling the first node to the third node;
a second resistor (R2) coupling the second node to the fourth node;
first means (75) for inductively coupling the first and second nodes to the twisted pair;
second means for responding to the input signal by supplying a first current (I1) to the first node and by supplying a second current (I2) to the second node;
third means (88A) responding to the first and second currents by providing first compensation current (I6–I8) into the third node of magnitude influenced by both the first and second currents;
and
fourth means (88B) for responding to the first and second currents by providing second compensation current (I12–I13) into the fourth node, of magnitude influenced by both the first and second currents.

5 more elements

A method for reducing an echo of an outgoing differential signal in an output signal of an apparatus for concurrently transmitting the outgoing differential signal on a twisted pair in response to an input signal and for amplifying an incoming differential signal arriving on the twisted pair to produce the output signal, wherein the apparatus includes a first resistor (R1) coupling a first node (N1) to a third node (N3), a second resistor (R2) coupling a second node (N2) to a fourth node (N4), a transformer (75) for coupling the first and second nodes to the twisted pair, means for responding to the input signal by supplying a first current (I1) to the first node and by supplying a second current (I2) to the second node, the first and second currents being asymmetric, and amplifier means (86A, 86B) for generating the output signal in response to signal appearing the third and fourth nodes, the method comprising the steps of:

a. providing first compensation current (I6–I8) into the third node of magnitude influenced by both the first and second currents;
and
b. providing second compensation current (I12–I13) into the fourth node, of magnitude influenced by both the first and second currents.

Dependencies are inferred from the claim text.

Power efficient line driver with high performance echo cancellation for 1000BASE-T

Life of this patent

Power efficient line driver with high performance echo cancellation for 1000BASE-T

Life of this patent

Abstract

Claims28