Transformerless hybrid circuit
AssigneeAT&T Corp.
InventorsDonald T. Cwynar, Donald R. Laturell
Life of this patent
Estimating the term…
Abstract
An electronic hybrid useful in telephone line-powered Data Access Arrangements. The hybrid has a transmit amplifier with an output driving the base of a bipolar transistor. The emitter of the transistor is connected to a sense resistor which is, in turn, connected to one wire of a telephone line. The collector of the transistor connects to another wire of the telephone line. A summing node couples together signals on the telephone line and signals across the sense resistor such that the remaining signal on the summing node is substantially the signal received from the telephone line without the signal to be transmitted.
Claims10
A hybrid circuit, for coupling a transmit signal from a transmit path to a bidirectional path and for coupling a received signal from the bidirectional path to a receive path with the transmit signal suppressed, having:
- a variable current device, responsive to the transmit signal, disposed in series with the bidirectional path;
- a sensing resistor, disposed in series with the variable current device, which generates a voltage in response to the current through the variable current element;
- and,
- a summing node coupling to the sensing resistor and to the bidirectional path;
- wherein the summing node has thereon the received signal from the bidirectional path substantially without a signal from the transmit path.
A hybrid circuit, for coupling a transmit signal from a transmit path to a bidirectional path and for coupling a received signal from the bidirectional path to a receive path with the transmit signal suppressed, having:
- a transmit amplifier having an input coupling to the transmit path and an output coupling to the bidirectional path;
- a receive amplifier having an input coupling to the bidirectional path at a summing node and an output couping to the receive path;
- a bipolar transistor having an emitter and a base, the base connecting to the output of the transmit amplifier;
- and,
- a sense resistor, disposed in series with the emitter of the transistor, which generates a voltage in response to the current through the transistor;
- CHARACTERIZED BY:
- a series resistor coupling the summing node to the sense resistor.
Dependencies are inferred from the claim text.