Balanced hybrid circuit
AssigneeInternational Business Machines Corporation
InventorsTodd Morgan Rasmus, James William Sylivant
Life of this patent
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Abstract
Large signal swings are obtained for the transmitted signal of a telephone line modem using differential drivers. Compensation for the complex nature of line impedance is provided without affecting the response of the receive circuits. Common-mode noise is effectively cancelled due to a fully balanced topology for the transmit and receive portions of the hybrid circuit.
Claims23
A circuit for connecting a full duplex two wire communication line for simultaneously conducting information signals in two directions to a signal source and to a signal receiver comprising:
- an H bridge compensation network;
- a first differential amplifier for coupling the signal source to said H bridge compensation network;
- and
- a second differential amplifier coupled to said H-bridge compensation network for coupling the H bridge compensation network to the signal receiver.
A balanced hybrid circuit adaptable for transmitting and receiving signals, said circuit comprising:
- means for receiving a differential signal;
- means, coupled to said means for receiving said differential signal, for driving a transformer with said differential signal resulting in a transmit signal corresponding to said differential signal being applied across said transformer;
- means for receiving a signal from said transformer;
- means, coupled to said means for receiving said signal from said transformer, for driving said signal received from said transformer to a receive terminal;
- and
- means for rejecting said transmit signal at said means for receiving a signal from said transformer.
A modem comprising:
- means adaptable for coupling to a data processing system;
- means adaptable for coupling to a two wire full duplex telephone line;
- an analog-to-digital converter for converting analog signals received from the two wire full duplex telephone line to digital signals;
- a digital-to-analog converter for converting digital signals from a source into analog signals for transmission over the full duplex two wire telephone line;
- and
- a balanced hybrid circuit comprising:
- an H-bridge compensation network;
- a differential transmit amplifier coupled to said H-bridge compensation network, said differential transmit amplifier coupled to said digital-to-analog converter;
- and
- a differential receive amplifier coupled to said H-bridge compensation network, said receive amplifier coupled to said analog-to-digital converter.
A circuit comprising:
- an H-bridge compensation network;
- and
- a differential transmit amplifier coupled to said H-bridge compensation network, wherein said differential transmit amplifier further comprises two symmetrical gain stages that drive said H-bridge compensation network with a differential input signal, wherein the differential input signal comprises an input signal and an inverse of said input signal.
A modem comprising:
- means adaptable for coupling to a data processing system;
- means adaptable for coupling to a telephone line;
- an analog-to-digital converter;
- a digital-to-analog converter;
- and
- a hybrid circuit comprising:
- a network;
- and
- a differential transmit amplifier coupled to said network, said differential transmit amplifier coupled to said digital-to-analog converter, wherein said differential transmit amplifier further comprises two symmetrical gain stages that drive said network with a differential input signal, wherein the differential input signal comprises an input signal and an inverse of said input signal.
Dependencies are inferred from the claim text.