System and methods for modem interface
First Claim
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1. An interface for coupling a modem port with a transmission line comprising:
- a hybrid converter including a variable gain amplifier coupling a transmit path of a first differential polarity and a receive path of a second differential polarity.
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Abstract
An interface for coupling a modem port with a transmission line includes a hybrid converter having a variable gain amplifier coupling a transmit path of a first differential polarity and a received path of a second differential polarity.
26 Citations
19 Claims
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1. An interface for coupling a modem port with a transmission line comprising:
a hybrid converter including a variable gain amplifier coupling a transmit path of a first differential polarity and a receive path of a second differential polarity. - View Dependent Claims (2, 3, 4, 5)
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6. A hybrid circuit for interfacing a modem and a telephone line comprising:
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a transformer having a first winding having first and second terminals coupled to first and second conductors of said telephone line and a second winding having first and second terminals;
a first transmit path of a first differential polarity of a pair of differential transmit paths coupled to said first terminal of said second winding;
a second transmit path of a second differential polarity of said pair of differential transmit paths coupled to said second terminal of said second winding;
a first receive path of said first differential polarity of a pair of differential receive paths coupled to said first terminal of said second winding;
a second receive path of said second differential polarity of said pair of differential receive paths coupled to said second terminal of said second winding;
a first variable gain amplifier coupling said first transmit path and said second receive path; and
a second variable gain amplifier coupling said second transmit path and said first receive path. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A modem comprising:
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a first signal path for receiving data, said first signal path comprising one of a differential pair of signal paths;
a second signal path for transmitting data, said second signal path comprising a second one of the differential pair of signal paths, said first and second signal paths carrying data of opposite polarity; and
signal cancellation circuitry including a variable output impedance amplifier circuit coupling said first and second signal paths. - View Dependent Claims (13, 14, 15)
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16. A method of tuning an interface between a modem having a differential transmit port and a differential receive port and a telephone line comprising the step of:
adjusting a gain of a variable gain amplifier coupling a selected path of the transmit port and a selected path of the receive port to match an impedance of a hybrid circuit coupling the modem and the telephone line with an impedance of the telephone line, the selected path of the transmit port and the selected path of the receive port carrying signals of different polarities. - View Dependent Claims (17, 18, 19)
Specification