Temperature compensation for trans-hybrid loss in a miniaturized data access arrangement
First Claim
1. A circuit comprising:
- a transformer having a first winding, said first winding having a first winding resistance, said first winding resistance having a first temperature coefficient of resistance;
a thermocompensating element coupled to said transformer for providing thermal compensation of transhybrid loss;
a transmit signal input coupled to said first winding of said transformer for applying a transmit signal to said transformer; and
a receive amplifier circuit coupled to said first winding of said transformer, said receive amplifier circuit for outputting a receive signal, said receive signal being independent of said transmit signal.
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Abstract
Method and apparatus for temperature compensation of transhybrid loss in a data access arrangement (DAA) is provided. A thermal compensation device is situated in proximity to a thermally sensitive device. If devices which dissipate substantial power cause heating of the thermally sensitive device and change its characteristics, the thermal compensation device is also heated and compensates for the changes. Thus, a DAA that is unaffected by temperature changes and self-heating is provided. The DAA is suitable for use with data communications equipment utilizing echo cancelling circuitry, such as CCITT V.32 and V.32 bis modems. When used with such modems, the present invention avoids the need to perform retraining and equalization during changes in DAA operating temperature.
107 Citations
30 Claims
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1. A circuit comprising:
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a transformer having a first winding, said first winding having a first winding resistance, said first winding resistance having a first temperature coefficient of resistance; a thermocompensating element coupled to said transformer for providing thermal compensation of transhybrid loss; a transmit signal input coupled to said first winding of said transformer for applying a transmit signal to said transformer; and a receive amplifier circuit coupled to said first winding of said transformer, said receive amplifier circuit for outputting a receive signal, said receive signal being independent of said transmit signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A telephone hybrid circuit comprising:
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a transformer having a first winding and a second winding for isolating a telephone line from user equipment; a hookswitch for selectively coupling said transformer to said telephone line; a receive amplifier coupled to said second winding of said transformer for amplifying a receive signal; a thermistor coupled to said second winding of said transformer for compensating for a thermal dependency of said transformer; a transmit signal input coupled to said second winding of said transformer for providing a transmit signal. - View Dependent Claims (16)
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17. A circuit comprising:
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an isolation transformer having a first winding and a second winding, said first winding having a first winding resistance, said first winding resistance having a first temperature coefficient of resistance, said isolation transformer for providing isolation of DC voltages between said first winding and said second winding; a thermocompensating element coupled to said isolation transformer for providing thermal compensation of transhybrid loss; a capacitor in series with said second winding of said isolation transformer for coupling said second winding of said isolation transformer to a subscriber telephone line; a summing amplifier circuit coupled to said first winding of said isolation transformer for amplifying a signal from said subscriber telephone line. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification