Line interface circuit, associated line drivers and methods of operating the same
First Claim
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1. A line driver for use with a power dissipating load, the line driver comprising:
- a hybrid circuit, a signal portion for connection to the load; and
a termination portion connected to an output of the hybrid circuit for load matching, the termination portion comprises;
a power dissipating termination impedance which is supplied in use by the hybrid circuit with a termination current, a back termination transformer, a first winding of the transformer being coupled in series with said termination impedance, and a second winding of the transformer being coupled in parallel with said termination impedance, wherein a portion of a voltage dropped across the termination portion is dropped across the first winding to thereby cause the power dissipated in said termination impedance to be less than the power available to the signal transmission portion for signal transmission to the load.
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Abstract
A line driver is disclosed comprising a termination portion which includes a termination resistance (Rterm) and which is supplied in use by an operational amplifier (op-amp), with a termination current (VNE/R) for load matching. The termination portion further comprises a back-termination transformer (1:α) which is series coupled with the termination resistance (Rterm). The power dissipated in the termination resistance (Rterm) is less than the power (P/2) available to a signal transmission portion for signal transmission along an associated transmission line (Rload) and the power consumption efficiency of the line driver is improved. (FIG. 4).
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Citations
29 Claims
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1. A line driver for use with a power dissipating load, the line driver comprising:
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a hybrid circuit, a signal portion for connection to the load; and
a termination portion connected to an output of the hybrid circuit for load matching, the termination portion comprises;
a power dissipating termination impedance which is supplied in use by the hybrid circuit with a termination current, a back termination transformer, a first winding of the transformer being coupled in series with said termination impedance, and a second winding of the transformer being coupled in parallel with said termination impedance, wherein a portion of a voltage dropped across the termination portion is dropped across the first winding to thereby cause the power dissipated in said termination impedance to be less than the power available to the signal transmission portion for signal transmission to the load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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- 24. A method of operating a line driver for use with an associated power dissipating load, said line driver comprising, a hybrid circuit, a signal portion and a termination portion which includes a power dissipating termination impedance and a back-termination transformer having at least two windings, and is coupled with said termination impedance, the method including dropping across one of said at least two windings of the back transformer a portion of a voltage dropped across the termination portion to thereby cause the power dissipated in said termination resistance to be less than the power available to the signal transmission portion for signal transmission to the load.
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28. A modem suitable for broadband communication, including a line driver comprising:
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a hybrid circuit, a signal portion for connection to the load; and
a termination portion having a back transformer, and connected to an output of the hybrid circuit for load matching, wherein the termination portion is operable to drop across one winding of at least two windings of the back transformer, a portion of a voltage dropped across the termination portion to thereby cause the power dissipated in said termination resistance to be less than the power available to the signal transmission portion for signal transmission to the load. - View Dependent Claims (29)
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Specification