| 摘要 |
An apparatus and method to implement a highly efficient low power line driver. In a first embodiment, the invention provides a method to increase the power efficiency of a line driver. The method includes supplying a digital signal processor output to a first subtractor; supplying the first subtractor output as an input to a modulator of a line driver; subtracting the line driver output from the digital signal processor output at the first subtractor; filtering the line driver output with a low pass filter; routing the line driver output to an impedance match filter; providing a first analog-to-digital converter and a second subtractor to subtract the line impedance match filter output from the low pass filter output; providing a digital filter and a second analog-to-digital converter; and subtracting the digital filter output from the first analog-to-digital converter output at a third subtractor to output a feedback signal to the digital signal processor. In a second embodiment, the invention provides an ADSL system with a line driver. The system line driver includes a first subtractor; a digital signal processor to supply a signal to the first subtractor; a line driver receiving an input from the first subtractor, wherein a first closed loop path is provided from the line driver output to the first subtractor; a line impedance match filter receiving the line driver output as an input; a low pass filter, receiving the line driver output as an input; a second subtractor circuit to subtract the line impedance match filter output from the low pass filter output, wherein the second subtractor provides an input to a first analog-to-digital converter; a second analog-to-digital converter; a digital filter to receive an input from the second analog-to-digital converter; and a third subtractor to subtract the digital filter output from the first analog-to-digital converter output, wherein the third subtractor produces a feedback input signal to the digital signal processor.
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