Patent ID: 7701284

Claim:
A line driver, comprising: a differential amplifier for amplifying an input signal to generate an output signal, said differential amplifier including an inverting input terminal, a non-inverting input terminal, an inverting output terminal, and a non-inverting output terminal, said inverting input terminal and said non-inverting input terminal receiving the input signal; first and second series resistors, said first series resistor being coupled to said non-inverting output terminal of said differential amplifier, said second series resistor being coupled to said inverting output terminal of said differential amplifier, the output signal generated by said differential amplifier being output through said first and second series resistors; first and second negative-feedback resistors, said first negative-feedback resistor being coupled between said inverting input terminal and said non-inverting output terminal of said differential amplifier, said second negative-feedback resistor being coupled between said non-inverting input terminal and said inverting output terminal of said differential amplifier; first and second positive-feedback variable resistors, said first positive-feedback variable resistor being coupled between said inverting input terminal of said differential amplifier and said second series resistor, said second positive-feedback variable resistor being coupled between said non-inverting input terminal of said differential amplifier and said first series resistor; and an adjusting unit coupled to said first and second positive-feedback variable resistors, said adjusting unit adjusting a resistance of each of said first and second positive-feedback variable resistors with reference to the output signal.