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US 5,825,819 AGranted
Asymmetrical digital subscriber line (ADSL) line driver circuit
AssigneeMotorola, Inc.
InventorOnis Cogburn
Life of this patent
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Abstract
A differential amplifier (40) receives a low level ADSL signal IN- and IN+ and produces an amplified differential signal. A pair of differential amplifiers (42, 44) receives the differential signal and provides phase shifting and further amplification to the differential signal. A set of differential pairs (46, 48, 50, 52) are coupled to the pair of differential amplifiers (42, 44) and provide further amplification and drive capability to the differential signal. A pair of driver pairs 54 and 56 are coupled to the differential pairs (46, 48, 50, 52) to provide a fully differential output signal OUT- and OUT+ with high linearity. A common mode feedback stage (58) and gain feedback stage (98) provide feedback.
Claims21
A line driver circuit, comprising:
- a first differential amplifier having a first input terminal for receiving a first input signal, a second input terminal for receiving a second input signal, a first output terminal, and a second output terminal;
- a second differential amplifier having a first input terminal coupled to the second output terminal of the first differential amplifier, a second input terminal coupled to the first output terminal of the first differential amplifier, a first output terminal, and a second output terminal;
- a third differential amplifier having a first input terminal coupled to the second output terminal of the first differential amplifier, and a second input terminal coupled to the first output terminal of the first differential amplifier, a first output terminal, and a second output terminal;
- a first differential pair having a first input terminal coupled to second output terminal of the second differential amplifier, a second input terminal coupled to the first output terminal of the second differential amplifier, a first output terminal, and a second output terminal;
- a second differential pair having a first input terminal coupled to the second output terminal of the third differential amplifier, a second input terminal coupled to the first output terminal of the third differential amplifier, a first output terminal, and a second output terminal;
- a third differential pair having a first input terminal coupled to the second output terminal of the second differential amplifier, a second input terminal coupled to the first output terminal of the second differential amplifier, a first output terminal, and a second output terminal;
- a fourth differential pair having a first input terminal coupled to the second output terminal of the third differential amplifier, a second input terminal coupled to the first output terminal of the third differential amplifier, a first output terminal, and a second output terminal;
- a first driver portion having a first input terminal coupled to both the second output terminal of the first differential pair and the second output terminal of the third differential pair, and a second input terminal coupled to both the second output terminal of the second differential pair and the second output terminal of the fourth differential pair, and an output terminal for providing a first output signal;
- and
- a second driver portion having a first input terminal coupled to both the first output terminal of the first differential pair and the first output terminal of the third differential pair, and a second input terminal coupled to both the first output terminal of the second differential pair and the first output terminal of the fourth differential pair, and an output terminal for providing a second output signal.
7 more elements
In a communications system compliant with an asymmetrical digital subscriber line (ADSL) communications standard, a differential line driver circuit for driving a transmission line, the differential line driver circuit comprising:
- a first differential amplifier having a first input terminal for receiving a first input signal, a second input terminal for receiving a second input signal, a first output terminal, and a second output terminal;
- a second differential amplifier having a first input terminal coupled to the second output terminal of the first differential amplifier, a second input terminal coupled to the first output terminal of the first differential amplifier, a first output terminal, and a second output terminal
- a third differential amplifier having a first input terminal coupled to the second output terminal of the first differential amplifier, and a second input terminal coupled to the first output terminal of the first differential amplifier, a first output terminal, and a second output terminal;
- a first differential pair having a first input terminal coupled to second output terminal of the second differential amplifier, a second input terminal coupled to the first output terminal of the second differential amplifier, a first output terminal, and a second output terminal;
- a second differential pair having a first input terminal coupled to the second output terminal of the third differential amplifier, a second input terminal coupled to the first output terminal of the third differential amplifier, a first output terminal, and a second output terminal;
- a third differential pair having a first input terminal coupled to the second output terminal of the second differential amplifier, a second input terminal coupled to the first output terminal of the second differential amplifier, a first output terminal, and a second output terminal;
- a fourth differential pair having a first input terminal coupled to the second output terminal of the third differential amplifier, a second input terminal coupled to the first output terminal of the third differential amplifier, a first output terminal, and a second output terminal;
- a first driver portion having a first input terminal coupled to both the second output terminal of the first differential pair and the second output terminal of the third differential pair, and a second input terminal coupled to both the second output terminal of the second differential pair and the second output terminal of the fourth differential pair, and an output terminal for providing a first output signal;
- and
- a second driver portion having a first input terminal coupled to both the first output terminal of the first differential pair and the first output terminal of the third differential pair, and a second input terminal coupled to both the first output terminal of the second differential pair and the first output terminal of the fourth differential pair, and an output terminal for providing a second output signal;
- a first feedback resistor coupled between the first output terminal of the first driver portion and the first input terminal of the first differential amplifier;
- and
- a second feedback resistor coupled between the output terminal of the second driver portion and the second input terminal of the first differential amplifier.
10 more elements
In a communications system compliant with an asymmetrical digital subscriber line (ADSL) communications standard, a differential line driver circuit for driving a transmission line, the differential line driver circuit comprising:
- a first differential amplifier having a first input terminal for receiving a first input signal, a second input terminal for receiving a second input signal, a first output terminal, and a second output terminal;
- a second differential amplifier having a first input terminal coupled to the second output terminal of the first differential amplifier, a second input terminal coupled to the first output terminal of the first differential amplifier, a first output terminal, and a second output terminal
- a third differential amplifier having a first input terminal coupled to the second output terminal of the first differential amplifier, and a second input terminal coupled to the first output terminal of the first differential amplifier, a first output terminal, and a second output terminal;
- a first differential pair having a first input terminal coupled to second output terminal of the second differential amplifier, a second input terminal coupled to the first output terminal of the second differential amplifier, a first output terminal, and a second output terminal;
- a second differential pair having a first input terminal coupled to the second output terminal of the third differential amplifier, a second input terminal coupled to the first output terminal of the third differential amplifier, a first output terminal, and a second output terminal;
- a third differential pair having a first input terminal coupled to the second output terminal of the second differential amplifier, a second input terminal coupled to the first output terminal of the second differential amplifier, a first output terminal, and a second output terminal;
- a fourth differential pair having a first input terminal coupled to the second output terminal of the third differential amplifier, a second input terminal coupled to the first output terminal of the third differential amplifier, a first output terminal, and a second output terminal;
- a first driver portion having a first input terminal coupled to both the second output terminal of the first differential pair and the second output terminal of the third differential pair, and a second input terminal coupled to both the second output terminal of the second differential pair and the second output terminal of the fourth differential pair, and an output terminal for providing a first output signal;
- a second driver portion having a first input terminal coupled to both the first output terminal of the first differential pair and the first output terminal of the third differential pair, and a second input terminal coupled to both the first output terminal of the second differential pair and the first output terminal of the fourth differential pair, and an output terminal for providing a second output signal;
- and
- a common-mode feedback circuit coupled between the first output terminal and the second output terminal, and the first differential amplifier, for sensing a common-mode voltage of the first output signal and the second output signal, and controlling a common-mode feedback voltage at the first output terminal and the second output terminal of the first differential amplifier.
8 more elements
Dependencies are inferred from the claim text.