Method and apparatus for controlling the common-mode output voltage of a differential buffer
AssigneeLucent Technologies Inc.
InventorsH. Scott Fetterman, David A. Rich
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Abstract
A method and device for controlling the common-node output voltage of a differential buffer is disclosed. According to the invention, the common-mode output voltage of the differential buffer is controlled to a desired value by supplying a first current to the output of the differential buffer and supplying a second current to the output of the differential buffer, the second current being opposite in polarity and lower in magnitude than the first current. The common-mode output voltage of the differential buffer is sensed and an adjustment current is added to the second current to adjust the common-mode output voltage to the desired value.
Claims35
A device for controlling the common-mode output voltage of a differential buffer to a desired value, comprising:
- a first current source providing a first current to the outputs of said differential buffer;
- a second current source providing a second current to the outputs of said differential buffer, said second current being opposite in polarity and lower in magnitude than said first current;
- sensing means for sensing the common-mode output voltage of said differential buffer and providing an adjustment current at a node of said sensing means;
- and
- adding means for adding said adjustment current to said second current to adjust the common-mode output voltage to said desired value.
An integrated circuit including a device for controlling the common-mode output voltage of a differential buffer to a desired value, comprising:
- a first current source providing a first current to the outputs of said differential buffer;
- a second current source providing a second current to the outputs of said differential buffer, said second current being opposite in polarity and lower in magnitude than said first current;
- sensing means for sensing the common-mode output voltage of said differential buffer and providing an adjustment current at a node of said sensing means;
- and
- adding means for adding said adjustment current to said second current to adjust the common-mode output voltage to said desired value.
A method of controlling the common-mode output voltage of a differential buffer to a desired value, comprising the steps of:
- supplying a first current to the outputs of said differential buffer;
- supplying a second current to the outputs of said differential buffer, said second current being opposite in polarity and lower in magnitude than said first current;
- sensing the common-mode output voltage of said differential buffer and providing an adjustment current at a node of said sensing means;
- and
- adding said adjustment current to said second current to adjust the common-mode output voltage to said desired value.
Dependencies are inferred from the claim text.