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US 7,084,674 B1Granted
Differential amplifier with reduced common-mode and method
AssigneeAnalog Devices, Inc.
InventorDavid G. Nairn
Life of this patent
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Abstract
A comparator includes a circuit which provides a plurality of common-mode difference signals in response to differential input signals. The circuit provides a common-mode feedback signal in response to the plurality of common-mode difference signals. The common-mode feedback signal is used to drive the common-mode level of an amplifier to a desired value.
Claims22
A comparator, comprising:
- a circuit which provides a plurality of common-mode and differential difference signals in response to differential input signals;
- said circuit providing a common-mode feedback signal in response to said plurality of common-mode difference signals;
- wherein said circuit includes a differential input stage which provides inverting and non-inverting difference signals in response to inverting and non-inverting input signals in said differential input signals;
- wherein said circuit further comprises an output stage coupled to said differential input stage, said output stage providing said plurality of common-mode and differential difference signals;
- and wherein said output stage includes first and second current mirror circuits which provide said plurality of common-mode and differential difference signals, respectively.
2 more elements
A comparator, comprising:
- a circuit with multiple differential inputs;
- said multiple differential inputs receiving separate differential input signals;
- said circuit providing a plurality of common-mode difference signals in response to said differential input signals;
- wherein said circuit further comprises a differential amplifier input stage with a first differential amplifier which provides first and second non-inverting difference signals in response to first and second non-inverting input signals from said differential input signals;
- and wherein said differential amplifier input stage includes a second differential amplifier which provides first and second inverting difference signals in response to first and second inverting input signals from said differential input signals.
2 more elements
A method of adjusting the difference between the common-modes of an amplifier and one or more comparators, said method comprising:
- sensing reference and amplifier output signals with said one or more comparators;
- forming corresponding common-mode difference signals with at least one comparator in response to said reference and amplifier output signals;
- and
- providing a common-mode feedback signal from said at least one comparator in response to said corresponding common-mode difference signals, the common-mode difference between said differential amplifier and one or more comparators being adjusted in response to said common-mode feedback signal(s);
- wherein each comparator provides a separate common-mode feedback signal in which the combination is used to adjust the common-mode level of said amplifier.
2 more elements
Dependencies are inferred from the claim text.