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US 6,774,722 B2Granted
Frequency compensation of common-mode feedback loops for differential amplifiers
AssigneeCentillium Communications, Inc.
InventorRon Hogervorst
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Abstract
Techniques for performing frequency compensation of common-mode feedback loops for differential amplifiers are disclosed.
Claims20
A circuit for performing frequency compensation of a common-mode feedback loop for a differential amplifier, the circuit comprising:
- a sensing network operatively coupled to a differential output of the differential amplifier, for sensing a common-mode voltage output by the differential amplifier;
- a comparing network operatively coupled to the sensing network, and adapted to compare the sensed common-mode voltage to a reference and generate an error signal;
- a current inverter operatively coupled to the comparing network for inverting the error signal;
- a gain stage operatively coupled to the current inverter and the differential amplifier for providing a gain adjusted error signal to the differential amplifier;
- and
- a pole-split network operatively coupled in parallel with the comparing network for compensating the frequency characteristic of the feedback loop.
3 more elements
A method for performing frequency compensation of a common-mode feedback loop for a differential amplifier, the method comprising:
- sensing a common-mode voltage output by a differential amplifier using a sensing network;
- comparing the sensed common-mode voltage with a reference to generate a common-mode error signal using a comparing network;
- inverting the common-mode error signal with a current inverter;
- providing a gain adjusted error signal to the differential amplifier via a gain stage coupled to the current inverter;
- and
- compensating for changes in the frequency characteristic of the common-mode feedback loop due to the gain stage using a pole-split network.
3 more elements
A circuit for performing frequency compensation of a common-mode feedback loop for a differential amplifier, the circuit comprising:
- a sensing network operatively coupled to a differential output of the differential amplifier, for sensing a common-mode voltage output by the differential amplifier;
- a comparing network operatively coupled to the sensing network, and adapted to compare the sensed common-mode voltage to a reference thereby generating a common-mode error signal;
- a gain stage operatively coupled to the comparing network and to the differential amplifier for providing a gain adjusted error signal to the differential amplifier;
- and
- a pole-split network operatively coupled in parallel with the comparing network for compensating the frequency characteristic of the feedback loop, wherein the pole-split network includes a current inverter.
2 more elements
Dependencies are inferred from the claim text.