Low drop-out voltage regulator with common-mode feedback
Assignee02Micro International Limited
InventorsXiaohu Tang, Wei Wang, XiaoHua Hou, Shiqiang Liu
Life of this patent
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Abstract
The present invention is a LDO voltage regulator circuit with common-mode feedback. The LDO voltage regulator includes an error amplifier with a common-mode feedback unit, a pass device and a compensation circuit. A signal from the pass device acts as an input signal to the error amplifier and is compared with another input signal, producing a differential signal. The differential signal is amplified and then provided to the pass device. A capacitor in the compensation unit provides frequency compensation to the LDO voltage regulator. The common-mode feedback unit incorporated into the error amplifier greatly improves a slew rate of a gate voltage of the pass device.
Claims23
A low drop-out (LDO) voltage regulator circuit with common-mode feedback, comprising:
- an error amplifier with an internal common-mode feedback unit for generating an amplified error voltage, the error amplifier having a first input terminal for receiving a reference voltage, a second input terminal for receiving a feedback voltage, a third input terminal, and an output terminal;
- a pass device for providing an output voltage to at least one external component, the pass device having an input terminal and an output terminal, the input terminal of the pass device being connected to the output terminal of the error amplifier;
- a feedback circuit for scaling down the output voltage, the feedback circuit having a first terminal and a second terminal, the first terminal of the feedback circuit being connected to the output terminal of the pass device, the second terminal of the feedback circuit being connected to the second input terminal of the error amplifier;
- and
- a compensation circuit for providing frequency compensation, the compensation circuit having a first terminal and a second terminal, the first terminal of the compensation circuit being connected to a common node between the pass device and the feedback circuit, and the second terminal of the compensation circuit being connected to the third terminal of the error amplifier,
- wherein the internal common-mode feedback unit further comprising two resistor-capacitor devices, each resistor-capacitor device comprising a resistor connected in parallel with a capacitor, each resistor-capacitor device having a first terminal and a second terminal, the first terminals of two resistor-capacitor devices being connected to a transistor.
A method for outputting a stable voltage in a low drop-out (LDO) voltage regulator circuit with common-mode feedback, comprising the steps for:
- generating an amplified voltage at an error amplifier;
- driving a pass device with the amplified voltage;
- increasing a slew rate for a gate voltage of the pass device through use of an internal common-mode feedback unit in the error amplifier;
- obtaining an output voltage from the pass device;
- generating a feedback voltage through division of the output voltage at a feedback circuit;
- and
- providing frequency compensation at a compensation circuit to the LDO voltage regulator to stabilize the output voltage, wherein the compensation circuit is connected between the error amplifier and a common node between the pass device and the feedback circuit.
Dependencies are inferred from the claim text.