Fast-disabled voltage regulator circuit with low-noise feedback loop and operating method thereof

A voltage regulator circuit comprising:

• an amplifier circuit comprising a first receiving terminal and a second receiving terminal for receiving a reference voltage and a feedback voltage respectively, the amplifier circuit outputting a driving voltage according to the reference voltage, the feedback voltage, and an enable signal;
• an output transistor comprising three terminals electrically connected to the amplifier circuit, an output node, and a first voltage source respectively, the output transistor outputting a regulated voltage at the output node according to the driving voltage output by the amplifier and a voltage provided by the first voltage source;
• a first discharge transistor having a first size and comprising three terminals electrically connected to a reverse enable signal, the output node, and a feedback node respectively, the first discharge transistor controlling whether or not the output node is electrically connected to the feedback node according to the reverse enable signal, wherein the feedback node is electrically connected to the second receiving terminal of the amplifier circuit for providing the amplifier circuit with the feedback voltage;
• a second discharge transistor having a second size being different than the first size and comprising three terminals electrically connected to the reverse enable signal, the feedback node, and a second voltage source, the first discharge transistor controlling whether or not the feedback node is electrically connected to the second voltage source according to the reverse enable signal;
• and
• a loading module electrically connected to the output node, the feedback node, and the second voltage source.