A linear regulator circuit having fast transient response includes an error amplifier (EA) circuit and an output stage circuit. The EA circuit amplifies a difference between a feedback signal and a reference signal to generate an error amplified signal. The output stage circuit includes at least one output power switch which is controlled by the error amplified signal to generate an output signal at an output node. The EA circuit includes at least one pre-stage amplifier circuit which includes a current source circuit, a differential input circuit, a first, a second and a third current mirror circuits and at least one feedback capacitor. One differential transistor of the differential input circuit, the first and the second current mirror circuit form a positive potential feedback (PPFB) loop. The feedback capacitor is coupled between the output node and at least one inverting node at the PPFB loop.