A feedback loop circuit of a voltage regulator includes a voltage extraction circuit and a loop filter circuit. The voltage extraction circuit receives an error voltage signal that is indicative of difference between an output voltage signal and a reference voltage of the voltage regulator, and generates a voltage extraction signal by extracting one representative voltage for one switching cycle of the voltage regulator according to the error voltage signal. The loop filter circuit applies filtering to the voltage extraction signal to set a feedback signal, and output the feedback signal to a controller circuit of the voltage regulator for regulating the output voltage signal.