A fan is provided. The fan includes a first power terminal, a second power terminal, a filter, a motor driver, a motor, a current sensor, and a controller. The filter includes an amplifying element, a resistor, and a capacitor, wherein a first terminal of the amplifying element is electrically connected to the first power terminal, a second terminal of the amplifying element is electrically connected to a first terminal of the resistor, and the capacitor is electrically connected between the second power terminal and a third terminal of the amplifying element. The motor is electrically connected to the third terminal of the amplifying element. The current sensor detects the current flowing through the motor and correspondingly generates a current sensing signal. The controller outputs a first control signal to the resistor according to the current sensing signal such that the amplifying element operating in an active region.