A voltage regulating circuit includes a pulse width modulation controller, a current sense circuit, a voltage feedback circuit, and a gain-and-bias circuit. The current sense circuit includes an inductor and a capacitor. The voltage feedback circuit includes first and second resistors. The gain-and-bias circuit includes an operational amplifier. A first terminal of the capacitor is connected to an inverting input terminal of the operational amplifier through a third resistor. A second terminal of the capacitor is connected to a non-inverting input terminal of the operational amplifier through a fourth resistor. The inverting input terminal of the amplifier is connected to an output terminal of the operational amplifier through a fifth resistor. The non-inverting input terminal of the operational amplifier is grounded through a sixth resistor. The output terminal of the operational amplifier is connected to the node between the first and second resistors through a seventh resistor.