A circuit includes a gate node, and a bias circuit coupled to the gate node. The bias circuit is configured to, in response to a change in a gate voltage on the gate node, provide a positive feedback to the gate voltage. A power circuit is coupled to the gate node, wherein the power circuit includes a power Metal-Oxide-Semiconductor (MOS) transistor. The power circuit is configured to, in response to a change in the gate voltage, provide a negative feedback to the gate voltage. An output node is coupled to the power circuit.