Aspects of the disclosure provide a circuit that can include a depletion mode transistor coupled to a power source and a current path coupled with the depletion mode transistor in series to provide a current to charge a capacitor. Further, a gate terminal of the depletion mode transistor is coupled to a clamping path that includes a diode and a switch that connected in series. The clamping path clamps the voltage at the gate terminal of the depletion mode transistor to the capacitor. The clamping and the current paths respectively have a first resistance during a first stage, such as when the circuit initially receives power, and have a second resistance during a second stage when the capacitor is charged to have a predetermined voltage level.