A voltage regulator circuit is operated by enabling a bias network operable to set a bias current in an amplifier. A startup circuit is connected to the bias network, the startup circuit operable to assist the bias network in setting the amplifier bias current during a startup period. The startup circuit is disconnected from the bias network responsive to the startup period lapsing while the voltage regulator circuit is enabled for resetting the startup circuit to an initial state. The bias network may be disabled to reduce the amplifier bias current. Subsequent re-enablement of the bias network is prevented until the amplifier is reliably disabled.