Apparatus and methods for voltage regulation

Apparatus and methods for voltage regulation are provided. In some implementations, a voltage regulator circuit includes a field-effect transistor including a source that receives a battery voltage from an input node and a drain coupled to an output node, an amplifier including an output coupled to a gate of the field-effect transistor, and a voltage generator that receives the battery voltage from the input node and provides a reference voltage and one or more bias voltages to the amplifier. The voltage generator controls the amplifier to operate the voltage regulator circuit in a regulation mode or in a bypass mode based on a voltage level of the battery voltage. The amplifier and the field-effect transistor regulate the battery voltage in the regulation mode to provide a regulated voltage at the output node, and the amplifier turns on the field-effect transistor in the bypass mode to provide a bypass voltage substantially equal to the battery voltage at the output node.