A method of operating an earbud configured to be removed from and inserted into a user's ear canal can include generating an input signal by an input signal generating device. The method can also include determining whether an insertion event has occurred based on the generated input signal and causing the earbud to operate in a low power mode responsive to an absence of an insertion event determination after a first period of time. The method can also include causing the earbud to operate in an ultra-low power mode responsive to the absence of an insertion event determination after a second period of time that occurs after the first period of time, the ultra-low power mode having a lower power consumption than the low power mode.

A method for controlling one or more parameters of an amplifier system may include receiving an indication of a physical quantity associated with the amplifier system, determining one or more parameters of the amplifier system in response to the indication, and causing the amplifier system to operate in accordance with the one or more parameters.

A method for controlling one or more parameters of an amplifier system may include receiving an indication of a physical quantity associated with the amplifier system, determining one or more parameters of the amplifier system in response to the indication, and causing the amplifier system to operate in accordance with the one or more parameters.

An amplifier circuit for a microphone, a microphone circuit and an electronic device are provided. The amplifier circuit includes a voltage regulator having an output terminal, a first constant current source having an input terminal connected to the output terminal of the voltage regulator, a first transistor having a gate serving as an input terminal of the amplifier circuit and a source serving as an output terminal of the amplifier circuit, a second transistor having a source connected to an output terminal of the first constant current source, a gate connected to the source of the first transistor and a drain connected to ground, a first driver configured to achieve high power supply rejection ratio of the amplifier circuit and a second driver configured to achieve high acoustic overload point of the amplifier circuit.

An amplifier circuit for a microphone, a microphone circuit and an electronic device are provided. The amplifier circuit includes a voltage regulator having an output terminal, a first constant current source having an input terminal connected to the output terminal of the voltage regulator, a first transistor having a gate serving as an input terminal of the amplifier circuit and a source serving as an output terminal of the amplifier circuit, a second transistor having a source connected to an output terminal of the first constant current source, a gate connected to the source of the first transistor and a drain connected to ground, a first driver configured to achieve high power supply rejection ratio of the amplifier circuit and a second driver configured to achieve high acoustic overload point of the amplifier circuit.