Patent ID: 8755544

Claim:
An earphone power amplifier, comprising a ground contact connected to a ground wire of an earphone, a left sound channel power amplifying circuit connected to a left sound channel of the earphone, and a right sound channel power amplifying circuit connected to a right sound channel of the earphone, wherein the left sound channel power amplifying circuit comprises a first operational amplifier, the right sound channel power amplifying circuit comprises a second operational amplifier; and the ground contact is serially connected to a first ferrite bead; the left sound channel power amplifying circuit further comprises a first positive feedback exported from an input end of the first ferrite bead to an in-phase input end of the first operational amplifier, wherein the first positive feedback exported from the input end of the first ferrite bead is imported to the in-phase input end of the first operational amplifier through a resistor; and the right sound channel power amplifying circuit further comprises a second positive feedback exported from the input end of the first ferrite bead to an in-phase input end of the second operational amplifier, wherein the second positive feedback exported from the input end of the first ferrite bead is imported to an the in-phase input end of the second operational amplifier through a resistor; wherein the power amplifier further comprises a filter, an input end of the filter is connected to the input end of the first ferrite bead, and the filter is a resistor-capacitor RC low pass filter formed of a resistor of 120 ohm and a capacitor of 22 nF.