The present invention relates to an electronic device, which comprises: a first module, comprising an I/O pad for being an interface between the electronic device and an external device, and receiving a first bias source; a second module, coupled to the first module, comprising a register, and receiving a second bias source; and a signal converter, coupled between the first module and the second module. Wherein when one of the first and second bias sources is stable and the other is unstable, the signal converter outputs a first predetermined bias value to the first or second modules receiving the unstable bias source.