A microphone circuit includes a signal generating module, a filtering module, a transmitting module and a switch module. The signal generating module transforms audio signals into electronic signals. The filtering module is connected to the signal generating module to filter the electronic signals sent from the signal generating module. The transmitting module is connected to the filtering module to transmit the signals sent from the filtering module. The switch module is connected to the signal generating module to selectively regulate the microphone circuit to function as a differential microphone circuit or a single-ended microphone circuit.