Impedance converting circuit and electronic device

An electronic device, comprising:

• a microphone;
• and
• a semiconductor circuit connected to the microphone, the semiconductor circuit including:
• an input terminal;
• an impedance converting portion configured to receive an input signal from the input terminal and to output an output signal corresponding to the input signal, an input impedance of the semiconductor circuit being higher than an output impedance of the semiconductor circuit;
• a detecting portion connected to a node between the input terminal and the impedance converting portion, and configured to detect whether the input signal is higher than a predetermined threshold;
• and
• a variable impedance connected to a reference voltage and the node, an impedance of the variable impedance configured to decrease after the input signal is detected as higher than the predetermined threshold,
• wherein the variable impedance includes a current mirror circuit connected to the node and the reference voltage.