A semiconductor integrated circuit includes a switch unit for controlling the supply of a power source voltage to a signal amplification circuit for receiving an input signal, and a control unit for selectively turning ON and OFF the switch unit in accordance with the amplitude or frequency of the input...http://www.google.de/patents/US6720804?utm_source=gb-gplus-sharePatent US6720804 - Semiconductor integrated circuit with input/output interface adapted for small-amplitude operation
