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 this input...http://www.google.com/patents/US5557221?utm_source=gb-gplus-sharePatent US5557221 - Semiconductor integrated circuit with input/output interface adapted for small-amplitude operation
