Patent ID: 7019578

Claim:
An input circuit for receiving a first input signal and for use with a first power supply and a second power supply that supplies a voltage of absolute value less than an absolute value of the first power supply, the input circuit comprising: a first differential amplification circuit powered by the first power supply to receive and amplify the first input signal and generate a second input signal; a level shift circuit powered by the first power supply to shift voltage of the second input signal and generate a shifted input signal, the level shift circuit including an output terminal; a second differential amplification circuit powered by the second power supply to amplify the shifted input signal and generate an amplified signal; and a current control circuit connected between the first power supply and the first differential amplification circuit to selectively switch the input circuit between an activated state and a standby state, wherein the level shift circuit further includes a first circuit for charging or discharging voltage at the output terminal of the level shift circuit so that voltage of the shifted input signal is less than or equal to the absolute value of the voltage of the second power supply when switched to the standby state.