Patent ID: 7425845

Claim:
A semiconductor integrated circuit comprising: a first input/output circuit operating on a first power source voltage; an internal circuit operating on a second power source voltage lower than the first power source voltage; and a second input/output circuit operating on a third power source voltage lower than the first power source voltage, wherein the first input/output circuit includes a first level shifter for converting a signal having signal amplitude corresponding to the second power source voltage to a first signal having signal amplitude corresponding to the first power source voltage, and a first output circuit constructed by a first P-channel MOSFET and a first N-channel MOSFET for generating an output signal having signal amplitude corresponding to the first power source voltage in response to the first signal generated by the first level shifter, and wherein the second input/output circuit includes a second level shifter for converting a signal having signal amplitude corresponding to the second power source voltage to a second signal having signal amplitude corresponding to the first power source voltage, and a second output circuit constructed by second and third N-channel MOSFETs for generating an output signal having signal amplitude corresponding to the third power source voltage in response to the second signal generated by the second level shifter.