Patent ID: 7358773

Claim:
A signal level conversion circuit having voltage sources for supplying a first power voltage higher than a predetermined reference voltage and a second power voltage higher than the first power voltage, respectively, and comprising at least a first terminal for a signal of the first power voltage, a second terminal for a signal of the second power voltage, and a level shifter circuit which is disposed in a signal path between the first terminal and the second terminal to convert the signal of the first power voltage into the signal of the second power voltage, the circuit further comprising: a first input buffer circuit including a first inverter which is connected to the first terminal and a one-way device which is interposed between the first inverter and the first power voltage and which supplies a current from the first power voltage to the first inverter; and the level shifter circuit including second and third inverters which are interposed between an output of the first input buffer circuit and the second terminal and which use the second power voltage and which are connected in series, an input of the second inverter and an output of the third inverter being connected to the output of the first input buffer circuit, wherein a circuit threshold value of the second inverter is set to be lower than a voltage obtained by subtracting a voltage drop of the one-way device from the first power voltage.