Patent ID: 8169250

Claim:
A signal level conversion circuit, comprising: (a) a first level shift circuit to output a first internal output signal upon receiving a first input signal including: a first electrical element supplied with a first voltage, a first common electrical element connected to the first electrical element and supplied with a common voltage lower than the first voltage; and a first buffer circuit provided in the first common electrical element and having an input tolerant function; (b) a second level shift circuit to output a second internal output signal upon receiving a second input signal including; a second electrical element supplied with a second voltage higher than the common voltage, a second common electrical element connected to the second electrical element and supplied with the common voltage, a second buffer circuit provided in the second common electrical element and having an input tolerant function, and (c) a third level shift circuit to output a third internal output signal upon receiving a third input signal including: a third electrical element supplied with a third voltage higher than the common voltage, a third common electrical element connected to the third electrical element and supplied with the common voltage, and a third buffer circuit provided in the third common electrical element and having an input tolerant function, and wherein each signal level of the first, second and third internal output signals is set lower than the first, second and third input signals by the first, second and third buffer circuits, and the internal output signal outputted from one of the first, second and third level shift circuits is further outputted via other level shift circuits, each of the first, second and third level shift circuits includes a level conversion circuit and an internal output signal outputted from one of the first, second and third level shift circuits is inputted to each level conversion circuit of other level shift circuits; and each of the first, second and third common electrical elements includes an inverter circuit connected to the level conversion circuit, and the internal output signal is inputted to the inverter circuit.