Patent ID: 7385441

Claim:
A level shifter circuit comprising: a buffer circuit comprising: a first transistor having a control terminal coupled to a variable input voltage of the level shifter circuit; a second transistor having a first terminal coupled to a first terminal of the first transistor; and a buffer switch having a first terminal coupled to the first terminal of the second transistor and a second terminal coupled to a control terminal of the second transistor; and a bootstrap circuit comprising: a diode circuit having a first terminal coupled to the variable input voltage of the level shifter circuit; a bootstrap switch having a first terminal coupled to the control terminal of the second transistor; a capacitor coupled between the first terminal of the second transistor and a second terminal of the bootstrap switch, and coupled to a second terminal of the diode circuit; and wherein the buffer switch closes to turn off the bootstrap switch when the input voltage at a low state and the buffer switch opens to enable the bootstrap switch when the input voltage is at a high state.