Patent ID: 7741872

Claim:
A level shifter for generating an output signal from an input signal comprising: an input buffer biased with both a first voltage and a ground voltage and receiving the input signal, wherein the input buffer has a first output end and a second output end; an output buffer biased with both a second voltage and the ground voltage and outputting the output signal; a level-processing unit coupled between the output buffer and the input buffer via the first output end and the second output end, wherein the level-processing unit is biased with both the second voltage and the ground voltage for shifting the input signal to provide the output signal; and a voltage-drop unit coupled to the level-processing unit, biased with both the first voltage and the second voltage, and providing an initializing voltage for the level-processing unit according to the second voltage while the first voltage source is in an OFF and the second voltage is switched on; wherein the voltage-drop unit comprises: a voltage-drop element coupled to the second voltage for providing a voltage drop of the second voltage; and a switching element coupled to the voltage-drop element in series, wherein the switching element is conducted in response to the OFF state of the first voltage and provides the initializing voltage for the level-processing unit.