Patent ID: 6768368
Filing Date: 2004-07-27
Classification: H03K

Abstract:
A level shifter circuit, comprising:an input unit for receiving a first signal that varies between a first voltage source and a second voltage source; and a level shifter unit for converting the first signal to a level-shifted signal that varies between the first voltage source and a third voltage source, the level shifter unit including a first transistor of a first conductivity type having a source electrode coupled to the third voltage source, a second transistor of the first conductivity type having a source electrode coupled to the third voltage source, a gate coupled to a drain of the first transistor, and a drain coupled to a gate of the first transistor and wherein the drain of the second transistor is an output terminal of the level shifter unit for providing the level-shifted signal, a voltage source cut-off circuit that isolates the level shifter unit from the first voltage source, and a high impedance setting circuit that places the output terminal of the level shifter unit into a high impedance state when the level shifter unit is isolated from the first voltage source.