Patent ID: 7265581

Claim:
A level shifter, comprising: a coupling device, which is coupled to a first signal via a first input end and coupled to a second signal via a second input end, outputting a first control signal in response to the second signal via a first output end and outputting a first reference voltage selectively via a second output end, wherein the first signal and the second signal are inverted, the first control signal having a first voltage in a first period and a second voltage in a second period, the coupling device comprising: a one-way conducting device, having a first end and a second end, the first end acting as the second output end to selectively output the first reference voltage, the voltage of the second end of the one-way conducting device being related to voltage of the second signal, the voltage of the second end of the one-way conducting device being a third voltage in the first period and being a fourth voltage in the second period; a first-type control transistor comprising a first gate, a first source and a first drain, wherein the first gate is controlled by the first control signal, while the first drain is for outputting a second reference voltage when the first-type control transistor is conductive; a first-type first transistor comprising a second gate, a second source and a second drain, wherein the second gate is controlled by the first control signal; and a first-type second transistor comprising a third gate, a third source, and a third drain, wherein the third gate is electrically connected to the first drain and the first end of the one-way conducting device, the third gate is controlled by the first reference voltage or the second reference voltage, and the third source is coupled to the second drain and generates an output signal; wherein in the first period, the first-type control transistor and the first-type first transistor are made conductive by the first voltage of the first control signal, the second reference voltage is generated so that the first-type second transistor is not conductive, the one-way conducting device is not conductive due to the second reference voltage and the third voltage of the second end of the one-way conducting device, and the voltage of the output signal is related to the voltage of the second source of the first-type first transistor; wherein in the second period, the first-type control transistor and the first-type first transistor are not conductive due the second voltage of the first control signal, the one-way conducting device is conductive due to the fourth voltage of the second end of the one-way conducting device to generate the first reference voltage, the first-type second transistor is made conductive by the first reference voltage, and the voltage of the output signal is related to the voltage of the third drain of the first-type second transistor.