Patent ID: 8093939

Claim:
A level shift circuit that converts input signal levels into a level between a first voltage and a second voltage which is higher than the first voltage, the level shift circuit comprising: a select circuit that generates an oscillation signal according to the input signal, at least one of a frequency and an amplitude of the oscillation signal changing; a filter circuit that removes a DC component of the oscillation signal output from the select circuit and outputs an AC component; a detect circuit that operates between the first voltage and an output side voltage of the filter circuit and generates a control signal having a signal voltage that changes according to a change of at least one of the frequency and the amplitude in the AC component of the oscillation signal; and an output circuit that generates an output signal according to the control signal, the output signal having a level between the first voltage and the second voltage, wherein the select circuit comprises: a first switching unit that generates the oscillation signal; a second switching unit connected in series with the first switching unit; and a third switching unit wherein: the first switching unit generates the oscillation signal based on an on or off state of the second switching unit, one of the second switching unit and the third switching unit receives an input control signal, and the other one of the second switching unit and the third switching unit receives an inverted input control signal.