Circuits and methods for preventing glitch in a circuit are disclosed. In one example, a circuit coupled to an input/output pad is disclosed. The circuit includes: a first level shifter, a second level shifter, and a control logic circuit. The first level shifter is configured for generating a data signal. The second level shifter is configured for generating an output enable signal. The first and second level shifters are controlled by first and second power-on-control signals, respectively. The control logic circuit is coupled to the first level shifter and the second level shifter.