An output buffer including a first switch circuit and a buffer is provided. The first switch circuit receives first and second input signals. The buffer circuit includes first and second input stages, first and second output stages and a second switch circuit. The first and the second input stages are coupled to the first switch circuit. The first and the second output stages are coupled to the second switch circuit. The second switch circuit, coupled to the first and the second input stages and the first and the second output stages, selectively couples one of first and the second input stages to the first output stage and selectively couples the other to the second output stage. The first switch circuit further selectively provides one of the first and the second input signals to the first input stage and selectively provides the other to the second input stage.