Apparatus for chip-to-chip communications may include a first driving unit and a second driving unit. The first driving unit may receive input data, generate a first output data based on the input data, and output the first output data. The second driving unit may receive the input data, generate a second output data with a pre-emphasis peak and output the second output data. The second output data may be generated by delaying and inverting the input data, and have a predetermined weight.