Transmitting device for high speed communication, interface circuit and system including the same

A transmission device comprising:

• a main driver configured to output an output signal with one level among a high level, a middle level and a low level, to an output node, based on an input signal;
• and
• a variable emphasis driver configured to drive the output node with one of first and second driving forces based on transition information of the input signal, wherein the variable emphasis driver drives the output node to a voltage level corresponding to the middle level when the input signal retains the middle level or when the input signal transitions from the low level or high level to the middle level,
• wherein the variable emphasis driver drives the output node to both a power supply voltage and a ground voltage simultaneously to drive the output node to the middle level.