Transmission Device and Near Field Communication Device Using the Same

A near field communication device, comprising:

• an operating circuit;
• an antenna;
• and
• a transmission device, coupled between the operating circuit and the antenna, for transmitting high-frequency signals outputted by the operating circuit to the antenna or transmitting high-frequency signals induced by the antenna to the operating circuit, the transmission device comprising:
• a matching circuit;
• a connecting interface with a first width, for connecting the operating circuit;
• a first transmission line, electrically connected between the antenna and the matching circuit;
• and
• a second transmission line, electrically connected between the connecting interface and the matching circuit, comprising an increasing width portion and a constant width portion, wherein a width of the second transmission line within the increasing width portion increases from the first width to a second width, a width of the second transmission line within the constant width portion substantially maintains the second width, and the second width is greater than and related to the first width.