A printed circuit board assembly includes a printed circuit board, a number of electronic components mounted thereon, and a number of conductive traces electrically connecting the components to form a number of transmission channels. Each of the channels has first and second transmission routes for transmitting differential signals. Each channel includes a common mode choke, a pair of capacitors, and an autotransformer. The common mode choke includes a first coil series connection with the first transmission route and a second coil series connection with the second transmission route. The capacitors include a first capacitor series connection with the first transmitting route and a second capacitor series connection with the second transmitting route.