The present invention provides an electro-magnetic interference protection circuit for a clock buffer. The present invention not only uses a ferrite bead that is serially connected with the power source of the clock buffer to protect the clock buffer from electro-magnetic interference. The ferrite bead also connects in parallel with a capacitor to reduce the distortion of a clock signal out-putting by the clock buffer due to the ferrite bead, thereby making the communication devices work properly.

A connecting cable for bridging a computer host and a peripheral device including a signal line for data transmission and a power cable. A portion of the power cable is wrapped around the signal line to form the coil wire. Therefore, rapid noise variation of a braided wire on the signal line can pass the coil wire to induce a rapid change of magnetic flux and then further to generate a reverse induced current for eliminating the noise intensity on the power cable.