Signal distortion and EM radiation of clock distribution net on multichip module

The clock distribution is important in high-speed multichip module or printed circuit board design. Because the clock distribution net is long and carries the highest frequency signal in the system, it is one of the major sources of electromagnetic (EM) radiation. On the other hand, the clock signal is the time base of all synchronized components, so the waveform and timing skew should be controlled carefully. There are many kinds of clock routing methods, such as daisy chain, control stub length route, star route, and H-type route. Both the signal distortion and the radiation characteristics of the star and the H-type route are studied. The placement of the IC chip in each of the two kinds of distribution net is the same