Design Guidelines of Spread Spectrum Clock for Suppression of Radiation and Interference from High-speed Interconnection Line

In the modern digital systems, the most amount of the radiation from the system is caused by the high-speed clock signal. As a method to reduce the radiated emission from the system clock, the spread spectrum clock technique that modulates the system clock frequency had been introduced. In this paper, we introduce the design guidelines of the spread spectrum clock for the suppression of electromagnetic radiation and interference from the high-speed digital interconnection line. We propose some formulas for the attenuation of maximum spectrum at odd harmonics of the spread spectrum clock with the triangular modulation profile using FFT algorithm. The formulas include jitter and peak deviation as well as fundamental and modulation frequencies. We expect that these formulas are helpful to designers who adopt the spread spectrum clock technique to suppress the electromagnetic radiation and interference from the highspeed digital interconnection line.