Pulse Timing Control of Multiple Signal Interconnections for Reduction of EMI

This paper presents pulse timing control method to reduce electromagnetic emission from multiple signal interconnections. Pulse timing control gives intentional skew between signals. Higher order harmonics are canceled because of the difference of the phase between the signals. Using this property, pulse timing control can reduce the EMI in wide frequency range. In this paper, we show that radiated electromagnetic field from multiple signal lines reduces its intensity to the same level of the field from one line by using pulse timing control. The result of measurement shows that EMI from four differential transmission lines can be reduced more than 9 dB in the 200 MHz to 800 MHz frequency range.