EMI reduction by chip-package-board co-design

Electromagnetic radiation is always headachy issue in developing various electronic systems. Because electromagnetic radiation and interference (EMI) is very sensitive to signal routing and physical layout of power distribution network (PDN) in package and board as well as chip design. Therefore, chip-package co-design is becoming important by taking into account the total PDN impedance seen from the chip. Especially, parallel resonance peaks in the PDN due to the chip-package interaction induces the unwanted power supply fluctuation, and results in serious EMI troubles. In this paper, three test chips were designed with different on-chip PDN properties. These three chips were intended to have typical characteristics; oscillatory region and damped condition. Then, the effects of the total PDN impedance on EMI have been studied. In particular, anti-resonance peak was properly suppressed by establishing critical damping condition in chip-package-board co-design. EMI has been proved to be dramatically reduced by proper combination of on-chip capacitance, on-chip resistance and package inductance.