Akihisa Sakurai

Practical analysis on 20H rule for PCB

There are many papers dealing with the 20-H rule, which recommend that the power plane should be shrunk against the ground plane by 20 times of the distance between the planes to realize lower EMI radiation. The effect of the 20-H rule was studied with EM solver using MoM. Bypass capacitors were populated to simulate a realistic printed circuit board (PCB). From the evaluation of the electric and magnetic dipole moment, the contributions of common and differential modes current were calculated. It was found that common mode current in the ground plane was generated when the 20H rule was applied. At the resonance frequencies, the common and differential mode radiations are observed in accordance with its resonance mode, the common mode radiation due to y- or x-directional electric dipole moment for TM01 or TM10 respectively. Considering the common mode current occurrence is a fundamental mechanism of the electromagnetic radiation, it is concluded that the application of the rule increases the radiation.

Analysis on the power/ground plane resonance damping and radiated field reduction with the RC termination

The RC termination method is studied to dampen the resonance due to a pair of buried power and ground plane in a multilayered printed circuit board, which can cause unexpected EMI noise. The detailed experimental analysis has been carried out and adequate parameters were obtained. As the evaluation, measured and calculated S/sub 11/ were compared and showed good agreement in certain conditions. The radiated field measured was reduced with obtained resistance value. For the purpose of actual EMI design, the adequate parameter can be obtained with numerical calculations and without an actual sample of printed circuit board.

Introduction to VCCI [EMC standards]

The authors present an overview of VCCI, a voluntary council for controlling the EMI of IT products marketed in Japan. Participation is worldwide and the membership has continuously grown, and the EMI levels of almost all IT products in the Japanese market are virtually controlled by VCCI and its members.

Quantifying EM noise coupling to antenna coax cable placed in a digital device

We clarified a coupling mechanism through the air of electromagnetic noise generated a LSI mounted in the printed circuit board to the antenna coaxial cable placed in the same digital device. It is quantified with experiment and numeric simulation that how much noise power can be transferred to the coaxial cable and its terminal ends. Shield characteristics of the coaxial cable placed near a noise source is also examined and presented interesting results that will be usable for product design.

Recent movement in VCCI [Voluntary Laboratory Accreditation Center]

The fundamental rules of the Voluntary Control Council for Interference (VCCI) were presented. Recent movement in the VCCI was also presented with some statistics. The Voluntary Laboratory Accreditation Center (VLAC) inaugurated in 1998 was introduced. Thereby, it was shown that how successfully the VCCI had controlled the EMI of information technology equipment (ITE) placed onto the Japanese market.