Effects influencing repeatability of direct power injection measurements

The electromagnetic compatibility (EMC) performance of the voltage regulators is the significant factor in the EMC performance of the complete electronic system. In this paper the characterization of the voltage regulator by direct power injection (DPI) method is presented. Although, the DPI method is defined by various standards, the repeatability of the measurement can be compromised by several factors. The DPI method measurement results are presented for the L4949 voltage regulator. The repeatability of the method is assessed by various factors related to the operating point of the voltage regulator and to the measurement set-up. The obtained results are compared to the results presented by other authors.