At the present stage of development of energy-efficient technologies – pulsed devices and systems for amplifying information signals and converting electrical energy, the problem of electromagnetic compatibility (EMC) of information and computing technology and radio-electronic equipment (REE) is becoming more and more acute. One of the most pressing EMC problems is caused by the presence of conducted electromagnetic interference (EMI) traveling along wires. This problem is eliminated by using EMI filters, which localize EMI at the place of its occurrence. Further development of functional REE (sensitivity, expansion of the frequency range by tens of thousands of times) requires the development of design theory, new design principles to meet new requirements for the EMI filters. The article discusses the development of EMI filter with overlapping frequency range 9 kHz – 100 MHz (eleven thousand times) with EMI attenuation of 50–60 dB on a domestic electronic component. Achieving this goal required new principles for designing EMI filter: development of new principles for the synthesis of structural-parametric electrical equivalent circuits of inductors and capacitors in EMI filter; study of the stability of the "filter-converter" system, caused by the negative real component of the complex input impedance of a pulsed voltage converter with negative feedback. A methodology for designing a broadband PDF with an overlap of the protected frequency range from EMI by eleven thousand times (9 kHz – 100 MHz) has been developed. The developed EMI filter with a frequency range of 9 kHz – 100 MHz is used in new radio navigation systems. The proposed methodology for designing EMI filters and methods for creating behavioral models of capacitors and inductors will be expanded to other groups of capacitors and inductors.