Eric Rolland

High frequency EMC impact of switching to improve DC-DC converter performances

This paper presents an analysis of the high frequency disturbances from switching operation in a SoC (System on Chip) Buck converter for EMC (Electromagnetic Compatibility) performance improvement. The impact of key design parameters is handled with an analytic approach, allowing Conducted Emission (CE) spectrum prediction.

Design for high EMC immunity of an alternator voltage regulator integrated circuit

Often in automotive applications, a well optimized board with decoupling capacitors in proximity of the Integrated Circuit is used to improve EMC performances in system level. With increased safety concerns on mechanical vibrations that leads to lost interconnections of components, there is demand to have a complete solution inside the IC. Being the cars electrical supply, the alternator has to pass stringent electromagnetic stresses such as Bulk Current Injection, BCI. In addition, due to the fact that the bare die is directly die attached to the slip ring brush holder, there is little space left for external components. The IC itself has to be designed for high immunity to guarantee parametric performance during electromagnetic interferences. This paper compares BCI performances of two silicon versions. The first being designed for typical EMC voltage injection of 2.5V peak and the second version was designed for high immunity against electromagnetic stress after laboratory measurements.

Benefits of multiphase Buck converters in reducing EME (Electromagnetic Emissions) Analysis and application to on-chip converters for automotive applications

Inside the car, all integrated circuits “IC” have to be optimized to survive against severe external aggressions. The noise generated by each activity inside each IC must be low enough, to not disturb the environment. As known nowadays, DC-DC converters can significantly impact the Electromagnetic Compatibility “EMC” performances, and mainly the emission ones. Unfortunately, simulation with linear models like ICEM or IBIS models [1, 2] remains very challenging for integrated analogue products due to the high number of parameters, plenty of possible applications and the extent of the frequency domain where the integrated circuit must be compliant. A paper describes an analytical approach to highlight the main contributors to the high frequency noise generated by switching activity in Buck converters [3]. This approach is here employed to evaluate Conducted Emission “CE” performance of multiphase interleaved Buck converters and to highlight benefits of increasing the number of phases in improving the emission profile.

Design of charge pump with very low conducted emission controlling the majority carrier injection

This work evaluates how reducing the conducted emission of battery line of an alternator regulator by reducing substrate majority carrier injection of a charge pump circuitry. The investigation shows the significant impact of substrate Nwell junction (PN junction) of poly poly capacitors on conducted emission on battery input /output during charge pumping. When Nwell layer of poly-poly capacitors is left open, parasitic Nwell to substrate capacitor will be added to the poly -poly capacitor and increase efficiency of charge pump in term of current delivered at a given voltage. In the other hand this parasitic capacitor will couple the generated noise during switching ON/OFF to charge/discharge the poly-poly capacitor to the substrate. This noise will be conducted to global pins through ESD parasitic capacitor and any other parasitic capacitor between substrate and a global pin. This study will give a solution to improve charge pump capability and at the same time reducing drastically its conducted emission.