A Condition-Adaptive △f3-EMI Control GaN Switching Regulator With Modulation Frequency Envelope Tracking For Full-Spectrum Automotive CISPR 25 Compliance

As the fastest growing sector of global IC market, automotive IC industry advances quickly toward record high levels of electrification, communication, sensing and autonomous driving. A tremendous hindrance it faces, however, is ever-deteriorating electromagnetic interference (EMI) as increasing numbers of electronic devices and functions are continuously integrated into the modern vehicles. Among them, switching power circuits account for a significant portion of EMI emission due to the nature of frequent switching and large power handling. This gets more severe considering limited vehicle space. Accordingly, high fsw operation has become an inevitable measure to achieve high power density, which, however, adversely elevates EMI level further, as di/dt and dv/dt get even larger at high f
sw
. Historically, passive EMI filters and active circuit techniques such as spread-spectrum modulation (SSM) [1] have been common remedies for EMI compliance. While passive filter solutions are widely used, they are bulky in general and not favorable for high power density. Moreover, they are usually designed for “the worst case” and cannot be readjusted as operation condition changes, leaving EMI performance in many conditions far from what it could be. This situation unfortunately also applies to nearly all existing SSM schemes, despite that they are active circuit based.