An Automotive-Use Battery-to-Load GaN-Based Switching Power Converter with Anti-Aliasing MR-SSM and In-Cycle Adaptive ZVS Techniques

Abstract

In modern automotive electronics, there are uprising demands on enhanced power density and reliability for power delivery systems. To achieve high power density, single-stage gallium-nitride (GaN)-based power converters at high switching frequencies (fSW) are highly desirable but face formidable reliability challenges in the aspects of electromagnetic interference (EMI) suppression and consequential output voltage VO regulation. To address these challenges, this article presents a GaN-based switching power converter that employs an anti-aliasing multi-rate spread-spectrum modulation (MR-SSM) technique for EMI suppression and an in-cycle adaptive zero-voltage switching (ZVS) technique to minimize switching power losses. Compared with classic fixed-rate SSM (FR-SSM), the proposed MR-SSM technique spreads EMI spectra in a wider frequency range without aliasing spikes and, thus, reduces peak EMI more effectively. To improve efficiency, an elastic dead-time (tdead) control facilitates in-cycle ZVS despite of a continuously changing fSW. An IC prototype based on this design was fabricated on a 180-nm HV BCD process, with an active die area of 0.87 mm2. The converter can handle a variable automotive-use battery voltage from 5 to 24 V and delivers up to 1.2-W power to a regulated output VO at 1 V, with a peak efficiency of 90.2%. It accomplishes a 29% further peak EMI reduction compared with the FR-SSM counterpart.