JSSC 2025第12期RF & Wireless0.18-µm BCD工艺

A Shoot-Through-Free 180-MHz Isolated Converter With PG-Downsized PA for Low EMI Tian Xia, Student Member , IEEE

一种180MHz低EMI隔离转换器，采用PG缩放的D类功率放大器，有效消除偶极子辐射并防止直通电流。

45.3%峰值效率，1W最大输出功率，符合CISPR-32 Class-B标准

隔离转换器低EMID类功率放大器频率跳跃PCB变压器

▸创新点1：对称拓扑结构消除偶极子辐射（电路创新）。通过采用对称的Class-D功率放大器拓扑，有效抵消了偶极子天线效应产生的电磁辐射，显著降低了EMI，符合CISPR-32 Class-B标准。

▸创新点2：串联电感防止直通电流（电路创新）。在交叉连接的高侧和低侧晶体管之间插入串联电感，物理阻断了直通电流路径，无需复杂控制电路即可实现天然隔离，提升可靠性。

▸创新点3：主动驱动晶体管解决振荡退化问题（方法创新）。采用小尺寸主动驱动晶体管辅助原始功率管的被动驱动模式，既维持了Class-D振荡器的栅极电荷回收特性（降低PG损耗），又避免了振荡退化，仅造成3%以内的效率损失。

▸创新点4：非对齐频率切换降低系统复杂度（系统创新）。允许开关频率与振荡频率存在偏差，省去校准电路的同时支持跳频扩频技术，进一步抑制EMI峰值，系统效率仍保持45.3%峰值。

Abstract

This article presents a 180-MHz low electromagnetic interference (EMI) isolated dc-dc converter using a PG-downsized Class-D power ampliﬁer (PA). This PA features a symmetrical topology that e ﬀectively cancels dipole emissions, while its series inductors placed between the cross-connected high-side and low- side transistors that inherently block shoot-through currents. To address the resulting degeneration states of oscillation, we introduce small, actively driven transistors, whereas the original power transistors operate in a passively driven manner, with their gate charge recycled like in a Class-D oscillator. This preserves the advantage of low gate drive loss ( PG) in high-frequency oscillators. The frequency misalignment between the switching and oscillation frequencies leads to only minor e ﬃciency degra- dation. This eliminates the requirement for switching frequency calibration, while enables the low-complexity frequency hopping to further reduce EMI. We fabricated the PA and the receiver (RX) chips using 0.18- µm bipolar–CMOS–DMOS (BCD) process and attached them with a 14.4-mm 2 PCB transformer. The converter achieves a 45.3% peak e ﬃciency and a maximum output power of 1 W. It complies with the CISPR-32 Class-B standard.