32.1 A 180MHz 45.3%-Peak-Efficiency Isolated Converter Using Q-Downsize Class-D Power Amplifier with Inherent Shoot-Through Current Blocking and High Tolerance for Efficiency Despite Frequency Misalignments

Isolated DC-DC converters [1]–[8] with low electromagnetic interference (EMI) are crucial for system safety and reliability in harsh industrial environments. Typically, input-to-output dipole radiation caused by the common-mode (CM) current <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$I_{CM}$</tex> across the isolation barrier leads to EMI issues (Fig. 32.1.1) [9]. A common practice to reduce dipole radiation is to suppress the variation of CM voltages <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\Delta V_{CM})$</tex> on the transformer [1], [2], which is achieved by fully symmetrical transmitter (TX) topologies. Meanwhile, a transformer pair with coils routed in opposite directions cancels magnetic field, further improving EMI performance [3].