A Through-Power-Link Hysteretic-Controlled Capacitive Isolated DC–DC Converter With Enhanced Efficiency and Common-Mode Transient Immunity

This article presents a capacitive isolated dc–dc converter with both the receiver (RX) and transmitter (TX) chips designed and verified in a standard 180-nm CMOS process with measurement results. This work achieves the following features. First, much higher efficiency, by using capacitive power links instead of low-quality micro-transformers and switching at a relatively lower frequency near resonance. Measurement shows a 68% peak efficiency, which is 15% higher than state-of-the-art miniature designs and is higher over almost the entire loading range. Second, RX local voltage and TX global power regulations are achieved with through-power-link feedback, neither using an extra pair of capacitors nor transformers. Third, the voltage-mode hysteretic control achieves a much faster transient response compared with previous works, with a simpler system complexity and neither small-signal bandwidth limitation nor stability concerns. Fourth, a two-layer “analog-keying” and “error-recovery” common-mode transient (CMT) immune strategy is introduced, achieving a ±8-kV CMT immunity (CMTI) measured in closed-loop operation. Fifth, reconfigurability to extend the power capacity with a shared TX chip, with measured 414-/828-mW capacity in one-/two-phase configuration. Sixth, low cost and high component compatibility, with measurements using different LC combinations, including high voltage (HV) capacitors with different dielectrics, voltage ratings, and footprints, and miniature 0402 inductors, and custom printed circuit board (PCB)-trace coil as the resonant inductors.