18.8 A Fully-Generic-Process Galvanic Isolator for Gate Driver with 123mW 23 Power Transfer and Full-Triplex 21/14/0.5Mb/s Bidirectional Communication Utilizing Reference-Free Dual-Modulation FSK

摘要

An up-to-date gate control technique for an advanced power converter with highspeed switching devices requires bidirectional, responsive and independent multiple communication, including gate PWM signal, monitoring and configuration signals for power stage protection and preventive maintenance (Fig. 18.8.1). Both the gate control and monitoring signals require over 1 OMb/s data rate while the configuration signal requires up to 100kb/s. For functional safety, over 50mW isolated power transfer for operating the diagnostic circuits is required as well in preparation for power supply loss in the high-voltage side caused by unexpected failure of the supply path. The magnetically coupled galvanic isolator is attracting attention [1]–[3], but the transformer implementation method combined with the coupler-sharing scheme is a key factor for compact and cost- effective realization. An on-chip transformer is area efficient but it requires a special dielectric process and its poor quality factor limits the power transfer efficiency even if high-voltage MOS transistors are employed [1], [3]. A post-process microtransformer [2] needs a special post-process and provides a quality factor of less than 10. As for the coupler-sharing scheme, ASK modulation over the power transformer is unsuitable for guaranteeing low BER because a large modulation index introduces power transfer quality degradation [1]. Sharing a coupler by half-duplex bidirectional communication [1], [3] cannot support the full-duplex communication required in this application.