Optimization of Body Diode Reverse Recovery Characteristics of Lateral Power MOSFETs for Synchronous Rectifier DC-DC Converters

This paper investigates the poor body diode reverse recovery characteristics of lateral power MOSFETs. It is found that the lightly doped P-substrate accommodates an excessive amount of minority carrier storage charge when the body diode between the P-substrate and N-drain is forward biased. The excessive storage charge causes a long tail in the reverse recovery current waveform of the body diode. Two LDMOS structural variations are explored to improve the body diode performance for hard-switching synchronous rectifier DC/DC converter applications. Both simulation and experimental results show that over 90% reduction in reverse recovery charge can be achieved with the new device structures.