As GaN-on-Si becomes more common in DC-DC converter designs, questions often arise from experienced designers about the impact of the unique characteristics of GaN transistors when used as synchronous rectifiers (SRs). In particular, the third quadrant off-state characteristics, better known as “body diode” conduction in Si MOSFETs, which is activated during converter dead-time, is of interest. For this article, the focus will be on the similarities and differences of Si MOSFETs and eGaN® FETs when operated as a “body diode” and outline their relative advantages and disadvantages.
Bodo’s Power Systems
By David Reusch & John Glaser