Asymmetric gate resistor power MOSFET

Power converters, e.g. in a popular synchronous buck topology, need high performance power MOSFETs in order to achieve high efficiency, low voltage ringing, ESD protection and low EMI. To satisfy these requirements, an asymmetric gate resistor power MOSFET is proposed by integrating a shunt resistor with a parallel LDMOSFET-connected diode in a source down power MOSFET (NexFET). The novel MOSFET has several advantages. First, the shunt resistor is used to slow down the turn-on speed of the high-side (HS) MOSFET, resulting in small voltage ringing of the switch node and low EMI in a synchronous buck converter. Second, the integrated diode preserves a fast turn-off speed and high conversion efficiency. Third, the bulk diode of the LDMOSFET can achieve ESD protection for gate oxide.