A new grooved gate lateral power MOSFET structure for synchronous rectification in DC/DC converters

A new U groove channel implanted lateral MOSFET structure, suitable for synchronous rectifier application, has been presented. The conversion efficiency of MOSFET based isolated DC/DC converters with synchronous rectification, have been evaluated A detailed analysis of their operation and performance, has been discussed. The dependence of efficiency on input primary duty cycle and output voltage, and also on the critical duty cycle, has been analysed. The region of optimum operation has been suggested. The new MOSFET structure proposed in this work, includes a channel implanted U groove gate. The variation of the non uniform lateral concentration profile is responsible for a higher channel current for a desired threshold voltage. Based on an analytical model the effects of the groove angle, dose and energy of the implantation and other groove dimension, on the electrical performance of the device was carried out. The simulation results demonstrates that if properly optimised, higher current conduction at desired threshold voltage, as compared to a conventional MOSFET can be achieved. Experimental results obtained from fabricated test device structure supports the simulated current-voltage characteristics based on the model. Due to lower channel resistance, as compared to conventional MOSFET with planar gate configuration, it can be concluded that the proposed structure is suitable for synchronous rectifier application in DC/DC converters and is also integrable for SMART low voltage switching regulator modules.