Impact of current sensing resistor on required MOSFET aspect ratio in PWM converters

This paper examines the impact of a current sensing resistor used in current-mode control of PWM converters on MOSFET aspect ratio. The results can also be applied to the impact of source parasitic resistance in a power MOSFET. These resistances introduce significant error in the required aspect ratio to achieve a desired maximum current capability. Experimental results are presented showing the validity of the theoretical results.