Consider a buck converter with the following parameters: input voltage Vin = 48 V, output voltage Vo = 12 V, load resistance R = 2 Q2, on-state resistance of the switch sw = 100 m2, diode forward voltage drop VD = 0.9 V, inductor de resistance r = 10 mQ. Assume CCM operation and find the duty ratio D and the efficiency of the converter.