2. (50 points) This question compares two different ways to implement a four-input CMOS OR gate. (a) A four input OR gate can be constructed by three two-input CMOS OR gates. The outputs of two two-input OR gates are connected to the inputs of the third two-input OR gate. Draw the corresponding circuit diagram. How many transistors (both PMOS and NMOS) are required? (b) Show how you can use only 2-input CMOS NAND and NOR gates to build the four- input OR gate. How many transistors (both PMOS and NMOS) are required? (Hint: Use DeMorgan's theorem.)