Calculate the propagation delay from the falling edge of the clock to the output. Use the following values: W = 2λ = 0.25 μm, L = 2λ = 0.25 μm, Cg = 2 fF/μm, Cd = 1 fF/μm and R = 13 kΩ (NMOS transistor with width W and PMOS transistor with width 2W ).