a method of simulating hot carrier deterioration of a p - mos transistor uses the following formulas , , and or the following formulas , , and , and coefficients a , n , b and m are determined by a preliminary measuring experiment , whereby a transistor lifetime r can be estimated : vth = vfb + σ • vd δvth = δvfb . sub . f = a • σ . sup . n τ = b •. sup .- m δvth = δvfb + δσ • vd