Design equation comparison between simplified device physic equation and exact device physic equations of the fully differential output 2 stage microwave amplifier implement with BJT

This paper presents for the first time analysis and design of the propose fully differential rail to rail input and output 2 stage amplifier by simplified Ebers Moll equation compared with device physics equation which can be optimize at the level of doping concentration which should have an influence on mobility models of the transistor. The author also compare the issue about when the circuit designer design the amplifier with same physical transistor size at the same current level but with different technology such as silicon versus silicon germanium, the transition frequency which is the frequency for small signal voltage gain fall below 0 dB is not the same.