Could you help me with this if you know about this and when you have time? From b4ld.c file of latest BSIM4 version this is the code section for calculating gm: Ids = Idsa * T0; Gm = T0 * dIdsa_dVg - Idsa * (dVdseff_dVg + T9 * dVASCBE_dVg) / VASCBE; Gds = T0 * dIdsa_dVd + Idsa * (1.0 - dVdseff_dVd - T9 * dVASCBE_dVd) / VASCBE; Gmb = T0 * dIdsa_dVb - Idsa* (dVdseff_dVb + T9 * dVASCBE_dVb) / VASCBE; tmp1 = Gds + Gm * dVgsteff_dVd; tmp2 = Gmb + Gm * dVgsteff_dVb; tmp3 = Gm; Gm = (Ids * dVdseff_dVg + Vdseff * tmp3) * dVgsteff_dVg; The first yellow line is Gm that is equal to derivative of Ids with respect to Vgs. I already checked and understood how to derive this result. However, I couldn't follow why Gm is calculated as the second yellow line? Where does this equation come from? Also, if I am not mistaken the dimensions are inconsistent here. The left hand side of the equation Gm has unit of current over voltage while the right hand side has unit of current.
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