We now have two problems that are related to temperature.

Firstly, according to the BSIM4's model, we should have linear equation between threshold voltage and temperature, while when we simulate the NMOS, it shows totally linear, but in PMOS it shows some non-linearity. I wonder is this temperature non-linearity is caused by which parameter since BSIM4 doesn't include that.

Secondly, when we simulate the output impedance(gds) of a NMOS working in saturation, then sweeping temperature range from 0 C to 120C, we found that gds has some positive slope and negative slope with different Vds. However, in your model, the prt parameter is 0, so we are confused that is there any parameter associated with temperature affects gds? Since we don't know how IBM 0.13um define its BSIM4 model and we don't think it uses the nominal BSIM4 to define the gds model. Thanks!