I have plotted Id versus Vg and also drawn log(Id) versus Vg curve for my MOSFETs in Origin software. I have also used linear fitting option in Origin to linear fit the linear part in Id vs. Vg curve. However, I am not able to understand about how to decide about the divisions or scales on the Y-axis i.e of log(Id) to get the readings in mV/Decade. Please tell me about the method of selection of divisions on the Y-axis that has been converted into log(Id) scale.

Thank You In Advance.