What Textbooks (and SPICE) Tell You About MOS Transistors is Wrong Slides

Abstract: Design of analog CMOS circuits requires a proper understanding of how MOS transistors work. Almost all design textbooks present incorrect small-signal models for MOS transistors. They emphasize Cgd, which for the intrinsic transistor is negligible in saturation, and completely ignore Cdg, which is the 2nd largest capacitance in saturation (where most MOS transistors in analog circuits operate). What is the difference between Cgd and Cdg? Why is the most important of these in saturation not Miller multiplied? Why are the gm and VDsat values that SPICE tells you wrong? Find out in this talk.