tailieunhanh - MOSFET MODELING FOR VLSI SIMULATION - Theory and Practice Episode 15

Tham khảo tài liệu 'mosfet modeling for vlsi simulation - theory and practice episode 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | I 1 SPICE Diode and MOSFET II Models and Their Parameters In this chapter we will discuss the injunction diode and MOSFET models as implemented in Berkeley SPICE2G and higher versions. No attempt will be made to derive the model equations as that has already been done at appropriate places in previous chapters. Here we will only describe equations used to model different regions of device operation. Emphasis will be on model parameters required to run SPICE and how to measure them. Berkeley SPICE has four different MOSFET models of varying complexity and accuracy l - 3 . These are 1 the Level 1 model a first order model suitable only for long channel devices 2 the Level 2 model that includes various second order effects present in small geometry devices and is considered to be a physical model 3 the Level 3 model a semi-empirical model that includes most of the second order effects described in the Level 2 model 4 the Level 4 model called the BSIM Berkeley Short-channel Igfet Model that is a parameter based model. These different models can be activated by a parameter called LEVEL. We will describe all four levels of MOSFET model equations and their parameters. However first we will describe the diode model parameters and how to determine them. Diode Model The SPICE diode model has been discussed in detail in section . Table shows model parameters that determine both DC and AC characteristics of a diode. Out of these ten parameters the first seven Is rj rs CjQ m and r are determined from diode drain current and capacitance measurements. The remaining three parameters are often not measured and default values are generally assumed for silicon pn junction diodes. For other type of diodes such as SBD Schotkey Barier Diode parameter XT I needs to be changed. In what follows we will discuss extraction for the first seven parameters. Diode Model 537 Table . SPICE Diode model parameters Parameter name in the text SPICE parameter name Parameter .