Advanced non-quasi-static MOSFET modeling for circuit simulations.

摘要

With the continuous advancements in silicon technology, CMOS has found wider applications in the wireless communication circuits. To provide accurate and efficient circuit simulations to the designers, compact MOSFET models need to keep pace with the development in new application areas by considering more physical effects.; Most compact MOSFET models assume that the device operation is quasi-static, which means that charges in the channel can respond instantaneously to the variations of the terminal voltages. This assumption breaks down and non-quasi-static effect needs to be considered in high speed, high frequency circuits, where time constants of the applied signal becomes comparable to the charge transit time.; In this work, an advanced non-quasi-static MOSFET model is introduced, which works in all regions of operation and includes all terminal currents and short-channel effects. Based on the spline-collocation-method to solve the continuity equation, this model provides an accurate and efficient solution to the non-quasi-static problem and gives the model user a choice of different accuracy and efficacy. Using a subcircuit-based implementation approach, the model works for large-signal as well as small signal analysis and provides consistent simulations between these two. Furthermore, the new non-quasi-static model will gradually convert into the quasi-static model for low speed and low frequency simulations and is totally compatible with the quasi-static model. The model has been verified using both independent partial-differential-equation solver and two-dimensional device simulators and implemented into circuit simulators using Verilog-A code. Additional verifications using RF experimental data from two different process technologies have also been given and the model introduced in this work is immediately available for engineering applications.