An accurate DC and RF modeling of nonlinear spiral polysilicon voltage divider in high voltage MOSFET transistor

This paper presents an accurate DC and RF modeling of nonlinear spiral high resistance polysilicon divider. The spiral divider is a sensing part of the high voltage start-up MOSFET transistor operating up to 700 V. The strong electric field in low doped drain drift area located under the low doped polysilicon spiral divider results in parasitic effects that have a significant influence on DC and RF device characteristics and makes divider ratio voltage and frequency dependent. This paper demonstrates the structure of a proposed macro model, implemented voltage and frequency dependency, and physical explanation of these phenomena. Finally, the comparison of measured data vs. simulation is presented in order to confirm the model validity.