Ldmos Electrical Properties Analysis And Modeling

Lateral high-voltage power device LDMOS has advantages of high-voltage, large gain, wide dynamic range, low distortion and compatibility with low-voltage circuit process. With the development of semiconductor technology, LDMOS is more and more widely used in power integrated circuits and smart power circuits. Therefore, it is very important to study and model electrical characteristic of LDMOS because of its practical application. The structure of LDMOS discussed in this paper is the key of PDP data driver's design. It ought to be compatible with low-voltage circuit process and satisfy requirement of high-voltage and large currentThis paper deeply discusses threshold voltage, on-resistance and current characteristic of LDMOS, and builds the approximately accurate model of these electrical parameters. The model of threshold voltage solves the problems of nonuniformly doped channel, short channel effect, implantation for adjusting threshold voltage, edge capacitance of gate, etc. Not only the model can be used in LDMOS, but it can perfectly describe the short channel effect of threshold voltage for all other MOS devices. It is demonstrated that the effect of short channel can cause the decrease of threshold voltage. In the model of on-resistance, we have considered the lateral doping distribution in LDMOS channel and vertical doping distribution in drift region. Then we provide the explicit dependence between on-resistance and doping distribution parameter. The research of LDMOS current characteristic involves the linear current region, cut-off saturation region, quasi-saturation region and providing the simplified analytical expression.During the course of modeling LDMOS, the paper puts forward the method in which Maxwell function in the static system is applied in analysis compute of LDMOS threshold voltage. Schwarz-Chritoffel transformationmethod is used to solve the gate self-capacitance with limited size. At the same time, It also provides the method which computes the drain and source self-capacitance by conformal transformation and the equivalent-voltage sharing-charge model. We have also given the equivalent circuit of on-resistance and compute method. According to the results of simulation, we achieve the satisfying effect by using these methods.