Steady State Temperature Study on RF LDMOS with Structure Modification

Xiaohong Sun,Haodong Wu,Huai Gao,Qiang Chen

doi:10.4236/eng.2012.47049

Xiaohong Sun, Haodong Wu + Show 2 more

Open Access

https://doi.org/10.4236/eng.2012.47049

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Abstract

This paper is devoted to temperature analysis on power RF LDMOS with different feature parameters of die thickness, pitch S length and finger width. The significance of these three parameters is determined from temperature comparison obtained by 3D Silvaco-Atlas device simulator. The first three simulations focus on temperature variation with the three factors at different output power density respectively. The results indicate that both the thinner die thickness and the broaden pitch S length have distinct advantages over the shorter finger width. The device, at the same time, exhibits higher temperature at a larger output power density. Simulations are further carried out on structure with combination of different pitch s length and die thickness at a large 1W/mm output power density and the temperature reduction reaches as high as 55%.

Highlights

RF LDMOS has become the most popular RF power technology for base station applications
This paper is devoted to temperature analysis on power RF LDMOS with different feature parameters of die thickness, pitch S length and finger width
The results indicate that both the thinner die thickness and the broaden pitch S length have distinct advantages over the shorter finger width

Summary

Introduction

RF LDMOS has become the most popular RF power technology for base station applications. As demand for much higher power level, device temperature increases due to self-heating effects taking place inside the active area. Treatment for thermal effect are mainly from circuit view with compensation network such as adaptive bias [3], predistortion linearizers [4], and multistage RC network [5]. In essence, process improvement with structure modification directing to reduce the temperature is a priority to guarantee the performance. A 40 μm ultra-thin RF LDMOS was first reported in [6], which gives a verification of junction temperature reduction. Other structure modification is tried in today’s device design. The objective of the presented work is a thermal study to compare the significance of changes on die thickness, pitch s length and finger width

Structure Description

Simulation Results

Structure Modification and Discussion

Conclusion