LDMOSFET的射頻特性及其切換開關應用

High-Voltage LDMOSFET Radio Frequency Characteristics and its Switching Circuit Applications

胡智閔(Chih-Min Hu)

指導教授 ： 龔正 ； 黃智方

國立清華大學/電機資訊學院/電子工程研究所/博士(2011年)

摘要

In recent years, due to the fast emerging for the communication products, demands for power devices have risen substantially. In keeping with the trend of circuit integration, traditional vertical power device needs to be modified as a lateral structure to achieve the possibility for the integration of power devices and logic circuit on a single chip. The LDMOSFET transistor is one of the main power devices for commercial communication applications and RF amplifying circuit. It is very important to build an accurate RF small-signal equivalent circuit which contains the frequency-dependent parts, such as capacitances, inductances, and extrinsic interconnection resistances. It is helpful for circuit designer to predict the RF circuit performance which is composed of these transistors.
This study proposed the RF small-signal equivalent circuit of the LDMOSFET device. Utilizing cold-FET method and high frequency approximation those extrinsic parameters of device can be extracted. Besides, the 2-port network equations were used for the extraction of intrinsic device parameters. This small-signal equivalent circuit is used to monitor the transistor electric behavior and this study also presents the comprehensive methods for the application of RF LDMOSFET Transmit/Receive (T/R) switching circuit with high output power-handling capability and low insertion loss. The simulated results of the RF switching characteristics show a good agreement as compared with the measured S-parameters.
The RF power device is fabricated by a 0.25-um LDMOSFET high voltage process. The measured trans-conductance up to 60 S, input 1-dB compression point of 23 dBm and the output power handling capability can be achieved to 27 dBm. The T/R RF switching circuit implemented using 0.25-um LDMOSFET transistors for 900-MHz switching circuit application is present. In particular, a 900-MHz switching circuit with measured insertion loss less than 1 dB, isolation up to 22 dB and input third-order intercept point of 25 dBm is obtained. It shows a good RF performance and increased the high integration level for the front-end module (FEM).

關鍵字

橫向雙擴散金氧半場效電晶體 ； 射頻小訊號等效電路模型 ； 射頻開關

並列摘要

無資料

並列關鍵字

LDMOSFET ； RF small-signal equivalent circuit model ； RF switch

參考文獻

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