Abstract
High-frequency high-power devices have been valued recently asthe demand of communication and power electronics increased.The main streams of material and structure are III-V family (egGaAs) and MESFET. Many small-signal models and analysis methodshave been presented and well-developed. However, as the greatprocess in IC technology, the channel length of a device hasbeen scaled down to submicron range. The frequency of operationof silicon MOSFET is competitive with that of GaAs MESFET.Moreover, the MOS technology has the advantages of low-cost andeasy-fabri- cation. In this paper we present a high-frequencymodel suited for MOSFET and establish procedures for extractingand analyzing parameters which is useful as guidelines ofresearch and for de- signing power MOS devices in the future.In Chapter two, we compare various small-signal models forMOSFET devices which are valid up to different upper frequencylimits. We concluded that the Non-Quasi-Static (NQS) modelwhich considers "transmission-line effects" is appropriate forhigh frequency operations. A simplified high-frequency modelbased on NQS analysis is presented, which is valid for three-terminal de- vices. In the next chapter, the design ofdifferent layouts of power devices is discussed. A mesh-structured transistor with benefits of high-packing density andminimum parasitic capaci- tance is preferable. Besides, we willintroduce a method of ex- tracting parameters includingintrinsic and extrinsic parts of a transistor without designingdummy devices. The d.c. character- istics and high frequencyperformances of designed MOSFET samples will be characterizedin Chapter four. The method of extracting parameters would bemodified to get high degree of precision. Concluding remarksand recommendations are given in the last chapter.