The boom of mobile communications leads to an increasing request of low cost and low power mixed mode integrated circuits. Maturity of SOI technology, and recent progresses of MOSFET's microwave performances, explain the success of silicon as compared to III-V technologies for low-cost multigigahertz analog applications. The design of efficient circuits requires accurate, wide-band models for both active and passive elements. Within this frame, passive components fabricated in SOI technologies have been studied, and a physical model of integrated square spiral inductors has been developed. Also, the performances of integrated MOSFETs have been analyzed. New alternative structures of transistor (the Graded Channel MOSFET and the Dynamic Threshold MOSFET) have been proposed and studied from Low to High frequencies. These transistors show very interesting properties for analog, low power, low voltage, and microwave applications. Furthermore, as their fabrication processes are fully CMOS compatible, they allow us to increase the performances of a CMOS technology without any modification of its process, and without extra-cost.

The boom of mobile communications leads to an increasing request of low cost and low power mixed mode integrated circuits. Maturity of SOI technology, and recent progresses of MOSFET's microwave performances, explain the success of silicon as compared to III-V technologies for low-cost multigigahertz analog applications. The design of efficient circuits requires accurate, wide-band models for both active and passive elements. Within this frame, passive components fabricated in SOI technologies have been studied, and a physical model of integrated square spiral inductors has been developed. Also, the performances of integrated MOSFETs have been analyzed. New alternative structures of transistor (the Graded Channel MOSFET and the Dynamic Threshold MOSFET) have been proposed and studied from Low to High frequencies. These transistors show very interesting properties for analog, low power, low voltage, and microwave applications. Furthermore, as their fabrication processes are fully CMOS compatible, they allow us to increase the performances of a CMOS technology without any modification of its process, and without extra-cost.