Linearly variable inductor with RF MEMS switches to enlarge a continuous tuning range

A variable MEMS inductor is one of the key components for reconfigurable RF circuits, but the variable inductors having continuous and large tuning range are very hard to implement. In this paper, we proposed the combination of continuous and discrete variable inductor to enlarge the continuous tuning range of inductance. In order to realize the proposed combination, we focused on the discrete variable inductors which showed a very high linearity to geometries such as the number of turns and core area of the inductor. Measured total tuning value is 1.5nH and tuning value per stage is about 0.75nH from 1.5GHz to 3.5GHz. Using the proposed concept, the total continuous tuning range can be enormously extended.