The Design and Simulation of an Optimized MEMS Varactor with High Q Factor for RF Circuits

This research concerns on design of high-performance MEMS tuning variable varactor. Varactors can be used as a part of LC-tank of an oscillator. Using MEMS technology causes an improvement in Q factor of varactor to achieve less phase noise and lower power consumption in an oscillator. In this work a two different gap varactor has been used to avoid the pull-in voltage at 2.4 GHz. The expected capacitance is 3 pF. The area and the gaps between the plates achieved based on a basic formula of the capacitor. The design of layout has been done by CoventorWare software 2006. The DC voltage is 2.5 nu which is applied to the plates and the results of 3.02 pF could be gained after analyzing. The Q factor of varactor calculated based on a distributed RC line and computed about 376.43 using MATLAB programming. The result is good enough to make low phase noise in VCO.