A CMOS voltage-to-frequency linearizing preprocessor for parallel plate RF MEMS varactors

A generalized parallel plate radio frequency microelectromechanical systems (MEMS) varactor is presented and studied. Its application in an RF oscillator is described and the nonlinear relationship between tuning voltage and realized output frequency is derived. A low power CMOS integrated circuit is proposed to linearize the response. The circuit consumes at most 100 /spl mu/W of power while linearizing the voltage-to-frequency response to a correlation coefficient (R/sup 2/) of 0.9988. The described circuit and theory can be employed in any application where the nonlinear response associated with parallel plate RF MEMS varactors must be compensated.