Varactors nonlinear effects in tunable RF filters

Abstract

Varactor-based tunable bandpass filters are challenging solutions for next generation mobile phones that allow using one RF front-end for multiple applications. However, these solutions suffer from varactors non-linear effects that may affect signal quality and may introduce important distortions. This paper presents a thorough study of varactors nonlinear effects and some solutions for their cancellation. These solutions are applied in tunable Dual Behavior Resonator (DBR) bandpass filter to reduce non-linear distortions. S-parameter and Harmonic balance simulations were conducted to study and compare the performances of the solutions reported in the literature.