New technique to design tunable quarter-wave lengt side coupled ring filters for multistandards operation

摘要

As an important key of Software Defined Radio (SDR) receivers, tunable filters field knows a continuous and a rapid growth to resolve some handicaps in performance like electrical specifications and physical properties, especially in weight and size. In this context, a tunable RF filter is proposed. It is based on the quarter-wave length side coupled ring topology and varactors as tuning elements. The filter is implemented on FR4 substrate. This filter covers four wireless bands: GSM, UMTS, Wi-Fi and LTE Band 7. S parameters simulations show a quite good agreement in terms of electrical specifications.