Planar tri-band filter based on dual behavior resonator (DBR)

This paper reports on the application of dual behavior resonators to design triband filters. The principle is briefly presented by considering monoband, dual-band and triband filters. A circuit is proposed by using an approximate synthesis. Then, a hybrid (electromagnetic / circuit) simulation is performed to take into account the parasitic effects induced by the junction discontinuities and to allow a fast triband optimization in the same time. An example of layout with associated simulated and experimental results is proposed.