Novel Synthesis Method for Reconfigurable Filtering Phase Shifter With Frequency-Dependent Coupling Using Optimization Technique

A novel optimization technique is proposed for reconfigurable filtering phase shifter with frequency-dependent coupling in this brief. It incorporates both the coupling matrix entries and the circuit elements into optimization process. With the proposed technique, it can not only obtain desired insertion phase at the center frequency, align the phase slope between different phase states to be same, but also maintain satisfactory return loss in the passband and have multiple transmission zeros in the stopband. The proposed method well suits the reconfiguration application scenario where frequency-dependent coupling is adopted between adjacent resonators. To validate the proposed idea, a microstrip prototype is fabricated and measured. Experimental results show that the operating center frequency can be tuned from 0.6 GHz to 0.71GHz, with a continuously tunable phase shifting range of larger than 175∘ at each frequency state.