Design of Miniaturized and Highly Selective On-Chip BPFs With Mixed-Coupled Resonators

In this letter, lumped-element GaAs integrated passive device (IPD) bandpass filters (BPFs) with controllable transmission zeros (TZs) and bandwidths are proposed. The mixed-electromagnetic couplings of a second-order distributed-element resonator and its various transmission responses are analyzed. Two equivalent lumped-element BPF units under different coupling conditions are investigated. To validate the feasibility of this design approach, two 5G N77-band fourth-order BPFs based on the two BPF units are designed and verified. These two BPFs show the superior advantages of small size, low insertion loss, deep rejection, and wide stopband.