Novel ultra-wideband coplanar-waveguide bandpass filter with inductance-loaded Y-shaped resonators

A novel ultra-wideband (UWB) coplanar waveguide (CPW) bandpass filter (BPF) with the inductance-loaded Y-shaped resonator has been presented in this letter.The proposed UWB BPF has been constructed by integrating the broadside-coupled microstrip-CPW structures into the inductance-loaded Y-shaped resonator. The broadside-coupled microstrip-CPW structures can get tight coupling for UWB performance. The external quality factor has been analyzed to design the proposed UWB filter. An UWB CPW BPF is designed, simulated, and fabricated to demonstrate the performance of the proposed filter structure. The measured results show good agreement with the simulated ones. The fabricated UWB CPW BPF exhibits excellent performance, including 3-dB insertion loss and 10-dB return loss bandwidths over the entire UWB band with a minimum insertion loss of 0.37 dB at 5.4 GHz, as well as 1-dB insertion loss bandwidth of 3.25-10.2 GHz and group delay variation from 0.18 to 0.28 ns over the frequency range of 3.9-11 GHz. © 2011 Wiley Periodicals, Inc.