Miniaturized Wide Stopband UWB Bandpass Filter Using Thin-film Lumped Elements

A miniaturized wide stopband UWB bandpass filter (BPF) using lumped elements based on thin-film technology was proposed in this paper. The filter is composed of three-order LC resonators by inductive coupling. The LC resonator is realized by spiral inductors and Metal-Oxide-Metal (MOM) capacitors based on thin-film technology. Three controllable transmission zeros (TZs) are added to realize wide stopband with high rejection level. The proposed filter was simulated, fabricated and measured. In final, the proposed filter has a passband of 3.1 GHz to 10.6 GHz, with insertion loss of less than 2 dB, and return loss better than 15 dB. The upper stopband attenuation more than 30 dB is up to 33.1 GHz. The overall dimensions of the proposed filter are $2.5 \mathrm{~mm}(\mathrm{~L}) \times 2 \mathrm{~mm}(\mathrm{W})$.