Novel Compact Chip Design of 5GHz LTCC Dual Mode 4 Poles Quasi-Elliptic Resonator Filter

One novel compact design of 5GHz LTCC dual mode 4 poles quasi-elliptic resonator filter was proposed. The two square-loop of resonators are coupled with one modified broadside-coupled line with 4 shunted capacitors terminated as patch or perturbation for degenerate modes excited by closed loop resonator cavity. Two transmission zeros and four reflection poles of the elliptic resonators filter was achieved for 5GHz LTCC resonator narrow-band bandpass filter application. The compact chip components was fabricated with LTCC technology in size of 3.2times2.5times0.8 mm³ and measurement yielded excellent band selectivity with high spurious rejection and harmonic suppression over 30~40dB and the insertion loss around 3.3dB at centre frequency of 5.35GHz with 3dB fractional bandwidth of 15.9% (FBW_3dB=4.9~5.75GHz). Two transmission zeros were measured and located at 4.2GHz and 7.6GHz individually.