Miniaturized LTCC bandpass filter with extended stopband

This paper presents two miniaturized LTCC bandpass filters with wide stopband. By selecting suitable coupling region, the discriminating coupling mechanism is realized, which can suppress harmonics without impact on passband performance. Based on the scheme, two bandpass filters are designed. The first one realizes third harmonic suppression in coupling region between feeding line and resonator. The second one owns wide stopband by using discriminating coupling region between resonators. Both two filters are fabricated using LTCC techniques. The size is 0.057 λ_g×0.039 λ_g× 0.032 λ_g and 0.058 λ_g × 0.058 λ_g× 0.011 λ_g, respectively. The simulated and measured results of the demonstrated LTCC bandpass filters are presented to validate the proposed design.