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 λg×0.039 λg× 0.032 λgand 0.058 λg× 0.058 λg× 0.011 λg, respectively. The simulated and measured results of the demonstrated LTCC bandpass filters are presented to validate the proposed design.