Design of multilayered broadband bandpass filter with LTCC technology

With two pairs of asymmetrical feeding short-circuit coupled lines, a multilayered broadband bandpass filter is proposed and constructed. To enhance the selectivity of the passband, two pairs of coupled lines need to be properly connected with both inductive and capacitive coupling to generate two transmission zeros at both sides of the passband skirts. Measured results show a bandwidth ratio of the passband of more than 44.6% when its centre frequency is 3.875 GHz.