Development of ultra-wideband LTCC filter

A novel method to realize the ultra-wideband filter with the low temperature co-fired ceramic (LTCC) technology has been proposed. This ultra-wideband LTCC filter was implemented using a four-resonator bandpass filter accompany with inductance feedback. According to the above mentioned method, a couple of transmission zeros can be generated at two-side of passband´s skirt of the ultra-wideband filter. This filter also can increase the sensitivity and linearity of the wireless communication system. The advantage of multi-layered structure may shrink the circuit size. The designed prototype filters, center frequencies around 4 GHz were selected and passband frequency is between 2.96-4.91 GHz. The bandwidth ratio is 48.75%. The fabricated ceramic sheet with dielectric constant of 7.8, and the size of filter is 119 mil × 79 mil × 33.72 mil.