Design of a wideband LTCC bandpass filter with high stopband rejection

A new wideband LTCC bandpass filter with high stopband rejection is proposed in this paper. The filter with a central frequency of 1.5 GHz and a 40% passband is implemented by using a five-resonator chebysheve bandpass filter circuit model. In order to achieve the excellent out-of-band suppression, an improved bandpass filter circuit with two transmission zeros by employing circuit transformation theory is presented. The design has been successfully realized in theory, and verified by both full wave electromagnetic simulation and microwave circuit simulation. The insertion loss in the passband is less than 1.0 dB and the attenuation is more than 30 dB in the lower stopband (0-0.8 GHz) and higher stopband (2.5-6 GHz). The size of filter is 8 mm×4 mm×1.6 mm.