A research of band-pass filter with highly steep band-edge based on semi-lumped structure

Abstract

To the practical demands of project, a set of solution on the highly steep band-edge band-pass filter based on LTCC technology was designed in this paper. Semi-lumped Structure is used in this design for operating convenience. With the help of advanced LTCC technology, miniaturization will eventually be realized. Cross coupling is used to add transmission zeros for better steep band-edge, but still cannot meet the needs of application in practice. So cascade two band-pass filter of identical structure by above and below become the best way to solve the difficulties. Simulation results are achieved with the help of circuit simulation and 3D simulation software. The center frequency is 1237.5MHz, its bandwidth is 575MHz, from 100MHz to 480MHz the stop-band attenuation is better than 40dB and it is better than 30dB from 1900MHz to 3050MHz. The size of product is only 4.5mm×3.2 mm×2.5 mm.