Low loss coupled line filters with transmission zeros in multi-layer thin film MCM-D technology

This paper presents the design and characterization of high-performance bandpass filters with transmission zeros, integrated in a multi-layer thin film MCM-D technology on high-resistivity Si. A mixed thin-film microstrip/coplanar waveguide transmission line has been used for the realization of the filters, as it presents lower loss than thin-film microstrip lines. The coupled line filters achieve an insertion loss of 2.3 dB at 25 GHz and 1.7 dB at 43 GHz with 3 dB bandwidths of 14% and 18% respectively. The use of transmission zeros provides a close in-band attenuation of more than 30 dB. The used topology allows changing the center frequency and the position of the transmission zeros more or less independently facilitating the design.