Design of 60-GHz vertically stacked waveguide filters in LTCC

This paper proposes a new type of vertically stacked waveguide filters in a multilayer low-temperature co-fired ceramic (LTCC) structure. The vertical metal walls of the waveguide resonators are realized by closely spaced metal filled vias, while adjacent resonators are coupled vertically by square apertures or narrow slots. Two kinds of filters with Chebyshev and elliptical response are designed for 60-GHz-band application. From the results, the circuit area of the filter with Chebyshev response can be reduced to 25% as compared to a conventional planar direct-coupled waveguide filter.