Miniaturized 60-GHz On-Chip Multimode Quasi-Elliptical Bandpass Filter

A 60-GHz on-chip multimode bandpass filter (BPF) is implemented using a sandwich capacitor. The proposed loaded sandwich capacitor shows functions of multimode perturbation and stopband control in the BPF design. An additional magnetic coupling path from the source to the load is introduced to generate two extra zeros. Thus the quasi-elliptical filter response is achieved. The proposed filter implemented with a commercial SiGe BiCMOS process demonstrates a low insertion loss of 4 dB and compact size of only 0.16 mm2.