Design of a 60/77 GHz dual-band bandpass filter with MMIC technology

This paper has presented a novel dual-band bandpass filter with two sets of resonators based on stepped-impedance, which can achieve size reduction. Two sets of resonators are employed in the filter, one resonate at the 60 GHz and the other at the 77 GHz. The dual-band filter can be realized flexible passband and bandwidth selections by utilizing impedance varying and source-load coupling. The fractional 3-dB bandwidths of 60 and 77 GHz are 7.1% and 7%, respectively. The |S₂₁| of 60 and 77 GHz are -1.66 dB and -1.89dB and |S₁₁| of 60 and 77 GHz are -22 dB and -16 dB, respectively. Between two passbands, the transmission zero at 68 GHz is nearly 40 dB isolation. Good performance and small size make it attractive for wireless communications.