A 60/77 GHz dual-band bandpass filter with MMIC technology

This paper presents a novel dual-band bandpass filter with two sets of stub-loaded open-loop resonator, using stepped-impedance, which results in a reduction in size. Two sets of resonators are synthesized using a doublet coupling scheme for 60/77 GHz resonance. The two passbands are flexible due to implement with two parallel transmission paths and tuning each bandwidth independently by changing even-mode resonant frequency. The fractional 3-dB bandwidths at 60 and 77 GHz are 11.4 and 8.3%, respectively. The values at 60 and 77 GHz are −2.26 and −2.63 dB and the values at 60 and 77 GHz are −24.8 and −18.5 dB, respectively. Between the two passbands, the transmission zero at 67 GHz gives nearly 22.6 dB isolation. Good performance makes this system attractive for wireless communications.