2020 Volume 13 Pages E19-019-1-E19-019-10
Eleventh-order Chebyshev function types of 2.6-GHz-band low-pass filter (LPF) and 5.4-GHz-band high-pass filter (HPF) are configured using both chip components and patterned lumped elements. Compact matching circuits for an LPF-HPF diplexer are also proposed. They are able to absorb the first elements of the LPF and the HPF. The fabricated LPF-HPF diplexer has realized high isolation characteristics of more than 45 dB, reflection characteristics of more than 15 dB, and low transmission loss of less than 1.74 dB in each passband. Finally, three types of the bandpass filter-bandpass filter (BPF-BPF) diplexers with two BPFs are composed with the proposed LPF-HPF diplexer, conventional matching circuits and a commercial diplexer. When compared using a circuit simulator, the BPF-BPF diplexer composed of the proposed LPF-HPF diplexer and two BPFs has higher isolation characteristics between two channels than other circuits.
