DOI: 10.1109/TMTT.2024.3430485   IEEEXplore: https://ieeexplore.ieee.org/document/10612266

Multilayer microstrip single-ended and balanced flat-group-delay RF low-pass filters with input-quasi-reflectionless behavior

Up to 20 GHz for this work

The filter design is based on a multilayered complimentary diplexer topology composed of a reflective-type main channel single pole low pass filter (LPF) with multiple out-of-band transmission zeros, and an reflectionless absorptive-type auxiliary channel high pass filter (HPF). These quasi-reflectionless filters dissipate the nontransmitted out-of-band RF-signal power inside themselves rather than reflecting it back to the source.

Digital telecommunications RF front end chains to replace isolators and attenuators.

Prototype A single ended with 4.17 GHz f3db cutoff: ±0.009 ns inband group delay variation, ≥14.55 dB stopband attenuation 8.71–20 GHz. Prototype B differential mode with 3.77 GHz f3db cutoff: ±0.011 ns inband group delay variation, ≥16.87 dB stopband attenuation 8.91–20 GHz. Prototype C differential mode with 2.66 GHz f3db cutoff: ±0.009 ns inband group delay variation, ≥29.63 dB stopband attenuation 8.72–20 GHz.