Design of the Wide-tuning-range Notch Filter with Wide Constant Absolute Bandwidth

摘要

A compact notch filter with a wide tunable frequency range is developed. This tunable filter is composed of two varactor-tuned resonators, shunted at input/output ports separately, and one quarter-wavelength transmission line connecting two varactor-tuned resonators. By enlarging impedance of the quarter-wavelength transmission line, the proposed tunable filter can obtain a wide and constant absolute bandwidth. The measured results show that there is a wide tuning range, 124.3%.