Tunable 500–1200-MHz Dual-Band and Wide Bandwidth Notch Filters Using RF Transformers

@article{Ko2015Tunable5D,
  title={Tunable 500–1200-MHz Dual-Band and Wide Bandwidth Notch Filters Using RF Transformers},
  author={C. H. Ko and Allen Quoc-Luan Tran and Gabriel M. Rebeiz},
  journal={IEEE Transactions on Microwave Theory and Techniques},
  year={2015},
  volume={63},
  pages={1854-1862}
}
This paper presents a novel tunable dual-band bandstop filter based on doubly tuned RF transformers. This design results in two distinct notch frequencies in a single resonator using silicon varactor diodes. The 2-pole tunable dual-band bandstop filters are implemented using printed circuit board (PCB) transformers and air-coil transformers. With PCB transformers, the lower frequency can be tuned at 513-845 MHz while the higher frequency can be tuned at 715-1151 MHz with a notch level > 16 dB… CONTINUE READING