A hybrid method for flat-passband filter with nonuniform Q resonators and predistortion

Qiu, Liang-Feng; Wu, Lin‐Sheng; Wang, Yin

doi:10.1109/ieee-iws.2014.6864212

Cited by 3 publications

(1 citation statement)

References 11 publications

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“…When the pair of resonators corresponding to the band edges are built up with higher-Q structures and the other pair of resonators related to the middle passband are realised by lower-Q structures, small in-band variation and sharp edges can be obtained. The synthesis procedure of the non-uniform Q method for an Nth order filter is presented in [6,22].…”

Section: Non-uniform-q Methodsmentioning

confidence: 99%

Hybrid non‐uniform‐ Q lossy filters with substrate integrated waveguide and microstrip resonators

Qiu

Wang

et al. 2017

IET Microwaves, Antennas & Propagation

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Three lossy filters with flat passband are proposed with substrate integrated waveguide (SIW) and microstrip resonators, designed with the non‐uniform‐Q method. By properly selecting the lower‐Q‐to‐higher‐Q ratio, the 0.2 dB bandwidth of the first filter is obtained to be 215 MHz (17% improvement), which is equivalent to a uniform unloaded Q‐factor of 820 at the cost of additional in‐band insertion loss (IL) of 0.5 dB, when compared with the full‐SIW filters. Further, two techniques are utilised to adjust the Q‐factor ratio. One method is implemented by mounting a resistor on each microstrip resonator to reduce its unloaded Q‐factor. Then, the 0.2 dB passband of 243 MHz is achieved for the second filter, equivalent to a uniform unloaded Q‐factor of 1420. The other method is realised by adjusting the Q‐factor due to radiation loss of microstrip resonators. By changing the input/output feeding structures, the 0.2 dB bandwidth of the third filter is enhanced by 32%, at the cost of minimum IL increased by 0.9 dB. The occupied area of the proposed planar hybrid filters is reduced by 15–21% and the passband flatness is much better than that of the uniform‐Q filter counterparts, as demonstrated by the simulated and measured results.

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Section: Non-uniform-q Methodsmentioning

confidence: 99%