A new type of miniaturized tunable bandstop filter (BSF) based on multilayer technology is presented in this letter. One of the transmission zero could be individually tuned by replacing an outer replaceable element, which can be considered as part of the inner resonant cell of the bandstop filter. Thus, a tradeoff between the stopband rejection depth and bandwidth can be conveniently realized according to different applications. A bandstop filter works from 3.1 to 4.2 GHz has been designed and fabricated in a low temperature cofired ceramic (LTCC) substrate to verify the proposed concept. By virtue of the LTCC multilayer technology, the filter occupies a very compact volume of 2.0 mm × 1.2 mm × 0.8 mm.

中文翻译：

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使用多层技术的小型可调谐带阻滤波器

这封信介绍了一种基于多层技术的新型微型可调带阻滤波器（BSF）。可以通过替换外部可替换元件来单独调整传输零之一，该外部可替换元件可以被视为带阻滤波器的内部谐振单元的一部分。因此，可以根据不同的应用方便地实现阻带抑制深度和带宽之间的折衷。已经在低温共烧陶瓷（LTCC）基板中设计并制造了从3.1到4.2 GHz的带阻滤波器，以验证所提出的概念。凭借LTCC多层技术，该过滤器占据了2.0 mm×1.2 mm×0.8 mm的非常紧凑的体积。