| 摘要 |
The inventive bandstop filter is suitable for use in a multi-layer ceramic (MLC) structure. Specifically, the filter is a semi-lumped type, formed by lumped capacitors and distributed transmission lines. Preferably, transmission lines are used as equivalent inductors, instead of as J, K inverters or resonators. The bandstop filter preferably has attenuation poles very close to lower passband edge, which results in a very sharp rejection near the stopband. The inventive filter may be utilized as a transmitter-end filter in, e.g., duplexer applications or for miniaturized applications, such as portable communications.
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