Varactor-Tuned Compact Dual-Mode Tunable Filter With Constant Passband Characteristics
Varactor-Tuned Compact Dual-Mode Tunable Filter With Constant Passband Characteristics
复制标题
DOI：
10.1109/tcpmt.2016.2599205
复制
发表时间：
2016-09-01
影响因子：
2.2
通讯作者：
Wu, Ruey-Beei
中科院分区：
文献类型：
--
作者：
Tsai, Han-Yun;Huang, Ting-Yi;Wu, Ruey-Beei
提出了一种二阶切比雪夫常数分数带宽（CFBW）可调谐带通滤波器，该滤波器具有体积小、频率不变的通带特性，外部质量因子可调。该滤波器采用一个短段加载的双模谐振器和两组变容器来调节中心频率和回波损耗水平。该设计的特点是采用了短接地根的网型滤波器，从而保证了CFBW的性能。在常规设计的基础上，在馈电传输线的两端增加一对变容管，以保证调谐时外部质量因素不变。在变容器的可调范围内，所提出的滤波器以5%的CFBW在1.7 ~ 2.1 GHz范围内可调。测量结果表明，在整个调谐范围内，回波损耗为20 dB，插入损耗低于2.9 dB。
This paper presents a second-order Chebyshev constant fractional bandwidth (CFBW) tunable bandpass filter with compact size and frequency invariant-passband characteristics using tunable external quality factors. The filter is designed using a stub loaded dual-mode resonator and two sets of varactors for tuning the center frequency and the return loss level. The design is featured with the net-type filter of a short grounded-stub so that the CFBW property can be assured. In addition to the conventional design, a pair of varactors is included at the ends of feeding transmission lines to keep the external quality factors constant while tuning. Within the tunable range of the varactors, the proposed filter is tunable from 1.7 to 2.1 GHz with a 5% CFBW. The measurement results show a 20-dB return loss and insertion loss below 2.9 dB over the entire tuning range.