ABSTRACT Based on the coupling-compensating technologies, a wide-frequency tunable bandpass filter with high-frequency selectivity has been presented in this paper. The coupling coefficient between a pair of resonator and the external quality can be easily controlled, the constant absolute bandwidth (ABW) and the characteristic of tunable wide-frequency can be achieved by changing the position of varactors. By introducing the source-load cross-coupling circuit, the bandpass filter has two transmission zeros, resulting in high-frequency selectivity for the passband. Moreover, only two varactor diodes have been used in the presented tunable bandpass filter. The measured results show that the tunable filter has an almost constant 3 dB absolute bandwidth of 90 ± 5 MHz from 1.55 GHz to 2.00 GHz. The measured insertion loss of the tunable bandpass filter is between 2.2 dB and 3.3 dB, while the return loss is greater than 10 dB within the tunable center frequencies. The measured results of the fabricated tunable bandpass filter show good agreement with the simulated ones.

中文翻译：

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具有高频选择性的宽频可调带通滤波器

摘要 本文基于耦合补偿技术，提出了一种具有高频选择性的宽频可调带通滤波器。一对谐振器之间的耦合系数和外部质量可以很容易地控制，可以通过改变变容二极管的位置来实现恒定的绝对带宽（ABW）和可调谐宽频的特性。通过引入源负载交叉耦合电路，带通滤波器具有两个传输零点，从而对通带产生高频选择性。此外，在提出的可调带通滤波器中只使用了两个变容二极管。测量结果表明，可调滤波器在 1.55 GHz 至 2.00 GHz 范围内具有几乎恒定的 3 dB 绝对带宽，为 90 ± 5 MHz。可调谐带通滤波器的实测插入损耗介于 2.2 dB 和 3.3 dB 之间，而回波损耗在可调谐中心频率内大于 10 dB。制作的可调带通滤波器的测量结果与模拟结果吻合良好。