A miniature 2.1-GHz low loss microstrip filter with independent electric and magnetic coupling

Park, S.-J.; Caekenberghe, K. Van; Rebeiz, Gabriel M.

doi:10.1109/lmwc.2004.836803

Cited by 23 publications

(13 citation statements)

References 4 publications

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“…To implement the capacitance, the first solution was to use a lumped element such as a metal-insulator-metal (MIM) capacitor or an interdigital capacitor [4]. The drawback of this method is the implementation process: it indeed requires good precision in the realization and a good mastery of the technology in use.…”

Section: Methodsmentioning

confidence: 99%

“…This is achieved by a narrow gap and a large coupling area to the connecting line. The gap is a very critical parameter (see Figure 2) [4]: if it is too narrow, matching is insufficient, and fitting the poles to the desired stopband is not possible. On the other hand, if the gap is too wide, the two modes separate from each other so that the filter becomes broadband and the insertion loss in the passband increases dramatically.…”

Section: Filter Designmentioning

confidence: 99%

“…This is required because the stopband of the filter is affected by the package [4]. In addition, HFSS is used to study the effect of critical design parameters and solve the tradeoff between radiation and conductor loss to minimize the attenuation in the passband [1].…”

Section: Filter Designmentioning

confidence: 99%

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Packaged X-band capacitive-coupled dual behavior resonator filter [Technical Committee]

et al. 2009

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Section: Methodsmentioning

confidence: 99%

Section: Filter Designmentioning

confidence: 99%

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Packaged X-band capacitive-coupled dual behavior resonator filter [Technical Committee]

et al. 2009

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“…The resonant frequency of the resonator can then be tuned by changing the capacitance of the varactor. This type of resonator is basically a microstrip ring resonator [10] as used in [7] and [11], except that the microstrip line has been reshaped for the convenience of magnetic coupling realization. With this resonator, it is also very convenient to adjust the center frequency in the filter design while the coupling coefficient remains unchanged.…”

Section: Resonator Designmentioning

confidence: 99%

“…The effects of the varactor diode on the resonant frequency of the resonator shown in Fig. 1 can be calculated by analysis as in [7] and [11]. However, it is more convenient to be simulated using full-wave EM simulations software.…”

Section: Resonator Designmentioning

confidence: 99%

A Tunable High Temperature Superconducting Bandpass Filter Realized Using Semiconductor Varactors

Bian

et al. 2014

IEEE Trans. Appl. Supercond.

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This paper presents a semiconductor varactor tuned four-pole bandpass filter. The filter was designed to have a constant fractional bandwidth of 3% and was tuned with single control voltage. The design methods of how to keep coupling coefficients constant and to make all the resonators tuned synchronously are described in details. The filter was built on a two-inch doubleside high temperature superconducting film. The center frequency of the filter can be tuned from 430 to 720 MHz with the direct voltage up to 20 V. The return loss is better than 10 dB in the whole tuning range. Insertion loss is in a range of 0.8∼3.8 dB with 3 dB fractional bandwidth about 3%.Index Terms-High temperature superconducting (HTS), single control voltage, tunable filter, varactor.

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Low‐temperature cofired ceramic planar helical filter with single‐sided transmission zeros

Che

Chin

et al. 2014

Electron. lett.

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A planar low-temperature cofired ceramic helical bandpass filter with a compact size is presented. The proposed filter is constructed from short-circuited λ g /4 helical resonators, while the size is reduced significantly by winding resonators vertically. Two single-sided transmission zeros can be created by the proposed mixed electric and magnetic coupling structure. A prototype with size of 6.2 × 4 mm 2 (0.049 × 0.032λ g 2 ) has been fabricated for demonstration. The measured fractional bandwidth is 5.9% at 0.845 GHz, and two transmission zeros are observed at 0.90 and 1.07 GHz.Introduction: Filters using a mixed electric and magnetic coupling ('mixed coupling' for short) structure have attracted much attention for both compactness and high frequency selectivity. The coexisted electric and magnetic couplings of two adjacent resonators may cause a cancellation effect to create transmission zeros (TZs) without using additional cross-coupling paths or source-load coupling structures [1]. In [2], a high-Q mixed coupling filter was proposed by terminating the slot line with a double-spiral inductive termination at both ends. In [3], the authors developed a patch-via-spiral resonator. The resulting second-order filter had a smaller size than those of the filters in [1, 2]. However, the filter size is still large because the spiral line occupied considerable space. Most of the filters mentioned above achieved symmetric frequency responses, which are unusable for some special applications requiring only a higher selectivity on one side of the passband. Therefore, in [4], two TZs were introduced in the upper stopband to obtain asymmetric frequency responses, while the filter size was much larger than expected.This Letter develops a low-temperature cofired ceramic (LTCC) planar helical filter with a very compact size of 0.049 × 0.032λ g 2 . The mixed coupling structure was utilised to create two TZs located in the upper stopband for successfully improving the frequency selectivity.

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A miniature 2.1-GHz low loss microstrip filter with independent electric and magnetic coupling

Cited by 23 publications

References 4 publications

Packaged X-band capacitive-coupled dual behavior resonator filter [Technical Committee]

Packaged X-band capacitive-coupled dual behavior resonator filter [Technical Committee]

A Tunable High Temperature Superconducting Bandpass Filter Realized Using Semiconductor Varactors

Low‐temperature cofired ceramic planar helical filter with single‐sided transmission zeros

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