Design of Microstrip Low-Pass Filter with Ultra-wide Stopband and Sharp Rejection (original) (raw)
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A Compact Lowpass Filter with Ultra Wide Stopband using Stepped Impedance Resonator
Radioengineering, 2017
In this paper, a compact asymmetric-shaped microstrip lowpass filter (LPF) using a stepped impedance resonator is presented. An ultra wide stopband with high attenuation in the stopband region, within very small circuit area is achieved for the proposed filter using novel asymmetric structures for resonator and suppressor. The transmission zeros of the resonators can be adjusted as a function of high impedance and low impedance microstrip lines, and due to the asymmetric structure, the proposed suppressing cell can be located within the resonator structure without occupying a large area. For verification, a 2.92 GHz LPF is designed and fabricated. The experimental results, in comparison with the other LPFs, show that the proposed LPF has significant advantages in the stopband characteristics with acceptable sharp roll off. The measured passband insertion loss is below 0.1 dB, and the rejection band over-20 dB is obtained from 3.42 GHz to 36.2 GHz. The size of filter corresponds to compact electrical size of 0.156 λ g × 0.128 λ g , where λ g is the guided wavelength at 2.92 GHz. Also, the maximum variation of the group delay in 80 percent of the passband region is only about 0.2 ns.
Compact low‐pass filter with ultra‐wide stopband using analysed triangular‐shaped resonator
Electronics Letters, 2017
Background and Objectives: In this paper, an ultra-wide stopband microstrip low pass filter (LPF) with sharp roll-off and compact size is designed and fabricated. Also, proposed filter is designed, simulated, optimized, fabricated and measured and we can see a good agreement between the simulations and measurement results. Methods: T-shaped and stepped impedance have been used, because these structures have a very small dimensions. This method provides a suitable cut off frequency. Results: The cut off frequency at-3dB is 3.1GHz. In the proposed structure, the insertion loss is lower than 0.12dB and the return loss is greater than 15dB. In order to achieve a-20dB attenuation level in the stopband, a modified L-shaped structure is utilized. This filter has an ultra-wide stopband that is expanded from 3.37GHz to 37.5GHz. Also, the suppression level is greater than-20dB. The fabricated LPF has a size about 16.6 × 13.5 mm 2 which is equal to 0.28ƛg × 0.22ƛg, where ƛg is the guided wavelength at 3.1GHz, which is very small. Conclusion: A microstrip LPF with 3.1GHz cutoff frequency consisting of Tshaped and stepped impedance resonators has been proposed, simulated and fabricated. The transition band (-3 to-40dB) is 0.38GHz, which is a very sharp response. The stopband of the proposed filter is from 3.37 to 37.5 GHz which is equal to 12.1f c. There was a significant agreement between the simulation and the measured results. With all these features, these filters are widely used in wireless communication systems.
Microstrip lowpass filter with ultra-wide stopband using triangular shaped CMRC
International Journal of Electronics, 2014
In this article, a new microstrip lowpass filter with ultra-wide stopband using T-shaped resonators and folded structures is described. The structure of this filter is very simple, so that only a T-shaped resonator is used as main resonator without any particular changes in these resonators. The designed T-shaped main resonator has a −3 dB cutoff frequency of 1.4 GHz. On the other hand, T-shaped resonators with low base length are utilized as suppressing cells. To provide an ultra-wide stopband, two pair of T-shaped resonator and two high frequency suppressing cells are employed. The structure of this filter is folded to have compact size. The measured results shows −3 dB cutoff frequency of 1.4 GHz. The transition band is equal to 0.25 GHz from 1.4 to 1.65 GHz, with corresponding attenuation levels of −3 to −20 dB. The ultra-wide stopband with −22 dB suppression level is from 1.68 to 40 GHz. Also, the total size of the proposed lowpass filter is 16.8 × 11.3 mm 2 .
Design of compact microstrip lowpass filter with ultra-wide stopband
Electronics Letters, 2012
behnam afzali 1 , mohammad mehdi karkhanehchi 2 and gholamreza karimi 2 A new microstrip lowpass filter with compact size and ultra-wide stopband using T-shaped resonator is proposed. To make smaller the circuit size of the filter, cursive transmission line is also suggested. Moreover, exact equation of most important transmission zero is calculated based on LC equivalent circuit and transformation function. A demonstration filter with 3 dB cutoff frequency at 1.02 has been designed, fabricated, and measured. Results show that a relative stopband band width of 166.3% (referred to suppression degree of 20 dB) is achieved while obtaining high figure of merit of 46 274.
Microstrip Lowpass Filter with Ultrawide Stopband and Sharp Roll-off
Arabian journal for science and engineering, 2014
In this article, a new microstrip lowpass filter with ultra-wide stopband using T-shaped resonators and folded structures is described. The structure of this filter is very simple, so that only a T-shaped resonator is used as main resonator without any particular changes in these resonators. The designed T-shaped main resonator has a −3 dB cutoff frequency of 1.4 GHz. On the other hand, T-shaped resonators with low base length are utilized as suppressing cells. To provide an ultra-wide stopband, two pair of T-shaped resonator and two high frequency suppressing cells are employed. The structure of this filter is folded to have compact size. The measured results shows −3 dB cutoff frequency of 1.4 GHz. The transition band is equal to 0.25 GHz from 1.4 to 1.65 GHz, with corresponding attenuation levels of −3 to −20 dB. The ultra-wide stopband with −22 dB suppression level is from 1.68 to 40 GHz. Also, the total size of the proposed lowpass filter is 16.8 × 11.3 mm 2 .
The Design and Investigation of the Low-Pass Filter with High Selectivity and Ultra-Wide Stopband
In this work, an ultra-wide stopband low-pass filter (LPF) is proposed using tapered step impedance resonators. The distributed equivalent of the proposed step impedance LPF is extracted, analyzed, and legitimated with simulated and fabricated results. The fabricated prototype has a 3 dB cutoff frequency (f c) of 2.92 GHz and an ultra-wide stop band extended up to 25.7 GHz (8.8fc) with an attenuation level of > 20 dB. The transition bandwidth (from 3 to 20 dB) is 0.20 GHz and the rolloff factor is 112 dB/GHz (a reference to 30 dB). The passband insertion loss is 0.32 dB at 1.5 GHz and the normalized circuit size of the filter is 0.055.
ETRI Journal, 2015
A novel microstrip low-pass filter is presented to achieve an ultra-wide stopband with 11 harmonic suppression and very sharp skirt characteristics. The filter is composed of a modified U-shaped resonator (which creates two fully adjustable transmission zeroes), a T-shaped resonator (which determines a cutoff frequency), and four radial stubs (which provide a wider stopband). The operating mechanism of the filter is investigated based on a proposed equivalent-circuit model, and the role of each section of the proposed filter in creating null points is theoretically discussed in detail. The presented filter with 3 dB cutoff frequency (f c = 2.35 GHz) has been fabricated and measured. Results show that a relative stopband bandwidth of 164% (referred to as a 22 dB suppression) is obtained while achieving a high figure-of-merit of 15,221.
Optik, 2016
A novel microstrip lowpass filter (LPF) with very sharp roll-off, compact size and ultra-wide stopband is presented in this paper. The structure consists of modified stepped impedance Hairpin resonator and a circular patch as a suppressor. The proposed LPF has the cutoff frequency of 1.07 GHz. The simulation results indicated that the transition-band of the proposed LPF is 0.09 GHz from −3 to −20 dB. Maximum insertion-loss at about 80% of the passband is 0.1 dB. The proposed LPF has been designed, fabricated and measured. From the measurements, good agreements with the simulated results are obtained. Also, an ultra-wide stopband was achieved. Proposed LPF has an ultra high figure-of-merit (FOM) of 151,523, which shows its strong efficiency.
Compact Low Pass Filter Using Sharp Roll-off Ultra-Wide Stopband T-shaped Resonator
2018
Background and Objectives: In this paper, an ultra-wide stopband microstrip low pass filter (LPF) with sharp roll-off and compact size is designed and fabricated. Also, proposed filter is designed, simulated, optimized, fabricated and measured and we can see a good agreement between the simulations and measurement results. Methods: T-shaped and stepped impedance have been used, because these structures have a very small dimensions. This method provides a suitable cut off frequency. Results: The cut off frequency at -3dB is 3.1GHz. In the proposed structure, the insertion loss is lower than 0.12dB and the return loss is greater than 15dB. In order to achieve a -20dB attenuation level in the stopband, a modified L-shaped structure is utilized. This filter has an ultra-wide stopband that is expanded from 3.37GHz to 37.5GHz. Also, the suppression level is greater than -20dB. The fabricated LPF has a size about 16.6 × 13.5 mm2 which is equal to 0.28ƛg × 0.22ƛg, where ƛg is the guided wa...
A Wide Stopband Low-Pass Filter With High Roll-Off Using Stepped Impedance Resonators
IEEE Microwave and Wireless Components Letters, 2018
In this letter, a microstrip low-pass filter (LPF) is presented with outstanding merits such as sharp roll-off, low insertion loss, and wide stopband bandwidth. The structure of the proposed filter comprises three coupled stepped impedance resonators which offer a very high selectivity. To extend the stopband rejection bandwidth, two circular slots are etched out in the ground plane. The lumped equivalent model of the proposed distributed LPF is extracted and validated by simulation and theory. The fabricated LPF demonstrates a small transition bandwidth of 50 MHz (−3 and −25 dB at 1.95 and 2 GHz, respectively) and high roll-off rate of 440 dB/GHz. The stopband bandwidth extends up to 16 GHz (8.2f c harmonic suppression) with an attenuation level better than −12 dB. Insertion loss is 0.4 dB at 1 GHz, and group delay is <1.73 ns in the entire passband. The size of the proposed filter is 0.03357λ 2 g .