Planar microstrip UWB bandpass filter using U-shaped slot coupling structure

A compact planar microstrip UWB bandpass filter is proposed. It is realised by cascading a lowpass filter and a highpass filter. A transmission line with U-shaped slots coupled with two DGS units on the back of the circuit board has the characteristic of highpass, while a periodic uniform DGS array has the characteristic of lowpass. Combining these two structures, a new UWB bandpass filter (BPF) is fabricated and measured. Measured results show that the proposed BPF has wide bandwidth from 3.0 to 10.9 GHz, all the measured return loss less than 13 dB in the passband. The BPF achieves a wide stopband with 18 dB attenuation up to 18.0 GHz     

Design of an RF Low-Noise Bandpass Filter Using Active Device Reduction Technique

This letter presents a new design for the radio frequency low-noise bandpass filter (BPF) using the active device reduction technique. In a conventional active BPF based on the negative resistance method, the number of active devices depends on the order of the BPF. In the proposed design, the number of active devices is reduced in half, using the suggested new technique. Compared with the conventional active BPF, the proposed one shows better noise figure and consumes less power. We apply this technique to the design of the second order BPF and verify that the measured results exhibit good active filter performances     

Bandpass Filter with Wide Stopband Using Composite Right/Left Handed Transmission Line

Abstract This paper presents a wide-stopband bandpass filter (BPF) based on mixed coupling of the composite right/left handed transmission line (CRLH-TL). First the CRLH-TL resonator is introduced and analyzed. Then mixed coupling (Both electric coupling path and magnetic coupling path exist) of the novel resonator is explained. Based on the structural features of the CRLH-TL resonators, this coupling path can generate an additional transmission zero near passband without increasing the overall size of the filter. Then, good selectivity of the proposed BPF can be obtained. Meanwhile, in order to get a wide stopband, two open stubs are employed to suppress harmonic response of the CRLH-TL resonator. The filter is developed and analyzed based on microwave network theory and equivalent circuit method. The proposed BPF has been designed, fabricated, and measured. The measured results agree with the predicted ones closely.     

Switchable Embedded Notch Structure for UWB Bandpass Filter

A reconfigurable ultra-wideband (UWB) bandpass filter (BPF) with switchable notch for UWB system is presented. The UWB BPF is embedded with two identical switchable notch structures, in which PIN diodes are used for electronic switching. A bias circuit for UWB applications was investigated and designed to control the state of PIN diodes in order to activate or deactivate the notch without an affect on the response of the BPF. A demonstrator for this type of switchable notch UWB filter is designed and fabricated. Simulated and measured results are described.      

Fractal Dual-Mode Open-Loop Quasi-Elliptic Bandpass Filter with Source-Load Coupling

To realize the feature of small size and high selectivity, a microstrip miniature fractal quasi-elliptic bandpass filter (BPF) with two transmission zeros (TZs) near each skirt is investigated in this paper. The TZs are created by source-load coupling between the input and output E-shaped feeding structures. By using a dual-mode Minkowski fractal shorted stub loaded open-loop resonator, the proposed BPF achieved a size reduction of 97.5% compared with the conventional square dual-mode loop BPF. Even mode analysis is adopted to characterize the Minkowski structure. The frequency responses of the current BPF were simulated and measured with good agreement.     

Design of a Wide Stopband Microstrip Bandpass Filter With Asymmetric Resonators

In this letter, a novel microstrip bandpass filter (BPF) with asymmetric resonators is presented. With the asymmetric structure and capacitively loaded coupling, a wide bandwidth with sufficient rejection level can be achieved easily. A full-wave electromagnetic simulator IE3D is used, and the prototype of the BPF is fabricated and measured. Comparisons of simulated results and experimental data are shown; moreover, good match validates the proposed filter.     

Ultra Wideband Bandpass Filter Using Embedded Stepped Impedance Resonators on Multilayer Liquid Crystal Polymer Substrate

This letter proposes an ultra wideband (UWB) bandpass filter (BPF) based on embedded stepped impedance resonators (SIRs). In this study, broad side coupled patches and high impedance microstrip lines are adopted as quasi-lumped elements for realizing the coupling between adjacent SIRs, which are used to suppress stopband harmonic response. An eight-pole UWB BPF is developed from lump-element bandpass prototype and verified by full-wave simulation. The proposed filter is fabricated using multilayer liquid crystal polymer (LCP) process and measured using vector network analyzer. Good agreement between simulated and measured response is observed. The measurement results show that the fabricated filter has a low insertion loss of 0.18 dB at center frequency 6.05 GHz, an ultra wide fractional bandwidth of 127.3% and excellent stopband rejection level higher than 32.01 dB from 10.9 to 18.0 GHz.      

Design of a New Tri-Band Microstrip BPF Using Combined Quarter-Wavelength SIRs

A new tri-band microstrip bandpass filter (BPF) is designed to produce three passbands at the commercially practical frequencies through a single piece of filter circuitry. The basic component used to build the proposed filter consists of two quarter-wavelength (lambda/4) stepped-impedance resonators (SIRs). One of the lambda/4 SIRs is designed to operate at 1.57 GHz and 5.25 GHz, and the other at 2.45 GHz. The feed positions for the two lambda/4 SIRs are carefully located to have the same distance from the via-hole ground and meanwhile to give the required external quality factors (Q_e's). In such a way, the microstripline sections between the via-hole and each of the feed positions can be combined into one to simplify the filter structure, and to reduce the BPF circuit size. Performance of the newly designed tri-band BPF is verified by measured results     

Design of a Wide Stopband Microstrip Bandpass Filter With Interdigital Resonators

In this letter, a novel microstrip bandpass filter (BPF) with interdigital resonators is presented. With the interdigital resonators and shorted asymmetrical coupled-lines, a wide bandwidth with sufficient rejection level can be achieved easily. A full-wave electromagnetic simulator IE3D is used, and the prototype of the BPF is fabricated and measured. Comparisons of simulated results and experimental data are shown; moreover, good match validates the proposed filter.      

A Ka-band narrow bandpass filter using LTCC technology

A Ka-band low-temperature co-fired ceramic (LTCC) narrow bandpass filter (BPF) is presented first. This BPF shows a very narrow 3 dB fractional bandwidth of 4.5% centered at 28.7 GHz. The advantages of multilayered LTCC technology such as high integration and vertical stacking capabilities were employed to design a three-dimensional interdigital end-coupled embedded microstrip narrow BPF. The difficulties in controlling the precise distance between two adjacent resonators in LTCC end-coupled BPF were overcome by locating the resonators on different layers. The measured insertion loss is 3 dB at 28.7 GHz.     

A Balun-BPF Using a Dual Mode Ring Resonator

In this letter, a Balun-bandpass filter (BPF) is proposed by using a dual-mode ring resonator. The Balun-BPF is not a simply combined or integrated component of a BPF and a Balun but a single BPF with the balun function. We obtained the proper balanced outputs and two-pole BPF characteristic by symmetrically placing the output ports at lambda/2 distance from each other on the dual-mode ring resonator. The fabricated Balun-BPF has a bandwidth of 40 MHz and an insertion loss of 2.4 dB at a center frequency of 2.45 GHz. The differences between the two outputs are 180-184deg in phase and within 1dB in magnitude. The measured frequency responses agree well with simulated ones.     

一种识别雷达用半集总参数LTCC双工器

介绍了一种基于低温共烧陶瓷(LTCC)工艺研制而成的小型化半集总高隔离度双工器.该双工器由L波段集总参数低通滤波器和X波段阶跃阻抗( SIR)分布参数带通滤波器组成.通过电磁仿真软件的仿真优化,实际加工滤波器的测试结果与软件仿真结果吻合.其中低通滤波器1dB截止频率为1.46GHz,带通滤波器中心频率为8.3GHz,1dB带宽为0.6GHz,通带内插损小于3.5dB,X波段端口对L波段端口隔离度大于60dB.该小型化LTCC双工器已成功应用于某毫米波战场识别系统的T/R组件中.     

Design of Switchable and Reconfigurable Semi‐lumped Wideband Bandpass Filter

A switchable single‐wideband (SWB)‐to‐dual‐wideband (DWB) bandpass filter (BPF), which is realized by using lumped switches, is presented in this paper. By alternating the operation modes—ON and OFF—in which the ON mode is achieved by placing the capacitors at the switching spots and the OFF mode is achieved by replacing the capacitors with inductors, DWB‐to‐SWB BPF can be achieved on the same device. In addition, by changing the capacitor values, the center frequency (CF) of the lower passband of DWB BPF can be easily tuned from 1.69 GHz to 2.22 GHz, while the higher passband stays almost unchanged. As an example, an SWB‐to‐DWB BPF is designed, fabricated, and measured. This BPF exhibits good performance including wideband, high isolation, compact size, and ability to switch.     

An Extended Doublet Substrate Integrated Waveguide (SIW) Bandpass Filter With a Complementary Split Ring Resonator (CSRR)

An “extended doublet” bandpass filter (BPF) is proposed using a substrate integrated waveguide (SIW) cavity with a complementary split ring resonator (CSRR) etched on its top metal plane. Thus, a single-layer BPF with two transmission zeros is realized successfully, with no additional area or layers occupied. The measured and simulated S-parameters of the filter are presented to show its predicted performance, with good agreements obtained between them.      

Analytical design of a microstrip UWB BPF with sharp rejection

This paper presents a new Ultra-WideBand (UWB) BandPass Filter (BPF) using half-wavelength (??/2) Stepped-Impedance Stub-Loaded Resonator (SISLR). Analytical equations derived by the even-odd mode analysis show the new filter has two tunable transmission zeros at both sides of the passband to provide a sharp rejection and seven transmission poles inside the passband to achieve U.S. UWB performance. For verification, a UWB BPF is designed, fabricated and measured. The measured results show that the fabricated filter has a -3 dB fractional bandwidth from 3.0 GHz to 10.9 GHz and its insertion loss less than 0.9 dB over the whole passband. Furthermore, the new filter exhibits a simple topology, sharp rejection, and deep stopband suppression.     

A new compact LTCC bandpass filter using negative coupling

This letter presents the design and realization of a new compact bandpass filter (BPF) fabricated on multilayered ceramic substrates. This BPF features coupled resonators with negative coupling coefficients. A BPF with center frequency 2.45 GHz is designed and fabricated. Its size is only 2.0 mm/spl times/1.8 mm/spl times/0.67 mm when implemented by a standard low temperature co-fired ceramic technology. The size reduction is due to the higher coupling coefficient between the negatively-coupled resonators than the positively-coupled ones, allowing tighter space between the resonators. The measured insertion losses of the previous BPF were less than 3dB and return losses more than 18dB in the passband. The measured result agrees very well with the electromagnetic (EM) designed response.     

Small Ultra-Wideband (UWB) Bandpass Filter With Notched Band

A compact ultra-wideband (UWB) bandpass filter (BPF) with notched band has been proposed and implemented in this letter. H-shaped slot is studied and adopted to tighten the coupling of inter-digital capacitor in order to improve the BPF's performance. Three pairs of tapered defected ground structures (DGS) are formed to assign their transmission zeros towards the out of band signal, thereby suppressing the spurious passband. Combining these two structures we obtain a small sized UWB BPF. Meander line slot is developed to reject the undesired wireless local-area network (WLAN) radio signals. An experimental UWB filter with notched band was fabricated with 35% less length as compared to an embedded open-circuited stub. The measured BPF insertion loss is less than 1.0 dB throughout the pass band of 2.8 to 10.8 GHz, the variation of group delay less than 0.20 ns in this band except for the notched band, and a wide stopband bandwidth with 20 dB attenuation up to at least 20.0 GHz.     

A wideband stepped-impedance rectangular-ring resonator bandpass filter with multiple notched bands

A configuration of wideband bandpass filter (BPF) with multiple notched bands is presented. Proposed BPF is based on stepped-impedance resonator. By utilising dual stepped-impedance resonators in folded topology a rectangular-ring resonator is formed. Two notched bands in the passband are achieved without using asymmetrical coupled lines. In other words, the filter configuration is capable of producing notched bands. It should be noted that additional information on filter performance and design is presented. Measurement results are presented to approve propounded filter characteristics. The measured passband of the second proposed filter is from 3.68 to 10.2 GHz with insertion loss of –1.76 dB in the first passband at the centre frequency of 4.45 GHz. The measured notched band frequencies are about 5.45 and 7.95 GHz with rejection of –21.77 and –20.82 dB, respectively. The return loss in the passband is better than –11.4 dB.     

A 3.3 mW K-Band 0.18-μ m 1P6M CMOS Active Bandpass Filter Using Complementary Current-Reuse Pair

This letter presents a low-power active bandpass filter (BPF) at K-band fabricated by the standard 0.18 mum 1P6M CMOS technology. The proposed filter is evolved from the conventional half-wavelength resonator filter, using the complementary-conducting-strip transmission line (CCS TL) as the half-wavelength resonator. Furthermore, the complementary MOS cross-couple pair is proposed as a form of current-reuse scheme for achieving low-power consumption and high Q-factor simultaneously. The simulated results indicate that the Q-factor of the proposed half-wavelength resonator can be boosted from 9 to 513 at 25.65 GHz compared with the resonator enhanced by the nMOS cross-couple pair to Q-factor of merely 43 under the same power consumption. The proposed active BPF of order two occupies the chip area of 360 mum times 360 mum without contact pads. The measured results show that the center frequency of the active BPF is 22.70 GHz and a bandwidth of 1.68 GHz (7.39 %). The measured P_{1 dB} and noise figure at 22.70 GHz are -7.65 dBm and 14.05 dB, respectively. There is a 56.84 dB suppression between the fundamental tone and the second harmonic when the input power is -11.26 dBm. While showing 0 dB loss and some residual gain, the active BPF consumes 2.0 mA at 1.65 V supply voltage with maximum of 0.15 dB insertion loss and 9.96 dB return loss at pass band.     

一种通带可控的双频SIW滤波器设计

提出了一种通过加载T形槽实现双频可控的基片集成波导带通滤波器。滤波器的双频特性由SIW腔内对称的T形槽线谐振器微扰TE101和TE102模得到。通过改变槽线谐振器的物理尺寸可以实现对滤波器两个通带中心频率的灵活控制。为了验证上述方法的可行性,设计了一个中心频率为3.77 GHz和9.27 GHz的双频滤波器。实测得该双频滤波器两个通带的回波损耗优于11 dB,在3.77 GHz时插入损耗为0.8 dB,第一通带的相对带宽可达13%。仿真和测试结果吻合较好,证实了设计方法的有效性。