基于环形谐振器的平衡式带通滤波器

提出了一种基于多模环形谐振器实现的平衡式带通滤波器, 其主要由加载了电阻和短路枝节的环形谐振器和两对平衡端口构成.所提出的滤波器能够以单个谐振器获得差模的双模响应, 并且具有结构简单, 共模抑制高, 带宽可进行有限控制(4% ~ 9%)的优点.为验证理论预期的可实现性, 在RO4003C基板上设计了一个工作在1.87 GHz的平衡式带通滤波器.实验结果表明该滤波器的20-dB阻抗匹配带宽为8.9%, 中心频率处的插入损耗为0.86 dB, 在1 ~ 3 GHz频率范围内的共模抑制大于30 dB.     

Novel Broadband Bandpass Filters Using Y-Shaped Dual-Mode Microstrip Resonators

A Y-shaped dual-mode microstrip bandpass filter (BPF) with input-output cross-coupling is presented. The characteristic of the Y-shaped dual-mode resonator has been investigated. The resonance frequencies of the degenerate modes can be adjusted easily to satisfy the bandwidth of the BPF. A parallel-coupling feed structure with a cross coupling has been used to generate two transmission zeros at the lower and upper stopband, which can improve the out-of-band performance. A broadband dual-mode microstrip BPF has been designed, fabricated, and measured. The simulated and measured results are in agreement generally. Within the 3.1 to 5.4 GHz bandwidth, the measured insertion loss, return loss and group delay variation are below 0.5 dB, above 15 dB, and below 0.2 ns, respectively.      

Millimeter-Wave Ultra-Wideband Bandpass Filter Employing Dual-Mode Ring Resonators Fed by Step-Impedance Coupled Lines

This paper presents a novel millimeter-wave ultra-wideband (UWB) bandpass filter (BPF) based on microstrip dual-mode rectangular ring resonators. In order to get strong coupling between the input/output line and the dual-mode ring resonators, a step-impedance parallel-coupled structure is adopted for the design of the filter. On the other hand, transmission zeros are produced by the dual-mode resonator. As a consequence, the filter has low insertion-loss in its passband, sharp attenuation in its lower and upper stopbands and very wide stopbands. As an example, a filter with two dual-mode ring resonators is designed and fabricated. The measured frequency property of the fabricated filter shows good agreement with the simulated response.     

Bandpass filter design using a microstrip triangular loop resonator with dual-mode operation

A bandpass filter (BPF) design using a dual-mode microstrip triangular loop resonator is presented for the first time. The circuit produces frequency responses with one real finite frequency transmission zero and one imaginary finite frequency zero on either side of the passband. Depending on the perturbation arrangement, the nature of the coupling between degenerate modes causes the zeros to exchange their axis locations from real to imaginary and from imaginary to real while keeping their magnitude. This behavior results in frequency responses that are suitable for applications with asymmetrical requirements. Results show 8% bandwidth filters with insertion loss ranging from 0.82 dB to 1.4dB at 10 GHz. Advantages in size reduction and design flexibility are demonstrated when the triangular loop is compared to other dual-mode resonators.     

A Balun-Bandpass filter with good in-band performance and wide stopband

A high performance Balun BandPass Filter (BPF) with capacitively loaded multiple coupled lines with very simple structure is proposed in this paper, this structure realizes simultaneous size reduction and superior harmonic response suppression performance in bandpass filtering meanwhile good differential performance of the Balun. The theory of this structure for unbalanced input into balanced output has been studied in this paper and a proper Balun and BPF characteristic by the symmetric feeding and skew symmetric feeding have been obtained to prove the theory. The enter frequency of the fabricated Balun-BPF is operated at 2.45 GHz with 6.93% Fractional Band Width (FBW), and this frequency is used for Bluetooth and some other communication systems. The differences between the two outputs are 180° ± 1.92° in phase and within 0.33 dB in magnitude. At f ₀, the amplitude imbalance and phase difference are within 0.25 dB and 180.86°, respectively. The measured frequency responses agree well with the simulated ones. With the theoretical analyses and practical results, it is shown that the proposed one has the advantages of simple structure, convenient analysis and good performance of both BPF and Balun.     

A novel microstrip dual-mode bandpass filter with harmonic suppression

A novel dual-mode microstrip bandpass filter (BPF) with harmonic suppression is presented in this letter. The filter is composed of a perturbed square-ring resonator and two end-open L-shaped microstrip lines for the input and output of the resonator. The harmonic suppression of the BPF may be realized by choosing a proper length for the L-shaped microstrip line. The BPF has been investigated numerically and experimentally. Measured results show that the stop-band of the filter is increased up to near the third-order harmonic of the square-ring resonator due to harmonic suppression, and the rejection level is kept below -27dB.     

Design of fractal-based CMOS bandpass filter for WirelessHD system

We proposed a fractal-based dual-mode bandpass filter (BPF) using a standard CMOS process for application of 60 GHz WirelessHD system. We first investigated the effect of coupling feedlines of I/O ports set at different layer of M3 and M4 layer on the transmission loss of the resonator, and verified the nature coupling of fractal-based dual-mode filter. Experimental result shows that the designed filter with a fractional-bandwidth (FBW) of 23%, an insertion loss about 7 dB and return loss larger than 10 dB. Additionally, two transmission zeros are appeared at the passband edges, thus much improve the selectivity of the proposed CMOS BPF. The result indicates that fractal-based structure is feasible and can meet the requirement in the mm-wave application.     

70 GHz Folded Loop Dual-Mode Bandpass Filter Fabricated Using 0.18 $mu$ m Standard CMOS Technology

This letter presents the design and implementation of a 70 GHz millimeter-wave compact folded loop dual-mode on-chip bandpass filter (BPF) using a 0.18 $mu$m standard CMOS process. A compact BPF, consisting of such a planar ring resonator structure having dual transmission zeros was fabricated and designed. The size of the designed filter is 650$,times,$ 670 $mu$ m$^{2}$ . Calculated circuit model, EM simulated and measured results of the proposed filter operating at 70 GHz are shown in a good agreement and have good performance. The filter has a 3-dB bandwidth of about 18 GHz at the center frequency of 70 GHz. The measured insertion loss of the passband is about 3.6 dB and the return loss is better than 10 dB within the passband.      

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.     

60-GHz Band Dual-Mode Microstrip Ring Resonator Bandpass Filter Using Micromachining Technology

A new compact millimeter-wave dual-mode ring resonator bandpass filter is proposed. This filter has a 15% bandwidth at 58 GHz with 3.4 dB insertion loss. Input/output lines and ring resonator are directly connected to obtain tight coupling, and an open-end stub is inserted for dual-mode operation. This filter is fabricated on a GaAs wafer by using MEMS technology and can be applied for the millimeter- wave SoC.     

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.     

A novel dual-mode bandpass filter with wide stopband using the properties of microstrip open-loop resonator

A novel dual-mode microstrip square loop resonator is proposed using the slow-wave and dispersion features of the microstrip slow-wave open-loop resonator. It is shown that the designed and fabricated dual-mode microstrip filter has a wide stopband including the first spurious resonance frequency. Also, it has a size reduction of about 50% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop, and ring resonator filter.     

Dual mode wideband band-pass filter with notched band for communication system

This paper presents a planar microstrip wideband dual mode Band-Pass Filter (BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz. The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at ?? =90° and ?? =0°, respectively. A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity. By using a parallel-coupled feed line, a narrow notched band is introduced at the required frequency and its Fractional BandWidth (FBW) is about 5%. The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic, the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz (calculated from 1.959 GHz with ?34.43 dB to 2.065 GHz with ?2.93 dB) and 228.10 dB/GHz (calculated from 3.395 GHz with ?2.873 dB to 3.507 GHz with ?28.42 dB). This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz. Having been presented in this article, the measurement results agree well with the simulation results, which validates our idea.     

A reduced-size dual-mode bandpass filter with capacitively loaded open-loop arms

A novel type of dual-mode microstrip bandpass filter using degenerate modes of a dual-mode microstrip square loop resonator with capacitively loaded open-loop arms is proposed. Such a dual-mode bandpass filter with a 0.75% bandwidth at the center frequency of 1.603 GHz is designed and fabricated to demonstrate the design of reduced-size microstrip filters. It is shown that the proposed filter has a size reduction of about 59% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop and ring resonator filter.     

Single-Cavity triangular substrate integrated waveguide bandpass filter with complementary triangular split ring resonator

A novel single-cavity equilateral triangular substrate integrated waveguide (TSIW) bandpass filter (BPF) with a complementary triangular split ring resonator (CTSRR) is designed in this paper. A metallic via-hole is used to split the degenerate modes and adjust the transmission zeros (TZs) properly. Meanwhile, the CTSRR is utilized as a resonator to work together with the degenerate modes of the TSIW cavity. The resonant frequency of the CTSRR can be adjusted by its own size. Meanwhile, a TZ is observed in the lower band due to the CTSRR. Finally, a 16% 3dB fractional bandwidth (FBW) triple-mode TSIW BPF with three TZs in both lower and upper bands is simulated, fabricated, and measured. There is a good agreement between the simulated and measured ones.     

Compact dual-mode elliptic-function bandpass filter using a singlering resonator with one coupling gap

A novel microwave dual-mode elliptic-function bandpass filter with one coupling gap structure is proposed. This filter has a 4.7% bandwidth at 1.805 GHz with 1.73 dB insertion loss. The filter provides less field perturbation of the ring resonator than conventional filters. Without the output coupling gap between the feed line and the ring resonator, a low insertion loss has been obtained. This compact, high performance filter is useful for mobile and personal communication systems     

A Fully Embedded 60-GHz Novel BPF for LTCC System-in-Package Applications

In this paper, a novel LTCC stripline (SL) 60-GHz band-pass filter (BPF) composed of transitions to coplanar waveguide (CPW) pads for monolithic microwave integrated circuit integration is presented. For low-loss interconnection with active devices, a CPW-to-SL vertical via transition integrating air cavities and a CPW-to-CPW planar transition using internal ground planes are proposed and implemented. The fabricated transition shows an insertion loss of 1.6 dB and a reflection loss below -20 dB at the passband of the filter. The implemented SL BPF using dual-mode patch resonators shows a center frequency of 60.4 GHz, 3.5 % bandwidth, and reflection losses below -15 dB at the passband. Excluding the insertion loss of the transitions, the filter insertion loss reveals 4.0 dB     

Microwave resonators with dual-mode oscillations

Analysis of microwave resonators with dual-mode oscillations is conducted. A new type of resonators is discovered in which dual-node oscillations are observed. It represents a half-wave resonator with a short-circuit in the middle part. The length of such a resonator is twice less than the length of a widely used ring resonator. It is shown that in resonators of the loop type combined frequency tuning of dual-mode oscillations is accomplished using capacity and inductance. In the loop-type resonators with a stub frequency tuning of dual-mode oscillations is accomplishing with two capacities synchronously changing their values according to a specific law. Resonance equations are obtained.     

Dual-mode microstrip bandpass filter using ring of arrows resonator

A dual-mode microstrip bandpass filter using the degenerate modes of a modified square ring structure is proposed. The size of the new structure is 50% less than conventional dual-mode bandpass microstrip square resonator filters at the same centre frequency. Measurements are in good agreement with designed values.     

An Ultra-Wideband Bandpass Filter With an Embedded Open-Circuited Stub Structure to Improve In-Band Performance

In this letter, we present a compact ultra-wideband bandpass filter (BPF) with a notch band in the BPF performance by using an embedded open-circuited stub structure. The filter mainly consists of conventional stepped impedance resonator (SIR) as the multiple-mode resonator and two enhanced coupled input/output lines. The bandwidth can be analyzed by using the image-parameter method to obtain the proper dimension of the coupled lines and verified by using electromagnetic (EM) simulation. The embedded open-circuited stub structure in the SIR is used to produce a narrow notched band at 5.8 GHz, which its frequency position and bandwidth can be tuned by its physical parameters. The measured 3 dB fractional bandwidth of 113.8% and narrow notched band with 25 dB rejection is achieved. Good agreement between the EM simulation and measurement is obtained.