Location Of Transmission Zeros Research Articles

Millimeter-Wave On-Chip Bandpass Filter Using Complementary-Broadside-Coupled Structure

A new millimeter-wave on-chip bandpass filter (BPF) using complementary-broadside-coupled (CBC) structure is presented. The transmission zeros (TZs) of the proposed BPF are calculated and analyzed through using an LC equivalent circuit. An overall guidance is given for tuning the locations of TZs through changing the physical parameters of the layout or the electrical parameters of the equivalent circuit. To prove the feasibility of the proposed BPF, a prototype with very compact size is designed and fabricated in a commercial 0.13-lm SiGe (Bi)-CMOS technology, whose center frequency and bandwidth are 67 GHz and 44.8%, respectively. Good agreement between simulated and measured results validates the proposed idea.

SIW Triplets Including Meander-Line and CRLH Resonators and Their Applications to Quasi-Elliptic Filters

This article presents a design technique of quasi-elliptic filters by applying two novel planar triplets, which eliminates the need for negative couplings. A composite right-/left-handed (CRLH) resonator, together with a meander-line resonator, is investigated first in this article. These two resonators demonstrate a significant difference with respect to their phase shift characteristics that are completely opposite below and above their resonant frequencies. With such a feature, two meander-line and CRLH-loaded substrate integrated waveguide (SIW) triplets are proposed, which can produce a transmission zero (TZ) above and below the passbands if an inductive cross coupling is applied. Therefore, all couplings would be positive regardless of the location of TZs. The applications of the two triplets to quasi-elliptic filters, which are realized by parallel and cascaded triplet topologies, are then illustrated. Two filter prototypes operating at the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$</tex-math> </inline-formula> -band are designed and fabricated for validation. They show outstanding electrical performance in terms of high selectivity, low loss, and compactness. It indicates that a joint application of conventional shunt <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant nodes and a CRLH node is a viable option in filter design.

A compact low‐cost dual‐band bandpass filter with enhanced suppression using substrate integrates suspended line technology

AbstractA compact dual‐band bandpass filter based on the substrate integrates suspended line platform is proposed in this letter. The design is implemented using low‐cost FR‐4 material, while the loss can be reduced by 3D metal connections with substrate cutout. 0.97 dB/1.6 dB improvement of insertion loss is achieved and verified at 3.45 GHz/4.9 GHz. By paralleling quarter wavelength step impedance resonators with different operating frequencies, two paths formed between source and load. Both bandwidth and location of transmission zeros can be adjusted independently. Two stubs are added working not only as feed structure but also as a stop band resonator, which can provide 20 dB out‐of‐band suppression up to 4.4f0. The obtained performances are good enough to compare with the state of art, though very low‐cost FR‐4 materials are used.

Design of a miniaturized planar microstrip Wilkinson power divider withharmonic cancellation

In this paper, a compact microstrip Wilkinson power divider is designed and proposed using rectangularshaped resonator cells. The presented resonator cells are used instead of quarter-wave length branches in the traditional structure to reduce the circuit size, increase the bandwidth, and eliminate the unwanted harmonics. The designed resonator behavior is studied analytically and the locations of transmission zeros are investigated using transfer function andLCequivalentcircuitmethods. The proposed power divider(PD)operates at 2GHz frequency and suppresses the 2nd to 14th unwanted harmonics. The proposed PD achieves approximately 50% size reduction and 40%fractional bandwidth (FBW). The abilities of desirable size reduction and harmonic suppression along with simple structure and wide FBW make the proposed divider a good choice for the modern communication systems, such as multistage power amplifier applications. The proposed divider is implemented and measured. The measurement results verify the simulation responses.

Bandpass filter based on asymmetric funnel shaped resonators with ultra wide upper stopband characteristics

A novel microstrip bandpass filter with wide passband, good skirt selectivity and very good passband reflection characteristics using asymmetric funnel shaped resonators is presented in this paper. IE3D simulation software is used for the design and analysis of the proposed filter and the electric field intensities at various frequencies of interest are plotted and verified the role of even and odd mode resonances in achieving wide passband. There are six modes, including three even and three odd modes for the developed filter. Novel equations are derived for finding out the location of transmission zeros and the role of resonators in achieving sharp selectivity are verified. The out of band performance of filter is very good with a suppression level greater than 20 dB upto 24.2 GHz. The centre frequency of the filter is 5.68 GHz with a fractional bandwidth of 97.57%. The fabrication process is carried out using MITS 11 Autolab fabrication machine with the low cost FR4 substrate and verified the performance improvement of the developed filter.

New negative coupling structure and its application on substrate integrated waveguide bandpass filters

To design cross-coupled substrate integrated waveguide (SIW) bandpass filters (BPFs) with high performance, a new negative coupling structure is proposed, which is constructed by two coupled lines with shorted ends. The negative coupling structure is analyzed in detail. The stracture which can realize both relatively weak and strong negative coupling strength. The optimization method based on characteristic polynomials and reference zeros and poles of scattering parameters is realized for the filter design. To verify the proposed negative coupling structure, two fourth-order cross-coupled SIW BPFs with the center frequency of 10 GHz based on the optimized coupling matrixes are designed. The first one has a normalized bandwidth of 3% with a negative coupling in one cross-coupling path to illustrate the realization of weak negative coupling strength, and the second one has a normalized bandwidth of 8% with a negative coupling in one main coupling path to illustrate the realization of strong negative coupling strength. Finally, the two BPFs are fabricated and measured. Simulation and measurement results are in good agreement, which demonstrates the feasibility of the proposed negative coupling structure and its application on cross-coupled SIW filters with high performance. The influence of weak disperse cross coupling on locations of transmission zeros is also discussed.

High-Selectivity Tunable Filters With Dual-Mode SIW Resonators in an L-Shaped Coupling Scheme

This article reports the design of high-selectivity tunable bandpass filters with constant absolute bandwidth (CABW) using dual-mode (DM) substrate-integrated-waveguide (SIW) resonators. The even and odd modes are coupled to the source and load using an L-shaped coupling scheme instead of the conventional doublet scheme, and thus, each mode produces either one reflection zero or one transmission zero (TZ). Each resonator has one contactless tuner to change the frequencies of both modes simultaneously, and a controllable separation between the two modes can be obtained over the whole tuning range (TR). The proposed resonator is utilized as the building block in four prototype filters with different TZ locations. The first filter is in a principle back-to-back topology, and it distributes TZs on both sides of the passband and has a CABW across the entire TR. The rest three further explore techniques to improve the out-of-band selectivity, i.e., introducing source/load coupling to increase the reject level and relocating the TZs on one side of the passband to build a spectrum with high rejection. All filters are based on two DM SIW resonators with only two tuners. Compared to state-of-the-art works, the proposed filters offer a wide constant-BW TR, low insertion loss, high selectivity, and good nonlinear performance.

Selectivity improved directional filters using cross-coupling introduced transmission zeros

ABSTRACTIn this paper, the realization of traveling-wave directional filters allowing for selectivity improvement without increasing filter’s order is presented and studied. It is shown that the introduction of loose cross-coupling between #(n-1)th loop resonator and isolated port of the nth-order directional filter allows for generating transmission zeros in the bandpass branch and thus to improve the filter`s roll-off. Moreover, the electrical length of the cross-coupling connecting transmission line allows for adjusting the location of transmission zeros and realizing symmetric or asymmetric frequency response. The presented approach is theoretically analyzed and experimentally verified. Exemplary second- and third-order directional filters with symmetrically placed transmission zeros were designed to operate at f0 = 1 GHz, manufactured and measured. The obtained results prove their applicability towards the realization of frequency multiplexers.

Fractally slotted patch resonator based compact dual-mode microstrip bandpass filter for Wireless LAN applications

A miniaturized dual-mode microstrip bandpass filter (BPF) based on fractally slotted patch resonator is presented in this paper. The proposed filter is centered at 2.4 GHz desirable for Wireless LAN applications. The dual-mode filter is realized using the fractally slotted structure on an octagonal patch resonator with perturbation. The design offers transmission zeros (TZs) at 2.19 GHz and 2.66 GHz on either side of the filter passband ensuring high selectivity. The locations of TZs from the center frequency can be adjusted by tuning the perturbation size. The filter is fabricated on a substrate with high permittivity and found to have a 3-dB fractional bandwidth (FBW) of 5% in the passband. Moreover, the measured minimum insertion loss is less than 0.91 dB and the return loss is greater than 23 dB in the passband. The prototype filter is fabricated and tested. Good agreement is accomplished between the experimental and simulation results. Furthermore, the footprint of the fabricated filter is about 0.416λg × 0.416λg where λg is the guided wavelength at 2.4 GHz.

Determination of the Overshoot Scalar Control Systems with Transfer Zero and Binomial Law of Poles Distribution

Background/Objectives: One of the most popular approaches to the design of automatic control systems is the modal method of controller synthesis. Methods: Its peculiarity is that the requirements for management process quality are formalized by ensuring the desired location on a complex plane of a closed system poles. At that, the introduction of the modal controller makes no effect on the location of transmission zeros. Finding: However, it is known that many transition process quality indicators (e.g., overshoot value) depend not only on the poles but the zeros of the transfer function as well. In work presented here, we analyzed the dependence of overshoot value on the relative position of a dynamic system zeros and poles. Calculation formulas which allow determining the value of a positive or a negative overshoot without the development of transient response are obtained for a scalar system with one zero and the binomial pole distribution law. The dependence of overshoot value on the relative position of the transmission zero and the dynamic system poles is studied. The conditions are formulated, the implementation of which will provide in control system such an overshoot value which does not exceed a predetermined value. Conclusion: The obtained results can be used for further theoretical studies as well as in practice in solving problems of analysis and synthesis of control systems with a modal controller.

Determination of the Overshoot Scalar Control Systems with Transfer Zero and Binomial Law of Poles Distribution

Background/Objectives: One of the most popular approaches to the design of automatic control systems is the modal method of controller synthesis. Methods: Its peculiarity is that the requirements for management process quality are formalized by ensuring the desired location on a complex plane of a closed system poles. At that, the introduction of the modal controller makes no effect on the location of transmission zeros. Finding: However, it is known that many transition process quality indicators (e.g., overshoot value) depend not only on the poles but the zeros of the transfer function as well. In work presented here, we analyzed the dependence of overshoot value on the relative position of a dynamic system zeros and poles. Calculation formulas which allow determining the value of a positive or a negative overshoot without the development of transient response are obtained for a scalar system with one zero and the binomial pole distribution law. The dependence of overshoot value on the relative position of the transmission zero and the dynamic system poles is studied. The conditions are formulated, the implementation of which will provide in control system such an overshoot value which does not exceed a predetermined value. Conclusion: The obtained results can be used for further theoretical studies as well as in practice in solving problems of analysis and synthesis of control systems with a modal controller.

Design of a compact microstrip lowpass filter with sharp roll‐off using combined T‐shaped and L‐shaped resonators

A novel compact microstrip lowpass filter with high performance is designed and analysed based on transfer function. The main resonator consists of L-shaped and T-shaped patches. The L-shaped resonator is used to increase the width of the stopband. The presented filter has −3 dB cut-off frequency at 2 GHz. It also has a wide stopband about 17.82 GHz with the suppression level of −21 dB. The transition band is ∼168 MHz from −3 to −40 dB. The locations of transmission zeros are calculated by transfer function. The presented lowpass filter has other advantages, such as high return loss more than 20 dB and low insertion loss <0.15 dB in the passband. The size of the filter is only 0.087 × 0.170 λg2, where λg is the guided wavelength at the cut-off frequency. The proposed lowpass filter has the figure of merit of 50,285, which shows its strong efficiency. The lowpass filter is simulated and fabricated and there is a good agreement between the simulation and measurement results.

A NOVEL WIDEBAND BANDPASS FILTER USING COUPLED LINES AND T-SHAPED TRANSMISSION LINES WITH WIDE STOPBAND ON LOW-COST SUBSTRATE

This paper presents the design, simulation, fabrication and measurement of a wideband bandpass filter with wide stopband performance operating at 3.5 GHz. The proposed filter consists of two parallel coupled lines (T-PCL) centred by T-inverted shape. The location of transmission zeros can be adjusted by varying the physical lengths of T-inverted shape to improve the filter selectivity. The wide bandwidth is achieved through enhanced coupling between the input and the parallel coupled lines. Due to the transmission zeros in the lower and upper stopbands, the filter exhibits good performance including an extremely wide stopband and sharp attenuations near the passband together with low insertion and good return losses in the passband. The filter performance is investigated numerically by using CST-MWS. Finally, the microstrip wideband BPF with minimum insertion losses 0.3 dB, centred at 3.5 GHz with a 3-dB fraction bandwidth of 70% and four transmission zeros is implemented and verified experimentally. In addition, good agreement between the simulated and measured results is achieved.

A novel microstrip bandpass filter with an elliptic-function response using improved dual-stub resonator

In this article, a new microstrip bandpass filter (BPF) with multiple transmission zeros is designed, simulated and measured. The presented filter is based on a composite dual-stub resonator. The modified resonator with dual-bandgap resonant characteristic is composed of the parallel open- and short-circuited stubs, and cascaded by an additional stub line. The location of transmission zeros can be adjusted independently by varying the physical lengths of shunt resonant stub or cascaded stub line, so as to improve the filter selectivity. The proposed filter consists of two identical main transmission lines and three equal-length combined resonators with different length ratios between the cascaded section and open-/short-circuited stubs. Finally, a planar BPF with minimum insertion loss 0.65 dB, centred at 2.08 GHz with a 3-dB fraction bandwidth of 26.8% and six transmission zeros is implemented and verified by experiment.

On-Chip Single-to-Balanced Multicoupled Line Bandpass Filters With Good Selectivity

In this work, on-chip single-to-balanced bandpass filters with good selectivity are proposed. The functions of bandpass filter and balun are integrated using a simple multicoupled line structure along with capacitive loadings. The use of inductor is avoided such that the proposed single-to-balanced bandpass filters can achieve very compact size when implemented on chip. They can be designed with the desired bandpass response and reference impedances through the proposed equivalent-circuit models and design equations. In addition, by introducing two cross-coupled capacitors, one tunable transmission zero can be achieved in either the lower or upper stopband to improve the selectivity. Specifically, two third-order single-to-balanced bandpass filter designs in commercial pHEMT process on 4-mil GaAs substrate with different transmission zero locations are presented. The circuit size is less than 1.02 mm × 0.86 mm for a center frequency of 5.5 GHz and a bandwidth of about 18.18%. The corresponding electrical size is only 0.054λg×0.045λg at the center frequency. Good selectivity and balanced performance are demonstrated.

Miniaturized Hairpin Filter using Asymmetrical Spurlines with Multiple Transmission Zeros

An improved asymmetrical spurline structure is introduced in this paper. Its dual-bandgap characteristics are discussed, and the equivalent circuit parameters are extracted from electromagnetic simulations. Then, a miniaturized tri-hairpin-shaped resonator filter with the proposed asymmetrical spurlines is designed, analyzed, and fabricated. The relationship between the independently controllable transmission zero locations and spurlines' length is described. Measurements verify that this bandpass filter centers at 1.46 GHz with a 3-dB bandwidth of 17%, and four transmission zeros are implemented. The circuit size occupies only 16.8 × 13 mm2 (≈ 0.13λg × 0.085λg ).

A Miniaturized Conductor-Backed Slot-Line Resonator Filter With Two Transmission Zeros

In this letter, a miniaturized planar two-pole microwave filter with two transmission zeros is presented. The building block of this filter is a high-Q double spiral slot resonator backed by a conductor plane. The provision of a float back conductor plane allows vertical integration of this filter with other passive and active RF electronic components usually found in miniaturized wireless transceivers. The conductor plane also provides a coupling mechanism between the input and output of the filter giving rise to transmission zeros. It is shown that the location of transmission zeros can easily be adjusted and significant out-of-band rejection be achieved using only two miniaturized double-spiral resonators. The design procedure and fabrication of a two-pole filter operating at 2.11GHz is demonstrated and a very good agreement between measured and simulated results is shown

Compact microstrip coupled-line bandpass filter with four transmission zeros

A compact coupled-line bandpass filter with multiple capacitive cross-couplings to create four transmission zeros is proposed. The locations of transmission zeros can be adjusted by varying the values of cross-coupled capacitances so as to improve the filter selectivity. The proposed filter is based on one-eighth-wavelength (/spl lambda//8) coupled-line sections and quarter-wavelength (/spl lambda//4) resonators, thus it occupies only half of the circuit area comparing with the conventional coupled-line bandpass filters. Specifically, a fourth-order microstrip coupled-line bandpass filter centered at 2.46GHz with a 3-dB bandwidth of 10.2% and four transmission zeros is implemented and examined.

Iterative design of two-channel IIR perfect construction QMG filters

A simple rapidly convergent method is described for the design of two-channel IIR perfect reconstruction quadrature mirror filters. For any prescribed characteristic, it has been shown how one can construct a stable two-channel IIR banks, starting from any random transmission zero locations. A simple rapidly convergent search algorithm is also described for the determination of the exact locations of these transmission zeros, such that the filter has equiripple pass and stop responses as well as almost constant group delay. Illustrative examples are also given to show that the proposed design method competes very well with the existing design methods. © 1998 John Wiley & Sons, Ltd.

Frequency-domain identification of transmission-zero locations of linear multivariable plants

In the case of asymptotically stable multivariable plants for which input-output decoupling is achievable, the location in the complex plane of the transmission zeros is identified on the basis of the low-frequency and high-frequency transfer-function matrices.