Differential bandpass filters with common-mode suppression based on stepped impedance resonators (SIRs)

A novel strategy for the design of common-mode suppressed differential (or balanced) filters, based on stepped impedance resonators (SIRs), is presented. The differential mode band pass response is achieved by coupling parallel LC resonators, implemented by a patch capacitance and a grounded inductance, through admittance inverters. Such inverters are implemented by means of 90 o transmission lines, whereas the grounded inductances are implemented by means of mirrored stepped impedance resonators (SIR). For the differential mode, the symmetry plane is a virtual ground, the wide strip section of the SIR is effectively grounded, and the SIR behaves as a shunt inductance. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIR is a shunt connected series resonator, providing a transmission zero, which can be used for the rejection of the common mode in the differential filter pass band. The equivalent circuit model of the proposed structure is validated through electromagnetic simulation and experimental data of order-3 and -5 Chebyshev differential bandpass filters. Moreover, guidelines for the design of balanced filters with wide bandwidths, including ultra-wideband (UWB) bandpass filters, are provided.Ministerio de Ciencia e Innovación TEC2010-17512, CSD2008-00066Generalitat de Catalunya 2009SGR-42

Miniature Microwave Notch Filters and Comparators Based on Transmission Lines Loaded with Stepped Impedance Resonators (SIRs)

In this paper, different configurations of transmission lines loaded with stepped impedance resonators (SIRs) are reviewed. This includes microstrip lines loaded with pairs of SIRs, and coplanar waveguides (CPW) loaded with multi-section SIRs. Due to the high electric coupling between the line and the resonant elements, the structures are electrically small, i.e., dimensions are small as compared to the wavelength at the fundamental resonance. The circuit models describing these structures are discussed and validated, and the potential applications as notch filters and comparators are highlighted

Coplanar waveguides loaded with symmetric and asymmetric multisection stepped impedance resonators : modeling and potential applications

This article is focused on the analysis and modeling of coplanar waveguide (CPW) transmission lines loaded with multisection stepped impedance resonators (MS-SIRs), transversely etched on the back substrate side. The considered structure consists of a CPW loaded with a 5-section SIR (5S-SIR) with wide (capacitive) central and external sections cascaded with narrow (inductive) sections. The general case of a 5S-SIR with arbitrary lengths and widths of the different sections is considered. The structure is described by a pair of inductively coupled grounded series resonators coupled to the line through the capacitance of the central 5S-SIR section. If the structure is symmetric, the transmission coefficient exhibits a single transmission zero. Hence, these structures can be used as notch filters exhibiting wide bandwidths, provided the inductance of the 5S-SIR can be made small, and the capacitance can be enhanced by virtue of the broadside coupling. However, if symmetry is broken, two notches separated a distance that depends on the level of asymmetry and inductive coupling appear. Therefore, these structures are also useful for the implementation of differential sensors and comparators. The proposed model is validated through parameter extraction and experiment, and a proof-of-concept of a comparator is reported

Automated design of balanced wideband bandpass filters based on mirrored stepped impedance resonators (SIRs) and interdigital capacitors

This paper presents small balanced bandpass filters exhibiting wide differential-mode pass bands and high common-mode suppression. The filters are implemented in microstrip technology and their topology consists of multisection mirrored stepped impedance resonators (SIRs) alternating with mirrored interdigital capacitors. The mirrored SIRs provide the required common-mode transmission zeros to achieve effective rejection of that mode in the region of interest, i.e. the differential-mode pass band. An automated design method for such filters, based on aggressive space mapping, is reported. The method uses the equivalent circuit model of both the mirrored SIRs and the interdigital capacitors, and filter synthesis is based on a quasi-Newton iterative algorithm where parameter extraction is the key aspect. The automated design approach is illustrated through an order-3 filter, where it is demonstrated that the filter topology is generated from the specifications. As compared with previous balanced filters based on mirrored SIRs coupled through admittance inverters, the proposed filters of this work are smaller and the design method is simplified, since bandwidth compensation due to the narrowband functionality of the inverters is avoided.This work was supported by MINECO-Spain (projects no. TEC2013-47037-C5-1-R, TEC2013-40600-R, and TEC2013-49221-EXP), Generalitat de Catalunya (project no. 2014SGR-157), and Institucio Catalana de Recerca i Estudis Avancats (who has awarded Ferran Martin).Sans, M.; Selga, J.; Vélez, P.; Rodriguez Perez, AM.; Bonache, J.; Boria Esbert, VE.; Martin, F. (2016). Automated design of balanced wideband bandpass filters based on mirrored stepped impedance resonators (SIRs) and interdigital capacitors. International Journal of Microwave and Wireless Technologies. 8(4-5):731-740. https://doi.org/10.1017/S1759078716000672S73174084-

Mechanically reconfigurable microstrip lines loaded with stepped impedance resonators and potential applications

This paper is focused on exploring the possibilities and potential applications of microstrip transmission lines loaded with stepped impedance resonators (SIRs) etched on top of the signal strip, in a separated substrate. It is shown that if the symmetry plane of the line (a magnetic wall) is perfectly aligned with the electric wall of the SIR at the fundamental resonance, the line is transparent. However, if symmetry is somehow ruptured, a notch in the transmission coefficient appears. The notch frequency and depth can thus be mechanically controlled, and this property can be of interest for the implementation of sensors and barcodes, as it is discussed

Design of planar wideband bandpass filters from specifications using a two-step aggressive space mapping (ASM) optimization algorithm

This paper is focused on the automated and unattended optimization of a type of planar wideband bandpass filters by means of aggressive space mapping (ASM). The considered filters are microstrip filters implemented through a combination of shunt connected stepped impedance resonators (SIRs) and grounded stubs coupled through admittance inverters. The most relevant and novel aspect of this paper is the fact that the filter layout is automatically generated from filter specifications, i.e., central frequency, fractional bandwidth, in-band ripple and order, without the need of any external aid to the design process. To achieve this layout generation, filter optimization has been divided into two independent ASM processes. The first one generates the filter schematic (circuit element values) providing the required specifications. This first iterative process is necessary since, due to the narrow band operation of the admittance inverters, the target specifications are achieved by compensating the effects of such narrow band operation. The purpose of the second ASM algorithm is to automatically generate the layout from the filter schematic resulting from the first ASM process. To validate the new two-step ASM optimization tool, two sets of filter specifications (inputs of the developed tool), are considered. The generated filter layouts exhibit frequency responses that satisfy the specifications, and are in excellent agreement with the responses of the schematics.This work was supported by MINECO-Spain (projects TEC2010-17512 METATRANSFER, TEC2010-21520-C04-01 and TEC2013-47037-C5-1-R, CONSOLIDER EMET CSD2008-00066, TEC2013-40600-R and TEC2013-49221-EXP), Generalitat de Catalunya (project 2014SGR-157), and Institucio Catalana de Recerca i Estudis Avancats (who has awarded F. Martin). This paper was presented in part at the IEEE MTT-S International Microwave Symposium, Tampa Bay, FL, USA, June 1-6, 2014.Sans, M.; Selga, J.; Rodríguez Pérez, AM.; Bonache, J.; Boria Esbert, VE.; Martín, F. (2014). Design of planar wideband bandpass filters from specifications using a two-step aggressive space mapping (ASM) optimization algorithm. IEEE Transactions on Microwave Theory and Techniques. 62(12):3341-3350. https://doi.org/10.1109/TMTT.2014.236547733413350621

Differential and Single-Ended Microstrip Lines Loaded with Slotted Magnetic-LC Resonators

This paper is focused on magnetic-LC (MLC) resonators, namely, slotted resonators that can be considered the complementary counterparts of the so-called electric-LC (ELC) resonators. Both resonators exhibit two symmetry planes (i.e., they are bisymmetric), one of them being an electric wall and the other a magnetic wall at the fundamental resonance. Therefore, compared to other electrically small resonators such as folded stepped impedance resonators (SIRs), split ring resonators (SRRs), and their complementary counterparts, MLC and ELC resonators exhibit a very rich phenomenology. In this paper, single-ended microstrip lines and differential microstrip lines loaded with MLC resonators are studied, and potential applications are highlighted

Automated Design of Common-Mode Suppressed Balanced Wideband Bandpass Filters by Means of Aggressive Space Mapping

The automated and unattended design of balanced microstrip wideband bandpass filters by means of aggressive space mapping (ASM) optimization is reported in this paper. The proposed filters are based on multisection mirrored stepped impedance resonators (SIRs) coupled through quarter-wavelength transmission lines, acting as admittance inverters.This work was supported by MINECO-Spain (projects TEC2013-47037-C5-1-R, TEC2013-40600-R, TEC2013-49221-EXP), Generalitat de Catalunya (project 2014SGR-157), Institucio Catalana de Recerca i Estudis Avancats (who awarded Ferran Martin), and by FEDER funds.Sans, M.; Selga, J.; Velez, P.; Rodriguez Perez, AM.; Bonache Albacete, J.; Boria Esbert, VE.; Martin, F. (2015). Automated Design of Common-Mode Suppressed Balanced Wideband Bandpass Filters by Means of Aggressive Space Mapping. IEEE Transactions on Microwave Theory and Techniques. 63(12):3896-3908. https://doi.org/10.1109/TMTT.2015.2495180S38963908631

Embroidered textile frequency-splitting sensor based on stepped-impedance resonators

©2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents an embroidered textile frequency-splitting microwave sensor based on a pair of identical stepped-impedance resonators (SIRs) loading a microstrip transmission line. The sensor is implemented by means of conductive threads. The sensing region of the proposed structure is the capacitive square patch of one of the SIRs. If such region is kept unaltered, the structure is symmetric, and the frequency response (transmission coefficient) exhibits a single transmission zero. However, if symmetry is broken (e.g., through liquid absorption in the sensing region), the frequency response of the proposed sensor exhibits two transmission zeros (frequency splitting). The difference (in frequency and magnitude) between such zeros (or notches) is intimately related to the dielectric properties of the absorbed liquids to be sensed / detected. The proposed sensing structure is applied to the detection of deionized (DI) water absorption, and to the quantification of the number of DI water drops. The maximum measured sensitivity is found to be 2.70 MHz /µl and 0.03 dB /µl for the incremental frequency and incremental magnitude of the notches.This work was supported by MICIIN-Spain (projects PID2019-103904RB-I00, TEC2016-79465-R, and PDC2021-121085-I00),Generalitat de Catalunya (project 2017SGR-1159), Institució Catalana de Recerca i Estudis Avançats (who awarded Ferran Martín), and by FEDER funds.Peer ReviewedPostprint (author's final draft

Multilayered balanced wideband bandpass filter with high filtering selectivity

2021 IEEE MTT-S International Microwave Filter Workshop (IMFW), 17-19 Nov. 2021, Peruggia, Italy.A type of multilayered balanced wideband bandpass filter (BPF) with high filtering selectivity is presented. It is composed of two back-to-back cascaded microstrip-tomicrostrip vertical transitions using slotline stepped-impedance resonators (SIRs). Under differential-mode excitation, a sharprejection fifth-order wideband filtering transfer function with two paired close-to-passband transmission zeros can be attained in the proposed balanced BPF. Moreover, high common-mode suppression levels within the differential-mode passband range are achieved. For experimental-demonstration purposes, a microstrip prototype of the devised balanced wideband BPF architecture is developed and tested. It exhibits a measured differential-mode fifth-order high-selectivity wideband filtering response with center frequency of 4.015 GHz, 3-dB fractional bandwidth of 38.06%, and minimum in-band power-insertionloss level of 0.947 dB. The common-mode suppression levels are above 20 dB from 2.075 to 5.588 GHz.European CommissionAgencia Estatal de Investigació