Special Issue "Filter Design Solutions for RF systems"

A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Circuit and Signal Processing".

Deadline for manuscript submissions: closed (31 May 2020).

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A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Leonardo Pantoli
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Guest Editor
Department of Industrial and Information Engineering and Economics, Università degli Studi dell'Aquila, Via Camponeschi, 19, 67100 L'Aquila AQ, Italy
Interests: microwave and mm-wave nonlinear circuits; active filters; stability analysis; MMIC
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Vincenzo Stornelli
E-Mail Website
Guest Editor
Department of Industrial and Information Engineering and Economics, Università degli Studi dell'Aquila, Via Camponeschi, 19, 67100 L'Aquila AQ, Italy
Interests: filters; integrated circuits; MMIC; sensors; sensors interfaces
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue will focus on the state-of-the-art results in the definition and design of filters for low- and high-frequency applications and systems. Different technologies and solutions are commonly adopted for filter definition, from electrical to electromechanical and mechanical solutions, from passive to active devices, and from hybrid to integrated designs. Aspects related to both theoretical and experimental research in filter design; CAD modeling; novel technologies and applications; and filter fabrication, characterization, and testing will be covered. Potential authors are invited to submit original research articles and review papers on the following topics:

  • The modelling, design, and simulation of filters;
  • Processes and fabrication technologies for filters;
  • The automated characterization and testing of filters;
  • Voltage and current-mode filters;
  • Integrated and discrete filters;
  • Passive and active filters;
  • Variable filters, characterization, and tunability.

Prof. Dr. Leonardo Pantoli
Prof. Dr. Vincenzo Stornelli
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Filter design
  • Filter solutions
  • Simulation and modeling
  • CAD techniques
  • Technology and applications

Published Papers (11 papers)

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Research

Article
Low-Current Design of GaAs Active Inductor for Active Filters Applications
Electronics 2020, 9(8), 1232; https://doi.org/10.3390/electronics9081232 - 31 Jul 2020
Cited by 1 | Viewed by 1013
Abstract
Active inductors are suitable for MMIC integration, especially for filters applications, and the definition of strategies for an efficient design of these circuits is becoming mandatory. In this work we present design considerations for the reduction of DC current in the case of [...] Read more.
Active inductors are suitable for MMIC integration, especially for filters applications, and the definition of strategies for an efficient design of these circuits is becoming mandatory. In this work we present design considerations for the reduction of DC current in the case of an active filter design based on the use of active inductors and for high-power handling. As an example of applications, the approach is demonstrated on a two-cell, integrated active filter realized with p-HEMT technology. The filter design is based on high-Q active inductors, whose equivalent inductance and resistance can be tuned by means of varactors. The prototype was realized and tested. It operates between 1800 and 2100 MHz with a 3 dB bandwidth of 30 MHz and a rejection ratio of 30 dB at 30 MHz from the center frequency. This solution allows to obtain a P1 dB compression point of about −8 dBm and a dynamic range of 75 dB considering a bias current of 15 mA per stage. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
Sinusoidal Oscillators Operating at Frequencies Exceeding Unity-Gain Bandwidth of Operational Amplifiers
Electronics 2020, 9(5), 845; https://doi.org/10.3390/electronics9050845 - 20 May 2020
Viewed by 1897
Abstract
This paper proposes a novel operational amplifier (OPA) voltage-controlled oscillator (VCO) circuits on the basis of impedance converters. The VCO can operate over a frequency range exceeding unity-gain bandwidth due to the location of the tank circuit, not at the output of the [...] Read more.
This paper proposes a novel operational amplifier (OPA) voltage-controlled oscillator (VCO) circuits on the basis of impedance converters. The VCO can operate over a frequency range exceeding unity-gain bandwidth due to the location of the tank circuit, not at the output of the OPA, but at the noninverting input. The paper presents the mathematical modeling of oscillated amplitude and start-up conditions. The simulation results confirm the theoretical achievements. The designed and simulated VCO uses an ultra-low noise wideband OPA LMH6629MF, covers a frequency band between 0.830 GHz and 1.429 GHz, and exhibits a maximum in-band total harmonic distortion (THD) of 1.7%. It has a maximum in-band phase noise of −139.3 dBc/Hz at 100 kHz offset frequency and has an outstanding value of a standard figure of merit (FoM) of −198.6 dBc/Hz. The zero-peak amplitude of output voltage is from 3.2 V to 4 V for all generated frequencies at a supply voltage of ±5 V. The fabricated prototype-oscillator based on OPA LMH6624 operates at a frequency of 583.1 MHz with a power level of 0 dBm. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
Open-Loop Switched-Capacitor Integrator for Low Voltage Applications
Electronics 2020, 9(5), 762; https://doi.org/10.3390/electronics9050762 - 06 May 2020
Viewed by 1074
Abstract
An architecture of a switched-capacitor integrator that includes a charge buffer operating in an open-loop is hereby proposed. As for the switched-capacitor filters, the gain of the proposed integrator, which is given by the input/output capacitor ratio, ensures desensitization to process, voltage, and [...] Read more.
An architecture of a switched-capacitor integrator that includes a charge buffer operating in an open-loop is hereby proposed. As for the switched-capacitor filters, the gain of the proposed integrator, which is given by the input/output capacitor ratio, ensures desensitization to process, voltage, and temperature variations. The proposed circuit is suitable for low voltage supplies. It enables a significant power saving compared to a traditional switched-capacitor integrator. This was demonstrated through an analytical comparison between the proposed integrator and a traditional switched-capacitor integrator. The mathematical results were supported and verified by simulations performed on a circuit prototype designed in 16 nm finFET technology with 0.95 V supply. The proposed switched-capacitor integrator consumes 76 µW, resulting in more than twice the efficiency for the traditional closed-loop switched-capacitor filter as an input voltage equal to 31.25 mV at 7 ns clock period is considered. The comparison of architectures was led among the proposed integrator and the state-of-the-art technology in terms of the figure of merit. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
10-GHz Fully Differential Sallen–Key Lowpass Biquad Filters in 55nm SiGe BiCMOS Technology
Electronics 2020, 9(4), 563; https://doi.org/10.3390/electronics9040563 - 28 Mar 2020
Cited by 1 | Viewed by 1114
Abstract
Multi-GHz lowpass filters are key components for many RF applications and are required for the implementation of integrated high-speed analog-to-digital and digital-to-analog converters and optical communication systems. In the last two decades, integrated filters in the Multi-GHz range have been implemented using III-V [...] Read more.
Multi-GHz lowpass filters are key components for many RF applications and are required for the implementation of integrated high-speed analog-to-digital and digital-to-analog converters and optical communication systems. In the last two decades, integrated filters in the Multi-GHz range have been implemented using III-V or SiGe technologies. In all cases in which the size of passive components is a concern, inductorless designs are preferred. Furthermore, due to the recent development of high-speed and high-resolution data converters, highly linear multi-GHz filters are required more and more. Classical open loop topologies are not able to achieve high linearity, and closed loop filters are preferred in all applications where linearity is a key requirement. In this work, we present a fully differential BiCMOS implementation of the classical Sallen Key filter, which is able to operate up to about 10 GHz by exploiting both the bipolar and MOS transistors of a commercial 55-nm BiCMOS technology. The layout of the biquad filter has been implemented, and the results of post-layout simulations are reported. The biquad stage exhibits excellent SFDR (64 dB) and dynamic range (about 50 dB) due to the closed loop operation, and good power efficiency (0.94 pW/Hz/pole) with respect to comparable active inductorless lowpass filters reported in the literature. Moreover, unlike other filters, it exploits the different active devices offered by commercial SiGe BiCMOS technologies. Parametric and Monte Carlo simulations are also included to assess the robustness of the proposed biquad filter against PVT and mismatch variations. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
Compact Ultra-Wideband Bandpass Filters Achieved by Using a Stub-Loaded Stepped Impedance Resonator
Electronics 2020, 9(2), 209; https://doi.org/10.3390/electronics9020209 - 22 Jan 2020
Cited by 6 | Viewed by 1290
Abstract
In this paper, we develop a bandpass filter using a stub-loaded stepped impedance resonator (SLSIR) and calculate the even and odd resonant modes of this type of resonator using the input impedance/admittance analysis. In this study, two impedance ratios and two length ratios [...] Read more.
In this paper, we develop a bandpass filter using a stub-loaded stepped impedance resonator (SLSIR) and calculate the even and odd resonant modes of this type of resonator using the input impedance/admittance analysis. In this study, two impedance ratios and two length ratios are operated as the design parameters for controlling the resonant modes of the SLSIR. Several resonant mode variation curves operating three resonant modes with different impedance ratios and two length ratios are developed. By tuning the desired impedance ratios and length ratios of the SLSIRs, compact ultra-wideband (UWB) bandpass filters (BPFs) can be achieved. Two examples of the UWB BPFs are designed in this study. The first example is UWB filter with a wide stopband and the second one is dual UWB BPF, namely, with UWB performance and a notch band. The first filter is designed for a UWB response from 3.1 to 5.26 GHz having a stopband from 5.3 to 11 GHz, with an attenuation level better than 18 dB. The second filter example is a dual UWB BPF with the frequency range from 3.1 to 5 GHz and 6 to 10.1 GHz using two sets of the proposed SLSIR. The measured results have insertion loss of less than 1 dB, and return loss greater than 10 dB. Furthermore, the coupling structures and open stub of the SLSIR also provide several transmission zeros at the skirt of the passbands for improving the passband selectivity. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
A Miniaturized Wideband Bandpass Filter Using Quarter-Wavelength Stepped-Impedance Resonators
Electronics 2019, 8(12), 1540; https://doi.org/10.3390/electronics8121540 - 13 Dec 2019
Cited by 6 | Viewed by 1074
Abstract
In this paper, we present a simple method to design a miniaturized wideband bandpass filter with suppression of the third harmonic, using only two quarter-wavelength stepped-impedance resonators (SIRs). The resonant modes of the quarter-wavelength SIR, depending on the impedance ratio (K) and electrical [...] Read more.
In this paper, we present a simple method to design a miniaturized wideband bandpass filter with suppression of the third harmonic, using only two quarter-wavelength stepped-impedance resonators (SIRs). The resonant modes of the quarter-wavelength SIR, depending on the impedance ratio (K) and electrical length ratio (α), are discussed first. As to setting the resonant frequency of the SIR for the lower band edge of the required band, the size parameters of two quarter-wavelength SIRs can be determined by selecting the desired impedance ratio (K) and length ratio (α). By using the opposite directional arrangement of two SIRs with direct taped input/output ports, the wideband response can be formed. A filter example is shown in this study to address this simple design procedure. The measured results of the fabricated filter have a wide passband response from 3.3 to 5.8 GHz, with an insertion loss of 1.5 dB, a return loss of 20 dB, an extended bandwidth ration of 55%, a low-average group delay of less than 0.75 ns, and a stopband from 6 to 12 GHz, with an attenuation level of 20 dB. Due to the similar 0° feeding, a transmission zero at 8.3 GHz appears near the band edge; thus, improving the band selectivity. The proposed filter can have a very simple structure and a miniature size. Simulated results and measured results are in good agreement. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
Additive Manufacturing of Monolithic Microwave Dielectric Ceramic Filters via Digital Light Processing
Electronics 2019, 8(10), 1067; https://doi.org/10.3390/electronics8101067 - 20 Sep 2019
Cited by 6 | Viewed by 1387
Abstract
Microwave dielectric ceramics are employed in filters as electromagnetic wave propagation media. Based on additive manufacturing (AM) techniques, microwave dielectric ceramic filters with complex and precise structures can be fabricated to satisfy filtering requirements. Digital light processing (DLP) is a promising AM technique [...] Read more.
Microwave dielectric ceramics are employed in filters as electromagnetic wave propagation media. Based on additive manufacturing (AM) techniques, microwave dielectric ceramic filters with complex and precise structures can be fabricated to satisfy filtering requirements. Digital light processing (DLP) is a promising AM technique that is capable of producing filters with high accuracy and efficiency. In this paper, monolithic filters made from Al2O3 and TiO2, with a molar ratio of 9:1 (0.9 Al2O3-0.1 TiO2), were fabricated by DLP. The difference in the dielectric properties between the as-sintered and post-annealed samples at different temperatures was studied. The experimental results showed that when sintered at 1550 °C for 2 h and post annealed at 1000 °C for 5 h, 0.9 Al2O3-0.1 TiO2 exhibited excellent dielectric properties: εr = 12.4, Q × f = 111,000 GHz, τf = +1.2 ppm/°C. After comparing the measured results with the simulated ones in the passband from 6.5 to 9 GHz, it was concluded that the insertion loss (IL) and return loss (RL) of the filter meet the design requirements. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
A New Low-Voltage Low-Power Dual-Mode VCII-Based SIMO Universal Filter
Electronics 2019, 8(7), 765; https://doi.org/10.3390/electronics8070765 - 09 Jul 2019
Cited by 18 | Viewed by 1427
Abstract
In this paper, a new low-voltage low-power dual-mode universal filter is presented. The proposed circuit is implemented using inverting current buffer (I-CB) and second-generation voltage conveyors (VCIIs) as active building blocks and five resistors and three capacitors as passive elements. The circuit is [...] Read more.
In this paper, a new low-voltage low-power dual-mode universal filter is presented. The proposed circuit is implemented using inverting current buffer (I-CB) and second-generation voltage conveyors (VCIIs) as active building blocks and five resistors and three capacitors as passive elements. The circuit is in single-input multiple-output (SIMO) structure and can produce second-order high-pass (HP), band-pass (BP), low-pass (LP), all-pass (AP), and band-stop (BS) transfer functions. The outputs are available as voltage signals at low impedance Z ports of the VCII. The HP, BP, AP, and BS outputs are also produced in the form of current signals at high impedance X ports of the VCIIs. In addition, the AP and BS outputs are also available in inverting type. The proposed circuit enjoys a dual-mode operation and, based on the application, the input signal can be either current or voltage. It is worth mentioning that the proposed filter does not require any component matching constraint and all sensitivities are low, moreover it can be easily cascadable. The simulation results using 0.18 μm CMOS technology parameters at a supply voltage of ±0.9 V are provided to support the presented theory. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
High-Performance Low-Pass Filter Using Stepped Impedance Resonator and Defected Ground Structure
Electronics 2019, 8(4), 403; https://doi.org/10.3390/electronics8040403 - 04 Apr 2019
Cited by 4 | Viewed by 2044
Abstract
A microstrip low-pass filter (LPF) using reformative stepped impedance resonator (SIR) and defected ground structure (DGS) is proposed in this paper. The proposed filter not only possesses the advantage of high frequency selectivity of SIR hairpin LPF with internal coupling, but also possesses [...] Read more.
A microstrip low-pass filter (LPF) using reformative stepped impedance resonator (SIR) and defected ground structure (DGS) is proposed in this paper. The proposed filter not only possesses the advantage of high frequency selectivity of SIR hairpin LPF with internal coupling, but also possesses the large stop-band (SB) bandwidth by adjusting the number and area of DGS units. The LPF proposed in this paper possesses the properties of miniaturization, wide SB, high selectivity, and low pass-band ripple (PBR) simultaneously. The characteristic parameters of the proposed LPF is that: the pass-band (PB) is 0~2 GHz, the PBR is 0.5 dB, the SB range is from 2.4 GHz to 9 GHz when the attenuation is under 20 dB, and the maximal attenuation could reach 45 dB in the SB. The size of this proposed LPF is 0.13 λ × 0.09 λ ; λ is the corresponding wavelength of the upper PB edge frequency of 2 GHz. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
Disturbance and Signal Filter for Power Line Communication
Electronics 2019, 8(4), 378; https://doi.org/10.3390/electronics8040378 - 28 Mar 2019
Cited by 2 | Viewed by 1465
Abstract
Today, to use home automation, intelligent home controls or remote controls in the office, electronic equipment is moving away from wireless communication in favor of Power Line Communication (PLC). In the standard PLC solutions, the corrections that result from error transmissions are based [...] Read more.
Today, to use home automation, intelligent home controls or remote controls in the office, electronic equipment is moving away from wireless communication in favor of Power Line Communication (PLC). In the standard PLC solutions, the corrections that result from error transmissions are based on complex digital modulation methods and algorithms for validating the transmitted data without paying attention to the causes of the errors. This article focuses on the implementation of a filtering system for interference and signals in the 120–150 kHz band (CENELEC band C), which is injected into the network by transmitters. Such a filter separates the desired signal from the interference that is occurring in the network, which can result in communication errors. Moreover, when used properly, the filter can be used as a subsystem separation element. The paper presents the requirements, design, construction, simulation and test results that were obtained under actual operating conditions. It is possible to use less complex methods for correcting errors in transmission signals and to guarantee an improvement in the transmission rate using the proposed filter system. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Article
Design and Development of a Reduced Form-Factor High Accuracy Three-Axis Teslameter
Electronics 2019, 8(3), 368; https://doi.org/10.3390/electronics8030368 - 26 Mar 2019
Cited by 4 | Viewed by 1428
Abstract
A novel three-axis teslameter and other similar machines have been designed and developed for SwissFEL at the Paul Scherrer Institute (PSI). The developed instrument will be used for high fidelity characterisation and optimisation of the undulators for the ATHOS soft X-ray beamline. The [...] Read more.
A novel three-axis teslameter and other similar machines have been designed and developed for SwissFEL at the Paul Scherrer Institute (PSI). The developed instrument will be used for high fidelity characterisation and optimisation of the undulators for the ATHOS soft X-ray beamline. The teslameter incorporates analogue signal conditioning for the three-axes interface to a SENIS Hall probe, an interface to a Heidenhain linear absolute encoder and an on-board high-resolution 24-bit analogue-to-digital conversion. This is in contrast to the old instrumentation setup used, which only comprises the analogue circuitry with digitization being done externally to the instrument. The new instrument fits in a volumetric space of 150 mm × 50 mm × 45 mm, being very compact in size and also compatible with the in-vacuum undulators. This paper describes the design and the development of the different components of the teslameter. Performance results are presented that demonstrate offset fluctuation and drift (0.1–10 Hz) with a standard deviation of 0.78 µT and a broadband noise (10–500 Hz) of 2.05 µT with an acquisition frequency of 2 kHz. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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