Frequency Selective Circuits Research Articles

Method for design and implementation of telecommunication devices for aircraft

This article highlights the importance of electrical filters in radio engineering devices, emphasizing their role in transmitting signals in the transparency band and suppressing signals in the stop band. We examined methods for designing frequency-selective circuits with lumped parameters, which, in general, are a complete field of radio engineering and allow the synthesis of devices of varying complexity. The focus of the article is the frequency region, where the distributed properties of the synthesized structures appear. The article also provides an overview of various methods for synthesizing ultra-high frequency (UHF) filters. It is emphasized that for low-pass filters a transition from a low-frequency prototype to a high-frequency representation is applied, which, despite the crudeness of the approach, provides satisfactory results that can be improved at the production stage. The article also discusses various methods for implementing bandpass filters on distributed elements, including the use of short-circuited and open-circuited stubs, as well as weak-coupled lines. In conclusion, the paper highlights the need to improve these methods to improve process accuracy and make filter designers more efficient in radio engineering.

Filtering and Detection of Ultra-Wideband Chaotic Radio Pulses with a Matched Frequency-Selective Circuit

An approach is proposed to the filtering of an additive mixture of ultra-wideband chaotic signals and white Gaussian noise, in order to retrieve the useful signal in the receiver. The role of the filter is performed by a passive frequency-selective circuit, identical to the one involved in the formation of oscillations in the chaos generator. A mathematical model of a modulating chaos generator, detecting and receiving a sequence of ultra-wideband chaotic radio pulses in a noisy channel is designed. For the receiver of sequences of symbols encoded by chaotic radio pulses with 2- and 4-position modulation, the bit error ratio as a function of the noise level and the pulse duration is estimated numerically.

CMOS series-shunt single-pole double-throw transmit/receive switch and low noise amplifier design for internet of things based radio frequency identification devices

The incompatibility between current RFID standards has led to the need for universal and Wi-Fi compatible RFID for IoT applications. Such a universal RFID requires an SPDT and an LNA to direct and amplify the received raw signal by the antenna. The SPDT suffers from low isolation, high insertion loss and low power handling capacity whereas the LNA suffers from bulky die area, lesser Q factor, limited tuning flexibility etc. because of passive inductor usage in current generation of devices. In this research, nano-CMOS inductorless SPDT and LNA designs are proposed. The SPDT adopts a series-shunt topology along with parallel resonant circuits and resistive body floating in order to achieve improved insertion loss and isolation performance whereas the LNA design is implemented with the gyrator concept in which the frequency selective tank circuit is formed with an active inductor accompanied by the buffer circuits. The post-layout simulation results, utilizing 90nm CMOS process of cadence virtuoso, exhibit that our SPDT design accomplishes 0.83dB insertion loss, a 45.3dB isolation, and a 11.3dBm power-handling capacity whereas the LNA achieves a peak gain of 33dB, bandwidth of 30MHz and NF of 6.6dB at 2.45GHz center frequency. Both the SPDT and LNA have very compact layout which are 0.003mm 2 and 127.7 μm 2 , respectively. Such SPDT and LNA design will boost the widespread adaptation of Wi-Fi-compatible IoT RFID technology.

On the Ground Potentials and Grounding Circuits of Transformerless Grid-Connected Multilevel Power Electronic Converters

Transformerless grid-connected power electronic converters (PECs) are used in photovoltaic systems, motor drives, and solid-state power transformers. In these applications, transformerless grid-connected multilevel PECs can reduce harmonic distortions, increase power, and voltage ratings. This article aims to develop models for the ground potentials in these PECs, and to design grounding circuits for them. The models for ground potentials are developed using the common-mode voltages across each leg of the multilevel PEC. Grounding circuits for transformerless grid-connected multilevel PECs are designed using frequency selective circuits to limit ground potentials, and block ground currents from flowing through grounding of the host grid. The developed models, and grounding circuits are evaluated for transformerless grid connected, diode clamped, flying capacitor, and cascaded $H$ -bridge multilevel PECs under different operating conditions. Test results demonstrate the significant advantages of the frequency-selective grounding for transformerless grid-connected PECs. Observed advantages include reduced harmonic distortion, minimized ground potentials, and improved efficiency.

Procedure of definition of structure and parameters of multi-band matching circuits on the basis of intracavitary complex criterion for conformity to the ideal filter

The article gives the procedure of structurally parametric synthesis of multi-band frequency-selective circuits. A short characteristic of approaches to solve the problems of synthesis of the multi-band frequencyselective circuits based on the use of multifrequency resonators, frequency transformations and parametric transformations using numerical procedures of optimisation is given. The research presents a short description of three widely used estimation criteria of the characteristics of frequency-selective circuits: Taylor, Chebyshev and average-degree criteria. Expedients of an estimate of joint approximation of amplitude-frequency and phasefrequency characteristics of synthesized circuits to those of the ideal filter are shown. The criterion is suggested and the procedure is presented for structurally parametrical synthesis of multi-band matching circuits on the basis of intracavitary complex criterion of conformity to the ideal filter in a transmission band and interband Chebyshev criterion realized by numerical optimization of synthesized circuits relative to the chosen criterion for affinessy is given. With that, the multi-band circuit is represented in form of a ladder-type connection that, generally, consists of n different reactive resistances. The example of using the proposed procedure to solve the problem of structurally parametric synthesis of a two-band matching circuit is given. As a matching load we selected the first-type equivalent consisting of a serial connection of active resistance and capacity. In the example there is an additional requirement to ensuring interband frequency selectivity. Such requirement is ensured by introducing zero to the function of transmission of the synthesized circuit on an interband average geometric frequency. The requirement is implemented by introducing a parallel oscillating circuit to the first serial arm of the synthesized circuit. The structurally parametric synthesis of the two-band matching circuit selected in the example is carried out through Mathcad 15 software based on the integrated method of Levenberg-Marquardt optimization.

Flexible frequency selective passive circuits based on memristor and capacitor

Abstract In analog electronic communication and signal processing applications, programmable analog filters are desirable to reduce the hardware requirement. Memristor is two states configurable nonvolatile resistor, which is small size, low power, and fast switching device. To achieve tunable cut-off frequency and bandwidth, flexible memristor-capacitor (MC) circuits are proposed, which can be applied as low pass, high pass, and band pass filters. They can be fabricated on a flexible polyethylene terephthalate (PET) substrate through electrohydrodynamic (EHD) technique. In the proposed filters, two cut-off frequencies are selected through switching two resistive states of the memristor either in high resistance state (HRS) or low resistance state (LRS), whereas the capacitor has a fixed value. The memristor is composed of graphene quantum dots (GQDs)/poly 4-vinlyphenol (PVP) composite to achieve highly stable and linear behavior and the dielectric layer of capacitor is consisted of graphene/PVP composite. The fabricated MC filters are electrically and mechanically characterized, which are matched quite well with theoretical results. From these results, it can be a good basis for tunable analog filters in wearable electronics.

Three-Port Frequency-Selective Absorptive Limiter

This letter describes a novel three-port absorptive limiter for frequency-selective circuits based on a configuration similar to a conventional 90° hybrid coupler. This circuit uses the switching behavior of common diodes to change between the nonlimiting and absorptive limiting states. Theoretical descriptions and designs are presented along with prototypes based on PIN diodes. Measurements of the limiting performance of the devices at approximately 2 GHz as a function of power demonstrate the viability of the concept.

Absorptive Limiter for Frequency-Selective Circuits

This letter describes a novel absorptive limiter for frequency-selective circuits. The proposed circuit allows the design of absorptive limiters based on a bi-state phase shifter, which is appropriate for integration into channelizing devices, such as hybrid-coupled input multiplexers. A preliminary prototype with shunt PIN diodes has been fabricated and measured to demonstrate the viability of the concept.

Some applications of Fourier's great discovery for beginners

Nearly two centuries ago, Fourier discovered that any periodic function of period T can be presented as a sum of sine waveforms of frequencies equal to an integer times the fundamental frequency ω = 2π/T (Fourier's series). It is impossible to overestimate the importance of Fourier's discovery, and all physics or engineering students should be familiar with this subject. A suitable device for demonstrating spectra of electrical signals is a digital storage oscilloscope. Spectra of various waveforms and of AM and FM signals are demonstrated, as well as AM signals from a broadcasting station. Changes in the signals filtered by frequency-selective circuits are seen by comparing the spectra of the input and output voltages. All the experiments are suitable for undergraduate laboratories and usable as classroom demonstrations.

Application of Frequency Selective Circuits for Crack Detection in Concrete Elements

Abstract Recent research has demonstrated that cracking can be monitored in concrete using conductive surface elements. One complication with using conductive surface elements is that each element requires a separate data acquisition channel. To overcome this hurdle, a frequency selective circuit (FSC) has been developed to rapidly and simultaneously interrogate the response of multiple conductive surface elements. The response of the FSC is analyzed using numerical methods and the use of the FSC is demonstrated using a pilot study in which conductive surface coatings were used to simultaneously monitor the time of cracking of multiple restrained concrete rings. Results indicate that the FSC can be used to monitor a large number of surface coating elements. This technology could be extended to other resistance based sensors. The FSC approach has the potential to be used for health monitoring of infrastructure elements where a large number of sensors are used.

Phase noise characteristics of oscillator circuits emphasizing impedance matching

AbstractThis paper describes improvement of phase noise characteristics of an Fr oscillator. We have examined the configuration of the Fr oscillator, the loaded Q of which is improved by using matching network, and we have predicted the value of the loaded Q. Furthermore, we actually made several configurations of the Fr oscillator and measured the SSB phase noise. We show that the measured loaded Q of the Fr oscillator corresponds to the calculation results well, and that the phase noise characteristics are improved by decreasing the characteristic impedance of the frequency selective circuit. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(10): 34–40, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10355

Phase Noise Characteristics of Oscillator Circuits Emphasizing Impedance Matching

This paper describes improvement of phase noise characteristics of an Fr oscillator. We have examined the configuration of the Fr oscillator, the loaded Q of which is improved by using matching network, and we have predicted value of the loaded Q. Furthermore, we actually made several configurations of Fr oscillator and measured the SSB phase noise. We show the measured loaded Q of Fr oscillator is corresponding to the calculation results well, and the phase noise characteristics are improved by decreasing characteristic impedance of the frequency selective circuit.

Evolutionary Programming in Electromagnetic Optimization: A Review

In this paper, we review recent advances in evolutionary programming (EP) and its implementation in various antenna, microwave, frequency selective surfaces and RF circuit optimization problems. EP, unlike the other two paradigms of evolutionary computational techniques, namely, genetic algorithms (GA) and evolution strategies (ES), uses a mutation only variation operator where adaptive and/or self-adaptive techniques exist, or can easily be designed, for adapting the parameters of mutation operator during the evolution process. We present the so-called meta-EP and design of its mutation operator, using Gaussian, Cauchy and Poisson mutations as well as a hybrid of these mutations, for continuous, discrete and mixed parameter electromagnetic optimization problems. In addition, an efficient hybrid use of EP, gradient search methods and cluster analysis, as well as a novel hybrid EP-GA algorithm are discussed. Examples presented include optimizations of corrugated horn antennas, multilayered stacked microstrip antennas, Yagi-Uda arrays, partially reflective surfaces, dielectric filters, meander-line polarizer and RF duplexers

Electromagnetically coupled microstrip square ring resonator: Inset/offset feed variation effects on resonance frequency

Inset/offset feed dependant variation of electromagnetically coupled (EMC) microstrip square ring resonator (MSRR) indicates overall increase in resonance frequency (fy). Based on experimental results an equation is suggested to determine fy. Very high values of quality factor (Q = 618) are obtained at two offset points near the ring edge, with VSWR ≈ 1. This advantage of EMC-MSRR could be used for applications such as frequency-selective circuits and sensors. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1922–1924, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21815

Flexible Frequency Discrimination Subsystems for Reconfigurable Radio Front Ends

The required flexibility of the software-defined radio front end may currently be met with better overall performance by employing tunable narrowband circuits rather than pursuing a truly wideband approach. A key component of narrowband transceivers is appropriate filtering to reduce spurious spectral content in the transmitter and limit out-of-band interference in the receiver. In this paper, recent advances in flexible, frequency-selective, circuit components applicable to reconfigurable SDR front ends are reviewed. The paper contains discussion regarding the filtering requirements in the SDR context and the use of intelligent, adaptive control to provide environment-aware frequency discrimination. Wide tuning-range frequency-selective circuit elements are surveyed including bandpass and bandstop filters and narrowband tunable antennas. The suitability of these elements to the mobile wireless SDR environment is discussed.

CMOS differential difference current conveyors and their applications

The authors present a new versatile circuit building block called a differential difference current conveyor (DDCC). An IC technique for implementing the DDCC is also presented. The DDCC-based frequency-selective circuits and nonlinear building blocks such as multiplier, squarer and square rooter are developed. Experimental results are given to demonstrate the feasibility of the proposed techniques, and they show that DDCC-based circuits offer a competitive design choice to CCII-based and DDA-based circuits.

A wide range differential difference amplifier: a basic block for analog signal processing in MOS technology

A CMOS implementation of a wide-input-range differential difference amplifier (DDA) using a V-I converter with large signal handling capability is presented. The DDA is used as a basic building block for continuous-time analog signal processing systems. The basic features of the DDA are verified experimentally using a 2- mu m CMOS process MOSIS chip. It is shown that it is generally possible to develop DDA-based analog circuitssth almost infinite input impedances, low component count and without the need to match components/devices external to the DDA. DDA-based circuits such as amplifiers, a MOS grounded resistor, four quadrant multipliers and amplitude modulators are presented. Applications of the DDA in the implementation of frequency selective circuits, e.g., resonator and state-variable second-order filters, are also given. All proposed circuits and design techniques are experimentally verified and demonstrate that DDA-based circuits offer a competitive alternative to op-amp-based circuits. >

Design of frequency-mode set-valued logic networks

A set-valued logic network is proposed to provide a potential solution to the interconnection problems in VLSI systems. The fundamental concept is frequency multiplexing of logic values for the increase of information density in logic networks. It is shown that the set-valued logic network can be constructed with two basic building blocks realised by frequency-selective circuits. A set-valued switching algebra is introduced for the systematic synthesis of networks. The setvalued logic network thus obtained has the attractive features of high information density, highly parallel structure and extensibility into ultrahigher-valued logic systems.

Transistor-only frequency-selective circuits

The possibility of implementing frequency-selective circuits using only MOS transistors is considered. The advantages of such circuits are small chip area, good matching properties for individual elements, a potential for very high frequency of operation, and suitability for fabrication using standard digital VLSI processes. Disadvantages include the implementation of automatic tuning schemes that reliably eliminate unpredictabilities and variations, device modeling difficulties of common simulators, and nonlinearity cancellation. A procedure for the topology development of filters in which transistors are used as URC elements is presented together with a technique which uses transistors as capacitors, along with first-order correction for the nonidealities of such 'capacitors' and of the active elements. Measured results from three experimental chips are reported in the 1-100-MHz range. >

Remote hearing aid volume control

A hearing aid comprises a microphone, a battery-operated earphone, and amplifying circuit connected to the microphone output, the amplifying circuit including a frequency-selective circuit component and a sound level adjustment circuit component connected to the frequency-selective circuit component, and a remote sound wave control signal emitter circuit separate from the microphone, earphone and amplifying circuit and emitting sound wave control signals within the range of the microphone input.