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Volumen 64 (2013): Heft 6 (November 2013)

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Volumen 62 (2011): Heft 5 (September 2011)

Volumen 62 (2011): Heft 4 (July 2011)

Volumen 62 (2011): Heft 3 (May 2011)

Volumen 62 (2011): Heft 2 (March 2011)

Volumen 62 (2011): Heft 1 (January 2011)

Volumen 61 (2010): Heft 6 (November 2010)

Volumen 61 (2010): Heft 5 (September 2010)

Volumen 61 (2010): Heft 4 (July 2010)

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Volumen 61 (2010): Heft 2 (March 2010)

Volumen 61 (2010): Heft 1 (January 2010)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1339-309X
Erstveröffentlichung
07 Jun 2011
Erscheinungsweise
6 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 72 (2021): Heft 3 (June 2021)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1339-309X
Erstveröffentlichung
07 Jun 2011
Erscheinungsweise
6 Hefte pro Jahr
Sprachen
Englisch

Suche

10 Artikel
Uneingeschränkter Zugang

A design methodology for programmable-gain low-noise TIA in CMOS

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 147 - 157

Zusammenfassung

Abstract

The work reports on the design of an area-efficient inductor-less low-noise CMOS transimpedance amplifier suitable for entry-level optical time-domain reflectometers. The work suggests a novel approach for implementing a programmable-gain in capacitive feedback TIA with an independent adjustment of the low- and high-frequency behavior using the input stage biasing impedance and one of the feedback capacitors. The approach addresses a typical noise problem of fast feed-forward or resistive feedback topologies while alleviating the trade-off of the key TIA performance indicators. A more accurate amplifier model is proposed which takes into account the effects due to capacitive isolation and both biasing circuits. Further modifications to the reference design are suggested including the PMOS-based implementation of the biasing circuit to address the voltage headroom issue. The circuit was implemented using a standard 180 nm CMOS process and operates from 1.8 V supply with the drawn current of 11.7 mA.

Schlüsselwörter

  • analog integrated circuits
  • broadband amplifiers
  • CMOS integrated circuits
  • optical time-domain reflectometry
  • transimpedance amplifier (TIA)
Uneingeschränkter Zugang

RF energy harvesting using a compact rectenna with an antenna array at 2.45 GHz for IoT applications

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 159 - 167

Zusammenfassung

Abstract

This work addresses the design, fabrication, and implementation of an RF energy harvester 2.45 GHz using a compact rectenna. Our proposed rectenna focuses on development of an antenna array and rectifier circuit. The proposed rectenna is fabricated using FR4 substrate with its overall size of 12.24 cm × 18.17 cm with a thickness of 1.6 mm. The measured results show that a 10 dB bandwidth covering in 2374-2549 MHz (175 MHz) with center frequency 2415 MHz at S11 of −18.2 dB. There is a bandwidth enhancement of 57.6% compared to the single antenna. Gaining of the antenna array is 6 dB that is double a single antenna gain. Spatial diversity technique in antenna array yields a bigger antenna gain thereby increasing the received power level. Experimental measurements are carried out that the rectenna is placed indoor (LOS) at 5 m and outdoor (NLOS) at 15 m. Furthermore, we also explore the rectifier circuit that to maximize the output voltage. The received RF power that transmitted from WiFi router is −55 dBm (0.15 nW/cm2) at 5 m and −59 dBm (0.06 nW/cm2) at 15 m, respectively. The output voltages are achieved that 1092.5 mV at a distance of 5 m (LOS) and 5.48 mV at a distance of 15 m (NLOS). The highest RF-DC conversion efficiency of our proposed rectenna reaches 77.6%. The rectenna potentially meets all requirements to power up the IoT applications.

Schlüsselwörter

  • RF
  • energy harvesting
  • rectenna
  • antenna array
  • IoT
Uneingeschränkter Zugang

Simulation of the optical erbium doped fiber amplification for performance analysis

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 168 - 175

Zusammenfassung

Abstract

In this contribution, innovations in the simulation of the optical transmission path are presented specifically, the dynamic performance analysis of erbium doped fiber amplifier (EDFA) properties for system applications is focused. Our EDFA simulation model is based on population equations of ions that can describe mutual relations between three states of ions in the EDFA amplifier. The presented numerical approach includes a signal gain and noise contributions to the single input channel amplification using the steady state modelling coming out of a dynamic model. The EDFA model in the steady state can be consequently applied for a purpose of advanced si mulations performed in the complete optical transmission path.

Schlüsselwörter

  • the EDFA amplifier
  • population equations of ions
  • output EDFA characteristics
  • the steady state model
  • numerical simulations
Uneingeschränkter Zugang

Electrical equivalent circuit for modelling permanent magnet synchronous motors

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 176 - 183

Zusammenfassung

Abstract

In permanent magnet synchronous motor (PMSM) models, only the stator part is given as an electrical circuit and mechanical equations are used for modelling the mechanical part of the machine. In this study, electrical equivalents of mechanical equations are also obtained and mechanical parameters of a PMSM are expressed as an electrical circuit element. In this way, an exact electrical equivalent circuit is proposed in which both the stator and the mechanical part can be modelled as an electrical circuit for the PMSMs dynamic model. Although PMSM model includes mechanical parameters and variables, the complete model is expressed only in electrical elements and variables. The proposed PMSM circuit was simulated for different load torques in the circuit simulation program. Simulation results show that the proposed circuit operates like a PMSM. Simulation results were verified by another method in the form of solution of the differential equations that constitute the mathematical model of PMSM. Due to the proposed circuit that enables the conversion of mechanical parameters into electrical parameters, PMSM can be modelled and simulated as an electrical circuit with completely electrical elements in a circuit simulation program.

Schlüsselwörter

  • equivalent circuits
  • circuit simulation
  • ac machines
  • permanent magnet motor
  • modelling
  • synchronous motor
Uneingeschränkter Zugang

The optical properties of different materials used for thermo-optical switches

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 184 - 191

Zusammenfassung

Abstract

With growing demands of internet protocol services for transmission capacity and speed, the solution for future high speed optical networks is optical burst switching that is a technology for transmitting large amounts of data bursts through a transparent optical switching network the optical switches in optical burst switching networks play important role in the resource reservation and are very important to ensure reliability and flexibility of the network. This paper is focused on the very important components of Optical Burst Switching networks, ieo ptical switches, specifically thermo-optical switches. In this paper are presented the simulation analysis of performance evaluation of thermo-optical switches executed in the model of Optical Burst Switching network and simulation study of investigation of influence of roughness and layer thickness on the optical properties (spectral reflectance, transmittance) of selected materials (SiO2, Ta2O5, Al2O3) for thermooptical switches.

Schlüsselwörter

  • optical burst switching
  • thermooptical switches
  • thin films
  • modified fresnel coefficients
  • transfer matrix theory
  • spectral reflectance
  • transmittance
Uneingeschränkter Zugang

Performance investigation of long-haul high data rate optical OFDM IM/DD system with different QAM modulations

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 192 - 197

Zusammenfassung

Abstract

In this paper and as a first time, we have designed and simulated 100 Gbps long haul intensity modulation and direct detection (IM/DD) optical orthogonal frequency division multiplexing (OFDM) system with high order modulation techniques by using optisystem software QAM IM/DD OFDM system was analyzed and simulated to provide high data rate for downstream signal by using dispersion compensation fiber (DCF) inside fiber link. 4-QAM OFDM system demonstrated the best BER performance compared to other simulated systems for long haul transmission distance. For comparison and investigation, important results as eye diagram, Q factor, Eb/No and BER are explained against propagation length for every simulated system.

Schlüsselwörter

  • intensity modulation and direct detection (IM/DD)
  • orthogonal frequency division multiplexing (OFDM)
  • quadrature amplitude modulation (QAM)
  • bit error rate ()
Uneingeschränkter Zugang

Deep convolutional neural networks for automatic coil pitches detection systems in induction motors

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 198 - 202

Zusammenfassung

Abstract

Stator winding structures are one of the most important parameters affecting motor performance in induction motor (IM). When deciding on the coil pitch, the winding structure and the power performance of the motor are also taken into consideration. The stator coil pitch of the IM is known at the design stage of the motor. The stator coil pitch of an IM manufactured and in use may be wanted to be changed with the desire to improve the performance of the motor and suppress some harmonics. In this case, it is necessary to determine the motor winding structure and coil pitch by opening the stator cover of the motor, removing the rotor, and manually examining the stator winding structure visually. However, this process prolongs this improvement process considerably. A system that can detect the stator coil pitch according to the stator current behavior while the motor is running can significantly shorten this improvement process. For this purpose, in this study, a deep convolutional neural network (DCNN) model that can automatically estimate IM stator coil pitch angle with an accuracy rate of 100% is designed and applied.

Schlüsselwörter

  • stator winding structure
  • stator coil pitch angles
  • IM
  • DCNN
Uneingeschränkter Zugang

Development and characterisation of photoelectrochemical MIS structures with RuO2/TiO2 gate stacs for water oxidation

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 203 - 207

Zusammenfassung

Abstract

This paper is dedicated to preparation and analysis of metal insulator semiconductor (MIS) photoanode with a metal organic chemical vapor deposited RuO2 layer and TiO2 protection layer for photoelectrochemical water splitting. It is shown that utilization of TiO2 layers of 2, 4, and 6 nm thickness preserve the catalytic activity of underlying RuO2. The origin of increased overpotential and decreased photovoltage of the photoanode upon the increase of TiO2 layer thickness is discussed in the paper. Results revealed that utilization of TiO2 layer in the MIS concept is suitable for photoelectrochemical water oxidation applications.

Schlüsselwörter

  • MIS
  • RuO
  • TiO
  • water splitting
  • water oxidation
Uneingeschränkter Zugang

Blind audio source separation based on a new system model and the Savitzky-Golay filter

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 208 - 212

Zusammenfassung

Abstract

Blind source separation (BSS) is a research hotspot in the field of signal processing. This scheme is widely applied to separate a group of source signals from a given set of observations or mixed signals. In the present study, the Savitzky-Golay filter is applied to smooth the mixed signals, adopt a simplified cost function based on the signal to noise ratio (SNR) and obtain the demixing matrix accordingly. To this end, the generalized eigenvalue problem is solved without conventional iterative methods. It is founded that the proposed algorithm has a simple structure and can be easily implemented in diverse problems. The obtained results demonstrate the good performance of the proposed model for separating audio signals in cases with high signal to noise ratios.

Schlüsselwörter

  • blind source separation
  • moving average
  • Savitzky-Golay smoothing
  • cost function
  • audio signal
Uneingeschränkter Zugang

Microwave lowpass filter with improved out-of-band performance based on tilted rectangular slots

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 213 - 216

Zusammenfassung

Abstract

A compact microwave lowpass filter with sharp selectivity and wide stopband based on tilted rectangular slots is proposed in this paper. The developed prototype filter is based on the log periodic theory, where tilted log-periodic rectangular slots are studied for the first time. Effects resulting from the tilted slots on the performance of the studied filter are discussed and conclusions are drawn. A prototype of the proposed lowpass filter was fabricated and measured. The measured results show that the lowpass filter features a high selectivity and a wide suppression band from 4.05 GHz to 24.91 GHz under a level of 19.2 dB. Both measured and simulated performances are presented with good consistency.

Schlüsselwörter

  • microwave filter
  • lowpass filter
  • rectangular slot
  • defected ground structure
10 Artikel
Uneingeschränkter Zugang

A design methodology for programmable-gain low-noise TIA in CMOS

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 147 - 157

Zusammenfassung

Abstract

The work reports on the design of an area-efficient inductor-less low-noise CMOS transimpedance amplifier suitable for entry-level optical time-domain reflectometers. The work suggests a novel approach for implementing a programmable-gain in capacitive feedback TIA with an independent adjustment of the low- and high-frequency behavior using the input stage biasing impedance and one of the feedback capacitors. The approach addresses a typical noise problem of fast feed-forward or resistive feedback topologies while alleviating the trade-off of the key TIA performance indicators. A more accurate amplifier model is proposed which takes into account the effects due to capacitive isolation and both biasing circuits. Further modifications to the reference design are suggested including the PMOS-based implementation of the biasing circuit to address the voltage headroom issue. The circuit was implemented using a standard 180 nm CMOS process and operates from 1.8 V supply with the drawn current of 11.7 mA.

Schlüsselwörter

  • analog integrated circuits
  • broadband amplifiers
  • CMOS integrated circuits
  • optical time-domain reflectometry
  • transimpedance amplifier (TIA)
Uneingeschränkter Zugang

RF energy harvesting using a compact rectenna with an antenna array at 2.45 GHz for IoT applications

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 159 - 167

Zusammenfassung

Abstract

This work addresses the design, fabrication, and implementation of an RF energy harvester 2.45 GHz using a compact rectenna. Our proposed rectenna focuses on development of an antenna array and rectifier circuit. The proposed rectenna is fabricated using FR4 substrate with its overall size of 12.24 cm × 18.17 cm with a thickness of 1.6 mm. The measured results show that a 10 dB bandwidth covering in 2374-2549 MHz (175 MHz) with center frequency 2415 MHz at S11 of −18.2 dB. There is a bandwidth enhancement of 57.6% compared to the single antenna. Gaining of the antenna array is 6 dB that is double a single antenna gain. Spatial diversity technique in antenna array yields a bigger antenna gain thereby increasing the received power level. Experimental measurements are carried out that the rectenna is placed indoor (LOS) at 5 m and outdoor (NLOS) at 15 m. Furthermore, we also explore the rectifier circuit that to maximize the output voltage. The received RF power that transmitted from WiFi router is −55 dBm (0.15 nW/cm2) at 5 m and −59 dBm (0.06 nW/cm2) at 15 m, respectively. The output voltages are achieved that 1092.5 mV at a distance of 5 m (LOS) and 5.48 mV at a distance of 15 m (NLOS). The highest RF-DC conversion efficiency of our proposed rectenna reaches 77.6%. The rectenna potentially meets all requirements to power up the IoT applications.

Schlüsselwörter

  • RF
  • energy harvesting
  • rectenna
  • antenna array
  • IoT
Uneingeschränkter Zugang

Simulation of the optical erbium doped fiber amplification for performance analysis

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 168 - 175

Zusammenfassung

Abstract

In this contribution, innovations in the simulation of the optical transmission path are presented specifically, the dynamic performance analysis of erbium doped fiber amplifier (EDFA) properties for system applications is focused. Our EDFA simulation model is based on population equations of ions that can describe mutual relations between three states of ions in the EDFA amplifier. The presented numerical approach includes a signal gain and noise contributions to the single input channel amplification using the steady state modelling coming out of a dynamic model. The EDFA model in the steady state can be consequently applied for a purpose of advanced si mulations performed in the complete optical transmission path.

Schlüsselwörter

  • the EDFA amplifier
  • population equations of ions
  • output EDFA characteristics
  • the steady state model
  • numerical simulations
Uneingeschränkter Zugang

Electrical equivalent circuit for modelling permanent magnet synchronous motors

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 176 - 183

Zusammenfassung

Abstract

In permanent magnet synchronous motor (PMSM) models, only the stator part is given as an electrical circuit and mechanical equations are used for modelling the mechanical part of the machine. In this study, electrical equivalents of mechanical equations are also obtained and mechanical parameters of a PMSM are expressed as an electrical circuit element. In this way, an exact electrical equivalent circuit is proposed in which both the stator and the mechanical part can be modelled as an electrical circuit for the PMSMs dynamic model. Although PMSM model includes mechanical parameters and variables, the complete model is expressed only in electrical elements and variables. The proposed PMSM circuit was simulated for different load torques in the circuit simulation program. Simulation results show that the proposed circuit operates like a PMSM. Simulation results were verified by another method in the form of solution of the differential equations that constitute the mathematical model of PMSM. Due to the proposed circuit that enables the conversion of mechanical parameters into electrical parameters, PMSM can be modelled and simulated as an electrical circuit with completely electrical elements in a circuit simulation program.

Schlüsselwörter

  • equivalent circuits
  • circuit simulation
  • ac machines
  • permanent magnet motor
  • modelling
  • synchronous motor
Uneingeschränkter Zugang

The optical properties of different materials used for thermo-optical switches

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 184 - 191

Zusammenfassung

Abstract

With growing demands of internet protocol services for transmission capacity and speed, the solution for future high speed optical networks is optical burst switching that is a technology for transmitting large amounts of data bursts through a transparent optical switching network the optical switches in optical burst switching networks play important role in the resource reservation and are very important to ensure reliability and flexibility of the network. This paper is focused on the very important components of Optical Burst Switching networks, ieo ptical switches, specifically thermo-optical switches. In this paper are presented the simulation analysis of performance evaluation of thermo-optical switches executed in the model of Optical Burst Switching network and simulation study of investigation of influence of roughness and layer thickness on the optical properties (spectral reflectance, transmittance) of selected materials (SiO2, Ta2O5, Al2O3) for thermooptical switches.

Schlüsselwörter

  • optical burst switching
  • thermooptical switches
  • thin films
  • modified fresnel coefficients
  • transfer matrix theory
  • spectral reflectance
  • transmittance
Uneingeschränkter Zugang

Performance investigation of long-haul high data rate optical OFDM IM/DD system with different QAM modulations

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 192 - 197

Zusammenfassung

Abstract

In this paper and as a first time, we have designed and simulated 100 Gbps long haul intensity modulation and direct detection (IM/DD) optical orthogonal frequency division multiplexing (OFDM) system with high order modulation techniques by using optisystem software QAM IM/DD OFDM system was analyzed and simulated to provide high data rate for downstream signal by using dispersion compensation fiber (DCF) inside fiber link. 4-QAM OFDM system demonstrated the best BER performance compared to other simulated systems for long haul transmission distance. For comparison and investigation, important results as eye diagram, Q factor, Eb/No and BER are explained against propagation length for every simulated system.

Schlüsselwörter

  • intensity modulation and direct detection (IM/DD)
  • orthogonal frequency division multiplexing (OFDM)
  • quadrature amplitude modulation (QAM)
  • bit error rate ()
Uneingeschränkter Zugang

Deep convolutional neural networks for automatic coil pitches detection systems in induction motors

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 198 - 202

Zusammenfassung

Abstract

Stator winding structures are one of the most important parameters affecting motor performance in induction motor (IM). When deciding on the coil pitch, the winding structure and the power performance of the motor are also taken into consideration. The stator coil pitch of the IM is known at the design stage of the motor. The stator coil pitch of an IM manufactured and in use may be wanted to be changed with the desire to improve the performance of the motor and suppress some harmonics. In this case, it is necessary to determine the motor winding structure and coil pitch by opening the stator cover of the motor, removing the rotor, and manually examining the stator winding structure visually. However, this process prolongs this improvement process considerably. A system that can detect the stator coil pitch according to the stator current behavior while the motor is running can significantly shorten this improvement process. For this purpose, in this study, a deep convolutional neural network (DCNN) model that can automatically estimate IM stator coil pitch angle with an accuracy rate of 100% is designed and applied.

Schlüsselwörter

  • stator winding structure
  • stator coil pitch angles
  • IM
  • DCNN
Uneingeschränkter Zugang

Development and characterisation of photoelectrochemical MIS structures with RuO2/TiO2 gate stacs for water oxidation

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 203 - 207

Zusammenfassung

Abstract

This paper is dedicated to preparation and analysis of metal insulator semiconductor (MIS) photoanode with a metal organic chemical vapor deposited RuO2 layer and TiO2 protection layer for photoelectrochemical water splitting. It is shown that utilization of TiO2 layers of 2, 4, and 6 nm thickness preserve the catalytic activity of underlying RuO2. The origin of increased overpotential and decreased photovoltage of the photoanode upon the increase of TiO2 layer thickness is discussed in the paper. Results revealed that utilization of TiO2 layer in the MIS concept is suitable for photoelectrochemical water oxidation applications.

Schlüsselwörter

  • MIS
  • RuO
  • TiO
  • water splitting
  • water oxidation
Uneingeschränkter Zugang

Blind audio source separation based on a new system model and the Savitzky-Golay filter

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 208 - 212

Zusammenfassung

Abstract

Blind source separation (BSS) is a research hotspot in the field of signal processing. This scheme is widely applied to separate a group of source signals from a given set of observations or mixed signals. In the present study, the Savitzky-Golay filter is applied to smooth the mixed signals, adopt a simplified cost function based on the signal to noise ratio (SNR) and obtain the demixing matrix accordingly. To this end, the generalized eigenvalue problem is solved without conventional iterative methods. It is founded that the proposed algorithm has a simple structure and can be easily implemented in diverse problems. The obtained results demonstrate the good performance of the proposed model for separating audio signals in cases with high signal to noise ratios.

Schlüsselwörter

  • blind source separation
  • moving average
  • Savitzky-Golay smoothing
  • cost function
  • audio signal
Uneingeschränkter Zugang

Microwave lowpass filter with improved out-of-band performance based on tilted rectangular slots

Online veröffentlicht: 15 Jul 2021
Seitenbereich: 213 - 216

Zusammenfassung

Abstract

A compact microwave lowpass filter with sharp selectivity and wide stopband based on tilted rectangular slots is proposed in this paper. The developed prototype filter is based on the log periodic theory, where tilted log-periodic rectangular slots are studied for the first time. Effects resulting from the tilted slots on the performance of the studied filter are discussed and conclusions are drawn. A prototype of the proposed lowpass filter was fabricated and measured. The measured results show that the lowpass filter features a high selectivity and a wide suppression band from 4.05 GHz to 24.91 GHz under a level of 19.2 dB. Both measured and simulated performances are presented with good consistency.

Schlüsselwörter

  • microwave filter
  • lowpass filter
  • rectangular slot
  • defected ground structure

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