RF Design and Applications Research Papers (original) (raw)

""High-field magnetic resonance imagers (MRI) give better signal-to-noise ratio (SNR) and image contrast. However clinical MRIs are currently limited to 3 Tesla (T) magnetic field strength. To create an uncommon 15 T scanner for research use, we evaluated several low-cost, intended for wireless communication, GaAs enhancement-mode pseudomorphic high electron mobility transistors (ePHEMT) in the critical preamplifier slot. This paper reports the experimental results that were obtained at both module and system levels. When evaluated in our prototype 15 T scanner front-end’s preamplifier slot, the candidate devices’ sub 1dB noise figures enabled image SNR ~ 110 in a water phantom (test object) with a standard pulse sequence. Crisp and artifact-free images could be obtained with these candidate devices. In conclusion, high performance pre-amplifiers for 15 T MRIs can be realized using low cost ePHEMTs originally marketed for wireless communications.
Keywords - pre-amplifier; magnetic resonance imaging; MRI;
15 Tesla; ePHEMT""

- by Chin-Leong Lim
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- Medical Imaging, MRI, RF Design and Applications, RF and Microwave Systems

COMPONENTES PASSIVOS EM RF
EEL7319 - CIRCUITOS RF

In this project,RF power amplifier has been designed.The input signal to RF PA is obtained from a programmable PLL with integrated VCO.This design consists of 2 stages of amplifier configurations.PA is optimized to give at least 30 dBm... more

In this paper, an antenna for 4G and WLAN devices is proposed. The proposed antenna is designed using Planar Inverted F Antenna (PIFA) structure. The antenna uses Rogers Duroid 5880 as a dielectric substrate and metallic ground plane. The dimensions of the top patch are 18.5 mm x 18.5 mm and thus making it a low profile antenna. The designed antenna covers WLAN (2.4-2.48 GHz) & 4G LTE (2300-2400 MHz & 2500-2690 MHz) communication standards. The overall volume occupied by the proposed antenna is 44mm × 20mm × 3.8mm. Metamaterial superstate is also analyzed which enhances the gain and bandwidth of the proposed antenna significantly. The antenna is designed and simulated using High Structure Frequency Simulator (HFSS).

This project is about the design and implementation of books identifier on the bookshelf. When any book is placed on the wrong bookshelf, the system will pop out a message in the computer to alert the librarian of the misplaced book. The popped out message doesn’t just show the information of misplaced books, but it also shows the details of the book to be placed on that shelf. When the books belonging to that bookshelf are correctly placed, the alert message will not pop out. For ease of demonstration in the prototype, two books were used for testing; a bookshelf was designed to place only two books and one interface system to connect the bookshelf to the computer. To display the alert message, a simple GUI window is designed and it runs independently in the computer to identify the misplacement of books on the bookshelf.

- by Peter Jnr I D Agboga
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- Electrical Engineering, Electronic Engineering, Power Electronics, RFID
- by Tuan Anh Luu
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- Materials Science, Thermodynamics, Structure, RF Design and Applications

En este trabajo se calcula, construye y ensaya un inductor de radiofrecuencia. Los ensayos re realizan con un Q-metro y se evaluaran los resultados con respecto a los cálculos. También e realizaran ensayos en frecuencia sobre una resistencia y sobre un circuito impreso. Se medirá el inductor con y sin núcleo de ferrita, la resistencia efectiva de un resistor determinado en función de la frecuencia y la medición de la constante dieléctrica de un circuito impreso y se determina la tangente de anguilo de pérdidas.

- by Ariel Ivan Diaz
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- Electronic Engineering, Electronics, RF Design and Applications, RF Electronic

—Radio signal propagation modeling plays an important role in designing wireless communication systems. The propagation models are used to calculate the number and position of base stations and predict the radio coverage. Different models have been developed to predict radio propagation behavior for wireless communication systems in different operating environments. In this paper we shall limit our discussion to the latest achievements in radio propagation modeling related to tunnels. The main modeling approaches used for propagation in tunnels are reviewed, namely, numerical methods for solving Maxwell equations, waveguide or modal approach, ray tracing based methods and two-slope path loss modeling. They are discussed in terms of modeling complexity and required information on the environment including tunnel geometry and electric as well as magnetic properties of walls.

This paper presents a 4GHz Low Noise Amplifier for satellite downlink communication.This frequency indicate in the IEEE C-band.Satellite downlink communication located at the front end of LNA.Thus,this LNA required to amplify the signal without adding much noise. This paper is present design and simulation of singlestage LNA circuits.The amplifier design were designed by using ATF 54143 transistor manufactured from Avago Technologies. The design circuit uses single stub matching to implement the matching network. The purpose single stage of input and output matching network is to produces 50Ω impedance at the input and output port of the LNA.The matching network is used at both sides of the transistor.The target simulation are gain (S21) with >10dB, noise figure with <2dB and input and output return loss <-10dB at 4 GHz. A single stage LNA has successfully designed with 11.112dB forward gain , 1.181 dB noise figure, -10.026 dB output return loss(S22) and -12.522 dB input return loss(S11) by using ADS software.

Quais são as melhores maneiras de medir o fluxo de corrente? Isso geralmente se resume ao aplicativo em questão-este artigo discute alguns dos prós e contras de alguns desses métodos. Paul Pickering | 30 de abril de 2019 Medir com precisão o fluxo de corrente é um requisito padrão em várias aplicações (Fig. 1). Dependendo da necessidade específica, as opções disponíveis para projetistas podem incluir projetos separados montados a partir de componentes padrão, dispositivos específicos de aplicativos e soluções prontas embutidas em outro bloco, como um micro controlador ou um dispositivo system-on-chip (SoC). Neste artigo veremos algumas dessas abordagens, suas vantagens e desvantagens e como fazer o melhor uso delas em um design.

- by Engr. Liakat Ali Bhuiyan
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- RF Design and Applications

This article presents the design, simulation, fabrication, and measurement of a compact power-harvesting circuit. A quadrature hybrid coupler is used for this harvesting circuit because of its advantageous matching, high isolation, and lossless characteristic. It properly feeds the bridge rectifier, combining the signals received with two antennas. The bridge rectifier component is a turnout full-wave rectification from a two-wire alternative current input. The measurements found output power to be −25.5 dBm using a 5 KΩ load resistor, at 5 GHz. The transmitter antenna input power level is 7 dBm, at 50 cm distance. Both results of the Friis Equation and the measurements are in agreement. According to the results, the power-harvesting circuit can operate for wireless local area network sensor applications.

Limiters can protect wireless receivers from physical damage and information loss. The Schottky-PIN limiter is especially protective because its limiting threshold is ~10dB lower than that of the self-biased PIN limiter. Unfortunately, the limiter diodes have parasitic capacitances that create insertion loss. Moreover, the extra diode in the Schottky-PIN limiter increases its loss over that of the PIN diode-only limiter. Techniques to minimize the parasitic capacitances include using bare chip, air cavity packaging, diode stacking, mesa construction, isolating the Schottky diode from the signal path and connecting the diodes to a low impedance node. But the aforementioned techniques either sacrifice cost, manufacturability, size, performances or thermal ruggedness. To reduce loss in a PIN-Schottky limiter fabricated from low-cost plastic packaged diodes, we connected the package parasitics into a low pass ladder network. This paper presents the circuit details and experimental results.
We observed performance improvements such as a doubling of the bandwidth at the -1 dB insertion loss point, a tripling of the bandwidth at the -10 dB return loss point, a 4 dB reduction in the output leakage power, and significantly less spike leakage. In conclusion, integrating the parasitics of Schottky-PIN limiter into a ladder network can improve the insertion loss, matching and other performances; these improvements can extend the upper frequency limit of plastic packaged limiter diodes.
Keywords - Limiter, receiver protection, Schottky assisted PIN limiter, Schottky enhanced PIN limiter, quasi-active limiter

- by Chin-Leong Lim
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- Wireless Communications, Electronics, Microwave, RF Design and Applications
- by Ana Gavrovska
- •
- RF Design and Applications

The overview of theory, design, development and application of matched bandstop filters using lossy resonators are presented in this paper. Theoretically, high notch depth and selectivity of matched bandstop filters can be produced by using only two lossy low Q resonators. Many matched bandstop ﬁlters have been developed during the last few years where the main targeted applications are advanced communication and electronic warfare systems. This article is mainly to provide the readers with some basic knowledge and insights about previous works of the matched bandstop filters using lossy resonators.

- by Badrul Hisham Ahmad and +1
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- Microwave, RF Design and Applications, RF and Microwave Systems, RF communication

This paper presents the design of a novel differential voltage octuple rectifier for wireless RF energy harvesting. Two rectifiers with common matching (CM) and two-branch matching (TBM) are presented for the CDMA850/GSM900 bands operation. Measured maximum efficiencies of CM and TBM rectifiers reach 66.5% and 70.6%, respectively. The results also show that both matching network-type rectifiers can produce higher output voltage. It is demonstrated that the designed rectifier-antenna structure powers up a battery-less LCD sensor by harvesting RF signal of a dialing cell phone. The proposed rectifier topology and matching mechanisms can be used for various energy harvesting applications , especially for those requiring high supply voltage.

High frequency models of transistors are of interest because they have
applications to computer aided design of high frequency circuits. When
these models are derived, a problem encountered is that measured transistor S-parameters do not agree with the hybrid-π model. In this article, a simplified method is described to obtain an optimized
classical hybrid-π model that predicts the measured S-parameters of the device across the desired frequency band. The modeling capabilities of the CAD program Touchstone (now is incorporated with ADS) were utilized to create such a transistor model. The optimization
goal is to minimize the error function between the measured S-parameters and those of the RF transistor equivalent circuit.
This technique has been implemented to obtain a high frequency circuit model for the RF transistor BFY 90 across the band from 100 MHz to 500 MHz. Such a model can be used in time-domain circuit analysis programs to predict the transistor behavior.

- by Firas Mohammed
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- RF Design and Applications, Microwave Devices
- by Miroslav Lutovac and +2
- •
- RF Design and Applications

This document shows the detailed design of a front-end of a superheterodyne receiver at 140Mhz.

FIGURA DE RUÍDO EM CIRCUITOS RF
EEL7319 - CIRCUITOS RF

"Abstract - Tower Mounted Amplifiers (TMA), which serves to lower the system Noise Figure (NF) in cellular base-stations, must present highly matched input and output. Traditionally, the conflicting low noise and good match requirements necessitate a balanced amplifier which increases the cost, size and power consumption. This paper describes a Low-Noise Amplifier (LNA) module for 1.4-3.0 GHz (e.g. W-CDMA, TD-SCDMA, Wibro, and Wimax) that satisfies the conflicting requirements without the balanced amplifier's disadvantages. The design revolves around a Microwave Monolithic Integrated Circuit (MMIC) containing a cascode amplifier with integrated bias is packaged in a 2 x 2 x 0.75 mm3 8-pin Thin Small Leadless Package (TSLP). It features an adjustable supply current range of 40-80 mA, and a variable gain of 15-20 dB. The adjustable gain function performs independently from the device’s noise figure. The device leverages on a proprietary 0.5 micron enhancement-mode Pseudomorphic High-Electron-Mobility Transistor (epHEMT) technology for best-in-class noise performance, linearity and batch-to-batch uniformity. Experimentally, a -20dB input match and a sub 1 dB noise figure are demonstrated at 1.9 GHz.
Index terms - Low noise amplifier, LNA, MMIC, tower mounted amplifier, base station

In this paper, a compact multiband Planar Inverted-F Antenna (PIFA) having two open ended slots on the ground plane is proposed. The ground plane also acts as a radiator element, the overall volume of PIFA can be reduced significantly, which further reduces thickness of the handheld devices such as mobile phones. The antenna operates at multiple bands i.e. GPS, GLONASS, DCS, PCS, UMTS, WLAN/Bluetooth, 4G LTE & HYPERLAN/2. The performance parameters of the proposed antenna are satisfying the requirements of advance wireless communication devices which can be observed from the simulation results The measured results are also presented and discussed. Both simulated and measured results are in good match.

- by Naveen Kumar
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- Antennas, Microstrip Antennas, Antennas & Radio Wave Propagation, GPS Applications

Los radares tienen múltiples aplicaciones y su uso es vital en el sector aeroespacial; de ahí la importancia de formar especialistas en esta área y, por lo tanto, la de contar con herramientas pedagógicas adecuadas. Se plantea la necesidad de implementar algún equipamiento a nivel educativo para potenciar el proceso de enseñanza-aprendizaje de aquellas personas que se encuentran transitando la etapa universitaria de ingeniería. Más precisamente, se busca desarrollar un sistema integral para el aprendizaje de los estudiantes de Ingeniería en Electrónica que cursan asignaturas vinculadas al área de microondas y radares en la Facultad de Ingeniería de la Universidad de Mendoza. El presente trabajo expone un caso de resolución práctica que permite satisfacer esta necesidad, al adaptar un equipo existente.

- by Mauricio Vilanova
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- Education, RF Propagation, Microwave, Radar

In this paper we present a modulator for an all-digital pulsewidth modulated (PWM) transmitter based on switching amplification. In this approach, each symbol is represented by a sequence of pre-computed PWM pulse widths stored in a table that results in reduced Error Vector Magnitude (EVM), achieving low distortion with a reduced pulse-rate. The modulator is implemented in a field programmable gate array
(FPGA) device. The performance of this approach is compared to standard uniform PWM modulator. Measurements using 64-QAM signals show a reduction of EVM values from 11.61% (−18.7 dB) for uniform PWM to 2.41%(−32.4 dB) for the proposed approach.

We present the design and implementation of a multi-constellation GNSS front-end. This front-end is able to operate in two different hardware configurations: using the L1/E1 band of GPS/Galileo and the L1 band of GLONASS, or the L2 band of GPS and GLONASS. Both of these operation modes can be implemented in the same printed circuit board by replacing only a few components. In the proposed design, the RF signals are down-converted to an intermediate frequency where the GPS and GLONASS bands are separated. Thanks to this separation, a considerable reduction of the necessary sampling rate for the digitalization stage is achieved. This simplifies and reduces the power consumption of this stage of the complete GNSS receiver. Measurements carried out to the implemented prototypes for the two different configurations are presented. The obtained results validate the proposed design.

- by Ramon Lopez La Valle
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- RF Design and Applications, GNSS receivers, Receiver Front End

—A T-shaped ring band pass filter using source-load coupled technique is proposed in this paper. T-shaped ring structure effectively utilizes the area and makes it easier to tune filter's center operating frequency, which is also helpful in expanding the bandwidth. Source-load coupled technique is used in the proposed design to increase the transmission zeros on the operating frequency in both sides so that the out-of-band rejection can be further improved. First, validation in simulation is carried out to prove the use of source-load coupling. Then a demonstrating filter has been designed, optimized, fabricated and measured. The filter has low insertion loss of 0.35dB, return loss of-18dB when operating in 2.47GHz, and measurement shows good agreement with simulation. Such filter can be in good use in microwave power transmission in microwave-RFID application.

This study aims to design, build, and implement an application that can increase the knowledge and interest of members to read books in one of community in Jakarta. Therefore made Gebuknas application where there are forums, news portals, library places, and chat. With this stage of analysis and design of Gebuknas application using Zachman framework methods and development method using a waterfall model.

"The main cause of loss in the PIN-Schottky limiter is the diodes’ parasitic capacitances. Techniques to counter the parasitic capacitances include using bare chip, air cavity packaging, diode stacking, mesa construction, isolating the Schottky diode from the signal path and connecting the diodes to a low impedance node. But the aforementioned techniques either sacrifice cost, manufacturability, size, performances or thermal ruggedness. To reduce loss in the PIN-Schottky limiter, we re-configured its parasitics into a low pass ladder network. This paper reports on the new configuration’s changed large signal and transient performances. We observed improved isolation at 0.9 and 2.4 GHz, and a beneficial reduction in the initial energy that slips through the limiter before limiting begins. In conclusion, this configuration simultaneously improves insertion loss, matching, isolation and spike leakage suppression. It has the potential to improve limiting performances in wideband receivers for wireless communication and medical imaging.
Index Terms — Limiter, receiver protection, Schottky assisted PIN limiter, Schottky enhanced PIN limiter, quasi-active limiter."

- by Chin-Leong Lim
- •
- Microwave, RF Design and Applications, RF and Microwave Systems, RF

Passive intermodulation distortion manifests itself as a nonlinear mixing product in passive devices. The nonlinearity in microstrip lines (MSL) has a distributed nature and can be associated with the dielectric substrate and/or the printed conductor. In this paper, the nonlinearity modeling of uniform microstrip line is discussed. It is partitioned into short segments; each described by its equivalent RLCG circuit, and has been analysed using Harmonic Balance nonlinear simulation to evaluate PIM (passive intermodulation) effect of the microstrip line for different lengths and widths. The proposed PIM MSL model is compared to Shitvov's model and recent reported measurements, and verified using X-parameter simulation. The generalized PIM MSL model is applied in device level such as Wilkinson power divider (WPD) and branch line coupler to predict the PIM effect of each. Finally, a comparison between conventional WPD, inductive loaded WPD and branch line coupler, is conducted based on the introduced MSL model.

- by Eslam Nasr
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- RF Design and Applications, RF and Microwave Systems, RF communication

— In this paper, two types of differential topology rectifier are studied and designed for RF energy harvesting at GSM1800 band 1.83GHz. The proposed differential serial rectifier and differential doubler rectifier are with odd harmonics suppression characteristics. Radial stubs are utilized to filter the output harmonics, which makes the rectifier more compact. The rectifiers with Schottky diodes (SMS7630) are fabricated on Teflon substrate. Measured maximum efficiencies of two rectifiers are 49% @ 0dBm and 53% @ 2dBm, respectively. The results show that the rectifiers are efficient, power sensitive and compact. An application scenario of proposed rectifier are demonstrated. The proposed rectifiers can be used in many RF energy harvesting system, including RFID applications.

- by sangyoub Lee
- •
- RF Design and Applications

This novel work presents a quadrature sandwich rectenna circuit for collecting RF from four input ports at different angles. The scheme's high efficiency and increase in output power are significant for the operation of wireless electronic devices. This work demonstrates the requirements of self-powering. Specifically, simulation efficiency is shown to achieve 77%, and input power is 0 dBm for a 5 KΩ resistance load and dual-band operation. The results of this experiment are encouraging in terms of wireless powering of some devices in wireless telecommunication systems. This scheme can also be applied to radio frequency wireless power transfer and harvesting, and would be useful in industrial, scientific, and medical applications. Furthermore, its mode of operation is sustainable, and it is compact.

This paper presents the design theory of conventional single-ended LNA and differential LNA based on CMOS technology. The design concepts give an useful indication to the design trade-offs associated with NF, gain and impedance matching. Four LNA's have been designed using technological design rules of TSMC 0.18-µm CMOS technology and this work mainly proposed for IEEE 802.11a applications. With 1.8V supply voltage, the proposed LNA's achieve a gain higher than 19dB, a noise figure less than 4dB and impedance matching less than-10dB at 5GHz frequency. The goal of this paper is to highlight the efficient LNA architecture for achieving simultaneous gain, noise and input matching at low supply voltage. The performance of all LNA's are analysed and compared using Agilent's Advanced Design System Electronic Design Automation tools.

- by Khaled Sharaf
- •
- RF Design and Applications, High Frequency, Transfer Function, Flicker Noise

This paper presents a model of a circuit receiver for self-power harvesting to connect wirelessly to an ambient base station. The circuit receiver combines dual alternative current into matching network for rectifier voltage doubler to produce a direct current. This work designs, simulates, fabricates, and measures for output power. The verification simulation and measurement were confirmed in the far-field distance radiation. In the measurement, input power from transmitter side was 0
dBm. The multiband was covered (L, S, and C bands) in 1650 - 3650, 6600 - 7250 MHz’s. The power receiver measurements listed in table 2 and 3 could be useful for selfpowering sensor applications through 3, 4, and 5G.

This paper proposes a circuit for power harvesting using a Wilkinson coupler to combine two patch antennas for dual collecting signals. A voltage doubler is connected through a rectifier stage to double. L-type
impedance matching network is applied before non-linear diode for maximum power transfer from source to the load.
Design, simulation, fabrication, and measurement results of power harvesting circuit that operates over L, and C bands are presented in this paper. The goal is to scavenge direct current, improve efficiency and sensitivity. From the measurement setup, it was found that the output power obtained is approximately identical with the Friis equation.
Therefore, the results are able to employ in the L and C bands for powering 3G and 5G sensors.

The article focuses the simplification of the design of a practical Class C power amplifier for communications applications from 225 to 400 megahertz through a straightforward method of developing input and output matching networks. A 10 watts amplifier was designed and built for a 10-decibel power gain from 225 to 400 megahertz to confirm the effectiveness of the approach.

Modern Radio Frequency (RF) transceivers cannot be imagined without high-performance (Transmit/ Receive) T/R switch. Available T/R switches suffer mainly due to the lack of good trade-off among the performance parameters, where high isolation and low insertion loss are very essential. In this study, a T/R switch with high isolation and low insertion loss performance has been designed by using Silterra 0.13µm CMOS process for 2.4GHz ISM band RF transceivers. Transistor aspect ratio optimization, proper gate bias resistance, resistive body floating and active inductor-based parallel resonance techniques have been implemented to achieve better trade-off. The proposed T/R switch exhibits 0.85dB insertion loss and 45.17dB isolation in both transmit and receive modes. Moreover, it shows very competitive values of power handling capability (P1dB) and linearity (IIP3) which are 11.35dBm and 19.60dBm, respectively. Due to avoiding bulky inductor and capacitor, the proposed active inductor-based T/R switch became highly compact occupying only 0.003mm 2 of silicon space; which will further trim down the total cost of the transceiver. Therefore, the proposed active inductor-based T/R switch in 0.13µm CMOS process will be highly useful for the electronic industries where low-power, high-performance and compactness of devices are the crucial concerns.

"The objective of this paper is to describe how a Microwave Monolithic Integrated Circuit (MMIC) can be paired with an external PIN diode bypass switch in the implementation of a Low Noise Amplifier (LNA) with overload protection feature for mobile TV receiver applications. In the preliminary phase of the design, competing schemes for reducing LNA gain were reviewed and their respective cost-performance trade-offs were benchmarked against the customer’s set of requirements. Based on the selected design, a “proof of concept” prototype was then assembled and tested. The key components of this switch by-passable LNA were sourced from in-house product portfolio, consisting of a noise and linearity optimized Gallium Arsenide Pseudomorphic High Electron Mobility Transistor (GaAs pHEMT) MMIC for the amplifier, and low loss PIN diodes as the switching elements. The components were mounted on a low cost FR4-dielectric Printed Circuit Board (PCB) by hand soldering. Ferrite bead inductors were used instead of conventional inductors in the diodes’ and MMIC’s biasing networks in order to minimize noise and gain degradation over the wide frequency range (47 to 870 MHz). The prototype demonstrated a low noise amplification (gain > 19 dB & noise figure ≤ 1.3 dB) and high linearity (3rd order intercept OIP3 > 30 dBm) over the 47 to 870 MHz frequency range. When the amplifier is operated in the bypassed mode, low loss (A > -4.5 dB) is achieved over the same frequency range. In conclusion, a combination of low noise pHEMT MMIC and PIN diodes can be used to implement a switch by-passable LNA for mobile TV receivers requiring high immunity to signal overload. The proposed design also meets the customer’s target specifications for bandwidth, noise figure, gain, linearity, current consumption, low switch loss and component cost.
Keywords - low noise amplifier, LNA, bypass switch, overload protection, mobile TV