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In this work, amine-carbon quantum dots (CQDs)/rhodamine B (RhB) ratiometric fluorescent (RF) sensor was employed for effective and selective determination of tamsulosin hydrochloride (TMS) based on a dual-emission fluorescence system. Although the function of amine-CQDs is to transfer the specific interaction between TMS and sensor into detectable fluorescence (FL) signals, RhB as a reference unit has been employed to omit internal and external effects. The FL signal was quenched by adding the TMS at 442 nm; nevertheless, it did not change at 569 nm. The material characterization and investigation of the sensing mechanism were done. The optimization of pH, the volumetric ratio of CQDs to RhB, and interaction time parameters were carried out by the one-variable-at-a-time (OVAT) method. The quantitative analysis of the concentration of TMS for this RF sensor in a linear range of 0.446–7.083 μg mL−1 (1.091–17.338 μM) was obtained (R2 = 0.9969, n = 3) under optimum conditions. The limit of detection and quantitation values were estimated to be 0.033 μg mL−1 (0.081 μM) and 0.109 μg mL−1 (0.267 μM), respectively. The repeatability of intra-day and inter-day were less than one percent. This inexpensive RF probe was well applied to determine TMS in biological fluids, and acceptable achievements were obtained.

This paper describes three-dimensional numerical simulations and Radio Frequency (RF) measurements of wave propagation in microwave-heated magnetized plasmas of ion sources. Full-wave solution of Maxwell's equations has been addressed through the Finite Element Method (FEM) commercial software COMSOL. Our numerical model takes into account the strongly inhomogeneous and anisotropic magnetized "cold" plasma medium. The simulations reproduce the main features of the wave-plasma interaction of the Flexible Plasma Trap (FPT) that recently came into operations at INFN-LNS. A two-pins RF probe has been ad-hoc developed and used as a plasmaimmersed antenna for measuring local wave electric fields in the FPT device. The measurements of plasma electron density and RF electric field, performed for different external magnetic field configuration, allowed a direct comparison with the assumed simulation model.

A prototype RF probe card is assembled to test the feasibility of Pogo-pins as robust probe tips for the automized testing of multiple-port millimeter-wave circuits. A custom-made ceramic housing machined from a low-loss dielectric holds an array of 157 Pogo-pins, each with 2.9 mm-length in fixed positions. The ceramic housing is then mounted onto a probe-card PCB for power-loss measurements on two signal-ground Pogo-pin connections arbitrarily selected from the array. The probing results on a test circuit with a simple thru-line indicate a successful power transfer with a small insertion loss of less than 0.5 dB per single Pogo-pin connection up to 25 GHz. A new probe card design using shorter Pogo-pins is being prepared to extend the operation frequency to beyond 40 GHz.

Background: Radiofrequency ablation (RF) is already a viable alternative to surgical resection for focal liver tumors treatment. The use of RF ablation in combination with surgery or chemotherapy and the large panel of RF tools need new experimental models to develop new opportunities for this kind of therapy. Purpose: The purpose of this study was to identify the optimal RF parameters that will allow in situ colic cancer liver metastases destruction with minimal secondary effects. Materials and Methods: The CC531s colic cancer tumor cells were used to induce liver metastases in 30 synergic Wag/Rij rats. When metastases reached at least 1 cm in diameter, RF generator RITA 1500X, and expandable tip RF probe Starburst SDE (Angiodynamics, USA) was used for the RF ablation. The animal survival rate and the RF-induced lesions have been studied, while only the generator delivered power has been modified (90W, 20W, and 10W, respectively). Results: Survival was significantly low in the group with 90W-delivered power RF. Moreover, statistically significant differences were revealed between groups with high and low RF power, regarding the morphological changes of the liver parenchyma and the adjacent organs, without significant difference on the RF therapeutically effect. Conclusions: In an experimental setting, an increased RF generator power induces important lesions of the abdominal organs with subsequently important mortality rate, without improving the RF therapeutic efficiency.

In this article, we present on-wafer thru-reflect-line (TRL)-calibrated measurements of silicon test structures fabricated using STMicroelectronics’ B55 technology up to 500 GHz. The structures are fabricated in two subsequent runs, and the respective structure in each run has a different design. The improvements in the test structures layout design are presented on the terminal capacitances of “open-M1,” which is an important test structure for the deembedding of the transistor accesses. The improvements are examined using high-frequency structure simulator (HFSS) electromagnetic (EM) simulations, including the RF probe models and the neighboring structures.

In the frequency dissemination system over fiber, users can obtain highly stable RF frequency signal from one frequency source. To ensure that the stability loss of the system meets the user's need, performance evaluation for RF frequency dissemination over fiber is necessary. Considering the numerous users over fiber links and the long dissemination distance, traditional transfer quality evaluation method is not very practical, because the cost of the loop-back configuration is relatively large. In this paper, we propose a method to directly evaluate the radio frequency transfer quality via fiber links at the remote site. At the local site, the radio frequency signal is amplitude-modulated on continuous-wave lasers with two wavelengths. After multiplexing, the frequency signal is disseminated to the remote site. At the remote site, RF signal is detected from the continuous-wave optical carrier and transfer performance can be evaluated by measuring the phase fluctuation difference between two different RF signals. The remote signal does not need to be sent back to the local site. It will greatly simplify the structure of the frequency dissemination link, like in an antenna array system.

Multiple frequency heating has been used since the '90 in ECR ion sources as heating schemes able to improve current intensities especially for highly charged ions. More recently, "Two Close Frequency Heating", where the frequency gap is comparable with the scale-length of the resonance, has been proposed, expected also to be sensitive to the relative waves phase relationship. At ATOMKI - Debrecen a dedicated experiment has been carried out for exploring the effects of the combined frequencies and their relative phase-difference in an argon plasma. The second frequency was finely tuned between 13.6-14.6 GHz with respect to the first one (fixed 14.25 GHz). An optimal frequency gap (in terms of Ar¹¹⁺/A⁶⁺ beam currents ratios) has been experimentally found, in agreement with the theory; the optimal power balance (total RF power was 200 W) between the two frequencies has been determined empirically. A weak but clear effect of the relative phase shift has been observed. Each configuration has been characterized by a multi-diagnostics set-up: HPGe and SDD detectors were used for the X-rays, a RF probe was introduced inside the plasma chamber to detect the radio-emission from the plasma., Proceedings of the 23th Int. Workshop on ECR Ion Sources, ECRIS2018, Catania, Italy

This paper describes three-dimensional numerical simulations and Radio Frequency (RF) measurements of wave propagation in the microwave-heated magnetized plasmas of ion sources. Our 3D Full-wave numerical model considers the inhomogeneous and anisotropic magnetized plasma medium in the “cold” plasma approximation. Maxwell's equations have been solved through the Finite Element Method (FEM). For the first time, by means of a two-pin RF probe, it has been possible to measure the electromagnetic field in a compact plasma trap where the experiment conditions resemble very closely the features of a common ion source for a direct comparison with the simulations. The numerical model has been supported by direct measurements of the plasma density profiles performed for different magnetic field configurations.

PURPOSE To develop a new optically controlled on-coil amplifier that facilitates safe use of multi-channel radiofrequency (RF) transmission in MRI by real-time monitoring of signal phase and amplitude. METHODS Monitoring was carried out with a 4-channel prototype system by sensing, down sampling, digitizing, and optically transmitting the RF transmit signal to a remote PC to control the amplifiers. Performance was evaluated with benchtop and 7 T MRI experiments. RESULTS Monitored amplitude and phase were stable across repetitions and had standard deviations of 0.061 μT and 0.0073 rad, respectively. The feedback system allowed inter-channel phase and B1 amplitude to be adjusted within two iterations. MRI experiments demonstrated the feasibility of this approach to perform safe and accurate multi-channel RF transmission and monitoring at high field. CONCLUSION We demonstrated a 4-channel transceiver system based on optically controlled on-coil amplifiers with RF signal monitoring and feedback control. The approach allows the safe and precise control of RF transmission fields, required to achieve uniform excitation at high field. Magn Reson Med 79:2833-2841, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Neuroinflammation can be monitored using fluorine-19 (19F)-containing nanoparticles and 19F MRI. Previously we studied neuroinflammation in experimental autoimmune encephalomyelitis (EAE) using room temperature (RT) 19F radiofrequency (RF) coils and low spatial resolution 19F MRI to overcome constraints in signal-to-noise ratio (SNR). This yielded an approximate localization of inflammatory lesions. Here we used a new 19F transceive cryogenic quadrature RF probe ( 19 F-CRP) that provides the SNR necessary to acquire superior spatially-resolved 19F MRI. First we characterized the signal-transmission profile of the 19 F-CRP. The 19 F-CRP was then benchmarked against a RT 19F/1H RF coil. For SNR comparison we used reference compounds including 19F-nanoparticles and ex vivo brains from EAE mice administered with 19F-nanoparticles. The transmit/receive profile of the 19 F-CRP diminished with increasing distance from the surface. This was counterbalanced by a substantial SNR gain compared to the RT coil. Intraparenchymal inflammation in the ex vivo EAE brains was more sharply defined when using 150 μm isotropic resolution with the 19 F-CRP, and reflected the known distribution of EAE histopathology. At this spatial resolution, most 19F signals were undetectable using the RT coil. The 19 F-CRP is a valuable tool that will allow us to study neuroinflammation with greater detail in future in vivo studies.

Nuclear instruments & methods in physics research / A 854, 113 - 126 (2017). doi:10.1016/j.nima.2017.02.058, To provide high quality electron bunches for linear accelerators used in free electron lasers and particle colliders, RF gun cavities operate with extreme electric fields, resulting in a high pulsed RF power. The main L-band superconducting linacs of such facilities also require a long RF pulse length, resulting in a high average dissipated RF power in the gun cavity. The newly developed cavity based on the proven advantages of the existing DESY RF gun cavities, underwent significant changes. The shape of the cells is optimized to reduce the maximal surface electric field and RF loss power. Furthermore, the cavity is equipped with an RF probe to measure the field amplitude and phase. The elaborated cooling circuit design results in a lower temperature rise on the cavity RF surface and permits higher dissipated RF power. The paper presents the main solutions and results of the cavity design., Published by Elsevier, Amsterdam

This paper presents the system and circuit design of a compact radio frequency (RF)-powered 2.4-GHz CMOS transmitter (TX) to be used for autonomous wireless sensor nodes (WSNs). The proposed TX utilizes the received dedicated RF signal for both energy harvesting as well as frequency synthesis. A TX RF carrier is derived from the received RF signal by means of a delay locked loop and XOR-based frequency multiplier. The 50- $\Omega $ load is subsequently driven by a tuned switching RF power amplifier (PA) with 25% duty cycle input for high global efficiency. The design is fabricated in 40-nm CMOS technology and occupies a die area of 0.16 mm2. Experimental results show a rectifier with 36.83% peak efficiency and power management circuit with 120-nA current consumption that enables a low start-up power of −18.4 dBm. The TX outputs a continuous 2.44-GHz RF signal at −2.57 dBm with 36.5% PA drain efficiency and 23.9% global efficiency from a 915-MHz RF input and supports ON–OFF keying modulation.

International audience; This paper presents the design of an offset reflectarray illuminated by a printed primary source. The proposed build-up is compatible with flip-chip technology, enabling a direct connection between the RFIC and the antenna source. Measurements are realized using a GSG RF probe and a good agreement is obtained with simulated data

International audience; This paper investigates the disagreements that may occur between on-wafer measurements and electromagnetic (EM) simulations of high-Q inductive devices. Such disagreements are highlighted on a planar spiral inductor and a 3-D solenoid which exhibit measured maximum Q-factors of 27 and 35 respectively, while 42 and 45 were expected from EM simulations. Both devices are fabricated on high-resistivity substrates. A radiative interaction is identified between RF probe and inductive device under test. By using EM simulations, extra-losses associated with this parasitic effect are fully modeled through the calculation of radiation and dissipation related Q-factors. Adjustments of on-wafer probe setup are proposed to reduce this parasitic effect. Finally, the 3-D solenoid inductor is characterized using a new experimental fixture, and the maximum Q of 45 predicted by EM simulation is retrieved.

U ovom radu razmatran je i dizajniran set kalibracijskih i testnih struktura za preciznu kalibraciju širokopojasnih radiofrekvencijskih (RF) sondi koje se koriste za mjerenja analognoga signala velike amplitude. U programskom alatu Agilent ADS provedene su simulacije na bazi teorije električnih krugova te elektromagnetske simulacije na temelju kojih je utvrđen optimalni dizajn tiskanih pločica te su odabrani prikladni tipovi prijenosnih linija i konektora. Nakon što tiskane pločice budu izrađene, odredit će se karakteristika RF sonde, što će u konačnici pridonijeti većoj točnosti i pouzdanosti mjernih rezultata. For precise calibration of the broadband radio-frequency (RF) probes used for large-amplitude analogue signal measurements, a set of calibration and test structures was proposed and designed. Circuit and EM Momentum simulations were performed in Agilent ADS for different transmission lines and connector types, based on whom an optimum design of the printed circuit boards (PCBs) was determined. After the PCBs are processed, a characteristic of the RF probe will be determined, which will ultimately lead to a tighter control of the signal performance, and more accurate signal measurements using the probe.

This paper presents a 900-2400 MHz AC-DC rectifier circuit for radio frequency (RF) energy harvesting. The proposed circuit consists of a rectifier and charge pump. The multi-stage NMOS RF-DC rectifier circuit is designed to convert the AC signal to DC signal while the charge pump helps to amplify the DC amplitude. The proposed circuits are designed and simulated using CMOS 0.13-μm technology. The simulation results show that the proposed circuit able to produce 2.9 V DC voltage at 10 kΩ load with an input voltage of 150 mV.

This work describes a new generation of instrumentation that aims to address the challenge of on-wafer measurement of nanodevices in the microwave regime. The system proposed is built up with a vector network analyzer, a scanning electron microscope and miniaturized ground-signal-ground probes fabricated using silicon-on-insulator technology with contact sizes of 2 µm2. Dedicated calibration standards are developed and the proof of concept of the operability of this novel system is demonstrated by first calibrated on-wafer microwave measurements up to 4 GHz.

A new method for the characterization of integrated circuits immunity is presented in this paper. The substantial evolution of the resistive radio frequency injection probe (RFIP) test method is introduced. Measurement setup characterization is discussed along with the technique’s limitations. The method is also validated through different measurements, particularly on an analog-to-digital converter embedded in a microcontroller. RFIP measurement results are compared with results of other measurement techniques, including vector network analyzer, direct power injection, and differential RF probe.

International audience; The aim of this paper is to show the possibility to harvest Radio Frequency (RF) energy to supply Wireless Sensor Networks (WSNs) in outdoor environment. In those conditions, the number of existing RF bands is unpredictable. The RF circuit has to harvest all the potential RF energy present and cannot be designed for a single RF tone. In this paper, the designed RF harvester adds powers coming from an unlimited number of sub-frequency bands. The harvester's output voltage ratios increase with the number of RF bands. As an application example, a 4-RF band rectenna is designed. The system harvests energy from GSM900 (Global System for Mobile Communications), GSM1800, UMTS (Universal Mobile Telecommunications System) and Wi-Fi bands simultaneously. RF-to-dc conversion efficiency is measured at 62% for a cumulative -10 dBm input power homogeneously widespread over the four RF bands and reaches 84% at 5.8 dBm. The relative error between the measured dc output power with all the 4 RF bands ON and the ideal sum of each of the four RF bands power contribution is less than 3%. It is shown that the RF-to-dc conversion efficiency is more than doubled compared to that measured with a single RF source, thanks to the proposed rectifier architecture.

International Symposium on Consumer Electronics (ISCE) -- JUN 24-26, 2015 -- Madrid, SPAIN, WOS: 000380467600073, In recent years, it is one of the biggest disadvantages of wireless sensors have vital importance that they are supplied by batteries. It is possible to overcome this deficiency by RF energy harvesting systems. In this work, the system generating electrical energy efficiently from two different RF signals have different frequencies is presented. Compared with conventional single frequency RF energy harvester, with the proposed dual band RF energy harvester, an increase is achieved 39% and 78% for 575 MHz and 900 MHz input frequencies at 0 dBm signal level, respectively. In a wide range of frequencies in the range of 400 MHz to 1000 MHz, the efficiency is obtained over 50% from the proposed system. Thus, the system can be used efficiently in an environment including any one or more DTV and GSM signal. The proposed circuit can be used effectively on the RF signals have the level of more than -15 and -10 dBm.

Modern research on nuclear fusion energy, based on the tokamak concept, has strong need of tools for actively driving non-inductive current especially at the periphery of plasma column, where tools available so far have poor efficiency. This is essential for solving one of the most critical problems for thermonuclear reactor, consisting in how to achieve the figure of fusion gain in the context of sufficient stability. The lower hybrid current drive (LHCD) effect has the potential capability of driving current at large radii of reactor plasma with high efficiency [1]. Experiments recently carried out on EAST showed that a strong activity of LH sideband waves (from the RF probe spectra), accompanied by weak core penetration of the coupled LH power, is present when operating at relatively high plasma densities. Previous theoretical results, confirmed by experiments on FTU, showed that the LH sideband phenomenon is produced by parametric instability (PI), which are mitigated by higher plasma edge temperatures. This condition is thus useful for enabling the LH power propagation when operating with profiles having high plasma densities even at the edge. In the present work, we show new PI modeling of EAST plasmas data, obtained in condition of higher plasma edge temperature due to chamber lithisation. The obtained trend of the PI frequencies and growth rates is consistent with data of RF probe spectra, available in different regimes of lithisated and not lithisated vessel. Moreover, these spectra are interpreted as PI effect occurring at the periphery of plasma column, however in the low field side where the LH power is coupled. © 2015 AIP Publishing LLC.

International audience; — Multiple Continuous-Wave (CW) Radio Frequency (RF) signals are used in many telecommunication applications, such as frequency aggregation in LTE-Advanced (LTE-A), intermodulation distortion measurements and …, in order to use more efficiently the frequency bands that are available. In this work a new method for generating three frequencies and more, with no a-priori condition on the frequency allocation, is elaborated in theory and practical results are presented, as well.

We report pump-probe experiments employing laser-synchronized reactions of para-hydrogen (para-H2) with transition metal dihydride complexes in conjunction with nuclear magnetic resonance (NMR) detection. The pump-probe experiment consists of a single nanosecond laser pump pulse followed, after a precisely defined delay, by a single radio frequency (rf) probe pulse. Laser irradiation eliminates H2 from either Ru(PPh3)3(CO)(H)2 1 or cis-Ru(dppe)2(H)2 2 in C6D6 solution. Reaction with para-H2 then regenerates 1 and 2 in a well-defined nuclear spin state. The rf probe pulse produces a high-resolution, single-scan (1)H NMR spectrum that can be recorded after a pump-probe delay of just 10 μs. The evolution of the spectra can be followed as the pump-probe delay is increased by micro- or millisecond increments. Due to the sensitivity of this para-H2 experiment, the resulting NMR spectra can have hydride signal-to-noise ratios exceeding 750:1. The spectra of 1 oscillate in amplitude with frequency 1101 ± 3 Hz, the chemical shift difference between the chemically inequivalent hydrides. The corresponding hydride signals of 2 oscillate with frequency 83 ± 5 Hz, which matches the difference between couplings of the hydrides to the equatorial (31)P nuclei. We use the product operator formalism to show that this oscillatory behavior arises from a magnetic coherence in the plane orthogonal to the magnetic field that is generated by use of the laser pulse without rf initialization. In addition, we demonstrate how chemical shift imaging can differentiate the region of laser irradiation thereby distinguishing between thermal and photochemical reactivity within the NMR tube.

International audience; A high sensitivity radiofrequency (RF) probe dedicated to contactless dielectric characterisations is presented. A method for the impedance measurement of a distant RF resonator is first proposed. The method is evaluated as a function of the measurement distance starting from experiments. The obtained results enable assessment of the accuracy of the method and optimisation of its implementation.

International audience; In the next generation of the mobile radio systems, the information will be distributed on discontinuous frequency bands. To demodulate the RF signal, a possible architecture is to use a number of receivers Rx equal to that of the discontinuous RF frequency bands. This paper demonstrates that this operation can be made with a single receiver Rx. The method is based on the mixing of the RF signal with a local oscillator (LO) signal constituted by several Continuous Wave (CW) signals. The technique is studied theoretically and then applied to the case of RF signal constituted of two frequency bands. The CW frequencies of the LO signal are selected to convert both bands of the RF signal in Zero Intermediate Frequency (ZIF) and LOW Intermediate Frequency (LIF).

The concept of photonics-assisted RF transceiver will be detailed. It provides extremely stable multiprotocol signals up to the millimeter waveband, and it optically samples directly at RF multiple heterogeneous RF signals, with increased resolution.

ISBN 978-1-4673-1594-4; International audience; This paper discusses a new type of sensors to enable a built-in test in RF circuits. The proposed sensors provide DC or low-frequency measurements, thus they can reduce drastically the testing cost. Their key characteristic is that they are nonintrusive, e.g. they are not connected electrically to the RF circuit. Thus, the performances of the RF circuit are unaffected by the monitoring operation. The sensors function as process monitors and share the same environment with the RF circuit. The underlying principle is that the sensors and the RF circuit are subject to the same process variations, thus shifts in the performances of the RF circuit can be inferred implicitly by shifts in the outputs of the sensors. We present experimental results on fabricated samples that include an LNA with embedded sensors. The samples are collected from different sites of a wafer such that they exhibit process variations. We demonstrate that the performances of the RF circuit can be predicted with sufficient accuracy through the sensors by employing the alternate test paradigm.

Purpose: The purpose of this study was to assess the feasibility of noninvasive thermometry using high-resolution computer tomography (CT) for the monitoring of bovine liver during radiofrequency (RF) ablation.Methods: Radiofrequency probes were used to ablate bovine livers from 20 degrees C to 98 degrees C. During the heating process, images were acquired using a multidetector CT scanner with simultaneous measurement of temperature using calibrated thermal sensors. The CT scanner's thermal sensitivity was derived from the correlation between the CT numbers and temperature. The CT scanner's thermal sensitivity was used to compute a temperature map, and this temperature map was overlaid on the original CT scan using a dedicated software application.Results: The CT numbers of the bovine liver showed a linear decline with an increase in temperature and a CT thermal sensitivity of -0.60 +/- 0.026 Hounsfield unit/degrees C (R-2 = 0.87). Temperature maps were calculated using this correlation and were superimposed onto the CT scans presenting temperature distribution around the RF probe in the bovine liver.Conclusions: Noninvasive temperature determination is feasible during RF ablation of bovine liver using a high-resolution CT system. Therefore, the proposed method can be of potential use in clinical practice for noninvasive temperature mapping during ablation.

A miniature batteryless implantable wireless pressure sensor that can be used deep inside the body is desired by the medical community. MEMS technology makes it possible to achieve high responsivity that directly determines the operating distance between a miniature implanted sensor and the external RF probe, while providing the read-out. In this paper, for the first time, an analytical expression of the system responsivity versus the sensor design is derived using an equivalent circuit model. Also, the integration of micro-coil inductors and pressure sensitive capacitors on a single silicon chip using MEMS fabrication techniques is demonstrated. Further, the derived analytical design theory is validated by the measured responsivity of these sensors.

[EN] We study the phase and amplitude stability of RF signals, generated at different frequencies by heterodyning pairs of modes from the optical spectrum of an active mode-locked laser, and we focus on the dependence of noise on the RF frequency. A specific theoretical model is derived, and the amplitude and timing jitter behaviour of the RF signals are analyzed and experimentally validated. The timing jitter reveals to be constant at any RF generated frequency, making the considered RF generation method suitable for the realization of flexible and highly stable micro-and millimeter-wave coherent radar transceivers. The performance of the considered RF generation architecture are compared with a state-of-the-art RF synthesizer, proving that the optically generated RF signals meet the high stability requirements of the new generation of coherent radar systems, even at extremely high frequencies (EHF)., Manuscript received May 17, 2011; revised September 27, 2011; accepted September 27, 2011. Date of publication October 06, 2011; date of current version November 25, 2011. This work has been supported in part by the EU projects PHODIR and EURO-FOS. The work of G. E. Villanueva and J. Palaci has been supported by the MEC-FPU and UPV-FPI programs. The work of P. Perez-Millan has been supported by the Juan de la Cierva program, JCI-2009-05805. The work of J. L. Cruz was supported in part by the Ministerio de Ciencia e Innovacion of Spain under Grant TEC2008-05490.

Coupling of ICRF (Ion Cyclotron Range of Frequencies) power to the plasma is one of the standard methods to heat plasmas in toroidal devices with magnetic confinement. However voltage limits on the ICRF antenna used to launch the waves sometimes lead to a limitation of the power. These limits are related to a variety of high voltage breakdown phenomena in the presence of plasma that depend, in particular, on spatial charge effects and particle fluxes to the electrodes. An ICRF probe has been developed to study the high voltage phenomena. The open end of a coaxial line models the high voltage region of the antenna. The voltage limits were studied in well defined conditions in a test facility without magnetic field and in the real conditions of the peripheral plasma of the ASDEX Upgrade divertor tokamak. The ICRF probe was installed in the test facility and conditioned in vacuum by high power pulses to reliable operation with 60 kV, 200 ms or 80 kV, 20 ms pulses. During the conditioning, vacuum arcs occur mainly at the probe head. The arcs appear often when dark field emission currents are measured. The presence of a plasma density of 1015m-3 (delivered by a high aperture ion source) does not affect the voltage stand-off of the probe unless the pressure of working gas is increased beyond a critical level: a semi-self-sustained glow discharge is ignited at a pressure of 0.15 Pa for He and 0.03 Pa for air. These pressures are about one order of magnitude lower than the pressures required for ignition of a self-sustained glow discharge at 80 kV. Cathode spots on the surface of the inner conductor are formed in the semi-self-sustained discharge and often lead to the formation of the arc discharge. When the ICRF probe is installed in ASDEX Upgrade and is well conditioned (to the maximal voltages achieved in the test facility), high voltage breakdown on the probe often correlates with activity of edge localized modes (ELMs). The breakdown characteristics are similar to that of the cathode spots formation in the semi-self-sustained discharge glow discharge. The maximal RF voltage on the ICRF probe increases from shot to shot, i.e. an additional conditioning effect is observed during plasma operation. The voltage limit of the probe can be increased by application of a positive DC bias to the inner conductor while at the same time the rectified current associated with the collection of ions across magnetic field is suppressed. It was found that the appearance of ELMs and other intermittent events in the scrape-off-layer (SOL) plasma in the region of the probe head lead to a local dissipation of a high fraction of RF power. The role of ELMs as RF breakdown trigger is confirmed by observations during operation of the full-size AUG ICRF antenna. A reliable arc detection system is required for the ICRF antennas (not every breakdown triggered by ELMs is easy to detect), otherwise the overall performance of the antennas degrades due to appearance of quasi-stationary arc discharges. The antennas operates more reliably when the antenna conductors are conditioned with plasma. Measures to improve the antenna voltage stand-off in the presence of plasma are suggested: an optically closed Faraday screen; glow discharge conditioning; a form of antenna conductors to minimize ion collection across the magnetic field and minimize asymmetry of electrodes along the field; neutral density reduction inside the antenna. Further work should be focused on the choice of the antenna materials, parasitic absorption of the RF power and the antenna-plasma interaction for different DC boundary conditions of the antenna circuit. Das Abstrahlen von Radiowellen nahe der Ionenzyloktronfrequenzen (ICRF) ist eine der üblichen Heizmethoden von magnetisch eingeschlossenen Plasmen. Jedoch begrenzt die Spannungsfestigkeit der ICRF Antenne die maximal abstrahlbare Leistung. Die Begrenzung kann die Folge unterschiedlicher Mechanismen sein, die von Raumladungseffekten und Teilchenflüssen zu den Elektroden abhängen. Eine ICRF Versuchsanordnung bestehend aus einem einseitig offenen koaxialen Resonator wurde für experimentelle Studien entwickelt. Dabei stellt das offene Ende ein Gebiet mit hoher Spannung in der Antenne dar. Die Spannungsfestigkeit dieses Bereichs wurde in einem Teststand unter definierten Bedingungen ohne Magnetfeld, und in dem Randplasmabereich des ASDEX Upgrade unter antennenähnlichen Bedingungen untersucht. Die Ergebnisse helfen die Überschlagsprozesse in einer ICRF Antenne besser zu verstehen und zeigen Methoden auf, mit denen die Spannungsfestigkeit von Antennen verbessert werden kann.

Built-in-test (BIT) for radio frequency integrated circuits (RFIC) is an effective method to reduce the testing cost, especially with the increase of integration level and operating frequency. In this work, a fully integrated CMOS BIT methodology is proposed. The BIT circuit used is rectifier-based and gate-source connected MOS transistor with substrate positively-biased (SPB) scheme is used to further improve the detecting sensitivity. With little current consumption, high input impedance and high frequency scalability this circuit can predict complex high frequency performances of RF circuits such as gain, operating frequency, bandwidth and linearity. Besides, the influence of process, supply voltage, and temperature (PVT) variations on the performance of RF circuits can also be monitored by using this BIT circuit.

Electrostatic actuated radio frequency microelectromechanical systems (RF-MEMS) switches and variable capacitors are susceptible to issues related to RF actuation or even RF pull-in under large-signal regime. This phenomenon is strictly related to the average RF voltage more than power, and the impedance environment of the device should be fully accounted for. We perform for the first time large-signal time-domain measurements to characterize the RF actuation effect on the real-time capacitance value of a suspended membrane-based RF-MEMS varactor, while controlling the load impedance presented to the device with an active load-pull. The dependence of RF-actuation on both real impedance and inductive admittance is directly extracted, giving strong insights on how power handling should be carefully scrutinized against each specific circuit design.

This work deals with a method for determining accurately reflection coefficient of one-port devices submitted to high RF power. A de-embedding theory based on S-matrix is carried out for mismatches of the test setup components: power amplifier, power circulator and probe. This bench was designed for reliability issues of RF components. An example of bench application on the new bulk acoustic wave resonator is presented. Those components are now widely used to build RF-filters in wireless-telecommunication systems. Moreover, an infrared camera with high spatial resolution (2 ?m/pixel) gives complementary information about the temperature induced by self-heating inside probe and device, and its dependence on the RF power.

A simple Q-damper device for active probe recovery time reduction is introduced along with a straightforward technique for the circuit's component value optimization. The device is inductively coupled to a probe through a coupling transformer positioned away from the main coil, which makes the design independent of the coil type being used. The Q-damper is a tuned circuit, which is resonant at the same frequency as the probe and can be actively interrupted. When the circuit is interrupted, it is detuned and, thereby, is uncoupled from the probe, which operates normally. Turning the device on leads to re-coupling of the circuits and causes splitting of the probe's resonance line, which can be observed through its drive port. A resistance of an appropriate value is introduced into the Q-damper circuit, resulting in smoothing of the resonance splitting into one broad line, representing the coupled system's low-Q state, in which the energy stored in the main coil is efficiently dissipated. The circuit's component values are optimized by monitoring the shape of this low-Q state. Probe recovery time reduction by, approximately, an order of magnitude has been obtained with this device. Application of the device during an NQR experiment led to an increase in the signal-to-noise ratio by a factor of 4.9. Fil: Peshkovsky, Alexey S.. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina Fil: Forguez, J.. No especifíca; Fil: Cerioni, Lucas Matias Ceferino. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pusiol, Daniel Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina

International audience; This paper presents a state-of-art review of on-wafer S-parameter characterization of THz silicon transistors for compact modelling purpose. After, a brief review of calibration/de-embedding techniques, the paper focuses on the on-wafer calibration techniques and especially on the design and dimensions of lines built on advanced silicon technologies. Other information such as the pad geometry, the ground plane and the floorplan of the devices under test are also compared. The influence of RF probe geometry on the coupling with the substrate and adjacent structures is also considered to evaluate the accuracy of the measurement, especially using EM simulation methodology. Finally, the importance of measuring above 110 GHz is demonstrated for SiGe HBT parameter extraction. The validation of the compact model is confirmed thanks to an EM-spice co-simulation that integrates the whole calibration cum de-embedding procedure.

The susceptibility of five instruments to radio-frequency (RF) fields has been measured by three laboratories in the frequency range of 27–470 MHz using a simple stripline equipment. There was little systematic difference between the results of the three laboratories. The standard deviation of measurement is estimated to be about 5 dB.

The RF system at TRIUMF is now operating with the highest Q, the lowest RF leakage into the beam gap, the best voltage stability, and the lowest resonator strongback temperatures ever measured since it was first put into operation. This paper describes the calculation of the RF impedance of the beam gap and its correlation to the RF problems encountered, which eventually led to modifications to the flux guides and resonator tips to accomplish the improved operation of the RF system.