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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.

Radiofrequency ablation of the renal tumors considered the least invasive technique to get rid of malignancies cells. High-frequency waves in the range of 0.9 – 2.5 GHz were applied to the cancerous cells. Consequently, resistive heating was generated used to destroy the cancerous cells. In this paper, this technique had been applied to a 3D accurate model of the kidney with similar dimensions and shape including its artery, vein, and ureter. The next step was to design an RF probe to get high values of specific absorption rate for the cancerous cells and minimum values for the normal cells of the kidney. Simulation results showed that the shape of the model has the greatest effect on the resulting lesion volume and shape. In this work, the internally cooled electrode using Gil was designed from aluminum material with its tines revolved to 270° and Gaussian signal as the excitation signal.

A high-temperature superconducting (HTS) radio frequency (RF) probe has been designed for nuclear magnetic resonance spectroscopy that is constructed of two newly developed HTS elliptical–coupled resonators that are placed on either side of the sample. The probe has a higher quality factor and a more uniform magnetic field along the z -axis than one with square resonators. The measured unloaded quality factor ( Qu ) of a pair of elliptical–coupled resonators fabricated using YBa2Cu3Oy thin films on an Al2O3 substrate was about 30 000 at 15 K, which is about 82 times higher than the simulated Qu of a copper counterpart at room temperature. Measurement of the input power dependence of Qu showed that a Qu of over 20 000 was obtained up to 16 dBm. Measurement of the RF magnetic field profile along the z -axis showed that the RF magnetic field was more than 85% uniform around the sample region.

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.

For the IFMIF/EVEDA accelerator prototype RFQ linac, a 175 MHz rf input coupler based on a 6 1/8 in. co-axial waveguide is designed and manufactured. The rf coupler has cooling channels into the loop antenna and inner/outer-conductors around the RF window for CW operation mode, and the rf vacuum window module is replaceable by flanged connection. For rf power capability, nominal rf power of 160 kW and maximum transmitted rf power of 200 kW are required. In order to test the rf power capability, rf power tests using a high-voltage standing waves on a high-Q load circuit are carried out. For manufactured nine rf couplers including one spare, a stable 14 s CW operation at the equivalent rf power of 200 kW were achieved within 3–5 days rf aging. No rf contact defects, no unnecessary low-Q value and no extraordinary outgassing were validated.

Spastic Cerebral Palsy is the most common type of Cerebral Palsy (CP) that affects muscle coordination and control. Using Radiofrequency Ablation (RFA) to target the motor branches of the median and ulnar nerve may provide an additional treatment to Botulinum Toxin for spasticity in the hand. However, there are a limited number of studies that report the use of RFA in treating upper-limb spasticity. This prompts the need to establish a simulation model that has been tested against physical phantom to help determine the efficacy of RFA as a treatment for spasticity. In this study, a 3D COMSOL Multiphysics model of a commercial RF probe was validated against a Thermochromic Liquid Crystal (TLC) homogeneous gel phantom. The results of the COMSOL model were compared to the TLC phantom in terms of temperature (0.42 ± 1.06°C for the TLC high temperature range and -1.90 ± 0.88°C for the TLC low temperature range), lesion shape (14.5 ± 5.0%) and lesion size (0.18 ± 0.06 mm). These results show that COMSOL Multiphysics may be feasible as a tool to characterise RF lesions if the reported errors are accounted for. Further work is required to develop a more complex COMSOL model that incorporates different tissue aspects. However, this is a first step to establishing a validated COMSOL model of a RF probe in homogeneous muscle tissue.

The goal of thermal ablation is to destroy cancerous cells by increasing the temperature of the target tissue. Among the ablative techniques, radiofrequency (RF) ablation is the most widespread since it can be used in both percutaneous and surgical settings, in safety and with relative ease of use. However, efforts to optimize the RF treatment are needed, considering that the size of necrotized lesions remains a central issue in the application of the ablative procedure. In this work we aimed to evaluate the temperature distribution around the RF probe during radiofrequency ablation (RFA) of ex-vivo animal livers. Temperature maps in the ablated area are obtained by equipping a commercial RF probe with 27 Fiber Bragg Grating sensors (FBGs). The experiments demonstrate the ability of the proposed setup to conduct multi-point measurements in tissues undergoing RFA and the dependence of temperature and thermal damage on insertion depth of the RF probe.

Radiofrequency (RF) ablation therapy is of great interest in cancer therapy as it is non-ionizing radiation and can effectively penetrate into the tissue. However, the current RF ablation technique is invasive that requires RF probe insertion into the tissue and generates a non-specific heating. Recently, RF-responsive nanomaterials such as gold nanoparticles (AuNPs) and iron oxide nanoparticles (IONPs) have led to tremendous progress in this area. They have been found to be able to absorb the RF field and induce a localized heating within the target, thereby affording a non-invasive and tumor-specific RF ablation strategy. In the present study, for the first time, we used a hybrid core-shell nanostructure comprising IONPs as the core and AuNPs as the shell (IO@Au) for targeted RF ablation therapy. Due to the magnetic core, the nanohybrid can be directed toward the tumor through a magnet. Moreover, IONPs enable the nanohybrid to be used as a magnetic resonance imaging (MRI) contrast agent. In vitro cytotoxicity experiment showed that the combination of IO@Au and 13.56-MHz RF field significantly reduced the viability of cancer cells. Next, during an in vivo experiment, we demonstrated that magnetically targeting of IO@Au to the tumor and subsequent RF exposure dramatically suppressed the tumor growth. Therefore, the integration of targeting, imaging, and therapeutic performances into IO@Au nanohybrid could afford the promise to improve the effectiveness of RF ablation therapy.

In this work, a measurement-based technique to determine LC-matching network for RF-to-DC converter is proposed. It is shown that the differential drive rectifier can be configured as the differential CMOS LC-oscillator by swapping input and output terminals. Thus, this oscillator can then be used to find the inductor (L) and capacitor (C) component values for the rectifier matching network at the intended frequency, which is the oscillation frequency of the oscillator. Measured results show that the absolute frequency error between resonant frequency obtained from oscillator mode and matching frequency obtained as rectifier is less than 2%. The switching core used in this work has been implemented in a standard 0.18 μm CMOS technology and external discrete passive components are used to form the LC network.

This paper presents the design, construction and test of a radio frequency self-oscillator-amplifier (SOA). The main goal is to develop a small reliable and non-expensive RF circuit generator capable to deliver up to 180 W of RF power to sustain ionization in waveguide-like electrodes in CO2 laser amplifying media. The laser media amplifier (LMA) is a specific designed (or homemade) setup that can be coupled to our RF SOA circuit. The LMA was built as a simple inductive-capacitive (LC) component which has the capability to efficiently absorb above the 95% of the RF energy delivered by the SOA. RF energy between the SOA and the laser head is achieved by the use of a matching circuit (MC) in order to assess the LMA transient ionization stability. In this work we complete our study by adding a 5-pass (WI) optical resonator to have laser light output. The proposed circuit was designed to oscillate in a frequency within the range of 60 MHz to 80 MHz and a center frequency of 70 MHz and its components were fine tuned to optimize its signal output power in the range from 120 W to 180 W (2–3 times the manufacturer output power specification at 70 MHz). Before we interconnect the RF SOA into the laser head we test its performance by using a dummy load with 50 W termination. The next step is to measure the complex impedance of our laser head. The LMA is a capacitive-like discharge that has several parallel-distributed inductors along the laser electrodes to create a steady and uniform plasma discharge. The complex impedance of our laser head is measured in two modes by using a Vector Impedance Analyzer (VIA) AEA-Via Echo 1000SF; in high vacuum and at the final gas mixture pressure. Once we know the complex impedance we input this value in the ADS software to find the best matching circuit (MC) between the SOA and the LMA. From this stage, we are able to perform an overall evaluation of the complete setup: SOA-MC-LMA. We proceed to test the ionization state of our laser performance using a typical gas mixture of CO2-N2-He with proportion of 1:1.2:3.7 correspondingly and at a final pressure of 70 Torr a maximum optical output power better than 20 W was obtained at a maximum RF feed power of 173 W.

The radiation equipment research division of Korea Atomic Energy Research Institute has developed a Container Inspection System (CIS) using a Radio Frequency (RF) electron linear accelerator for port security. The primary purpose of the CIS is to detect nuclear materials and explosives, as well country-specific prohibited substances, e.g., smuggled. The CIS consists of a 9/6 MeV dualenergy electron linear accelerator for distinguishing between organic and inorganic materials. The accelerator consists of an electron gun, an RF accelerating structure, an RF driver, a modulator, electromagnets, a cooling system, a X-ray generating target, X-ray collimator, a detector, and a container moving system. The RF driver is an important part of the configuration because it is the RF power source: it supplies the RF power to the accelerating structure. A unique aspect of the RF driver is that it generates dual RF power to generate dual energy (9/6 MeV). The advantage of this RF driver is that it can allow the pulse width to vary and can be used to obtain a wide range of energy output, and pulse repetition rates up to 300 Hz. For this reason, 140 W (5 MW − 9 MeV) and 37 W (3.4 MW − 6 MeV) power outputs are available independently. A high power test for 20 minutes demonstrate that stable dual output powers can be generated. Moreover, the dual power can be applied to the accelerator which has stable accelerator operation. In this paper, the design, fabrication and high power test of the RF driver for the RF electron linear accelerator (linac) are presented.

An Opto-VLSI based dynamic RF signal combiner structure is proposed and experimentally demonstrated. The structure utilizes an Opto-VLSI processor in conjunction with an optical fiber array, a photo-detector, and a 4-f imaging lens system to dynamically combine multiple analog RF signals into a single output RF port with a user-defined combination ratio. A proof-of-concept $2\times 1$ analogue RF signal combiner is experimentally demonstrated, and experimental results show that RF signal combination with arbitrary ratio can be achieved by uploading different optimized phase holograms onto the Opto-VLSI processor.

Power transformer partial discharge signal measurement using Radio Frequency method has advantages over IEC 60270 ‘apparent charge’ measurement method for online monitoring due to greater immunity against external interference. However, the lack of a well-defined calibration relationship between the two methods is main disadvantage of RF method. Simultaneous measurements, using these two methods, carried out on various transformer PD source models, in laboratory, to investigate main parameters that affect the relationship of results of these two methods. In this paper, factors that influence this relationship are classified into three groups: (i) type of PD sources, (ii) transformer windings as PD signal transmitter, and (iii) the inner structure of the transformer. Firstly, the relationship between these two methods has been investigated for some simple types of PD sources. Subsequently, by adding the winding structure model to the void, which is the PD source, its impact on each measurement method and the relationship between them have been studied. The impact of inner structure on the relation between the two methods is compensated through a formula which is proposed as a means for calibration of the RF partial discharge measurement setup. However to compensate for internal insulating system effects more research is required.

This paper presents an update of the current in-situ antenna characterization and calibration of a radar system using an Unmanned Aircraft System (UAS) developed by the Advanced Radar Research Center (ARRC) at The University of Oklahoma. A large multirotor platform was customized for long endurance (~ 30 minutes), high positioning accuracy (< 3cm), and high stability, and was integrated with a high precision 3-axis gimbal that holds an antenna array and pulse generator-transmitter. The platform was designed to support measurements from 2 GHz to 10 GHz, however, the current setup described in this article includes an S-band array probe of 3×3 elements. The RF probe beamwidth was optimized to minimize reflections from the UAS frame and to provide accurate antenna measurements in flight conditions.

Electromagnetic (EM) field simulation plays a key role in the design of magnetic resonance imaging radio frequency (RF) coils. However, the values of the components in tuning and matching circuits often need to be iterated repeatedly in the conventional simulation method in order to achieve optimal scattering parameters. This leads to a time-consuming optimization to tune and match RF coils, particularly dual-tuned coils that are comprised of multiple lumped elements. A method combining EM field simulation and circuit simulation was employed in this paper, which can dramatically improve simulation efficiency for the optimization of the values of the lumped elements and corresponding EM field distribution. A systematical theoretical analysis of the co-simulation method was presented. To validate the accuracy and efficiency of the co-simulation method, a comparison study was conducted between the conventional simulation and the proposed co-simulation approaches.

In this paper, an inductor of meander topology is designed using Cadence integrated circuit toolchain. The structure is fabricated using a 130 nm standard CMOS technology node. Characterization is performed at frequencies up to 35 GHz and at temperatures of 20°C, 50°C and 80°C. For the experiment an RF probe station with a temperature controllable chuck has been used. The results this set-up yielded include inductance, Q-factor and parasitic resistance behavior versus temperature. Meander topology temperature performance is presented and discussed.

This paper introduces a fully integrated direct power detector that monitors both RF current and RF voltage to detect the RF output power of the on-chip RF PA realized in a standard 40 nm CMOS process. The RF current measurement is realized by a sense winding in the output transformer, while the RF voltage waveform measurement is performed by capacitive division of the RF output voltage. Since the RF current and the RF voltage are both acquired, this power detector accurately and continuously determines the real output power of the RF PA with a maximum inaccuracy of ±0.5 dB over a wide 32.5 dB dynamic range. This power detector was integrated together with a 5 GHz RF PA designed for the WLAN IEEE 802.11ac communication standard. The power detector is capable of performing a RF output power measurement even for an antenna impedance mismatch up to voltage standing wave ratio (VSWR) 2.8:1 with an accuracy of ±1 dB, which allows the power detector to be used in an automatic antenna-mismatch correction system to prevent performance degradation in the RF PA. Finally, since the proposed power detector can be completely incorporated inside the RF PA output transformer. It results in zero area overhead, proving a very cost effective design.

For optimizing sensitivity and RF excitation, high resolution NMR probes have to be tuned at the Larmor frequency and matched to 50 Ω-transmission lines to which they are connected. For achieving this setting, one usually resorts to the wobulation function which consists in sweeping the frequency of the power source while monitoring and minimizing the reflected power taken from a directional coupler through adjusting the tuning and matching capacitors. However, the presence of a transmission-reception switch between the directional coupler and the probe leads to the appearance of extra loss and reactance, and affects the determined values of the previous mentioned capacitors. Even if this situation is usually satisfactory, the true tuning-matching condition is required for optimal NMR sensitivity and for reliable spectra analyses when nonlinear effects are present (radiation damping, spin-noise experiments, etc.). To circumvent the need of network analyzer directly attached to the probe for finding this optimal tuning-matching condition, in the current work, we report a procedure which combines wobulation and choice of a transmission-line phase shift obtained by a variable phase shifter inserted between the probe and the switch. The technique was successfully validated with help of a network analyzer. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 45B: 59–68, 2015

RF probe measurements are widely used for characterizing circuits in the millimeter-wave frequency range. Especially above 200 GHz the large dimensions of the RF probe, in comparison to the wavelength, lead to parasitic effects which will effect the device under test. Since the measurement is influenced by the electro-magnetic coupling between probe tip and the test structures on the substrate, the standard on-wafer calibration becomes unprecise. This paper discusses a method of simulating this influence by means of 3D electromagnetic simulations. Confirmation of the approach was done by comparing measured and simulated results of impedance substrate standards and galium arsenid (GaAs) monolithic millimeter-wave integrated circuits (MMICs). A very good agreement to measured results in the investigated WR3 frequency range (220–325 GHz) is presented, showing effects which were unobserved in earlier simulations.

A low frequency electric field probe with high sensitivity was designed for locating radiated emissions source in electronic systems from 10 kHz to 100 MHz. This probe consists of a dipole at probe tip loaded with an op-amp built instrumentation amplifier, whose output then is amplified by a cascaded RF amplifier. The probe dipole is capacitively loaded by the instrumentation amplifier, resulting in a flat frequency response with high sensitivity at low frequency. The instrumentation amplifier also converts differential dipole output to single-ended signal without the need of an external hybrid. Additionally, the instrument amplifier suppresses common-mode noise picked up by the probe dipole. Measured data from probe above a microstrip trace shows flat frequency response of wanted field coupling and 30 dB – 40 dB suppression of unwanted field coupling from 10 kHz to 100 MHz.

Fiber Bragg Grating (FBG) sensors applied to bio-medical procedures such as surgery and rehabilitation are a valid alternative to traditional sensing techniques due to their unique characteristics. Herein we propose the use of FBG sensor arrays for accurate real-time temperature measurements during multi-step RadioFrequency Ablation (RFA) based thermal tumor treatment. Real-time temperature monitoring in the RF-applied region represents a valid feedback for the success of the thermo-ablation procedure. In order to create a thermal multi-point map around the tumor area to be treated, a proper sensing configuration was developed. In particular, the RF probe of a commercial medical instrumentation, has been equipped with properly packaged FBGs sensors. Moreover, in order to discriminate the treatment areas to be ablated as precisely as possible, a second array 3.5 cm long, made by several FBGs was used. The results of the temperature measurements during the RFA experiments conducted on ex-vivo animal liver and kidney tissues are presented herein. The proposed FBGs based solution has proven to be capable of distinguish different and consecutive discharges and for each of them, to measure the temperature profile with a resolution of 0.1 °C and a minimum spatial resolution of 5mm. Based upon our experiments, it is possible to confirm that the temperature decreases with distance from a RF peak ablation, in accordance with RF theory. The proposed solution promises to be very useful for the surgeon because a real-time temperature feedback allows for the adaptation of RFA parameters during surgery and better delineates the area under treatment.

Accurate measurement of intracranial hypertension is crucial for the management of elevated intracranial pressure (ICP). Catheter-based intraventricular ICP measurement is regarded as the gold standard for accurate ICP monitoring. However, this method is invasive, time-limited, and associated with complications. In this paper, we propose an implantable passive sensor that could be used for continuous intraparenchymal and intraventricular ICP monitoring. Moreover, the sensor can be placed simultaneously along with a cerebrospinal fluid shunt system in order to monitor its function. The sensor consists of a flexible coil which is connected to a miniature pressure sensor via an 8-cm long, ultra-thin coaxial cable. An external orthogonal-coil RF probe communicates with the sensor to detect pressure variation. The performance of the sensor was evaluated in an in vitro model for intraparenchymal and intraventricular ICP monitoring. The findings from this study demonstrate proof-of-concept of intraparenchymal and intraventricular ICP measurement using inductive passive pressure sensors.

It is not so easy to correlate DC Kelvin measurement data of an RF transistor and its non-Kelvin RF measurement data, because the actual bias voltages in the latter are not known precisely. Knowing the bias voltages requires accurate characterization of its embedding structure. This paper reports on an attempt at correlating DC and RF measurements of parasitic resistances associated with a MOSFET test structure, including a transmission line, on a CMOS chip.

The performance of radio frequency (RF) exciting He-Ne laser is exposed. This text sets out from power circuit, aiming at providing the pumping of gain medium. In order to study the frequency characteristic of RF excitation in He- Ne laser, the frequency ranging from 300MHz to 700MHz is chose to test the discharge property of active medium. It also obtains the optimal RF frequency (432MHz) through experiment, which is important to the improved design of RF exciting He-Ne laser.

The performance of radio frequency (RF) exciting He-Ne laser is exposed. This text sets out from kinetics property of the electronics inside the high-frequency, aiming at getting the relationship between radio frequency and plasma energy. In order to study the frequency characteristic of RF excitation in He-Ne laser, the frequency ranging from 300MHz to 700MHz is chose to test the discharge property of active medium. It also obtains the optimal RF frequency (432MHz) through experiment, which is important to the improved design of RF exciting He-Ne laser.

In this paper a radio frequency (RF) to direct current (DC) voltage converter with multi-stage rectifiers is reported for micro power conversion in RF power harvesting systems. The purpose of this paper is to select an appropriate structure for the micro power-converters, operating in high frequencies. The main idea is to convert RF range sinusoidal signals to a DC voltage to produce power for the rest of the electrical circuit or a system. The reported rectifier demonstrated an efficiency of 10% at large span of frequency for input signal of 350 mV. In the presented work, an analytical and numerical study of the micro power-converters is reported for various applications. Different design parameters have been investigated for an efficient structure design including, number of MOSs, DC current of a known load, size of MOSFETs capacitors, and frequency of the operation. Consequently, optimized parameters have been reported in order to improve the RF to DC conversion efficiency. Reported circuits were designed and simulated in 180 nm twin-well CMOS process with low threshold metal-oxide semiconductor field-effect transistors (MOSFETS); this multistage rectifier occupied an area of 0.23 mm × 0.146 mm and it produced an output voltage of 2 V at its output. This output voltage can provide the supply voltage required to operate the RFID processing circuitry. Post layout simulations demonstrated that for thirteen stages of the rectifiers, the efficiency of 10% for a capacitive load of 10 pF has been achieved.

Microwave detection techniques requiring high penetration are often reliant on the use of centimeter wavelengths. Systems such as these can also potentially be capable of being highly portable as well as being suitable for use in harsh and demanding environments. Further advantages of these systems are that they can also be cost effective, offer low levels of RF exposure, and are of potential use in short range nondestructive evaluation applications. Lack of resolution is overcome by the use of a phase contrast technique. Using antennas specifically developed for this purpose, the use of polarization adds a further measurement plane. The 5-GHz crossed patch design described here utilizes commercially available RF switches for ease of implementation and exhibits typically 22-dB isolation between each orthogonal-linearly polarized plane. This allows independent E-plane measurements to be conducted from a common point. Phase sensitive information is preserved by a low power optical bidirectional transmission system based around directly modulated vertical cavity surface emitting lasers. The use of these techniques in combination enables a high resolution, dual plane scanning system capable of remote operation in demanding environments.

Multichannel die probing increases test speed and lowers the overall cost of testing. A new high-density wafer probe card based on MEMS technology is presented in this paper. MEMS-based microtest-channels have been designed to establish high-speed low-resistance connectivity between the die-under-test and the tester at the wafer level. The proposed test scheme can be used to probe fine pitch pads and interconnects of a new generation of 3-D integrated circuits. The proposed MEMS probe, which is fabricated with two masks, supports \(10^{6}\) lifetime touchdowns. Measurement results using a prototype indicate that the proposed architecture can be used to conduct manufacturing tests up to 38.6 GHz with less than -1-dB insertion loss while maintaining 11.4-m\(\Omega \) contact resistance. The measured return loss of the probe at 39.6 GHz is -12.05 dB.

In recent years, there has been great interest in the study of nonlinear transmission lines (NLTLs) for high-power radio frequency (RF) generation. The periodicity of the NLTL accounts for dispersion effects, whereas its nonlinear elements (inductors and/or capacitors) are responsible for the nonlinear processes. Both of these mechanisms acting simultaneously on a propagating pulse allow the generation of high-frequency oscillations at the output. The objective of this paper is to study the quantifiable characteristics of these lines for RF generation by means of SPICE circuit simulation and on basis of experiments. The RF generation at 40 MHz is demonstrated through measure- ment of the fast Fourier transform of the RF signal extracted at the load and by comparison with the corresponding simulated spectrum. It is expected that the technique presented here can be useful for the design of NLTLs to drive compact RF antennas for space applications and defense mobile platforms.

RF front-end is an important part of the communication system. It realizes the functions such as low noise amplifier application, filtering and mixing, completes the conversion between the IF signal and the RF signal, and ensures effective communication system flexibility and versatility. In the paper, according to the superheterodyne structure, a receiver RF front-end has been designed. The total gain of the link circuit is more than 100 dB, with 50 dB AGC range, the center frequency is 750 MHz with 100MHz bandwidth, local oscillator (LO) signal with frequency 935MHz is generated by PLL and the stability is-82dBc/Hz@1KHz.

To test the performance of an expandable bipolar probe as a simple technical solution for extending the coagulation volume.On the basis of a commercially available monopolar radiofrequency (RF) probe (LeVeen), an expandable bipolar RF probe was developed by integrating a second electrode into the probe shaft. The influence of length on the second electrode, and the distance between both electrodes and generator output was investigated by performing ten ablations for each condition on a freshly excised bovine liver. Macroscopically quantified coagulation volumes, lesion shape characteristics, and procedure durations were recorded. Results of the prototype featuring the optimal configuration were compared to the original LeVeen probe and commonly used bipolar RF probe (CelonLabPower).Extension of the shaft electrode length, increasing distance between the shaft electrode and the tip electrode, and reduction of generator output resulted in increasing coagulation volumes. The coagulation volumes the prototype generated were significantly smaller and more elliptically shaped than the monopolar probe (9.4 ± 1.5 cm(3) vs. 12.1 ± 1.6 cm(3)), but were larger than the commercially available bipolar RF probe (vs. 7.3 ± 0.5). The procedure duration of the prototype was comparable to the monopolar probe (467 ± 31 s vs. 464 ± 17 s) and shorter than the bipolar probe (vs. 2009 ± 444 s). In comparison to the commercially available bipolar system, the developed prototype exhibited favorable results.The first benchmark testing of the developed bipolar prototype had promising results. However, further optimization of the applicator design and ablation protocol is needed to enlarge the achievable coagulation volume.

Modern integrated circuits (ICs) are becoming an integrated parts of analog, digital, and radio frequency (RF) circuits. Testing these RF circuits on a chip is an important task, not only for fabrication quality control but also for tuning RF circuit elements to fit multi-standard wireless systems. In this paper, RF test circuits suitable for embedded testing are introduced: RF power detectors, power control circuits, directional couplers, and six-port reflectometers. Various types of embedded RF power detectors are reviewed. The conventional approach and our approach for the RF power control circuits are compared. Also, embedded tunable active directional couplers are presented. Then, six-port reflectometers for embedded RF testing are introduced including a 77-GHz six-port reflectometer circuit in a 130 nm process. This circuit demonstrates successful calibrated reflection coefficient simulation results for 37 well distributed samples in a Smith chart. The details including the theory, calibration, circuit design techniques, and simulations of the 77-GHz six-port reflectometer are presented in this paper.

For a PET insert to be placed inside an MR system, shielding for the detector modules is crucial as otherwise there can be mutual interference between the two modalities. In this work, we have assessed various shielding designs for both RF shielding effectiveness and gradient-induced eddy current performances. We designed six shielding configurations with various thicknesses, patterns and materials: 36, 18 and 9 urn thick solid copper; 36 urn thick segmented copper; 36 urn thick phosphor bronze mesh; and 0.8 mm thick carbon fiber composite. To evaluate the shielding performance, we performed transmission measurements (S21) and acquired the induced voltage from a MRI spin echo sequence using an RF probe. The eddy current performance was evaluated by the reflection measurement (S11) and observing the ghosting artifact and temperature rise from a MRI echo planar imaging (EPI) sequence. For the shielding effectiveness in both in/outside the MR system, the S21 magnitude for the solid copper (−43.1±1.7, −42.5±3.4, and −42.3±2.6 dB) and phosphor bronze mesh (−37.6±3.6 dB) configurations performed significantly better compared to other configurations (carbon fiber −29.2±1.5 dB and segmented copper −11.0±0.7 dB). For the eddy current performance, the phase delay acquired from the S11 measurement was less than 45° for segmented copper, phosphor bronze mesh and carbon fiber composites and significantly higher at ∼120° for the solid copper configurations. The EPI ghosting artifact and temperature measurements showed similar trends inside the MR system as seen in the outside. In summary, we have evaluated the shielding effectiveness and the eddy current performances of several shielding designs, with the phosphor bronze mesh showing the best overall outcomes.

This paper presents simulation-based optimization of an orthogonal-coil RF probe for miniature implantable pressure sensors. The geometric parameters of the orthogonal coils were optimized for the most efficient telemetry operation. In addition, impact of the operating frequency on sensitivity of the pressure measurement was investigated. The simulation results demonstrate that optimized orthogonal coils considerably improve the telemetry operation. Also, sensors with higher operation frequency could provide more sensitive pressure measurement.

Test submicron application specific Integrated Circuit (IC) for wideband RF short-distance locator is described. IC has been developed and manufactured using 130 nm silicon CMOS technology. Results of test IC elements measurements are presented, including RF oscillator 10 GHz, frequency divider by 32 (10 GHz to 312.5 MHz), noise generator and custom RF pads.

This paper presents the description and theory of the novel amplitude-locked loop (ALL) circuit to support RF energy solutions as well as RF plasma and microwave heating applications. This analog control circuit includes scalar hot S-parameter measurements to lock to the best S11-value in the 2.45 GHz ISM band. The necessary architecture including a new amplitude discriminator circuit is presented in detail. The second part of the paper describes hardware solutions, one with discrete integrated circuits and the current solution, which is fully integrated in a patented C11N CMOS-IC. These ALL solutions were tested in low speed applications (e.g. lamps) and high speed systems (e.g. spark plugs). The measurement results of the ALL hardware solutions wind up this paper. These measurement results exemplify the very good quality of this novel amplitude-locked loop circuit for different dynamic loads.

Two straightforward methods for recovering the current-voltage characteristic of an electrical probe are proposed. Basically, they consist of replacing the usual power supply from the probe circuit with a capacitor which can be charged or discharged by the probe current drained from the plasma. The experiment requires the registration of only one time-dependent electrical parameter, either the probe current or the probe voltage. The corresponding time-dependence of the second parameter, the probe voltage, or the probe current, respectively, can be calculated using an integral or a differential relation and the current-voltage characteristic of the probe can be obtained.

In this work, a passive rectifier circuit is presented, which is operating at 868 MHz. It allows energy harvesting from low power RF waves with a high efficiency. It consists of a novel multiplier circuit design and high quality components to reduce parasitic effects, losses and reaches a low startup voltage. Using lower capacitor rises up the switching speed of the whole circuit. An inductor L serves to store energy in a magnetic field during the negative cycle wave and returns it during the positive one. A low pass filter is arranged in cascade with the rectifier circuit to reduce ripple at high frequencies and to get a stable DC signal. A 50 kΩ load is added at the output to measure the output power and to visualize the behavior of the whole circuit. Simulation results show an outstanding potential of this RF-DC converter witch has a relative high sensitivity beginning with −40 dBm.

This paper presents a design of a high efficiency RFDC converter which can operate at an RF input power of -20 dBm (10 mu W) at 2.4 GHz. The design is done in UMC 130nm MM/RF CMOS technology. RF to DC Power Conversion Efficiency (PCE) is considered as the performance metric. Fully Gate Cross-Coupled Rectifier (FGCCR) is used for RF-DC conversion, impedance matched to 50 Omega and the circuit parameters are optimized. Simulation results show that the circuit gives a DC output of 5.5 mu W (55% PCE) at 0.267 V for a load of 13 k Omega. A protection circuit to limit internal voltages at high input power is designed.

The RF energy Harvester with frequency reconfigurable microstrip patch antenna is presented in this paper. The antenna is design for ambient RF energy harvester system for two different frequency bands. The proposed antenna has two different frequency bands, to be reconfigurable at 1.6GHz and 2.4GHz using RF PIN diodes. The energy harvester is a simple rectifier circuit that converts RF energy to usable DC power for wireless charging device. The sufficient transmitted RF power is achieved from proposed antenna. The rectifier circuit with six stage gives DC voltage of 21V at 1.6GHz and 22V at 2.45GHz which is suitable for wireless charging Application.

This work reports an induced strain in a piezoelectric cantilever due to radio frequency signal propagation. The piezoelectric actuator is coupled to radio frequency (RF) line through a gap of 0.25 mm. When a voltage signal of 10 Vpp propagates in the line it sets an alternating current in the actuator electrodes. This flowing current drives the piezoelectric cantilever to mechanical movement, especially when the frequency of the RF signal matches the mechanical resonant frequency of the cantilever. Output voltage signals versus frequency for both mechanical vibrational and RF signal excitations have been measured using different loads.

Purpose: The aim of this paper was to establish non-invasive CT-based temperature monitoring during hepatic radiofrequency (RF) ablation in an ex vivo porcine model followed by transfer of the technique into a feasibility in vivo experiment.Materials and methods: Bipolar RF ablations were performed in 10 specimens of porcine liver. Parallel to the needle-shaped RF applicator three optical temperature probes were inserted into the liver specimens at fixed distances of 5, 10 and 15mm from the RF probe. During energy application (20W) unenhanced sequential MSCT scans were acquired using the following scan protocol: 140 kV tube voltage, 300 mAs/rotation tube current time product, collimation 24 x 1.2 mm, rotation time 0.5 s. Axial image data was reconstructed using a soft tissue convolution kernel. Temperature data was recorded during every CT scan. Using a circular 0.5 cm(2) region of interest local CT values were measured at the tips of the temperature probes and matched with the measured temperatures. Regression analysis was performed to analyse the relationship between local temperatures and CT values for each temperature probe position. Furthermore, the same experimental design was used in four anaesthetised female pigs in order to investigate the potential of this technique for an in vivo application.Results: A negative correlation was found for the relationship between temperature and CT value. Regression coefficients were -0.44 (5 mm), -0.35 (10mm) and -0.37 (15mm) for ex vivo data. Analysis of in vivo experiments showed regression coefficients between -0.025 and -0.434.Conclusion: Multislice computed tomography is able to depict temperature changes in liver tissue during RFA.

In this paper, we present MEMS-enhanced integrated package design which provides the capability to self-test and self-calibrate integrated circuit chips. We have developed a novel test technique where the test stimulus is generated by modulating the RF carrier signal with another signal mixed with additive white Gaussian noise. This novel test stimulus is provided as the input to the RF circuit and the peak-to-average ratio (PAR) is measured at the output. Simulations were carried out for fault-free and fault-induced circuit conditions, and their corresponding PARs were stored in the look-up table (LUT). Test simulations were performed and the results were compared with the look-up table to verify whether the device is fault-free. In faulty circuit conditions, calibration was performed using a tuning circuit made of MEMS switches. The entire validation of the design using the test technique and self-calibration of the RF circuit was automated using the calibration algorithm. This testing and self-calibration technique is exhaustive and efficient for present-day communication systems.

This paper presents on-chip Design-for-Testability (DFT) circuit for radio frequency System-on-Chip (SoC) applications. The proposed circuit measures functional specifications of RF integrated circuits such as input impedance, gain, noise figure, input voltage standing wave ratio (VSWRin) and output signal-to-noise ratio (SNRout) without any expensive external equipment. The RF DFT scheme is based on developed theoretical expressions that produce the actual RF device specifications by output DC voltages from the DFT chip. The proposed DFT showed deviation of less than 2% as compared to expensive external equipment measurement. It is expected that this circuit can save marginally failing chips in the production testing as well as in the RF system; hence, saving tremendous amount of revenue for unnecessary device replacements.

A metal—oxide—semiconductor field—effect transistor (MOSFET) radio frequency current-voltage (RF I–V) curve with the drain breakdown effect considered is demonstrated for the first time. The validity of the presented approach is extended to the breakdown region by including the breakdown conductance when realizing the RF I–V curve. The presented RF I–V is verified by implementing this curve into a large signal model, and then the simulated output spectrum can agree well with the measured results. Therefore, this accurate breakdown RF I–V can provide a guideline for output performance analysis and RF circuit design.

In the deep-submicrometer design regime, RF circuits are expected to be increasingly susceptible to process variations, and thereby suffer from significant loss of parametric yield. To address this problem, a postmanufacture self-tuning technique that aims to compensate for multiparameter variations is presented. The proposed method incorporates a ?response feature? detector and ?hardware tuning knobs,? designed into the RF circuit. The RF device test response to a specially crafted diagnostic test stimulus is logged via the built-in detector and embedded analog-to-digital converter. Analysis and prediction of the optimal tuning knob control values for performance compensation is performed using software running on the baseband DSP processor. As a result, the RF circuit performance can be diagnosed and tuned with minimal assistance from external test equipment. Multiple RF performance parameters can be adjusted simultaneously under tuning knob control. The proposed concepts are illustrated for an RF low-noise amplifier (LNA) design and can be applied to other RF circuits as well. A simulation case study and hardware measurements on a fabricated 1.9-GHz LNAs show significant parametric yield enhancement (up to 58%) across the critical RF performance specifications of interest.

The purpose of this study was to investigate the optimal setting for radiofrequency (RF) ablation combined with direct electrical current (DC) ablation in ex vivo bovine liver. An electrical circuit combining a commercially available RF ablation system with DC was developed. The negative electrode of a rectifier that provides DC was connected to a 3-cm multitined expandable RF probe. A 100-mH inductor was used to prevent electrical leakage from the RF generator. DC was applied for 15 min and followed by RF ablation in freshly excised bovine livers. Electric current was measured by an ammeter. Coagulation volume, ablation duration, and mean amperage were assessed for various DC voltages (no DC, 2.2, 4.5, and 9.0 V) and different RF ablation protocols (stepwise increase from 40 to 80 W, 40 W fixed, and 80 W fixed). Results were compared using Kruskal-Wallis and Mann-Whitney U test. Applying DC with 4.5 or 9.0 V, in combination with 40 W fixed or a stepwise increase of RF energy, resulted in significantly increased zone of ablation size compared with 2.2 V or no DC (P = 0.009). At 4.5 V DC, the stepwise increase of RF energy resulted in the same necrosis size as a 40 W fixed protocol (26.6 +/- 3.9 vs. 26.5 +/- 4.0 ml), but ablation duration was significantly decreased (296 +/- 85 s vs. 423 +/- 104 s; P = 0.028). Mean amperage was significantly lower at 4.5 V compared with 9.0 V (P = 0.028). Combining a stepwise increase of RF energy with a DC voltage of 4.5 V is most appropriate to increase coagulation volume and to minimize procedure time.

The design, construction, and test of a radio frequency oscillator-amplifier is presented in this paper. The RF circuit is inserted as part of the electrodes of an in-house-built compact CO2 waveguide laser. Our circuit was designed to have a frequency at 81 MHz and its signal output between 90 W and 150 W. Capacitive discharge is evaluated over a period of time and, after a correct positioning of several inductors parallel-distributed along the laser electrodes, a steady and uniform plasma discharge was created. The overall RF circuit-laser test is done with a typical gas mixture of CO2-N2-He with proportion of 1:1:3, correspondingly, and at a final pressure of 40 Torr. Under these conditions, a maximum optical output power greater than 10.7 W was obtained for an input feed RF power of 147 W.

This letter presents the results of the research conducted on the design, construction and test of a two stage ra- dio frequency power generator-amplifier directed adapted to an in-house-built compact CO2 waveguide laser. The main characteristic of this power supply lies in the fact its design is based on MOSFET technology for both the oscillator and the amplifier stages. RF output power is centered at 81MHz frequency signal between 100W to 150W. The two-stage sys- tem device has a minimum electric conversion efficiency of 64%. Consequently, the laser head and RF excitation design must have an electrical termination of 50� impedance and the whole system may include a proper matching circuit. The overall test, for the entire system: RF excitation along with our CO2 laser head, is made with a typical gas mixture of CO2- N2-He with proportion of 1:1:3 correspondingly and at a final pressure of 40Torr. Under these specific conditions, a maximum optical output power of 10.7W was obtained for an input feed RF power of 147W. Regarding the optical qual- ity we measured the transverse mode of propagation TEM00 which indicate the entire system work very near the diffrac- tion limit specifications for similar laser systems.