Tank Circuit Research Articles

Magnetic Sensor for Building Structural Vibrations

This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building.

Average Current Mode Control for LLC Series Resonant DC-to-DC Converters

An average current mode control scheme that consistently offers good dynamic performance for LLC series resonant DC-to-DC converters irrespective of the changes in the operational conditions is presented in this paper. The proposed control scheme employs current feedback from the resonant tank circuit through an integrator-type compensation amplifier to improve the dynamic performance and enhance the noise immunity and reliability of the feedback controller. Design guidelines are provided for both current feedback and voltage feedback compensation. The performance of the new control scheme is demonstrated through an experimental 150 W converter operating with 340 V to 390 V input voltage to provide a 24 V output voltage.

CdS based novel photo-impedance light sensor

A novel photo-impedance (hybrid photocapacitive-photoresistive) sensor for visible light employs gated cadmium sulfide photoresistance connecting two fixed capacitances. The changes of the photoresistance and of the metal–insulator (dielectric)-semiconductor (MIS) under illumination affect the overall device capacitance. The MIS and photoresistor frequency dispersion allows for increasing the dynamic range by measuring the capacitance response at lower frequencies. By making this device a part of the tank circuit of a radio frequency oscillator, the information on illumination intensity can be relayed as the signal frequency and detected remotely.

Radio-Frequency Tank Circuit for DNA Sequencing

DNA sequencing by now is a ubiquitous technique in biology and medicine. Nanopore sequencers turn out to be a promising approach for high-speed sequencing of long DNA-strands while cutting costs by many orders of magnitude.We present a resonant RLC-circuit operating at radio frequency (Bhat, Soft Nanoscience Letters (2013)). DNA is driven through a nanopore which causes a shift in the resonance of the circuit. The nanopore is embedded within a resonant CPW structure, a so-called tank circuit that enables the measurement of extremely small capacitance changes caused by the transition of the macromolecule through the pore. In contrast to existing nanopore-sequencing technologies, such a design does not rely on a molecular motor to slow down the translocating DNA. Furthermore, the presented method is not limited by the length or a specific design of the pore, allowing a plethora of pore modifications and designs to be used.Finite element simulation techniques provide an insight into the behavior of different tank-circuit geometries. We present several studies on how the circuit geometry can be modified to increase the sensitivity. Additionally, different concepts for amplification of the atto-Farad signal levels are discussed (Ramachandran et al., Applied Physics Letter 99 (2011)), a degree of sensitivity sufficient for resolving the different DNA bases and paving the way for DNA sequencing in the MHz regime.

Thermal-hydraulic Modeling and Simulation of the Hydraulic System based on the Electro-hydrostatic Actuator

Electro-hydrostatic actuator (EHA) was a typical power-by-wire (PBW) actuator, which was widely-used in large commercial aircrafts, such as Airbus A380. The electro-hydrostatic actuator(EHA) had the advantages of small sizes, light weight, high power density, high reliability and maintainability. With the application of EHA in large commercial airplanes, the airworthiness certification of EHA became an new problem. The precondition of the airworthiness certification of EHA was to understand its operating principle and characteristic. Because of no centralized hydraulic oil tank and short cycle oil circuit, the temperature-rise of the hydraulic system in EHA always kept high during operation. Therefore, it was important to build the thermal-hydraulic models of the hydraulic system in EHA, and to do the thermal analysis of the EHA by this model. In this paper, a lumped-parameter thermal-hydraulic model of the hydraulic part in EHA was proposed. The model was built based on the detailed analysis of the heat transfer of the hydraulic part in EHA. By the simulation of a practical system and the comparison with the traditional hydraulic system, the accuracy and practicality of this model was verified.

Study of the effect of distance and misalignment between magnetically coupled coils for wireless power transfer in intraocular pressure measurement.

An analysis of the effect of distance and alignment between two magnetically coupled coils for wireless power transfer in intraocular pressure measurement is presented. For measurement purposes, a system was fabricated consisting of an external device, which is a Maxwell-Wien bridge circuit variation, in charge of transferring energy to a biomedical implant and reading data from it. The biomedical implant is an RLC tank circuit, encapsulated by a polyimide coating. Power transfer was done by magnetic induction coupling method, by placing one of the inductors of the Maxwell-Wien bridge circuit and the inductor of the implant in close proximity. The Maxwell-Wien bridge circuit was biased with a 10 MHz sinusoidal signal. The analysis presented in this paper proves that wireless transmission of power for intraocular pressure measurement is feasible with the measurement system proposed. In order to have a proper inductive coupling link, special care must be taken when placing the two coils in proximity to avoid misalignment between them.

Development of a new device control system for β-NMR experiments

We have developed a device-control system of a β-NMR apparatus for the measurement of nuclear electromagnetic nuclear moments of rare isotopes. In this development, we installed fast relay switches into a high-power tank circuit in order to apply a strong oscillating magnetic field and to sweep its frequency as wide as possible. The system enables to conduct NMR frequency scans with wide frequency windows by dynamically changing the tank-circuit resonant frequency. Furthermore, logical electric-circuit modules of the data taking system were replaced by a programmable logic module. The system performance was evaluated in the β-NMR experiments conducted at the RIBF facility using 20F and 33Cl radioactive isotopes.

Design and analysis of a single-stage source coupled complementary metal oxide semiconductor voltage control oscillator using 45 nm technology

This paper deals with the design and performance analysis of a single-stage source coupled complementary metal oxide semiconductor voltage controlled oscillator (VCO). VCO is a crucial component in many wireless communication and signal processing systems. Single-stage VCO provides effective power reduction in comparison to the traditional LC tank (LC circuit known as resonant circuit, or tank circuit, which consists of an inductor [L] and a capacitor [C]) and ring VCO. By reducing the noise source, we have provided the single-stage VCO circuit with a low phase noise performance. The VCO is intended to control as a frequency synthesiser in a phase locked loop (PLL) to generate local oscillation frequency. The proposed single-stage VCO is implemented in 180 nm and 45 nm cadence virtuoso environment. VCO provides high oscillation frequency (THz), less power dissipation (1.708 × 10‒21 W) and lower delay (50.4 fsec) in 45 nm technology with (V dd = 0.7 V). Simulation result shows an effective performance improvement in 45 nm technology in comparison to 180 nm technology.

ANALYSIS OF THE FRACTIONAL-ORDER PARALLEL TANK CIRCUIT

A parallel LβCα tank circuit with an α-order capacitor and a β-order inductor is proposed in this paper, where α and β are positive real numbers. The impedance of the parallel LβCα tank circuit, which could perform as a pure real, pure imaginary or short impedance, is discussed in detail, followed by the phase response analysis in α – β plane. The results show that the parallel LβCα tank circuit could act as a constant phase element. The resonance frequency analysis demonstrates that there exists more than one resonance frequency. And the time domain response expression of the proposed LβCα tank circuit is given by applying the inverse Laplace transform. The dual transformation relationship between the series and parallel LβCα tank circuit is summarized at last.

Broadband Fabry‐Pérot radiation based on non‐Foster cavity boundary

Fabry-Pérot (FP) cavities having at least one partially reflective surface are widely used as compact and efficient high-directivity radiators. However, they inherently suffer from very narrow directivity bandwidths around the FP resonance. Here it is shown that this constraint can be overcome by using an active non-Foster cavity boundary behaving as a series negative LC tank circuit. Analytical and full-wave numerical results reveal the possibility of nearly tenfold improvement of − 1 dB directivity bandwidth while preserving the original overall antenna size and directivity of the antenna.

Radio Frequency Tank Circuit for Probing Planar Lipid Bilayers

We present first results from a hybrid coplanar waveguide microfluidic tank circuit for monitoring lipid bilayer formation and fluctuations of integrated proteins. The coplanar waveguide is a radio frequency resonator operating at ~250 MHz. Changes within the integrated microfluidic chamber, such as vesicle bursting and subsequent nanopore formation alter the reflected signal, and can be detected with nanosecond resolution. We show experimental evidence of such alterations when the microfluidic channel is filled with giant unilamellar vesicles (GUVs). Subsequent settling and bursting of the GUVs form planar lipid bilayers, yielding a detectable change in the resonant frequency of the device. Results from finite element simulations of our device correlate well with our experimental evidence. These simulations also indicate that nanopore formation within the bilayer is easily detectable. The simulated structure allows for incorporation of microfluidics as well as simultaneous RF and DC recordings. The technique holds promise for high throughput drug screening applications and could also be used as an in-plane probe for various other applications. It opens up possibilities of exploring ion channels and other nano scale pores in a whole new frequency band allowing for operating at bandwidths well above the traditional DC methods.

Noncontact technique for measuring the electrical resistivity and magnetic susceptibility of electrostatically levitated materials

We describe the development of a new method for measuring the electrical resistivity and magnetic susceptibility of high temperature liquids and solids. The technique combines a tunnel diode oscillator with an electrostatic levitation furnace to perform noncontact measurements on spherical samples 2-3 mm in diameter. The tank circuit of the oscillator is inductively coupled to the sample, and measurements of the oscillator frequency as a function of sample temperature can be translated into changes in the sample's electrical resistivity and magnetic susceptibility. Particular emphasis is given on the need to improve the positional stability of the levitated samples, as well as the need to stabilize the temperature of the measurement coil. To demonstrate the validity of the technique, measurements have been performed on solid spheres of pure zirconium and low-carbon steel. In the case of zirconium, while absolute values of the resistivity were not determined, the temperature dependence of the resistivity was measured over the range of 640-1770 K and found to be in good agreement with literature data. In the case of low-carbon steel, the ferromagnetic-paramagnetic transition was clearly observable and, when combined with thermal data, appears to occur simultaneously with the solid-solid structural transition.

Note: Radio frequency inductance-capacitance band-stop filter circuit to perform contactless conductivity measurements in pulsed magnetic fields

We present a new technique to perform radio frequency (rf) contactless conductivity measurements in pulsed magnetic fields to probe different ground states in condensed matter physics. The new method utilizes a simple analog band-stop filter circuit implemented in a radio frequency transmission setup to perform contactless conductivity measurements. The new method is more sensitive than the other methods (e.g., the tunnel diode oscillator and the proximity detector oscillator) due to more sensitive dependence of the circuit resonance frequency on the tank circuit inductance (not the transmission line). More important, the new method is more robust than other methods when used to perform measurements in very high magnetic fields, works for a wide range of temperatures (i.e., 300 K-1.4 K) and is less sensitive to noise and mechanical vibrations during pulse magnet operation. The new technique was successfully applied to measure the Shubnikov-de Haas effect in Bi(2)Se(3) in pulsed magnetic fields of up to 60 T.

Overall performance evaluation using an equivalent circuit model for radio-frequency single-electron transistors

Charge sensitivities of a radio-frequency single-electron transistor (RF-SET) by using amplitude (AD) and phase-shift detection (PSD) of the reflected RF signals were experimentally studied. It was found that AD is most sensitive at the resonant frequency while PSD is most sensitive at a frequency slightly off the resonance. The best PSD sensitivity is better than the best AD one when the quality factor of a tank circuit is higher than 10; the higher Q-value is, the superior PSD. The maximal change in reflection amplitude and phase-shift were found proportional to the SET conductance change. The above experimental findings were confirmed by the calculation based on an equivalent circuit model.

Control of ZCS-SR Inverter-Fed Voltage Multiplier-Based High-Voltage DC–DC Converter by Digitally Tuning Tank Capacitance and Slightly Varying Pulse Frequency

Conventional pulse-frequency-modulated (PFM) zero-current switching series resonant (SR) inverter-fed voltage-multiplier-based high-voltage dc power supplies have nearly zero switching loss. However, they have limitations of poor controllability at light load and large output voltage ripple at low switching frequencies. To address these problems, this letter proposes a new control scheme that is based on digitally tuning tank capacitance and slightly varying pulse frequency of SR inverter. For the realization of the proposed control approach, the tank circuit of the resonant inverter is made up of several tank capacitors that are switched into or out of the tank circuit by electromechanical switches. By digitally modulating the tank capacitance, the output voltage changes in steps. The regulation of output voltage between two adjacent steps is achieved by slightly varying the pulse frequency. The proposed control scheme has several features, namely, a wide range of output voltage controllability even at light loads, less output voltage ripple, and less current stress on the inverter's power switches at light loads. Therefore, the proposed control approach alleviates most of the problems associated with conventional PFM. Experimental results obtained from a scaled-down laboratory prototype are presented to verify the effectiveness of the proposed system.

Stability Analysis of Superluminal Metamaterial Transmission Line with Realistic Non-Foster Negative Capacitors

Recently, it has been shown possible to go around basic dispersion energy constraints that limit bandwidth of every passive metamaterial and construct a broadband active Epsilon-Near-Zero superluminal transmission line. A basic building block of this unusual transmission line is an active ‘tank circuit’ that contains both conventional (positive) capacitor and non-Foster negative capacitor. Published theoretical studies revealed that such a ‘tank circuit’ is stable if an overall capacitance is positive. These studies assumed lossless host transmission line periodically loaded with ideal dispersionless negative capacitors. However, a possible influence of the imperfections of a realistic negative capacitor (its dispersion and loss/gain) on the stability has not been investigated so far. Here, stability analysis of realistic superluminal transmission line is performed in Laplace domain. The obtained results are in a good agreement with those obtained in recent experiments on active transmission line developed at University of Zagreb.

High Bandwidth Resonant Radio Frequency Circuit for Lipid Bilayer Detection

Research on ion channels are traditionally performed in the DC regime. Only a few attempts having been made to conduct RF measurements for probing ion channel properties. We present here simulations and subsequent measurements of an integrated coplanar waveguide and microfluidic tank circuit detecting bilayer formation. We observe a 5 MHz shift in resonant frequency and a 1.4 dB shift in amplitude when a lipid bilayer is formed. These measurements allow for in-vitro radio frequency recordings with nanosecond readout times. The designed structure also enables the incorporation of simultaneous RF and DC recordings from lipid bilayer embedded proteins such as ion channels.

Optical-Pumping Double-Nuclear-Magnetic-Resonance System with a Gifford–McMahon Cryocooler

We have developed a system for performing optical-pumping and double-resonance NMR of semiconductors simultaneously or sequentially. The components include a cryosystem equipped with a Gifford–McMahon (GM) cryocooler, which cools the samples via thermal contact. The following benefits are derived from this feature. (1) A pickup coil and tank circuits for NMR can be built in a vacuum, which excludes rf discharges and/or arcing (breakdown) occurring in conventional systems employing a helium-gas atmosphere, allowing application of the stronger and more stable rf-pulses required for broad-line double-resonance NMR. (2) Heat around a sample generated by light irradiation can be drained through the thermal connection to a heat anchor, permitting the use of a light-power high enough to achieve large nuclear polarization by optical pumping. (3) A bottom-loading style can be adopted for the installation of a cryostat and a probe to an NMR magnet, allowing a more compact system.

Higher order parametric excitation modes for spaceborne quadrupole mass spectrometers

This paper describes a technique to significantly improve upon the mass peak shape and mass resolution of spaceborne quadrupole mass spectrometers (QMSs) through higher order auxiliary excitation of the quadrupole field. Using a novel multiresonant tank circuit, additional frequency components can be used to drive modulating voltages on the quadrupole rods in a practical manner, suitable for both improved commercial applications and spaceflight instruments. Auxiliary excitation at frequencies near twice that of the fundamental quadrupole RF frequency provides the advantages of previously studied parametric excitation techniques, but with the added benefit of increased sensed excitation amplitude dynamic range and the ability to operate voltage scan lines through the center of upper stability islands. Using a field programmable gate array, the amplitudes and frequencies of all QMS signals are digitally generated and managed, providing a robust and stable voltage control system. These techniques are experimentally verified through an interface with a commercial Pfeiffer QMG422 quadrupole rod system. When operating through the center of a stability island formed from higher order auxiliary excitation, approximately 50% and 400% improvements in 1% mass resolution and peak stability were measured, respectively, when compared with traditional QMS operation. Although tested with a circular rod system, the presented techniques have the potential to improve the performance of both circular and hyperbolic rod geometry QMS sensors.

Performance evaluation of solar-assisted air-conditioning system with chilled water storage (CIESOL building)

This study presents the performance of solar-assisted air-conditioning system with two chilled water storage tanks installed in the Solar Energy Research Center building. The system consists mainly of solar collectors’ array, a hot-water driven absorption chiller, a cooling tower, two hot storage tanks, an auxiliary heater as well as two chilled storage tanks. The chilled water storage tank circuit was further investigated in order to find the optimum solar system’s operation sequence while providing the best energy performance. Firstly, we carried out a study about the dynamics of building’s cooling load and the necessity of the integration of chilled water storage tanks to solar system. Subsequently, the new system’s operation mode was proposed to reduce the energy consumption. The results demonstrate that we can save about 20% of the total energy consumption and about 30% of water consumption applying the new operation sequence, which takes into account the chilled water tanks action. Moreover, it was demonstrated that the integration of chilled water storage tanks allows to reduce the sudden absorption chiller on/off cycles, thereby improving the efficiency of the solar-assisted system.