Lumped-element Circuit Research Articles

The relationship between local field potentials (LFPs) and the electromagnetic fields that give rise to them.

The relationship between local field potentials (LFPs) and the electromagnetic fields that give rise to them.

Blackbox quantization of superconducting circuits using exact impedance synthesis

We propose a new quantization method for superconducting electronic circuits involving a Josephson-junction device coupled to a linear microwave environment. The method is based on an exact impedance synthesis of the microwave environment considered as a blackbox with impedance function $Z(s)$. The synthesized circuit captures dissipative dynamics of the system with resistors coupled to the reactive part of the circuit in a nontrivial way. We quantize the circuit and compute relaxation rates following previous formalisms for lumped element circuit quantization. Up to the errors in the fit our method gives an exact description of the system and its losses.

LTCC Bandpass Filter With Wide Stopband Based on Electric and Magnetic Coupling Cancellation

This paper presents a new method of using electric and magnetic coupling cancellation to extend the stopband of bandpass filters (BPFs). The mechanism is theoretically analyzed based on the lumped-element equivalent circuit. Due to the cancellation of electric and magnetic coupling between two resonators, three transmission zeros (TZs) can be generated and controlled by manipulating the coupling strength. Using the proposed method together with source-load coupling, a low temperature cofire ceramic (LTCC) BPF is designed with four TZs at the passband edges and within the stopband, resulting in high skirt selectivity and harmonic suppression. Due to the LTCC multilayer structure, the filter size is 0.054 λ g *0.045λ g *0.013λ g , or 2.48 mm ×2.02 mm ×0.6 mm. The theoretical, simulated and measured results of the LTCC BPF are presented to validate the proposed design.

Compact metamaterial‐inspired band‐pass filter

ABSTARCTIn this article, a compact, metamaterial‐inspired band‐pass filter is introduced for the passband frequencies between 3.9 and 4.54 GHz with the physical size of main filtering section as compact as λo/11 ×λo/14. The design and operation principles are verified with numerical and experimental results. The measured and simulated results show good agreement. The proposed filter is additionally modeled with lumped circuit elements as equivalent circuit model to confirm the operation and design principle. This compact filter in comparison to the conventional stepped impedance or coupled line filter designs does not require an external matching network, which reduces the filter physical size significantly. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2903–2907, 2014

Quantum-limited amplification and entanglement in coupled nonlinear resonators.

We demonstrate a coupled cavity realization of a Bose-Hubbard dimer to achieve quantum-limited amplification and to generate frequency entangled microwave fields with squeezing parameters well below -12 dB. In contrast to previous implementations of parametric amplifiers, our dimer can be operated both as a degenerate and as a nondegenerate amplifier. The large measured gain-bandwidth product of more than 250MHz for the nondegenerate operation and the saturation at input photon numbers as high as 2000 per μs are both expected to be improvable even further, while maintaining wide frequency tunability of about 2GHz. Featuring flexible control over all relevant system parameters, the presented Bose-Hubbard dimer based on lumped element circuits has significant potential as an elementary cell in nonlinear cavity arrays for quantum simulations.

Estimation of the accuracy of the microwave FET equivalent circuit using the quasi-hydrodynamic model of electron transport

Computational methods are considered for the time- and frequency-domain simulations of a microwave power amplifier with a transistor built on a diamond-like semiconductor. The first method is based only on a two-dimensional model of the intrinsic transistor that includes the quasi-hydrodynamic model of electron transport and electric field equations. The second method, which is less accurate but much more computer-time-saving, is based on the intrinsic transistor large-signal lumped-element equivalent circuit model with the parameters and spline characteristics calculated by means of the abovementioned two-dimensional model. Using these two methods, the microwave parameters of the amplifier are calculated for frequencies varying from 15 to 90GHz. When using the equivalent circuit at frequencies of up to 60GHz, the calculation error (equal to the difference between the results of the time- and frequency-domain simulations) does not exceed 5% for the input impedance and 0.6dB for the transducer power gain.

Dielectric characterization of various soil types using modified microstrip ring resonators techniques

ABSTRACTIn this article, four nondestructive sensor tool of microstrip ring resonator (MRR) with mean diameter 84.8 mm were developed to determine different soil types based on the dielectric constant, εr′ of respective soil types using frequency‐variation method. The four MRR were designed with different angles of microstrip bends (conventional sensor = 0.98 rad, Sensor A = 1.34 rad, Sensor B = 1.57 rad, and Sensor C = 1.64 rad) at the sides of each corner and each sensor was modeled in resistor‐inductor‐capacitor (RLC)‐lumped element circuit with proper adjustment of capacitances. Seven types of soil samples were placed, respectively, on the MRR holder up to 25 mm. The S‐parameters measurement was made with E5071C vector network analyzer. In this article, the measured dielectric constant using proposed Sensor B has better accuracy with smallest overall uncertainties of 2.14% against commercial dielectric probe HP85070D and 2.43% against coaxial cavity technique while its sensitivity was determined at 0.125 toward the seven soil samples and measurement resolution of 0.849. Both mentioned parameters were the highest as compared to the other three proposed sensors. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2498–2502, 2014

Design of Low Pass Microwave Filter using Impulse Invariant Transform

paper introduces a new approach to design low pass microwave filter using impulse invariant transform. In this approach, the analog specifications of desired low pass filter is transformed into the digital specification and then apply an optimization technique (DSP based) to get an approximate transfer function in digital domain. Further, the transfer function in continuous time domain is obtained by applying inverse impulse invariant technique. Now the lumped element circuit is obtained by using a classical network synthesis technique on the transfer function in analog domain. The theoretical result of low pass microwave filter is also verified on ADS Simulation tool. Keywordsinvariant transform, Low-pass filter, Microwave Filter, Quasi-Newton algorithm.

On the Current Shunts Modeling

This paper describes mathematical modeling of cage-type ac current shunts. A calculable model was developed using lumped circuit elements. The transimpedance, ac–dc difference, and the phase angle error of a shunt can be derived from the model. An uncertainty analysis of the model was done by means of Monte Carlo methods. Comparison of the calculated and measured values shows an agreement better than 6 $\mu\Omega/\Omega$ in the ac–dc difference and 110 $\mu{\rm rad}$ in the phase angle error at frequencies up to 100 kHz.

Finite Element Model of a Superconducting Fault Current Limiter Calibrated by Hardware-in-the-Loop Measurements

A bench top model of an inductive superconducting fault current limiter (iSFCL) has been designed based on wide tape of second generation high temperature superconducting (2GHTS) coated conductor. The tape forms a ring shielding a reduced size ferromagnetic core. The design was optimized using a finite element model, which was calibrated and refined by impedance measurements and power hardware-in-the-loop testing of the bench top iSFCL. The finite-element model was coupled with a lumped element circuit model that simulates the electric power grid. Usefulness of such coupled models for design optimization studies and for reduction of uncertainty in transient simulation models is demonstrated.

A Lumped-Element Directional Coupler With High Isolation for Mobile RFID Reader

A lumped-element directional coupler with a high isolation characteristic for mobile RFID reader systems is proposed and experimentally demonstrated. Compared with the conventional lumped-element circuit, the proposed structure utilizes compensation capacitors and achieves a very high isolation despite low quality factor on-chip inductors. It was fabricated on a high-resistivity silicon substrate and showed an isolation of 79 dB, a coupling level of 14.8 dB, and an insertion loss of 1.74 dB at 910 MHz.

Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA

The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100 ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6–1.0 Ω in about 10–20 ns.

Electrical Modeling of Three-Dimensional Carbon-Based Heterogeneous Interconnects

One three-dimensional (3-D) carbon-based heterogeneous interconnect scheme, consisting of a couple of horizontal multilayer graphene transmission lines (MLG-TL) and vertical through silicon carbon nanotube bundle vias (TS-CNTBV), is proposed and investigated theoretically. For its realization, some metallic bumps are used to integrate MLG-TLs with TS-CNTBVs, and contact resistance among them are characterized and compared. The lumped-element circuit model of a couple of MLG-TLs is also combined with that of TS-CNTBVs, with anomalous skin effect treated in an appropriate way. Numerical studies are performed for capturing distributed parameters as well as transmission characteristics of MLG-TLs, TS-CNTBVs, and whole 3-D interconnects at different operating frequencies. It is believed that this study can provide some useful information about carbon-based heterogeneous interconnects, where both graphene and carbon nanotube advantages can be exploited for the future 3-D ICs.

Quantitative Extraction of Equivalent Lumped Circuit Elements for Complex Plasmonic Nanostructures

We establish a general method to bridge the gap between full-field electromagnetic calculations and equivalent lumped circuit elements to describe the optical response of plasmonic nanostructures. The exact value of each lumped element is extracted from one single full-field calculation using the Poynting vector and considerations on the energy flow in the system. The equivalent circuit obtained this way describes the complete response of the system at any frequency and can be used to optimize it for specific applications or perform parametric studies. This powerful approach can accurately reproduce the behavior of complex plasmonic nanostructures, such as Fano resonances, retardation effects, and polarization coupling. Furthermore, the influence of coupling parameters within the different modes supported by a given plasmonic structure can be investigated, thus providing new physical insights into its functioning mechanisms.

High-Q series coupled microstrip split-ring resonator device

A quarter wavelength high-Q resonator based on the well-known split-ring resonator (SRR) element in series configuration on a microstrip line is proposed in this letter. The small size is achieved by working at the quasi-static resonant frequency of the SRR. A relatively high value of unloaded-Q of 137 is achieved, which is considerably higher than other microstrip resonators like closed-loop resonators. An equivalent lumped-element circuit model for this new resonator and the ground plane influence in the unloaded-Q particle are studied. A good agreement between simulation, equivalent circuit, and experimental results is shown and discussed, leading to a simple and effective design.

Analysis of slow‐wave propagation in coplanar transmission lines with inkjet printed multiwalled carbon nanotubes network

AbstractThis article investigates the propagation along coplanar waveguide (CPW) structures, where multiwalled carbon nanotubes (MWCNTs) network layers are deposited using inkjet printing. Electrical parameters are extracted from measured S‐parameters data over the frequency range from 10 MHz to 26.5 GHz. The results clearly demonstrate two distinct propagation modes. At low‐frequencies, a slow‐wave factor up to 7 is achieved. With increasing frequency, attenuation becomes significant, while the propagation constant tends to a linear TEM regime. An equivalent lumped element circuit for CPW structure with MWCNTs network is developed and describes well the measured behavior up to 26.5 GHz. Thanks to the extracted equivalent circuit, the origin of the observed slow‐wave phenomenon is confirmed: it is ascribed to a larger capacitance per unit length of the CPW line induced by the presence of the CNTs network that prevents/limits the expansion of fields into air. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1118–1124, 2014

Compact Dual-Mode Wideband Filter Based on Complementary Split-Ring Resonator

This letter proposes a microstrip filter based on a dual-mode complementary split-ring resonator (DMCSRR). For the input/output coupling, a dual C-shaped feed structure is implemented together with the DMCSRR to acheive a wideband response. The resonator offers a wide fractional bandwidth of 62% at the central frequency of 2.23 GHz and a very compact structure with a footprint of 0.0625λg×0.18λg, where λg is the guided wavelength at the midband frequency. A comprehensive lumped element circuit analysis accompanies the simulation and measurement results.

An Integral Formulation for the Computation of 3-D Eddy Current Using Facet Elements

A volume integral formulation to compute eddy currents in nonmagnetic conductive media is presented. The current distribution is approximated with facet finite elements. The formulation is general and leads to an equivalent lumped elements circuit. To ensure the solenoidality of the current distribution, an algorithm detecting the independent loops is then used for the resolution. The formulation is tested on TEAM workshop Problem 7. Even with coarse meshes, its accuracy is demonstrated.

Modeling of Stepped-Impedance Slot Antenna

In this study, the resonant analysis and modeling of the microstrip-fed stepped-impedance (SI) slot antenna are presented by utilizing the transmission-line and lumped-element circuit topologies. This study analyzes the SI-slot antenna and systematically summarizes its frequency response characteristics, such as the resonance condition, spurious response, and equivalent circuit. Design formulas with respect to the impedance ratio of the SI slot antenna were analytically derived. The antenna designers can predict the resonant modes of the SI slot antenna without utilizing expensive EM-simulation software.

Analytical Circuit Model for 1-D Periodic T-Shaped Corrugated Surfaces

An analytical circuit model is obtained to study the reflection of TM polarized electromagnetic waves that impinge obliquely on a 1-D periodic corrugated surface consisting of dielectric-loaded T-shaped planar corrugations backed by an infinite ground plane. The model is based on transmission line theory and equivalent lumped-element circuits. For the case of perfect conductors, the topology of the circuit is directly inferred from a rigorous full-wave formulation of the periodic problem without using any heuristic argument. This procedure leads to fully analytical expressions for all the circuit parameters. Ohmic losses are further incorporated in the model under the assumption of strong skin effect. The results thus obtained are compared with those given by an accurate Method of Moments numerical code and HFSS software showing a very good agreement. The strong numerical efficiency as well as the good physical insight provided by the present equivalent circuit model can be advantageously employed for the analysis and/or design of a variety of devices. As examples of the latter, the circuit model is used for the first-stage design of an electrically thin hard impedance surface, a corrugated surface that prevents specular reflection, and an absorber.